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148-595: The BSA Bantam is a two-stroke unit construction motorcycle that was produced by the Birmingham Small Arms Company (BSA) from 1948 (as a 123 cc) until 1971 (as a 173 cc). Exact production figures are unknown, but it was between 350,000 and 500,000. The Bantam was based on a German design, the DKW RT 125 , which the Allies of World War II received as war reparations. BSA launched

296-444: A blunderbuss , each guard carried a secure timepiece by which departure times at each stage of the journey were strictly regulated. In 1830 mail was carried by train for the first time, on the newly-opened Liverpool and Manchester Railway ; over the next decade the railways replaced mail coaches as the principal means of conveyance (the last mail coach departed from London on 6 January 1846). The first Travelling Post Office (TPO)

444-571: A lottery bond called the Premium Bond was introduced. In the mid-1960s the GPO was asked by the government to expand into banking services which resulted in the creation of the National Giro in 1968. When new forms of communication came into existence in the 19th and early 20th centuries the GPO claimed monopoly rights on the basis that like the postal service they involved delivery from

592-415: A power-valve system . The valves are normally in or around the exhaust ports. They work in one of two ways; either they alter the exhaust port by closing off the top part of the port, which alters port timing, such as Rotax R.A.V.E, Yamaha YPVS, Honda RC-Valve, Kawasaki K.I.P.S., Cagiva C.T.S., or Suzuki AETC systems, or by altering the volume of the exhaust, which changes the resonant frequency of

740-557: A proclamation 'for the settling of the Letter-office of England and Scotland', an event which 'may properly be regarded as the origin of the British post-office'. By this decree, Thomas Witherings (who had been appointed 'Postmaster of England for foreign parts' three years earlier) was empowered to provide for the carriage of private letters at fixed rates 'betwixt London and all parts of His Majesty's dominions'. To this end,

888-421: A rotary valve is that it enables the two-stroke engine's intake timing to be asymmetrical, which is not possible with piston-port type engines. The piston-port type engine's intake timing opens and closes before and after top dead center at the same crank angle, making it symmetrical, whereas the rotary valve allows the opening to begin and close earlier. Rotary valve engines can be tailored to deliver power over

1036-494: A sender and to a receiver . The theory was used to expand state control of the mail service into every form of electronic communication possible on the basis that every sender used some form of distribution service. These distribution services were considered in law as forms of electronic post offices. This applied to telegraph and telephone switching stations. In 1846, the Electric Telegraph Company ,

1184-421: A DKW design that proved reasonably successful employing loop charging. The original SAAB 92 had a two-cylinder engine of comparatively low efficiency. At cruising speed, reflected-wave, exhaust-port blocking occurred at too low a frequency. Using the asymmetrical three-port exhaust manifold employed in the identical DKW engine improved fuel economy. The 750-cc standard engine produced 36 to 42 hp, depending on

1332-675: A bell to attract custom was adopted by the Post Office and went on to be employed in major cities until the mid-19th century. In 1761 permission was given for the establishment of penny-post arrangements elsewhere in the realm, to function along the same lines as the London office, if they could be made financially viable; by the end of the century there were penny-post systems operating in Birmingham, Bristol, Dublin, Edinburgh and Manchester (to be joined by Glasgow and Newcastle-upon-Tyne in

1480-642: A court ruling obliged the London Penny Post to come under the authority of the Postmaster General. Although now part of the GPO, the London Penny Post continued to operate entirely independently of the General (or 'Inland') Post until 1854 (when the two systems were combined). An attempt by Charles Povey to set up a rival halfpenny post in 1709 was halted after several months' operation; however Povey's practice of having letter-carriers ring

1628-448: A crossflow engine) is always best and support is good. In some engines, the small end is offset to reduce thrust in the intended rotational direction and the forward face of the piston has been made thinner and lighter to compensate, but when running backward, this weaker forward face suffers increased mechanical stress it was not designed to resist. This can be avoided by the use of crossheads and also using thrust bearings to isolate

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1776-545: A fee. The trade in these 'ship letters' was acknowledged (and legitimised) in the Post Office Acts of 1657 and 1660. Attempts were made to levy Post Office fees on these letters and 'ship letter money' was offered to captains for each letter given to a postmaster on arrival in England in order for these charges to be applied; however they were under no legal obligation to comply and the majority of ship letters evaded

1924-430: A hand bell. While postmasters were not obliged to deliver items to places outside the boundary, they could agree to do so on payment of an extra fee. In the 1780s, Britain's General Post network was revolutionised by theatrical impresario John Palmer 's idea of using mail coaches in place of the longstanding use of post horses. After initial resistance from the postal authorities, a trial took place in 1784, by which it

2072-630: A higher power-to-weight ratio than a four-stroke engine, since their power stroke occurs twice as often. Two-stroke engines can also have fewer moving parts , and thus be cheaper to manufacture and weigh less. In countries and regions with stringent emissions regulation, two-stroke engines have been phased out in automotive and motorcycle uses. In regions where regulations are less stringent, small displacement two-stroke engines remain popular in mopeds and motorcycles. They are also used in power tools such as chainsaws and leaf blowers . The first commercial two-stroke engine involving cylinder compression

2220-409: A horse and cart or waggon, while the universities, along with certain municipal and other corporations, maintained their own correspondence networks. Many letters went by foot-post rather than on horseback. Footposts or runners were employed by many towns, cities and other communities, and had been for many years. A 16th-century footpost would cover around 30 miles per day, on average. At the time of

2368-887: A lettering system for their range of motorcycles and started the "D" series for their first two-stroke. The D175 was marketed as the B175 as BSA struggled against imports in the late 60s to its closure in 1972 (the larger capacity "B" series having helped make them the largest motorcycle manufacturer in the world). The engine size shown is nominal, British motorcycles were made 1 or 3 cc smaller than their tax bracket maximum to allow for re-bores and wear. D14/4 Sports & Bushman Sports: Flamboyant Red & Chrome, Bushman orange and white Bushman: orange and white Pre-1958 (D1 to D3) had 19 inch wheels and 4.5 inch brakes. The 1958 D5 had 18 inch wheels and 4.5 inch brakes. 1959 D7 and later models had 18 inch wheels and 5 inch brakes front and rear. The D1 (the original model) 123cc

2516-546: A number of post houses were established at twenty-mile intervals along the Great North Road , between London and Berwick , to provide the king's messengers with fresh horses for each stage of the journey; in this way they were able to travel up to a hundred miles a day. Under King Henry VIII a concerted effort was made to maintain a regular postal system for the conveyance of royal and government despatches (in times of peace as well as in time of war). To oversee

2664-470: A patent in 1880 in Germany. The first truly practical two-stroke engine is attributed to Yorkshireman Alfred Angas Scott , who started producing twin-cylinder water-cooled motorcycles in 1908. Two-stroke gasoline engines with electrical spark ignition are particularly useful in lightweight or portable applications such as chainsaws and motorcycles. However, when weight and size are not an issue,

2812-549: A regular mail-carrying service in exchange for a fee or subsidy. In the following century, packet services out of Falmouth began to sail to the West Indies, North America and other transatlantic destinations. Packet boats, however, were not the only means of conveying letters overseas: there had always been the option of sending them by merchant ship, and coffee houses had long been accustomed to receiving letters and packages on behalf of ships' captains, who would carry them for

2960-511: A regular public postal service came the need for waterborne mail services (carrying letters to and from Ireland, continental Europe and other destinations) to be placed on a more regular footing. ' Packet boats ', offering a regular scheduled mail service, were already in use for the passage between Holyhead and Dublin; but for letters to and from the Continent the post was entrusted to messengers, who would make their own travel arrangements. This

3108-558: A result of the British Telecommunications Act 1981 . In 1986 the Post Office Counters business was made functionally separate from Royal Mail Letters and Royal Mail Parcels (the latter being rebranded as ' Parcelforce '). At the start of the 21st century the Post Office became a public limited company (initially called 'Consignia plc'), which was renamed ' Royal Mail Group plc' in 2002. In 2012

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3256-565: A rubber hose. After the demise of BSA, remaining stocks of B175s were sold until at least 1973. The off-road Bushman version was available as an export model, for Africa and Australia in particular, but 300 were sold in the UK. All UK Bushman models have the engine number prefix BB. The precursor to the Bushman was a stripped down D7 called a Bronc Buck. Bushman models proper were equipped with lights, high-level exhaust, side stand, and dualseat. There

3404-449: A scavenging function. The units run in pairs, with the lower half of one piston charging an adjacent combustion chamber. The upper section of the piston still relies on total-loss lubrication, but the other engine parts are sump lubricated with cleanliness and reliability benefits. The mass of the piston is only about 20% more than a loop-scavenged engine's piston because skirt thicknesses can be less. Many modern two-stroke engines employ

3552-580: A similar manner to the Wipac DC system. In 1953 BSA introduced a foam-upholstered dualseat as an optional alternative to the single saddle. In the same year it built the 100,000th D1. From 1958 the D1 was offered in maroon as an alternative to mist green. The D1 continued to be offered to the public until 1963, and was still made for the General Post Office for at least two more years. This model

3700-658: A similar system. Traditional flywheel magnetos (using contact-breaker points, but no external coil) worked equally well in reverse because the cam controlling the points is symmetrical, breaking contact before top dead center equally well whether running forward or backward. Reed-valve engines run backward just as well as piston-controlled porting, though rotary valve engines have asymmetrical inlet timing and do not run very well. Serious disadvantages exist for running many engines backward under load for any length of time, and some of these reasons are general, applying equally to both two-stroke and four-stroke engines. This disadvantage

3848-455: A small dry "torch" cell battery to illuminate the forward-facing "pilot" bulb within the headlamp shell. The remaining lighting was available for use only when the engine was running. The dry cell was disposable. It could not be recharged, and had to be replaced when exhausted. The DC system included a lead acid battery and operated in a conventional manner. For a short period some D1's were equipped with Lucas lighting systems, and these operated in

3996-556: A system for the conveyance of foreign dispatches had been set up, organised by Flemish merchants in the City of London ; but in 1558, after a dispute arose between Italian, Flemish and English merchants on the matter, the Master of the King's Posts was granted oversight of it instead. In 1619, James I appointed a separate Postmaster General 'for foreign parts', granting him (and his appointees)

4144-441: A team of four horses, rather than six as was usual for a stage coach at that time). The long-established practice of 'riding post' was acknowledged through the provision of four seats inside the coach for passengers. The mail bags were carried in a locked box at the back, above which sat a scarlet-coated guard. While the coaches and coachmen were provided by contractors, the guards worked for the Post Office. As well as two pistols and

4292-465: A three-speed gearbox, and a telescopic front fork with undamped springs. In its original form the D1 had no rear suspension; "direct" electrics; and a "fishtail" silencer. The front mudguard was deeply valanced, to allow for the fact that it was fitted to the "sprung" part of the front fork, meaning that the front wheel moves up and down within the mudguard. At first the D1 was offered in only one colour, Mist Green, with an ivory panel painted on each side of

4440-518: A turbocharger. Crankcase-compression two-stroke engines, such as common small gasoline-powered engines, are lubricated by a petroil mixture in a total-loss system . Oil is mixed in with their petrol fuel beforehand, in a fuel-to-oil ratio of around 32:1. This oil then forms emissions, either by being burned in the engine or as droplets in the exhaust, historically resulting in more exhaust emissions, particularly hydrocarbons, than four-stroke engines of comparable power output. The combined opening time of

4588-400: A wider speed range or higher power over a narrower speed range than either a piston-port or reed-valve engine. Where a portion of the rotary valve is a portion of the crankcase itself, of particular importance, no wear should be allowed to take place. In a cross-flow engine, the transfer and exhaust ports are on opposite sides of the cylinder, and a deflector on the top of the piston directs

BSA Bantam - Misplaced Pages Continue

4736-424: Is a matter of general concernment, and of great advantage, as well for the preservation of trade and commerce as otherwise". To begin with the Post Office was again farmed, nominally to Henry Bishop , but the deal was bankrolled by John Wildman (a gentleman of dubious repute, who kept a tight rein on his investment). Two years later Wildman was imprisoned, implicated in a plot against the King, whereupon Bishop sold

4884-413: Is accepted in most cases where cost, weight, and size are major considerations. The problem comes about because in "forward" running, the major thrust face of the piston is on the back face of the cylinder, which in a two-stroke particularly, is the coolest and best-lubricated part. The forward face of the piston in a trunk engine is less well-suited to be the major thrust face, since it covers and uncovers

5032-422: Is attributed to Scottish engineer Dugald Clerk , who patented his design in 1881. However, unlike most later two-stroke engines, his had a separate charging cylinder. The crankcase -scavenged engine, employing the area below the piston as a charging pump, is generally credited to Englishman Joseph Day . On 31 December 1879, German inventor Karl Benz produced a two-stroke gas engine, for which he received

5180-597: Is being phased out. Honda , for instance, ceased selling two-stroke off-road motorcycles in the United States in 2007, after abandoning road-going models considerably earlier. Due to their high power-to-weight ratio and ability to be used in any orientation, two-stroke engines are common in handheld outdoor power tools including leaf blowers , chainsaws , and string trimmers . Two-stroke diesel engines are found mostly in large industrial and marine applications, as well as some trucks and heavy machinery. Although

5328-574: Is common in on-road, off-road, and stationary two-stroke engines ( Detroit Diesel ), certain small marine two-stroke engines ( Gray Marine Motor Company , which adapted the Detroit Diesel Series 71 for marine use ), certain railroad two-stroke diesel locomotives ( Electro-Motive Diesel ) and large marine two-stroke main propulsion engines ( Wärtsilä ). Ported types are represented by the opposed piston design in which two pistons are in each cylinder, working in opposite directions such as

5476-524: Is identical to the standard D1, except for a black tank with chromium strip on top and cream side panels; black frame and mudguards; chromium plated wheel-rims; polished primary chain cover; and crash bars; legshields; and larger luggage rack. The model was available by special order from 1949 to 1953 in the overseas market, primarily in Canada, US, Australia, but not in the UK. There was no production records for this model or where they were sent. BSA introduced

5624-404: Is of two types: a Lucas battery-powered coil in earlier machines, or a Wipac magneto . The magneto is on a composite assembly within the flywheel with its magnet inserts. Windings give power either directly to the lights (with a dry cell for when the engine was stopped) or via a rectifier to a lead-acid battery. Early D1s have a "fishtail" style silencer. This was hard to clean inside, which

5772-432: Is that the two-stroke's crankcase is sealed and forms part of the induction process in gasoline and hot-bulb engines . Diesel two-strokes often add a Roots blower or piston pump for scavenging . The reed valve is a simple but highly effective form of check valve commonly fitted in the intake tract of the piston-controlled port. It allows asymmetric intake of the fuel charge, improving power and economy, while widening

5920-409: Is under every circumstance more efficient than cross-flow scavenging. In a uniflow engine, the mixture, or "charge air" in the case of a diesel, enters at one end of the cylinder controlled by the piston and the exhaust exits at the other end controlled by an exhaust valve or piston. The scavenging gas-flow is, therefore, in one direction only, hence the name uniflow. The design using exhaust valve(s)

6068-464: The Junkers Jumo 205 and Napier Deltic . The once-popular split-single design falls into this class, being effectively a folded uniflow. With advanced-angle exhaust timing, uniflow engines can be supercharged with a crankshaft-driven blower, either piston or Roots-type. The piston of this engine is "top-hat"-shaped; the upper section forms the regular cylinder, and the lower section performs

BSA Bantam - Misplaced Pages Continue

6216-765: The Leeward Islands was enjoined. The Irish post at this time operated as part of the GPO under a Deputy Postmaster General based in Dublin; but in 1784 an Act was passed by the Parliament of Ireland providing for an independent Post Office in Ireland under its own Postmaster General (an arrangement that remained in place until 1831). The established post roads in Britain ran to and from London. The use of other roads required government permission (for example, it

6364-757: The Royal Mail Steam Packet Company ran ships out of Southampton to the West Indies and South America, the British and North American Royal Mail Steam-Packet Company (aka the Cunard Line ) covered the North Atlantic route, while the Peninsular and Oriental Steam Navigation Company provided services on eastward routes to the Mediterranean, India and Australia. From 1840 vessels carrying mail under Admiralty contract had

6512-484: The Spanish Armada every parish was by royal command required to provide a footpost, and every town a horse-post, to help convey news in the event of an imminent invasion. By the early 1600s there were two options for couriers using the post system: they could either ride 'through-post', carrying the correspondence the full distance; or they could use the 'post of the packet', whereby the letters were carried by

6660-630: The Strowger system for small and medium cities and towns. The telephone systems of Jersey and the Isle of Man , obtained from the NTC were offered for sale to the respective governments of the islands. Both initially refused, but the States of Jersey did eventually take control of their island's telephones in 1923. On 27 July 1896, Guglielmo Marconi gave the first demonstration of wireless telegraphy from

6808-646: The War of the Spanish Succession ). The distribution network was centred on the General Letter Office in London (which was on Threadneedle Street prior to the Great Fire of London , after which it moved first to Bishopsgate and then to Lombard Street in 1678). The incoming post arrived each week on Mondays, Wednesdays and Fridays; it was sorted and stamped : London letters went to

6956-512: The expansion chamber , such as the Suzuki SAEC and Honda V-TACS system. The result is an engine with better low-speed power without sacrificing high-speed power. However, as power valves are in the hot gas flow, they need regular maintenance to perform well. Direct injection has considerable advantages in two-stroke engines. In carburetted two-strokes, a major problem is a portion of the fuel/air mixture going directly out, unburned, through

7104-479: The oil reservoir does not depend on gravity. A number of mainstream automobile manufacturers have used two-stroke engines in the past, including the Swedish Saab , German manufacturers DKW , Auto-Union , VEB Sachsenring Automobilwerke Zwickau , VEB Automobilwerk Eisenach , and VEB Fahrzeug- und Jagdwaffenwerk , and Polish manufacturers FSO and FSM . The Japanese manufacturers Suzuki and Subaru did

7252-452: The sole privilege of carrying foreign correspondence to and from London. (The separate Postmaster General appointments were consolidated in 1637, but the 'foreign' and 'inland' postal services remained separate in terms of administration and accounting until the mid-19th century). It was not until 1635 that a general or public post was properly established, for inland letters as for foreign ones. On 31 July that year, King Charles I issued

7400-426: The 'windows' where members of the public were able to collect them from the office in person (once they had paid the requisite fee), while 'Country letters' were dispatched along the relevant post road. The outgoing post went on Tuesdays, Thursdays and Saturdays. Postage was payable by the recipient (rather than the sender) and depended on the length of the letter and the distance it had travelled; each individual charge

7548-645: The 1830s). In 1801 the cost of posting a letter within the central London area was doubled; thenceforward the London District Post was known as the 'Two-penny Post' until its amalgamation into the General Post 53 years later. During the reign of King William III , the General Post Office created a network of 'receiving-houses', in London and the larger provincial towns, where senders could submit items. A Scottish Post Office

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7696-528: The 1960s due in no small way to the increased power afforded by loop scavenging. An additional benefit of loop scavenging was the piston could be made nearly flat or slightly domed, which allowed the piston to be appreciably lighter and stronger, and consequently to tolerate higher engine speeds. The "flat top" piston also has better thermal properties and is less prone to uneven heating, expansion, piston seizures, dimensional changes, and compression losses. SAAB built 750- and 850-cc three-cylinder engines based on

7844-407: The 1960s, especially for motorcycles, but for smaller or slower engines using direct injection, the deflector piston can still be an acceptable approach. This method of scavenging uses carefully shaped and positioned transfer ports to direct the flow of fresh mixture toward the combustion chamber as it enters the cylinder. The fuel/air mixture strikes the cylinder head , then follows the curvature of

7992-458: The Admiralty took over managing the long-distance routes out of Falmouth, while services to and from Ireland and the continent were increasingly put out to commercial tender. Eventually, in 1837, the Admiralty took over control of the whole operation (and with it the remaining Post Office vessels). Subsequently, contracts for carrying mail began to be awarded to new large-scale shipping lines :

8140-566: The Bantam, the D18, before financial troubles in 1971 led to a drastic reduction of the BSA model range. The D18 was intended to be an interim model before the introduction of a new range of two-strokes that were in development. The D18 had an alloy barrel and a new head with a central spark plug. A prototype was built before the project was cancelled. Two-stroke engine Two-stroke engines often have

8288-752: The British Isles (the nations of which had been unified under Oliver Cromwell as a result of the Wars of the Three Kingdoms ), stating that 'there shall be one General Post-Office, and one office stiled the Postmaster-Generall of England and Comptroller of the Post-Office'. The Act also reasserted the postal monopoly for letter delivery and for post-horses; and it set new rates both for carriage of letters and for 'riding post'. During

8436-534: The Commonwealth, what had been a weekly post service to and from London was increased to a thrice-weekly service: letters were despatched from the General Letter Office in London every Tuesday, Thursday and Saturday evening, while the inbound post arrived early in the morning on Mondays, Wednesdays and Fridays. Usually the recipient of the post paid the fee (and had the right to refuse to accept

8584-514: The D3 Major in 1954. It was the first development from the original Bantam. BSA increased the engine cylinder bore from 52 mm to 58 mm, which gives the D3 a displacement of 148cc, and increased its power from 4.5 to 5.3 bhp. The air-cooling fins were also enlarged, which changed the external appearance of the engine. The D1 engine was given same increase in finning from this date. A dualseat

8732-492: The D3 in 1958. The D5 Super is a development of the swinging-arm D3, with a lengthened rear section to give more upright mounts for the rear suspension. BSA increased the cylinder bore to 61.5 mm, which increased the displacement to 173 cc, and the power to 7.5 bhp. BSA fitted an Amal Monobloc carburettor. The D5 has a larger, more rounded fuel tank, which increased capacity to two Imperial gallons. BSA finished all D5s in maroon, with an ivory side panel on either side of

8880-549: The D7 a new hydraulically damped front fork, with fork legs that are a shortened version of the front fork of the Triumph Tiger Cub . The headlamp is mounted in a nacelle, which was fashionable at the time, but prevents the angle of the headlamp from being adjusted. Originally BSA offered two colour options: "royal red", or black. In both cases, an ivory side panel was originally painted on the fuel tank. For 1961 BSA restyled

9028-611: The GPO (in particular the Hull Telephones Department (now privatised) and the telephone system of Guernsey ). The GPO took over the company on 1 January 1912; transferring 1,565 exchanges and 9,000 employees at a cost of £12,515,264. The GPO installed several automatic telephone exchanges from several vendors in trials at Darlington on 10 October 1914 and Dudley on 9 September 1916 ( rotary system ), Fleetwood (relay exchange from Sweden), Grimsby (Siemens), Hereford (Lorimer) and Leeds (Strowger). The GPO then selected

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9176-516: The GPO came to be viewed less as a revenue-raising body and more as a public service . The Post Office Savings Bank was introduced in 1861, when there were few banks outside major towns. By 1863, 2,500 post offices were offering a savings service . Gradually more financial services were offered by post offices, including government stocks and bonds in 1880, insurance and annuities in 1888, and war savings certificates in 1916. In 1909 old age pensions were introduced, payable at post offices. In 1956

9324-452: The German inventor of an early form in the mid-1920s, it became widely adopted in Germany country during the 1930s and spread further afield after World War II . Loop scavenging is the most common type of fuel/air mixture transfer used on modern two-stroke engines. Suzuki was one of the first manufacturers outside of Europe to adopt loop-scavenged, two-stroke engines. This operational feature

9472-454: The Peace had been ordered to arrange appointment of two to three foot-posts in every parish for the conveyance of letters), though in practice precise details were often left to the local postmaster. On the return journey to London, bags of letters would be picked up from each post-house on the way, and taken to the General Letter Office to be sorted for despatch. With the establishment of

9620-622: The Post Master General obtained a court judgement that telephone conversations were, technically, within the remit of the Telegraph Act. The General Post Office then licensed all existing telephone networks. The effective nationalisation of the UK telecommunications industry occurred in 1912 with the takeover of the National Telephone Company which left only a few municipal undertakings independent of

9768-482: The Post Office , so changing it from a Department of State to a statutory corporation . Responsibility for telecommunications was given to Post Office Telecommunications , the successor of the GPO Telegraph and Telephones department. In 1980, the telecommunications and postal sides were split prior to British Telecommunications ' conversion into a totally separate publicly owned corporation the following year as

9916-463: The Post Office.) The expansion of the service beyond the main post-roads was in no small part due to the enterprise of the Deputy post-masters themselves, who were allowed to profit from branch services which they established and operated. In this way, the network of 'by-posts' greatly expanded in the 1670s: in 1673 Blome could write that 'there is scarce any Market-Town of note [which does not have]

10064-494: The Postmaster General. Alongside money orders, postal orders were introduced in 1881, which were cheaper and easier to cash. Postal orders and money orders were vital at this time for transactions between small businesses, as well as individuals, because bank transfer facilities were only available to major businesses and for larger sums of money. In 1840 the Uniform Penny Post was introduced, which incorporated

10212-770: The Research Section of the Telegraph Office, which had its origins in innovative areas of work being pursued by staff in the Engineering Department. In the 1920s a dedicated research station was set up by the GPO seven miles away in Dollis Hill ; during the Second World War the world's first electronic computer, ' Colossus ', was designed and constructed there by Tommy Flowers and other GPO engineers. The Telegraph Office

10360-509: The Royal Household of King Henry I , for the conveyance of royal and official correspondence. The messengers delivered their messages in person, each travelling on his own horse and taking time as needed for rest and refreshment (including stopping overnight if the length of journey required it). Under Edward IV , however, a more efficient system was put in place (albeit temporarily) to aid communications during his war with Scotland :

10508-455: The UK. The responsibility for the 'electric telegraphs' was officially transferred to the GPO in 1870. Overseas telegraphs did not fall within the monopoly. The private telegraph companies that already existed were bought out. The new combined telegraph service had 1,058 telegraph offices in towns and cities and 1,874 offices at railway stations. 6,830,812 telegrams were transmitted in 1869 producing revenue of £550,000. London's Central Office in

10656-481: The benefit of the conveyance of letters to and fro'; he went on to list, County by County, both the 'Stages' on the post-roads (of which there were over 140) and the Post-towns on the branch roads (which by then numbered over 380 in total), where members of the public were able to leave letters with a Post-Master 'to be sent as directed'. Before long moves were made to incorporate the by-posts (and their income) into

10804-423: The bore diameter for reasonable piston ring life. Beyond this, the piston rings bulge into the exhaust port and wear quickly. A maximum 70% of bore width is possible in racing engines, where rings are changed every few races. Intake duration is between 120 and 160°. Transfer port time is set at a minimum of 26°. The strong, low-pressure pulse of a racing two-stroke expansion chamber can drop the pressure to -7 psi when

10952-459: The combustion chamber, and then is deflected downward. This not only prevents the fuel/air mixture from traveling directly out the exhaust port, but also creates a swirling turbulence which improves combustion efficiency , power, and economy. Usually, a piston deflector is not required, so this approach has a distinct advantage over the cross-flow scheme (above). Often referred to as "Schnuerle" (or "Schnürle") loop scavenging after Adolf Schnürle,

11100-697: The compression ratio to 10 to 1, which increased power to 12.6 bhp. The "/4" in the model name signifies the fact that all models had four-speed transmission, as BSA had at last discontinued the three-speed gearbox. BSA discontinued the Silver Bantam, and offered only three models: Supreme, Sports, and Bushman. BSA gave the Sports and Bushman models a heavier front fork, based on that of the BSA C12 . The engine flywheel had compression plates that were held on by rivets, which in some cases failed. On some D14/4s,

11248-458: The continent . A similar system connected Holyhead and Milford to Ireland (and by the end of the 16th century a packet service had been established on the Holyhead to Dublin route). Private citizens could make use of the post-horse network, if they could afford it (in 1583 they had to pay twopence per mile for the horse, plus fourpence per stage for the guide), but it was primarily designed for

11396-454: The counters business (known as ' Post Office Limited ' since 2002) was taken out of Royal Mail Group, prior to the latter's privatisation in 2013. The privatised holding company (Royal Mail plc) was renamed International Distributions Services plc in 2022. In the medieval period, nobles generally employed messengers to deliver letters and other items on their behalf. In the 12th century a permanent body of messengers had been formed within

11544-463: The country. The 1850s also saw the widespread introduction of red-painted post boxes where the public could deposit their outgoing mail. Few other organisations (either of state or of commerce) could rival the early Victorian Post Office in the extent of its national coverage. Its counters began to be relied upon for providing other government services (e.g. the issuing of licences of various types); and increasingly (and significantly) in this period,

11692-453: The crankshaft commonly spins in the same axis and direction as do the wheels i.e. "forward". Some of the considerations discussed here apply to four-stroke engines (which cannot reverse their direction of rotation without considerable modification), almost all of which spin forward, too. It is also useful to note that the "front" and "back" faces of the piston are - respectively - the exhaust port and intake port sides of it, and are not to do with

11840-415: The cycle's potential for high thermodynamic efficiency makes it ideal for diesel compression ignition engines operating in large, weight-insensitive applications, such as marine propulsion , railway locomotives , and electricity generation . In a two-stroke engine, the exhaust gases transfer less heat to the cooling system than a four-stroke, which means more energy to drive the piston, and if present,

11988-605: The dispatch of items from a specific sender to a specific receiver (which was to be of great importance when new forms of communication were invented); it was overseen by a Government minister , the Postmaster General . Over time its remit was extended to Scotland and Ireland, and across parts of the British Empire . The GPO was abolished by the Post Office Act 1969 , which transferred its assets to

12136-400: The engine from end loads. Large two-stroke ship diesels are sometimes made to be reversible. Like four-stroke ship engines (some of which are also reversible), they use mechanically operated valves, so require additional camshaft mechanisms. These engines use crossheads to eliminate sidethrust on the piston and isolate the under-piston space from the crankcase. On top of other considerations,

12284-503: The engine to protect the crankcase; high-level exhaust; 19-inch wheels; 58-tooth rear sprocket; increased ground clearance; and a unique colour scheme of orange and white. The Supreme and Silver have a headlamp nacelle and three-speed gearbox like the D7. The Silver has less chrome, making it the economy option. BSA made the D10 models for 1967 only. In 1968 BSA introduced the D14/4. It increased

12432-546: The establishment of the Penny Post, the only location where letters could be posted in London was the General Letter Office in Lombard Street .) The receiving-houses were often found in public houses, coffee houses or other retail premises. Deliveries were made six or eight times a day in central London (and a minimum of four times a day in the outskirts). The innovation was a great success, and within two years

12580-415: The exhaust port in the cylinder, the hottest part of the engine, where piston lubrication is at its most marginal. The front face of the piston is also more vulnerable since the exhaust port, the largest in the engine, is in the front wall of the cylinder. Piston skirts and rings risk being extruded into this port, so having them pressing hardest on the opposite wall (where there are only the transfer ports in

12728-409: The exhaust port, and direct injection effectively eliminates this problem. Two systems are in use: low-pressure air-assisted injection and high-pressure injection. Since the fuel does not pass through the crankcase, a separate source of lubrication is needed. For the purpose of this discussion, it is convenient to think in motorcycle terms, where the exhaust pipe faces into the cooling air stream, and

12876-507: The extra charges. In 1680 William Dockwra and Robert Murray founded the 'Penny Post', which enabled letters and parcels to be sent cheaply to and from destinations in and around London. A flat fee of a penny was charged for sending letters or parcels up to a pound in weight within an area comprising the City of London, the City of Westminster and the Borough of Southwark ; while two-pence

13024-417: The first decade of nationalized telegraphy created two levels of service. High-status circuits catering to the state, international trade, sporting life, and imperial business. Low-status circuits directed toward the local and the provincial. These distinct telegraphic orbits were connected to different types of telegraph instruments operated by differently gendered telegraphists. 1909 saw the establishment of

13172-1156: The first model, the D1, in 1948. Motorcycles based on the RT125 also went into production in other countries. The DKW factory was in Zschopau in the Soviet occupation zone in Germany , and in about 1946 the Soviet Union launched the Moskva M1A made in Moscow. Harley-Davidson launched its Model 125 late in 1947. Auto Union , DKW's parent company, was re-founded in Ingolstadt in the American occupation zone in Germany , and resumed RT 125 production in 1949. The former DKW factory in Zschopau became part of IFA , which resumed RT 125 production in 1950. The Zschopau factory later became MZ In 1955 Yamaha launched its YA-1 , which

13320-410: The form of the original engine remained recognisable throughout the 23 years of Bantam production. The engine is a unit-construction (engine and gearbox of one piece) single-cylinder two-stroke. The barrel is cast iron and the cylinder head is alloy. Models built from 1948 until 1968 have a three-speed gearbox. Models from 1968 to 1971 have a four-speed gearbox. All models have a "wet" clutch. Ignition

13468-413: The fresh intake charge into the upper part of the cylinder, pushing the residual exhaust gas down the other side of the deflector and out the exhaust port. The deflector increases the piston's weight and exposed surface area, and the fact that it makes piston cooling and achieving an effective combustion chamber shape more difficult is why this design has been largely superseded by uniflow scavenging after

13616-407: The fuel tank, with a chrome-plated panel and pear-shaped plastic BSA badge on each side. This matched four-stroke models in the BSA range at the time. In the same year BSA introduced "sapphire blue" as a colour option, alongside black or royal red. In 1965 BSA revised the tank again, with an indentation on each side for the rider's knees, and a round plastic BSA badge instead of pear-shaped. BSA painted

13764-569: The fuel tank. It made the D5 for 1958 only. BSA introduced the D7 Super was introduced for 1959. It has a 173cc engine, similar to the D5, but with the addition of an alloy outer cover on the left side of the crankcase, concealing the Wipac "geni-mag", to match the streamlined shape of the right side. The D7 has a swinging-arm frame, but it was a new design that departed from that of the D3 and D5. BSA gave

13912-452: The fuel tank. It was priced at £60 plus purchase tax. In subsequent years BSA developed the Bantam with battery electrics; damped front suspension; rear suspension with plungers, and then with a swinging arm; larger engines; a steel silencer that could be dismantled for cleaning; and a four-speed gearbox. Models from 1959 onward have a swinging arm frame that bears little relation to the rigid, plunger and initial swinging-arm versions. However,

14060-412: The guides from one post house to the next in a cotton-lined leather bag (although this method was only available for royal, government or diplomatic correspondence). The guides at this time were provided with a post horn , which they had to sound at regular intervals or when encountering others on the road (other road users were expected to give way to the post riders ). At the start of the 16th century

14208-483: The inhabitants of the nation. At that time there were 182 Deputy Post-Masters (or 'Deputies') in England [and Wales], most of whom were stationed at the 'Stages' or stops which lay along the six main post-roads; and under them were sub-Post-masters , based at market towns which were not on the main post-roads but to which the service had been extended. (The sub-Post-masters, unlike the Deputies, were not employed by

14356-443: The intake and exhaust ports in some two-stroke designs can also allow some amount of unburned fuel vapors to exit in the exhaust stream. The high combustion temperatures of small, air-cooled engines may also produce NO x emissions. Two-stroke gasoline engines are preferred when mechanical simplicity, light weight, and high power-to-weight ratio are design priorities. By mixing oil with fuel, they can operate in any orientation as

14504-465: The item if they did not wish to pay); the charge was based on the distance the item had been carried so the Post Office had to keep a separate account for each item. After the Restoration , the Post Office Act 1660 ( 12 Cha. 2 . c. 35) was passed (the previous Cromwellian Act being void), confirming the arrangements in place for the Post Office, and the post of Postmaster General, and emphasizing

14652-452: The last version of the D7. BSA offered four versions of the D10: the Sports, Supreme, Silver, and Bushman. The Sports and Bushman were the first Bantams to have a four-speed gearbox. BSA gave both models a separately-mounted headlamp, without a nacelle. It gave the Sports chrome mudguards; a fly-screen; and a hump on the rear of the dualseat. The Bushman is the off-road version, with a plate under

14800-536: The latter's accession to the throne as King James II , this income became part of the hereditary revenues of the Crown ; and subsequently, under the growing scrutiny of HM Treasury , the postal service came increasingly to be viewed as a source of government income (as seen in the Post Office (Revenues) Act 1710 , which increased postal charges and levied tax on the income in order to finance Britain's involvement in

14948-575: The lease on to the King's gunpowder manufacturer, Daniel O'Neill ; after the latter's death, his widow the Countess of Chesterfield served out the remainder of the original seven-year term (so becoming the first female Postmaster General). Meanwhile, under the terms of a 1663 Act of Parliament, the 'rents, issues and profits' of the Post Office had been settled by the King on his brother, the Duke of York, to provide for his support and maintenance. Following

15096-517: The mail bags from one post-house to the next; the postmaster at the next post-house would then record the time of arrival, before transferring the bags to a new horse, ridden by a new post-boy, for the next stage of the journey. On the outbound journey from London, the mail for each Stage (and its associated Post-towns) was left at the relevant post-house. Arrangements for its onward delivery varied somewhat from place to place. Witherings had envisaged using 'foot-posts' for this purpose (in 1620 Justices of

15244-524: The messengers appointed by the said Thomas Witherings', thus establishing a monopoly, which (under the auspices of the Royal Mail ) would remain in place until 2006. Under the Commonwealth the Post Office was farmed to John Manley and John Thurloe , successively. In 1657 an Act of Parliament entitled Postage of England, Scotland and Ireland Settled set up a postal system for the whole of

15392-475: The model year. The Monte Carlo Rally variant, 750-cc (with a filled crankshaft for higher base compression), generated 65 hp. An 850-cc version was available in the 1966 SAAB Sport (a standard trim model in comparison to the deluxe trim of the Monte Carlo). Base compression comprises a portion of the overall compression ratio of a two-stroke engine. Work published at SAE in 2012 points that loop scavenging

15540-506: The national network: 'Riding Surveyors' were appointed in 1682, to travel with the post and scrutinise the Deputies' income and activity at each Stage (particularly in relation to by-letters); in later years the Surveyors served as the GPO's inspectorate , tasked with maintaining efficiency and consistency across the network (until they were finally disbanded in the 1930s). It was usual for each postmaster to employ post-boys to ride with

15688-507: The network of post towns served by the General Post, and at the same time did much to reform its workings. In 1772 the Court of the King's Bench ruled that letters ought to be delivered directly to recipients within the boundaries of each post town at no additional cost. Often a messenger with a locked satchel would be employed by the postmaster to deliver and receive items of mail around town; he would alert people to his presence by ringing

15836-548: The new arrangement, the King commanded 'all his postmasters, upon all the roads of England, to have ready in their stables one or two horses [...] to carry such messengers, with their portmantles , as shall be imployed in the said service', and they were forbidden from hiring out these horses to others on days when the mail was due. Furthermore, it was enjoined that (with a few specific exceptions) 'no other messenger or messengers, footpost or footposts, shall take up, carry, receive or deliver any letter or letters whatsoever, other than

15984-399: The oil pump of a modern two-stroke may not work in reverse, in which case the engine suffers oil starvation within a short time. Running a motorcycle engine backward is relatively easy to initiate, and in rare cases, can be triggered by a back-fire. It is not advisable. Model airplane engines with reed valves can be mounted in either tractor or pusher configuration without needing to change

16132-487: The other - the inlet pipe having passage to the crankcase only when the two cutouts coincide. The crankshaft itself may form one of the members, as in most glow-plug model engines. In another version, the crank disc is arranged to be a close-clearance fit in the crankcase, and is provided with a cutout that lines up with an inlet passage in the crankcase wall at the appropriate time, as in Vespa motor scooters. The advantage of

16280-436: The packet ship services. Since the 1780s these had been run on behalf of the Post Office by private contractors, who depended on supplementary income from fee-paying passengers in order to make a profit; but in the 19th-century steamships began to lure the passengers away. At some considerable cost the Post Office resolved to build and operate its own fleet of steam vessels, but the service became increasingly inefficient. In 1823

16428-434: The piston covering and uncovering the ports as it moves up and down in the cylinder. In the 1970s, Yamaha worked out some basic principles for this system. They found that, in general, widening an exhaust port increases the power by the same amount as raising the port, but the power band does not narrow as it does when the port is raised. However, a mechanical limit exists to the width of a single exhaust port, at about 62% of

16576-440: The piston is at bottom dead center, and the transfer ports nearly wide open. One of the reasons for high fuel consumption in two-strokes is that some of the incoming pressurized fuel-air mixture is forced across the top of the piston, where it has a cooling action, and straight out the exhaust pipe. An expansion chamber with a strong reverse pulse stops this outgoing flow. A fundamental difference from typical four-stroke engines

16724-550: The power band. Such valves are widely used in motorcycle, ATV, and marine outboard engines. The intake pathway is opened and closed by a rotating member. A familiar type sometimes seen on small motorcycles is a slotted disk attached to the crankshaft , which covers and uncovers an opening in the end of the crankcase, allowing charge to enter during one portion of the cycle (called a disc valve). Another form of rotary inlet valve used on two-stroke engines employs two cylindrical members with suitable cutouts arranged to rotate one within

16872-466: The principles remain the same, the mechanical details of various two-stroke engines differ depending on the type. The design types vary according to the method of introducing the charge to the cylinder, the method of scavenging the cylinder (exchanging burnt exhaust for fresh mixture) and the method of exhausting the cylinder. Piston port is the simplest of the designs and the most common in small two-stroke engines. All functions are controlled solely by

17020-483: The privilege of being badged and designated as Royal Mail Ships (RMS). In 1838 the Money Order Office was established, to provide a secure means of transferring money to people in different parts of the country (or world), and to discourage people from sending cash by post. The money order system had first been introduced as a private enterprise by three Post Office clerks in 1792, with the permission of

17168-476: The propeller. These motors are compression ignition, so no ignition timing issues and little difference between running forward and running backward are seen. General Post Office The General Post Office ( GPO ) was the state postal system and telecommunications carrier of the United Kingdom until 1969. Established in England in the 17th century, the GPO was a state monopoly covering

17316-422: The public and economic benefits of a General Post system: "Whereas for the maintenance of mutual correspondencies, and prevention of many inconveniences happening by private posts, several public post-offices have been heretofore erected for carrying and recarrying of letters by post to and from all parts and places within England, Scotland, and Ireland, and several posts beyond the seas, the well-ordering whereof

17464-416: The relaying of state and royal correspondence, or for the conveyance from one place to another of individuals engaged on official state business (who paid a reduced rate). Private correspondence was often sent using common carriers at this time, or with others who regularly journeyed from place to place (such as travelling pedlars ); towns often made use of local licensed carriers, who plied their trade using

17612-460: The rest of the realm). Witherings was required to extend the new system to other post roads 'as soon as possibly may be' (beginning with the routes to Oxford and Bristol, and to Colchester, Norwich and Yarmouth); and provision was also made for the establishment of 'bye-posts' to run to and from places not directly served by the post road system (such as Lincoln and Hull). The new system was fully and profitably running by 1636. In order to facilitate

17760-457: The revised D7 in a colour that it called "flamboyant red". In the same year it introduced coil ignition for the De Luxe model. In 1966 BSA introduced an economy version called the "Silver Bantam", which was in sapphire blue, and had silver paint on the sides of its fuel tank instead of chrome. This was short-lived, as BSA stopped making the D7 that year. In 1967 BSA introduced the D10. Its engine

17908-555: The roof of the Telegraph Office in St. Martin's Le Grand. The development of radio links for sending telegraphs led to the Wireless Telegraphy Act 1904 , which granted control of radio waves to the General Post Office, who licensed all senders and receivers. This placed the Post Office in a position of control over radio and television broadcasting as those technologies were developed. By 1900 house-to-house mail delivery

18056-455: The royal proclamation instructed him to establish 'a running post, to run night and day', initially between London and Edinburgh, London and Holyhead and London and Plymouth, 'for the advancement of all His Majesty's subjects in their trade and correspondence'. (A similar system, running between London and Dover, had already been established by Witherings as part of his administration of the foreign posts, and he himself had proposed its extension to

18204-821: The same in the 1970s. Production of two-stroke cars ended in the 1980s in the West, due to increasingly stringent regulation of air pollution . Eastern Bloc countries continued until around 1991, with the Trabant and Wartburg in East Germany. Two-stroke engines are still found in a variety of small propulsion applications, such as outboard motors , small on- and off-road motorcycles , mopeds , motor scooters , motorized bicycles , tuk-tuks , snowmobiles , go-karts , RC cars , ultralight and model airplanes. Particularly in developed countries, pollution regulations have meant that their use for many of these applications

18352-499: The small end bearing on the connecting rod failed. Both faults led to warranty claims. In 1969 BSA introduced the D175, which it later redesignated the B175. This was the final Bantam model series. It is arguably the best for power and handling. BSA revised the engine, with different finning on the cylinder barrel, and a revised cylinder head with a central, vertical spark plug and efficient squish combustion chamber. The compression ratio

18500-479: The system, the king appointed Brian Tuke to serve as 'Master of the Postes'. By the 1550s five post roads were in place, connecting London with Dover , Edinburgh , Holyhead (via Chester ), Milford Haven (via Bristol ) and Plymouth . (A sixth post road, to Norwich via Colchester , would be added in the early 17th century.) Each post-house on the road was staffed by a postmaster , whose main responsibility

18648-520: The top or bottom of the piston. Regular gasoline two-stroke engines can run backward for short periods and under light load with little problem, and this has been used to provide a reversing facility in microcars , such as the Messerschmitt KR200 , that lacked reverse gearing. Where the vehicle has electric starting, the motor is turned off and restarted backward by turning the key in the opposite direction. Two-stroke golf carts have used

18796-474: The two key innovations of a uniform postal rate, which cut administrative costs and encouraged use of the system, and adhesive pre-paid stamp. Packets (weighing up to 16 ounces (450 g)) could also be sent by post, the cost of postage varying with the weight. The reforms were devised and overseen by Rowland Hill , having been initially proposed in Parliament by Robert Wallace MP . A book post service

18944-537: The world's first public telegraph company, was established in the UK and developed a nationwide communications network. Several other private telegraph companies soon followed. The Telegraph Act 1868 granted the Postmaster General the right to acquire inland telegraph companies in the United Kingdom and the Telegraph Act 1869 conferred on the Postmaster General a monopoly in telegraphic communication in

19092-400: Was a Pastoral model for commercial farming that had single saddle and carrier rack instead of a dualseat. The first Bushmans were derived from the D7, but they were made in far greater numbers as D10s, some D14/4s and ultimately the D175 / B175 Bushman. Various air filters were fitted to the Bushman models but all were mounted remotely from the carburettor behind the side panels where the battery

19240-399: Was available at first only with a rigid rear suspension. BSA introduced optional plunger rear suspension in 1950, and stopped making the rigid-framed version in 1956. All D1s have undamped front suspension, which gives a bouncy ride. BSA offered D1's with different electrical lighting systems. Wipac systems were available either in 6 Volt AC (known as direct lighting) or DC. The AC system used

19388-478: Was calculated in London and entered into a book, which went with the letters on the road, indicating the amounts due from each postmaster for the letters delivered into his care. At first the new postal network was not especially well publicised; but in his 1673 publication Britannia , Richard Blome sought to remedy this by describing in some detail the geographical disposition of the new 'general Post-Office' , which he called an 'exceeding great conveniency' for

19536-413: Was charged for items posted or delivered in the surrounding 'country' area (which included places such as Hackney, Newington, Lambeth and Islington). The Penny Post letter-carriers operated from seven main sorting offices around London, which were supplemented by between four and five hundred 'receiving houses' in all the principal streets in the area, where members of the public could post items. (Prior to

19684-436: Was demonstrated that a mail coach departing from Bristol at 4pm would regularly arrive in London at 9 o'clock the following morning: a day and a half quicker than the post horses. As a result, the conveyance of letters by mail coach, under armed guard, was approved by Act of Parliament. Mail coaches were similar in design to the passenger-carrying stage coaches , but were smaller, lighter and more manoeuvrable (being pulled by

19832-454: Was discontinued. This final model was produced from 1969 to 1971, finished in metallic red and blue or plain black, all with white painted linings on the fuel tank, mudguards and side panels like the D14/4. It has an outline text decal in yellow reading "Bantam 175" on the side panels. The right hand side panel covers an efficient large air filter that feeds the Amal 626 Concentric carburettor via

19980-549: Was established in 1695 (although the post-road to Edinburgh continued to be managed from London); in 1710 the Scottish and English establishments were united by statute . By virtue of the same Act of Parliament (the Post Office (Revenues) Act 1710 ), the functions of the 'general letter office and post office' in the City of London were set out, and the establishment of 'chief letter offices' in Edinburgh, Dublin, New York and

20128-492: Was far from reliable, so in the 1630s Thomas Witherings set about establishing a regular Dover-Calais packet service. By the end of the century additional packet services had been established between Harwich (off the Yarmouth post road) and Helvoetsluys , between Dover and Ostend / Nieuport , and between Falmouth and Corunna . The packet services were generally arranged by contract with an agent, who would commit to provide

20276-410: Was fitted as standard. The D3 has a shallower front mudguard, fitted to the lower part of the front fork, so that it stays close to the front wheel and moves up and down with it. D1's built from 1953 onward have the same arrangement. BSA finished all D3s in pastel grey, with ivory panels on either side of the fuel tank. In 1956 BSA changed the rear suspension from plunger to swinging arm. It stopped making

20424-408: Was introduced in 1837, and these began to be widely used enabling mail to be sorted in transit; TPO operation was greatly aided by the invention in 1852 of a trackside ' mail-bag apparatus ' which enabled bags to be collected and deposited en route . By the 1860s the Post Office had contracts with around thirty different rail companies. The development of marine steam propulsion inevitably affected

20572-417: Was introduced in 1848, and parcel post in 1883; that same year the term 'letter-carrier' was replaced with ' postman ' in the GPO's official nomenclature. By the 1850s the postal system was described as having become 'universal all over the three kingdoms: no village, however insignificant, being without its receiving-house'. In 1855 a network of 920 post offices and 9,578 sub-offices were in place around

20720-517: Was its first production motorcycle. BSA built the Bantam in Redditch . It was designed as a mirror image of the RT 125, so that the gearchange was on the right side, in conformity with other British motorcycles of the period, and with measurements changed from metric to inches. The model Bantam, the D1, was launched in 1948 outside of the UK and in 1949 within the UK. It was in production until 1963. It had

20868-431: Was on road Bantams, Bushman models had direct lighting so dispensed with the battery. Most featured sump guard plates and the engine mounts are raised slightly to give the engine cases better clearance from rocks etc. Even by the mid-1970s the Bushman models were sought after by collectors and they are even more so today an amazing 49 years after BSA produced the last ones in 1971. BSA engineers were working on an upgrade to

21016-434: Was only after much lobbying that a 'cross-post' between Bristol and Exeter was authorised, in 1698; previously mail between the two cities had to be sent via London). In 1720 Bath postmaster Ralph Allen , who had a vision for improving the situation, took over responsibility for the cross-posts (i.e. routes connecting one post road to another) and bye-posts (connecting to places off the main post roads). He greatly expanded

21164-415: Was problematic for a two-stroke. On later D1s BSA fitted a more conventional cylindrical silencer, from which the baffles can easily be removed for cleaning. High-level exhausts were made for the trials and off-road models, in which the only electrics are the magneto-powered ignition. This listing shows only the main variants and most models were available with refinements or in competition form. BSA had used

21312-554: Was slightly damaged by a German bomb in 1917 and in 1940, was set alight during the London Blitz , destroying much of the interior. It reopened in 1943. By the 1950s, the volume of telegraph traffic had declined and the Telegraph Office closed in 1963. In 1984 the new British Telecom Centre was opened on the site. The Post Office commenced its telephone business in 1878, however the vast majority of telephones were initially connected to independently run networks. In December 1880,

21460-605: Was slightly reduced, to 9.5 to 1. This makes the engine smoother and more reliable than the D14/4, but just as powerful. BSA revised the fixing on crankshaft compression disc plates to cure the problem with the D14/4. BSA also changed the front fork, using that of the Triumph T20SH Sports Cub instead of the BSA C12. The D175 has exposed suspension springs both front and rear. The kickstart has a stronger shaft and folding pedal. The headlight main-beam indicator light

21608-411: Was still 173cc, but BSA increased its compression ratio to 8.65 to 1, which increased its power to 10 bhp. The D10 was the first model to have an Amal Concentric carburettor. BSA revised the electrical system, with a new type of Wipac alternator. The points were moved from the left side to a separate housing in the primary drive cover on the right side. Apart from this, the D10 looked very similar to

21756-453: Was to provide the horses; he would also provide a guide to accompany the messenger as far as the next post house (and then see to the return of the horses afterwards). In practice most post-houses were established at roadside inns and the innkeeper served as postmaster (in return for a small salary from the Crown). At Dover merchant ships were regularly employed to convey letters to and from

21904-541: Was used in conjunction with the expansion chamber exhaust developed by German motorcycle manufacturer, MZ, and Walter Kaaden. Loop scavenging, disc valves, and expansion chambers worked in a highly coordinated way to significantly increase the power output of two-stroke engines, particularly from the Japanese manufacturers Suzuki, Yamaha, and Kawasaki. Suzuki and Yamaha enjoyed success in Grand Prix motorcycle racing in

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