132-401: Suspension is the system of tires , tire air, springs , shock absorbers and linkages that connects a vehicle to its wheels and allows relative motion between the two. Suspension systems must support both road holding/ handling and ride quality , which are at odds with each other. The tuning of suspensions involves finding the right compromise. It is important for the suspension to keep
264-535: A torque tube to restrain this force, for his differential was attached to the chassis by a lateral leaf spring and two narrow rods. The torque tube surrounded the true driveshaft and exerted the force to its ball joint at the extreme rear of the transmission, which was attached to the engine. A similar method like this was used in the late 1930s by Buick and by Hudson 's bathtub car in 1948, which used helical springs that could not take fore-and-aft thrust. The Hotchkiss drive , invented by Albert Hotchkiss,
396-506: A vertical fire-tube boiler . By 1905 they had also begun to build petrol-engined wagons. The Lancashire Steam Motor Company was renamed Leyland Motors in 1907 when it took over Coulthards of Preston , who had been making steam wagons since 1897. They also built a second factory in the neighbouring town of Chorley which still remains today as the headquarters of the Lex Autolease and parts company. In 1920, Leyland Motors produced
528-440: A wheelwright , would cause the tire to expand by heating it in a forge fire, placing it over the wheel, and quenching it, causing the metal to contract back to its original size to fit tightly on the wheel. The first patent for what appears to be a standard pneumatic tire appeared in 1847 and was lodged by Scottish inventor Robert William Thomson . However, this idea never went into production. The first practical pneumatic tire
660-494: A 1968 article in an influential American magazine, Consumer Reports , highlighting the superiority of radial construction. The US tire industry lost its market share to Japanese and European manufacturers, which bought out US companies. Tires may be classified according to the type of vehicle they serve. They may be distinguished by the load they carry and by their application, e.g. to a motor vehicle, aircraft, or bicycle. Light-duty tires for passenger vehicles carry loads in
792-520: A 5.9 L Cummins was introduced. It was notable at the time for its low-level passenger side windscreen, featured as a safety aid to enable the driver to see the kerb, although this was removed on later models. The basic cab had a long service life, being used later on the Leyland DAF 45. The Leyland Constructor was a 6x4, three axle wagon with gross weight up to 24 tonnes used as a tipper or on short haul distribution duties. The Leyland Roadtrain
924-633: A bias tire are many, including longer tread life, better steering control, lower rolling resistance , improved fuel economy, more uniform wear, higher heat resistance, fewer blowouts, and a steadier, more comfortable ride at speed. Disadvantages, besides a higher cost than that of bias tires, are a harder ride at low speeds and generally worse performance on rough terrain. Radial tires are also seldom seen in diameters of greater than 42 inches, as such tires are difficult to make. Bias tire (bias-ply, or cross-ply) construction utilizes body ply cords that extend diagonally from bead to bead, usually at angles in
1056-446: A bow. Horse-drawn carriages and Ford Model T used this system, and it is still used today in larger vehicles, mainly mounted in the rear suspension. Leaf springs were the first modern suspension system, and, along with advances in the construction of roads , heralded the single greatest improvement in road transport until the advent of the automobile . The British steel springs were not well-suited for use on America 's rough roads of
1188-425: A complete new vehicle at the time, so designers were instructed to utilise as many existing in-house components as possible. It was perceived at the time that the resulting model would be a stopgap until the new T45 range was ready for production toward the latter half of the 1970s. The cab was a re-worked version of the "Ergomatic" tilt cab of 1965, heavily modified with different lower panels, raised height etc., and
1320-820: A day's production through industrial action. During World War II , Leyland Motors, along with most vehicle manufacturers, was involved in war production. Leyland built the Cromwell tank at its works from 1943 as well as medium/large trucks such as the Hippo and Retriever . After the war, Leyland Motors continued military manufacture with the Centurion tank . In 1946, AEC and Leyland Motors formed British United Traction to build trolleybuses. In 1955, through an equity agreement, manufacture of commercial vehicles under licence from Leyland Motors commenced in Madras , India at
1452-413: A fairly complex fully-independent, multi-link suspension to locate the rear wheels securely, while providing decent ride quality . The spring rate (or suspension rate) is a component in setting the vehicle's ride height or its location in the suspension stroke. When a spring is compressed or stretched, the force it exerts, is proportional to its change in length. The spring rate or spring constant of
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#17328009239001584-564: A geared flywheel, but without adding significant mass. It was initially employed in Formula One in secrecy, but has since spread to wider motorsport. For front-wheel drive cars , rear suspension has few constraints, and a variety of beam axles and independent suspensions are used. For rear-wheel drive cars , rear suspension has many constraints, and the development of the superior, but more expensive independent suspension layout has been difficult. Henry Ford 's Model T used
1716-463: A high-speed off-road vehicle encounters. Damping is the control of motion or oscillation, as seen with the use of hydraulic gates and valves in a vehicle's shock absorber. This may also vary, intentionally or unintentionally. Like spring rate, the optimal damping for comfort may be less, than for control. Damping controls the travel speed and resistance of the vehicle's suspension. An undamped car will oscillate up and down. With proper damping levels,
1848-528: A number of customers who had traditionally purchased other marques from within the Leyland empire—Albion, AEC, Scammell, etcetera – who were now left with no alternative but to have a Leyland-branded vehicle or purchase from elsewhere. Some Constructors, with their Scammell-based chassis, were built with Scammell badging as well. Throughout its production run, engine choices included the AEC-based TL12,
1980-405: A number of roadtrains in its fleet which enjoyed a comparatively long service life (until the late 1990s) before being replaced by the newer DAF 85. Sales were never quite satisfactory, however, with the vacation closure extended in 1986 to reduce unsold stock. Production ended in 1990, a few years after the sale of Leyland Trucks to Dutch firm DAF in 1987, although as a postscript DAF relaunched
2112-479: A separate inner tube . Semi-pneumatic tires have a hollow center, but they are not pressurized. They are lightweight, low-cost, puncture-proof, and provide cushioning. These tires often come as a complete assembly with the wheel and even integral ball bearings . They are used on lawn mowers , wheelchairs , and wheelbarrows . They can also be rugged, typically used in industrial applications, and are designed to not pull off their rim under use. An airless tire
2244-450: A spring is the change in the force it exerts, divided by the change in deflection of the spring. Vehicles that carry heavy loads, will often have heavier springs to compensate for the additional weight that would otherwise collapse a vehicle to the bottom of its travel (stroke). Heavier springs are also used in performance applications, where the loading conditions experienced are more significant. Springs that are too hard or too soft cause
2376-472: A straight carry over from the preceding "stopgap" model Marathon range, The Rolls-Royce Eagle 265/300 and the Cummins 290 L10 and 14-litre 350 coupled to a Spicer or Eaton transmission, although all versions produced a distinctive whine from the propshaft knuckle joint when approaching 60 mph (97 km/h). The TL12 engine was dropped early on in the production run, with most large fleet buyers choosing
2508-610: A subsidiary of Paccar . Leyland Motors has a long history dating from 1896, when the Sumner and Spurrier families founded the Lancashire Steam Motor Company in the town of Leyland in North West England. Their first products included steam powered lawn mowers . The company's first vehicle was a 1.5-ton-capacity steam powered van. This was followed by a number of undertype steam wagons using
2640-524: A thin layer of brass, various additives will also be added to the rubber to improve binding, such as resorcinol / HMMM mixtures. The elastomer, which forms the tread and encases the cords to protect them from abrasion and hold them in place, is a key component of pneumatic tire design. It can be composed of various composites of rubber material – the most common being styrene-butadiene copolymer – with other chemical compounds such as silica and carbon black . Optimizing rolling resistance in
2772-507: A variety of profiles and carry loads in the range of 4,000 to 5,500 pounds (1,800 to 2,500 kg) on the drive wheel. These are typically mounted in tandem on the drive axle. Aircraft, bicycles, and a variety of industrial applications have distinct design requirements. Tire construction spans pneumatic tires used on cars, trucks, and aircraft, but also includes non-automotive applications with slow-moving, light-duty, or railroad applications, which may have non-pneumatic tires. Following
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#17328009239002904-413: A vehicle can, and usually, does differ front-to-rear, which allows for the tuning ability of a vehicle for transient and steady-state handling. The roll rate of a vehicle does not change the total amount of weight transfer on the vehicle, but shifts the speed and percentage of weight transferred on a particular axle to another axle through the vehicle chassis. Generally, the higher the roll rate on an axle of
3036-414: A vehicle, the faster and higher percentage the weight transfer on that axle . By 2021, some vehicles were offering dynamic roll control with ride-height adjustable air suspension and adaptive dampers. Roll couple percentage is a simplified method of describing lateral load transfer distribution front to rear, and subsequently handling balance. It is the effective wheel rate, in roll, of each axle of
3168-466: A vehicle. Roll rate is analogous to a vehicle's ride rate, but for actions that include lateral accelerations, causing a vehicle's sprung mass to roll. It is expressed as torque per degree of roll of the vehicle sprung mass. It is influenced by factors including but not limited to vehicle sprung mass, track width, CG height, spring and damper rates, roll centre heights of front and rear, anti-roll bar stiffness and tire pressure/construction. The roll rate of
3300-687: A whole, providing the main advantage of this construction, better traction and smoother motion on uneven surfaces, with a greater tendency to conform to rocky ground and throw off mud and clay, especially because the rubber is usually of a softer compound than that used on radial tires. However, this conformity increases a bias tire's rolling resistance, and its stiffness allows less control, traction , and comfort at higher speeds, while shear between its overlapping plies causes friction that generates heat. Still, bias tires benefit from simpler structure and so cost less than like-size radials, and they remain in use on heavy equipment and off-road vehicles, although
3432-557: Is a non-pneumatic tire that is not supported by air pressure. They are most commonly used on small vehicles, such as golf carts, and on utility vehicles in situations where the risk of puncture is high, such as on construction equipment. Many tires used in industrial and commercial applications are non-pneumatic, and are manufactured from solid rubber and plastic compounds via molding operations. Solid tires include those used for lawnmowers, skateboards, golf carts, scooters , and many types of light industrial vehicles, carts, and trailers. One of
3564-430: Is a term used for a tire that failed inspection during manufacturing - but only for superficial/cosmetic/aesthetic reasons. For example, a tire with white painted lettering which is smudged or incomplete might be classified as a "blem". Blem tires are fully functional and generally carry the same warranty as flawless tires - but are sold at a discount. The materials of modern pneumatic tires can be divided into two groups,
3696-416: Is characterized by a system of circumferential grooves, lateral sipes, and slots for road tires or a system of lugs and voids for tires designed for soft terrain or snow. Grooves run circumferentially around the tire and are needed to channel away water. Lugs are that portion of the tread design that contacts the road surface. Grooves, sipes, and slots allow tires to evacuate water. The design of treads and
3828-426: Is constructed with robust steel cables encased in durable, specially formulated rubber designed to resist stretching. The precision of the bead's fit is crucial, as it seals the tire against the wheel, maintaining air pressure integrity and preventing any loss of air. The bead's design ensures a secure, non-slip connection, preventing the tire from rotating independently from the wheel during vehicle motion. Additionally,
3960-412: Is determined by the instantaneous front view swing arm (FVSA) length of suspension geometry, or in other words, the tendency of the tire to camber inward when compressed in bump. Roll center height is a product of suspension instant center heights and is a useful metric in analyzing weight transfer effects, body roll and front to rear roll stiffness distribution. Conventionally, roll stiffness distribution
4092-454: Is different from what it is under acceleration and braking. This variation in wheel rate may be minimised by locating the spring as close to the wheel as possible. Wheel rates are usually summed and compared with the sprung mass of a vehicle to create a "ride rate" and the corresponding suspension natural frequency in ride (also referred to as "heave"). This can be useful in creating a metric for suspension stiffness and travel requirements for
Car suspension - Misplaced Pages Continue
4224-578: Is entering the European truck market directly. With its purchase of a 26% stake in UK-based bus manufacturer Optare in 2010, Ashok Leyland has taken a step closer to reconnecting with its British heritage, as Optare is a direct descendant of Leyland's UK bus-making division. On 21 December 2011, Ashok Leyland bought an additional 49% stake in Optare, bringing its total to 75%. Historically, Leyland Motors
4356-479: Is equal to the G-force times the sprung weight times the roll moment arm length divided by the effective track width. The front sprung weight transfer is calculated by multiplying the roll couple percentage times the total sprung weight transfer. The rear is the total minus the front transfer. Jacking forces are the sum of the vertical force components experienced by suspension links. The resultant force acts to lift
4488-527: Is key in achieving safety and fuel efficiency in the transportation sector. The most common elastomer material used today is a styrene - butadiene copolymer. It combines the properties of polybutadiene , which is a highly rubbery polymer ( Tg = -100 °C) having high hysteresis and thus offering good wet grip properties, with the properties of polystyrene , which is a glassy polymer ( Tg = 100 °C) having low hysteresis and thus offering low rolling resistance in addition to wear resistance. Therefore,
4620-441: Is key information used in finding the force-based roll center as well. In this respect, the instant centers are more important to the handling of the vehicle, than the kinematic roll center alone, in that the ratio of geometric-to-elastic weight transfer is determined by the forces at the tires and their directions in relation to the position of their respective instant centers. Anti-dive and anti-squat are percentages that indicate
4752-425: Is limited by contact of suspension members (See Triumph TR3B .) Many off-road vehicles , such as desert racers, use straps called "limiting straps" to limit the suspensions' downward travel to a point within safe limits for the linkages and shock absorbers. This is necessary, since these trucks are intended to travel over very rough terrain at high speeds, and even become airborne at times. Without something to limit
4884-617: Is not now accepted by the best English authorities, and is unrecognized in the US" , while Fowler's Modern English Usage of 1926 describes that "there is nothing to be said for 'tyre', which is etymologically wrong, as well as needlessly divergent from our own [sc. British] older & the present American usage". However, over the 20th century, tyre became established as the standard British spelling. The earliest tires were bands of leather , then iron (later steel ) placed on wooden wheels used on carts and wagons . A skilled worker, known as
5016-669: Is still in service, but has now been replaced by the MAN version. In this format the British Army purchased 1,440 vehicles plus a significant number of spare Roadtrain cabs, to allow for accident damage The Leyland Landtrain was produced between 1980 and 1987, specifically for export markets. A bonneted design, it was built in the UK and exported in completed and kit form, the latter for local construction in Kenya and Nigeria. The Leyland Comet
5148-437: Is that part of the tire at the edge of the tread as it makes the transition to the sidewall. Plies are layers of relatively inextensible cords embedded in the rubber to hold its shape by preventing the rubber from stretching in response to the internal pressure. The orientations of the plies play a large role in the performance of the tire and are one of the main ways that tires are categorized. Blem (short for "blemished")
5280-410: Is the "bump-stop", which protects the suspension and the vehicle (as well as the occupants) from the violent "bottoming" of the suspension, caused when an obstruction (or a hard landing) causes suspension to run out of upward travel without fully absorbing the energy of the stroke. Without bump-stops, a vehicle that "bottoms out", will experience a very hard shock when the suspension contacts the bottom of
5412-660: Is tuned adjusting antiroll bars rather than roll center height (as both tend to have a similar effect on the sprung mass), but the height of the roll center is significant when considering the amount of jacking forces experienced. Due to the fact that the wheel and tire's motion is constrained by the vehicle's suspension links, the motion of the wheel package in the front view will scribe an imaginary arc in space with an "instantaneous center" of rotation at any given point along its path. The instant center for any wheel package can be found by following imaginary lines drawn through suspension links to their intersection point. A component of
Car suspension - Misplaced Pages Continue
5544-692: The British Leyland Motor Corporation , formed when it merged with British Motor Holdings in 1968, to become British Leyland after being nationalised . British Leyland later changed its name to simply BL, then in 1986 to Rover Group . After the various vehicle manufacturing businesses of BL and its successors went defunct or were divested, the following marques survived: Jaguar and Land Rover , now built by Jaguar Land Rover owned by TATA Motors ; MG , now built by MG Motor , and Mini , now built by BMW . The truck building operation survived largely intact as Leyland Trucks ,
5676-546: The Kingston upon Thames factory at Ham from 1922 to 1928. Three generations of Spurriers controlled Leyland Motors from its foundation until the retirement of Henry Spurrier in 1964. Spurrier inherited control of Leyland Motors from his father in 1942, and successfully guided its growth during the postwar years. Whilst the Spurrier family were in control the company enjoyed excellent labour relations—reputedly never losing
5808-567: The Landau . By the middle of the 19th century, elliptical springs might additionally start to be used on carriages. Automobiles were initially developed as self-propelled versions of horse-drawn vehicles. However, horse-drawn vehicles had been designed for relatively slow speeds, and their suspension was not well suited to the higher speeds permitted by the internal combustion engine. The first workable spring-suspension required advanced metallurgical knowledge and skill, and only became possible with
5940-551: The Leyland Eight luxury touring car, a development of which was driven by J.G. Parry-Thomas at Brooklands . Parry-Thomas was later killed in an attempt on the land speed record when the car overturned. Rumours that a chain drive broke were found to be incorrect when the car was disinterred late in the 20th century as the chains were intact. At the other extreme, they also produced the Trojan Utility Car in
6072-517: The Rover brand that Leyland had bought in the 1960s, and would eventually gain prominence as BL gradually retired most of its marques. The equity stake in Ashok Leyland was controlled by Land Rover Leyland International Holdings, and sold in 1987. At this point, while building about 10,000 trucks per annum, Leyland was more and more depending on outside engines as production of their own 98-series
6204-479: The radial tire method of construction. Michelin had bought the bankrupt Citroën automobile company in 1934 to utilize this new technology. Because of its superiority in handling and fuel economy, use of this technology quickly spread throughout Europe and Asia. In the US, the outdated bias-ply tire construction persisted until the Ford Motor Company adopted radial tires in the early 1970s, following
6336-529: The vulcanization of natural rubber using sulfur, as well as the development of the "clincher" rim for holding the tire in place laterally on the wheel rim. Synthetic rubbers were invented in the laboratories of Bayer in the 1920s. Rubber shortages in the United Kingdom during WWII prompted research on alternatives to rubber tires with suggestions including leather, compressed asbestos, rayon, felt, bristles, and paper. In 1946, Michelin developed
6468-420: The " Polyglas " trademark tire featuring a polyester carcass with belts of fiberglass. The "belted" tire starts two main plies of polyester, rayon, or nylon annealed as in conventional tires, and then placed on top are circumferential belts at different angles that improve performance compared to non-belted bias tires. The belts may be fiberglass or steel. Tubeless tires are pneumatic tires that do not require
6600-582: The 1840s when the English began shrink-fitting railway car wheels with malleable iron. Nevertheless, many publishers continued using tire . The Times newspaper in London was still using tire as late as 1905. The spelling tyre began to be commonly used in the 19th century for pneumatic tires in the UK. The 1911 edition of the Encyclopædia Britannica states that "The spelling 'tyre'
6732-479: The 1968 Consumer Reports announcement of the superiority of the radial design, radial tires began an inexorable climb in market share, reaching 100% of the North American market in the 1980s. Radial tire technology is now the standard design for essentially all automotive tires, but other methods have been used. Radial (or radial-ply) tire construction utilizes body ply cords extending straight across
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#17328009239006864-472: The G-force times the front unsprung center of gravity height divided by the front track width. The same is true for the rear. Sprung weight transfer is the weight transferred by only the weight of the vehicle resting on its springs, and not by total vehicle weight. Calculating this requires knowing the vehicle's sprung weight (total weight less the unsprung weight), the front and rear roll center heights, and
6996-483: The Rolls-Royce engine. The Roadtrain was available in day- and sleeper-cabbed form, in high and low datum versions—this refers to the cab height—high datum versions were intended as long haul vehicles with higher mounted cabs and more internal space. 6x2 versions were built in high cab form only on a chassis that was basically that of the ageing Scammell trunker. The Constructor's chassis was entirely Routeman behind
7128-465: The TL12. Other engine options included a 200 bhp Leyland L11, as well as Cummins 10- and 14-litre engines at 250 and 330 bhp, respectively. Production began in 1973, and various shortcomings were noted, including below-par heating and ventilation, and pronounced cab roll. However, road testers of the time were very impressed by the truck's power and performance. In 1977, the redesigned "Marathon 2"
7260-534: The Titan and Tiger ranges in 1927 that revolutionised bus design. After 1945, Leyland created another milestone with the trend-setting Atlantean rear-engined double-decker bus design produced between 1956 and 1986. See List of Leyland buses for the list of bus products. The G-series cab was built in Bathgate and was available with several different names, such as Terrier, Clydesdale, and Reiver. After this cab
7392-586: The admittedly short life of commercial vehicles, any Roadtrain in commercial operation is now a very rare sight indeed. However, a small number remain in use throughout the country as towing-and-recovery vehicles. The army made use of an 8x6 version of the Roadtrain as a hook loader until recently. This is known to the British Army as Medium Mobility Load System (MMLS) Demountable Rack Offload and Pickup System (DROPS), which has seen action in Iraq and Afghanistan and
7524-522: The advent of industrialisation . Obadiah Elliott registered the first patent for a spring-suspension vehicle; each wheel had two durable steel leaf springs on each side and the body of the carriage was fixed directly to the springs which were attached to the axles . Within a decade, most British horse carriages were equipped with springs; wooden springs in the case of light one-horse vehicles to avoid taxation , and steel springs in larger vehicles. These were often made of low-carbon steel and usually took
7656-408: The bottom of the tread grooves that indicate the tire has reached its wear limit. When the tread lugs are worn to the point that the wear bars connect across the lugs, the tires are fully worn and should be taken out of service, typically at a remaining tread depth of 1.6 millimetres (0.063 in). The tire bead is the part of the tire that contacts the rim on the wheel. This essential component
7788-634: The bus and truck production becoming the Leyland Truck & Bus division within the Land Rover Leyland Group . This division was split into Leyland Bus and Leyland Trucks in 1981. Leyland Trucks depended on British sales as well as export markets, mainly Commonwealth and ex-Commonwealth markets. The early 1980s were very hard, with export sales drying up in many places such as oil-dependent Nigeria . In 1986, BL changed its name to Rover Group , with its name being derived from
7920-575: The cab, albeit with altered suspension and with the front chassis rails splayed wider apart to fit the new C40 cab. In 1986, the high roofed Roadtrain interstate was introduced, a top of the range long distance truck with standing room inside. The Roadtrain was a common sight throughout most of the 1980s, with a great many of the major fleet users in the UK such as Tesco , Blue Circle Industries (unusually with high datum day cabs) and BRS running them. The firm of Swain's based in Rochester , Kent had
8052-428: The car will settle back to a normal state in a minimal amount of time. Most damping in modern vehicles can be controlled by increasing or decreasing the resistance to fluid flow in the shock absorber. See dependent and independent below. Camber changes due to wheel travel, body roll and suspension system deflection or compliance. In general, a tire wears and brakes best at -1 to -2° of camber from vertical. Depending on
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#17328009239008184-414: The case of the straight axle. When viewed from the front or rear, the wheel rate can be measured by the means above. Yet, because the wheels are not independent, when viewed from the side under acceleration or braking, the pivot point is at infinity (because both wheels have moved) and the spring is directly inline with the wheel contact patch. The result is often, that the effective wheel rate under cornering
8316-416: The cords that make up the ply and the elastomer which encases them. The cords, which form the ply and bead and provide the tensile strength necessary to contain the inflation pressure, can be composed of steel , natural fibers such as cotton or silk , or synthetic fibers such as nylon or kevlar . Good adhesion between the cords and the rubber is important. To achieve this the steel cords are coated in
8448-495: The degree to which the front dives under braking, and the rear squats under acceleration. They can be thought of as the counterparts for braking and acceleration, as jacking forces are to cornering. The main reason for the difference is due to the different design goals between front and rear suspension, whereas suspension is usually symmetrical between the left and the right of the vehicle. The method of determining anti-dive or anti-squat depends on whether suspension linkages react to
8580-464: The distance between wheel centers (wheelbase in the case of braking, or track width in the case of cornering), the height of the center of gravity, the mass of the vehicle, and the amount of acceleration experienced. The speed at which weight transfer occurs, as well as through which components it transfers, is complex, and is determined by many factors; including, but not limited to: roll center height, spring and damper rates, anti-roll bar stiffness, and
8712-567: The dynamic defects of this design were suppressed by the enormous weight of U.S. passenger vehicles before the implementation of the Corporate Average Fuel Economy (CAFE) standard. Another Frenchman invented the De Dion tube , which is sometimes called "semi-independent". Like true independent rear suspension, this employs two universal joints , or their equivalent from the centre of the differential to each wheel. But
8844-401: The earthmoving market has shifted to radials. A belted bias tire starts with two or more bias plies to which stabilizer belts are bonded directly beneath the tread. This construction provides a smoother ride that is similar to the bias tire, while lessening rolling resistance because the belts increase tread stiffness. The design was introduced by Armstrong, while Goodyear made it popular with
8976-421: The elastomer material is a key challenge for reducing fuel consumption in the transportation sector. It is estimated that passenger vehicles consume approximately 5~15% of their fuel to overcome rolling resistance, while the estimate is understood to be higher for heavy trucks. However, there is a trade-off between rolling resistance and wet traction and grip: while low rolling resistance can be achieved by reducing
9108-503: The environment. Moreover, the regular use of tires produces micro-plastic particles that contain these chemicals that both enter the environment and affect human health. The word tire is a short form of attire , from the idea that a wheel with a tire is a dressed wheel. Tyre is the oldest spelling, and both tyre and tire were used during the 15th and 16th centuries. During the 17th and 18th centuries, tire became more common in print. The spelling tyre did not reappear until
9240-475: The first named Volvo Bus model, the Volvo Olympian , and aside from minor frame changes the major alterations were the fitment of Volvo axles, braking system, and controls. Both were the best selling double-deck bus chassis of their time. The Leyland name and logo continues as a recognised and respected marque across India, the wider subcontinent and parts of Africa in the form of Ashok Leyland . Part of
9372-487: The first pneumatic tires. Cyclist Willie Hume demonstrated the supremacy of Dunlop's tires in 1889, winning the tire's first-ever races in Ireland and then England. In Dunlop's tire patent specification dated 31 October 1888, his interest is only in its use in cycles and light vehicles. In September 1890, he was made aware of an earlier development, but the company kept the information to itself. In 1892, Dunlop's patent
9504-413: The form of multiple layer leaf springs. Leaf springs have been around since the early Egyptians . Ancient military engineers used leaf springs in the form of bows to power their siege engines , with little success at first. The use of leaf springs in catapults was later refined and made to work years later. Springs were not only made of metal; a sturdy tree branch could be used as a spring, such as with
9636-430: The frame or body, which is transferred to the occupants and every connector and weld on the vehicle. Factory vehicles often come with plain rubber "nubs" to absorb the worst of the forces, and insulate the shock. A desert race vehicle, which must routinely absorb far higher impact forces, might be provided with pneumatic or hydro-pneumatic bump-stops. These are essentially miniature shock absorbers (dampers) that are fixed to
9768-661: The giant Hinduja Group , Ashok Leyland manufactures buses, trucks, defence vehicles and engines. The company is a leader in the heavy transportation sector within India and has an aggressive expansionary policy. In 1987 the London based Hinduja Group bought the Indian-based Ashok Leyland company. Today, Ashok-Leyland is pursuing a joint venture with Nissan , and through its acquisition of the Czech truck maker, Avia,
9900-436: The global automotive tire market indicate continued growth through 2027. Estimates put the value of worldwide sales volume around $ 126 billion in 2022, it is expected to reach the value of over $ 176 billion by 2027. Production of tires is also experiencing growth. In 2015, the US manufactured almost 170 million tires. Over 2.5 billion tires are manufactured annually, making the tire industry a major consumer of natural rubber. It
10032-419: The grooves, which allow the water from the grooves to escape sideways and mitigate hydroplaning . Different tread designs address a variety of driving conditions. As the ratio of tire tread area to groove area increases, so does tire friction on dry pavement, as seen on Formula One tires , some of which have no grooves. High-performance tires often have smaller void areas to provide more rubber in contact with
10164-413: The ground, which reduces the overall amount of compression available to the suspension, and increases the amount of body lean. Performance vehicles can sometimes have spring rate requirements other than vehicle weight and load. Wheel rate is the effective spring rate when measured at the wheel, as opposed to simply measuring the spring rate alone. Wheel rate is usually equal to or considerably less than
10296-408: The interaction of specific tire types with the roadway surface affects roadway noise , a source of noise pollution emanating from moving vehicles. These sound intensities increase with higher vehicle speeds. Tires treads may incorporate a variety of distances between slots ( pitch lengths ) to minimize noise levels at discrete frequencies. Sipes are slits cut across the tire, usually perpendicular to
10428-495: The interplay between the bead's dimensions and the wheel's width significantly influences the vehicle's steering responsiveness and stability, as it helps to maintain the tire’s intended shape and contact with the road. The sidewall is that part of the tire, or bicycle tire , that bridges between the tread and bead. The sidewall is largely rubber but reinforced with fabric or steel cords that provide for tensile strength and flexibility. The sidewall contains air pressure and transmits
10560-430: The kinematic design of suspension links. In most conventional applications, when weight is transferred through intentionally compliant elements, such as springs, dampers, and anti-roll bars, the weight transfer is said to be "elastic", while the weight which is transferred through more rigid suspension links, such as A-arms and toe links, is said to be "geometric". Unsprung weight transfer is calculated based on weight of
10692-466: The lever arm ratio would be 0.75:1. The wheel rate is calculated by taking the square of the ratio (0.5625) times the spring rate, thus obtaining 281.25 lbs/inch (49.25 N/mm). The ratio is squared because it has two effects on the wheel rate: it applies to both the force and the distance traveled. Wheel rate on independent suspension is fairly straightforward. However, special consideration must be taken with some non-independent suspension designs. Take
10824-468: The model in low-datum form (it was already manufacturing the large DAF 95) as the DAF 80, using the Roadtrain cab with the 11.6-litre (710 cu in) DAF 330 ATi engine (quite ironic, given that this engine had its roots in the Leyland O.680 ). This model was produced for a relatively short time until 1993 with the launch of the brand new cabbed DAF 85. Due partly to the cab's propensity to rust and also to
10956-458: The most common applications for solid tires is for material handling equipment (forklifts). Such tires are installed utilizing a hydraulic tire press. Wooden wheels for horse-drawn vehicles usually have a wrought iron tire. This construction was extended to wagons on horse-drawn tramways, rolling on granite setts or cast iron rails . The wheels of some railway engines and older types of rolling stock are fitted with railway tires to prevent
11088-423: The need to replace the entirety of a wheel. The tire, usually made of steel, surrounds the wheel and is primarily held in place by interference fit . Aircraft tires may operate at pressures that exceed 200 pounds per square inch (14 bar ; 1,400 kPa ). Some aircraft tires are inflated with nitrogen to "eliminate the possibility of a chemical reaction between atmospheric oxygen and volatile gases from
11220-486: The new Ashok factory. The products were branded as Ashok Leyland . Leyland Motors acquired other companies in the post war years: Donald Stokes , previously Sales Director, was appointed managing director of Leyland Motors Limited in September 1962. Originally a Leyland student apprentice he had grown up with the company. He became chairman in 1966. Chronologically, the 1960s growth of Leyland Motor Corporation (LMC)
11352-402: The range of 30 to 40 degrees from the direction of travel. Successive plies are laid at opposing angles, forming a crisscross pattern to which the tread is applied. Such a design is resistant to sidewall deformation and punctures (and to punctures’ expansion, or “torque splitting”) and therefore durable in severe use. Since the tread and sidewalls share their casing plies, the tire body flexes as
11484-639: The range of 550 to 1,100 pounds (250 to 500 kg) on the drive wheel. Light-to-medium duty trucks and vans carry loads in the range of 1,100 to 3,300 pounds (500 to 1,500 kg) on the drive wheel. They are differentiated by speed rating for different vehicles, including (starting from the lowest speed to the highest): winter tires, light truck tires, entry-level car tires, sedans and vans, sport sedans, and high-performance cars. Apart from road tires, there are special categories: Other types of light-duty automotive tires include run-flat tires and race car tires: Heavy-duty tires for large trucks and buses come in
11616-530: The ratio of the two monomers in the styrene-butadiene copolymer is considered key in determining the glass transition temperature of the material, which is correlated to its grip and resistance properties. Non-exhaust emissions of particulate matter, generated by the wearing down of brakes, clutches, tires, and road surfaces, as well as by the suspension of road dust, constitute a little-known but rising share of emissions from road traffic and significantly harm public health. Associated components of tires include
11748-435: The road for higher traction, but may be compounded with softer rubber that provides better traction, but wears quickly. Mud and snow (M&S) tires employ larger and deeper slots to engage mud and snow. Snow tires have still larger and deeper slots that compact snow and create shear strength within the compacted snow to improve braking and cornering performance. Wear bars (or wear indicators) are raised features located at
11880-442: The road wheel in contact with the road surface as much as possible, because all the road or ground forces acting on the vehicle do so through the contact patches of the tires . The suspension also protects the vehicle itself and any cargo or luggage from damage and wear. The design of front and rear suspension of a car may be different. An early form of suspension on ox -drawn carts had the platform swing on iron chains attached to
12012-402: The spring rate. Commonly, springs are mounted on control arms, swing arms or some other pivoting suspension member. Consider the example above, where the spring rate was calculated to be 500 lbs/inch (87.5 N/mm), if one were to move the wheel 1 in (2.5 cm) (without moving the car), the spring more than likely compresses a smaller amount. If the spring moved 0.75 in (19 mm),
12144-438: The sprung center of gravity height (used to calculate the roll moment arm length). Calculating the front and rear sprung weight transfer will also require knowing the roll couple percentage. The roll axis is the line through the front and rear roll centers that the vehicle rolls around during cornering. The distance from this axis to the sprung center of gravity height is the roll moment arm length. The total sprung weight transfer
12276-430: The sprung mass, if the roll center is above ground, or compress it, if underground. Generally, the higher the roll center , the more jacking force is experienced. Travel is the measure of distance from the bottom of the suspension stroke (such as when the vehicle is on a jack, and the wheel hangs freely) to the top of the suspension stroke (such as when the vehicle's wheel can no longer travel in an upward direction toward
12408-431: The surface over which the wheel travels. Most tires, such as those for automobiles and bicycles, are pneumatically inflated structures, providing a flexible cushion that absorbs shock as the tire rolls over rough features on the surface. Tires provide a footprint, called a contact patch , designed to match the vehicle's weight and the bearing on the surface that it rolls over by exerting a pressure that will avoid deforming
12540-403: The surface. The materials of modern pneumatic tires are synthetic rubber , natural rubber , fabric, and wire, along with carbon black and other chemical compounds. They consist of a tread and a body. The tread provides traction while the body provides containment for a quantity of compressed air . Before rubber was developed, tires were metal bands fitted around wooden wheels to hold
12672-530: The suspension to become ineffective – mostly because they fail to properly isolate the vehicle from the road. Vehicles that commonly experience suspension loads heavier than normal, have heavy or hard springs, with a spring rate close to the upper limit for that vehicle's weight. This allows the vehicle to perform properly under a heavy load, when control is limited by the inertia of the load. Riding in an empty truck meant for carrying loads can be uncomfortable for passengers, because of its high spring rate relative to
12804-516: The time, so the Abbot-Downing Company of Concord, New Hampshire re-introduced leather strap suspension, which gave a swinging motion instead of the jolting up-and-down of spring suspension. In 1901, Mors of Paris first fitted an automobile with shock absorbers . With the advantage of a damped suspension system on his 'Mors Machine', Henri Fournier won the prestigious Paris-to-Berlin race on 20 June 1901. Fournier's superior time
12936-476: The tire and the road surface, it may hold the road best at a slightly different angle. Small changes in camber, front and rear, can be used to tune handling. Some racecars are tuned with -2 to -7° camber, depending on the type of handling desired, and tire construction. Often, too much camber will result in the decrease of braking performance due to a reduced contact patch size through excessive camber variation in suspension geometry. The amount of camber change in bump
13068-400: The tire inner liner producing a tire explosion". Pneumatic tires are manufactured in about 450 tire factories around the world. Tire production starts with bulk raw materials such as rubber, carbon black, and chemicals and produces numerous specialized components that are assembled and cured. Many kinds of rubber are used, the most common being styrene-butadiene copolymer . Forecasts for
13200-435: The tire's force vector points from the contact patch of the tire through instant center. The larger this component is, the less suspension motion will occur. Theoretically, if the resultant of the vertical load on the tire and the lateral force generated by it points directly into the instant center, the suspension links will not move. In this case, all weight transfer at that end of the vehicle will be geometric in nature. This
13332-461: The torque applied by the drive axle to the tread to create traction but supports little of the weight of the vehicle, as is clear from the total collapse of the tire when punctured. Sidewalls are molded with manufacturer-specific detail, government-mandated warning labels, and other consumer information. Sidewall may also have sometimes decorative ornamentation that includes whitewall or red-line inserts as well as tire lettering . The shoulder
13464-427: The torque of braking and accelerating. For example, with inboard brakes and half-shaft-driven rear wheels, the suspension linkages do not react, but with outboard brakes and a swing-axle driveline, they do. Tires A tire ( British spelling : tyre ) is a ring-shaped component that surrounds a wheel's rim to transfer a vehicle's load from the axle through the wheel to the ground and to provide traction on
13596-413: The travel, the suspension bushings would take all the force, when suspension reaches "full droop", and it can even cause the coil springs to come out of their "buckets", if they are held in by compression forces only. A limiting strap is a simple strap, often from nylon of a predetermined length, that stops downward movement at a pre-set point before theoretical maximum travel is reached. The opposite of this
13728-507: The tread from bead to bead—so that the cords are laid at approximately right angles to the centerline of the tread, and parallel to one another—as well as stabilizer belts directly beneath the tread. The plies are generally made of nylon, polyester, or steel, and the belts of steel, fiberglass, or Kevlar . The tire’s footprint, wider than a bias tire’s, and flexible sidewalls provide a better grip in turns, and its circumferential belts stabilize it. The advantages of this construction over that of
13860-414: The vehicle as a ratio of the vehicle's total roll rate. It is commonly adjusted through the use of anti-roll bars , but can also be changed through the use of different springs. Weight transfer during cornering, acceleration, or braking is usually calculated per individual wheel, and compared with the static weights for the same wheels. The total amount of weight transfer is only affected by four factors:
13992-429: The vehicle in a location, such, that the suspension will contact the end of the piston when it nears the upward travel limit. These absorb the impact far more effectively than a solid rubber bump-stop will, essential, because a rubber bump-stop is considered a "last-ditch" emergency insulator for the occasional accidental bottoming of the suspension; it is entirely insufficient to absorb repeated and heavy bottoming, such as
14124-590: The vehicle inoperable to blowouts , where tires explode during operation and possibly damage vehicles and injure people. The manufacture of tires is often highly regulated for this reason. Because of the widespread use of tires for motor vehicles, tire waste is a substantial portion of global waste. There is a need for tire recycling through mechanical recycling and reuse, such as for crumb rubber and other tire-derived aggregate , and pyrolysis for chemical reuse, such as for tire-derived fuel . If not recycled properly or burned , waste tires release toxic chemicals into
14256-433: The vehicle's components that are not supported by the springs. This includes tires, wheels, brakes, spindles, half the control arm's weight, and other components. These components are then (for calculation purposes) assumed to be connected to a vehicle with zero sprung weight. They are then put through the same dynamic loads. The weight transfer for cornering in the front would be equal to the total unsprung front weight times
14388-408: The vehicle). Bottoming or lifting a wheel can cause serious control problems, or directly cause damage. "Bottoming" can be caused by the suspension, tires, fenders, etc. running out of space to move, or the body or other components of the car hitting the road. Control problems caused by lifting a wheel are less severe, if the wheel lifts when the spring reaches its unloaded shape than they are, if travel
14520-468: The viscoelastic properties of the rubber compound (low tangent (δ) ), it comes at the cost of wet traction and grip, which requires hysteresis and energy dissipation (high tangent (δ)). A low tangent (δ) value at 60 °C is used as an indicator of low rolling resistance, while a high tangent (δ) value at 0 °C is used as an indicator of high wet traction. Designing an elastomer material that can achieve both high wet traction and low rolling resistance
14652-495: The weight of the vehicle. A race car could also be described as having heavy springs, and would also be uncomfortably bumpy. However, even though we say they both have heavy springs, the actual spring rates for a 2,000 lb (910 kg) racecar and a 10,000 lb (4,500 kg) truck are very different. A luxury car, taxi, or passenger bus would be described as having soft springs, for the comfort of their passengers or driver. Vehicles with worn-out or damaged springs ride lower to
14784-580: The wheel on which it is mounted, the valve stem through which air is introduced, and, for some tires, an inner tube that provides the airtight means for maintaining tire pressure. Leyland Motors Leyland Motors Limited (later known as the Leyland Motor Corporation ) was an English vehicle manufacturer of lorries , buses and trolleybuses . The company diversified into car manufacturing with its acquisitions of Triumph and Rover in 1960 and 1967, respectively. It gave its name to
14916-567: The wheel together under load and to prevent wear and tear. Early rubber tires were solid (not pneumatic). Pneumatic tires are used on many vehicles, including cars , bicycles , motorcycles , buses , trucks , heavy equipment , and aircraft . Metal tires are used on locomotives and railcars , and solid rubber (or other polymers) tires are also used in various non-automotive applications, such as casters , carts , lawnmowers , and wheelbarrows . Unmaintained tires can lead to severe hazards for vehicles and people, ranging from flat tires making
15048-403: The wheeled frame of the carriage. This system remained the basis for most suspension systems until the turn of the 19th century, although the iron chains were replaced with the use of leather straps called thoroughbraces by the 17th century. No modern automobiles have used the thoroughbrace suspension system. By approximately 1750, leaf springs began appearing on certain types of carriage, such as
15180-514: The wheels cannot entirely rise and fall independently of each other; they are tied by a yoke that goes around the differential, below and behind it. This method has had little use in the United States . Its use around 1900 was probably due to the poor quality of tires, which wore out quickly. By removing a good deal of unsprung weight , as independent rear suspensions do, it made them last longer. Rear-wheel drive vehicles today frequently use
15312-593: Was 11 hours 46 minutes and 10 seconds, while the best competitor was Léonce Girardot in a Panhard with a time of 12 hours, 15 minutes, and 40 seconds. Coil springs first appeared on a production vehicle in 1906 in the Brush Runabout made by the Brush Motor Company. Today, coil springs are used in most cars. In 1920, Leyland Motors used torsion bars in a suspension system. In 1922, independent front suspension
15444-597: Was a major manufacturer of buses used in the United Kingdom and worldwide. It achieved a number of firsts or milestones that set trends for the bus industry. It was one of the first manufacturers to devise chassis designs for buses that were different from trucks, with a lower chassis level to help passengers board more easily. Its chief designer, John George Rackham, who had experience at the Yellow Coach Company in Chicago before returning to England, created
15576-742: Was a max weight model with distance work in mind. The T45's cab is called the C40 and its design was a joint effort between Leyland, BRS and Ogle Design and was seen as the height of modernity when compared with its predecessors, the idea being to have one basic design to replace the various outgoing models (for example, the Bathgate built the G cab on the Terrier, the Ergomatic cabbed the Lynx, Beaver etc.). This did indeed make good economic sense; however, there has been speculation that Leyland did in fact alienate
15708-461: Was a range of heavy goods vehicle tractor units manufactured by Leyland Trucks between 1980 and 1990. The nomenclature "T45" refers to the truck range as a whole and encompasses models such as the lightweight 7.5-ton Roadrunner, Freighter (fourwheel rigid truck), Constructor (multi-axle rigid tipper or mixer chassis – its chassis owing much to the outgoing Scammell 8-wheeler Routeman ), and Cruiser (basic spec low weight tractor unit). The Roadtrain itself
15840-686: Was as follows: In 1968 Leyland Motors merged with British Motor Holdings (BMH) to form the British Leyland Motor Corporation (BLMC). BMH, which was the product of an earlier merger between the British Motor Corporation , the Pressed Steel Company and Jaguar , brought with it more marques , including Daimler , Guy , BMC , Austin , MG and Morris . Leyland diesel engines were used in Finnish Sisu and Vanaja lorries and buses in 1960s. The BLMC group
15972-472: Was available in day and sleeper cab form. Engines were decided from the outset to be in the higher power category to be competitive with rival vehicles. The only existing engine within the Leyland empire suitable for such an application (following the demise of the ill-fated fixed-head 500 series and AEC's underdeveloped and unreliable V8) was the AEC AV760 straight-six, which was turbocharged and designated as
16104-697: Was declared invalid because of the prior art by forgotten fellow Scot Robert William Thomson of London (patents London 1845, France 1846, USA 1847). However, Dunlop is credited with "realizing rubber could withstand the wear and tear of being a tire while retaining its resilience". John Boyd Dunlop and Harvey du Cros worked through the ensuing considerable difficulties. They employed inventor Charles Kingston Welch and acquired other rights and patents, which allowed them some limited protection of their Pneumatic Tyre business's position. Pneumatic Tyre would become Dunlop Rubber and Dunlop Tyres . The development of this technology hinged on myriad engineering advances, including
16236-591: Was difficult to manage because of the many companies under its control, often making similar products. This, and other reasons, led to financial difficulties and in December 1974 British Leyland had to receive a guarantee from the British government. In 1975, after the publication of the Ryder Report and the company's bankruptcy, BLMC was nationalised as British Leyland (BL) and split into four divisions with
16368-528: Was estimated that for 2019 onwards, at least 3 billion tires would be sold globally every year. However, other estimates put worldwide tire production of 2,268 million in 2021 and is predicted to reach 2,665 million tires by 2027. As of 2011, the top three tire manufacturing companies by revenue were Bridgestone (manufacturing 190 million tires), Michelin (184 million), Goodyear (181 million); they were followed by Continental , and Pirelli . The Lego group produced over 318 million toy tires in 2011 and
16500-560: Was introduced in 1986, also designed for export markets mainly in the developing world. As such, it was a no-frills vehicle of a simple and sturdy design, with five- or six-speed transmissions rather than the multi-speed units used on European models. The cabin was a simplified all-steel version of that used by the Roadrunner, designed to enable local assembly. The three-axle version is called the Super Comet. Leyland Motors produced
16632-534: Was launched, an updated and revised vehicle that attempted to address some of the previous criticisms of the earlier vehicle. Relatively few Marathons of all types were sold before production ended in 1979 with the introduction of the T45 "roadtrain" range of vehicles. This was Leyland's answer to the Ford cargo in the non-HGV 7.5-ton truck sector. Launched in 1984, it utilised a Leyland 698 straight-six engine until 1986, when
16764-410: Was made in 1888 on May Street, Belfast , by Scots-born John Boyd Dunlop , owner of one of Ireland's most prosperous veterinary practices. It was an effort to prevent the headaches of his 10-year-old son Johnnie while riding his tricycle on rough pavements. His doctor, John, later Sir John Fagan, had prescribed cycling as an exercise for the boy and was a regular visitor. Fagan participated in designing
16896-412: Was pioneered on Lancia Lambda , and became more common in mass market cars from 1932. Today, most cars have independent suspension on all four wheels. The part on which pre-1950 springs were supported is called a dumb iron . In 2002, a new passive suspension component, the inerter , was invented by Malcolm C. Smith . This has the ability to increase the effective inertia of wheel suspension using
17028-549: Was recognized by Guinness World Records as having the highest annual production of tires by any manufacturer. A tire comprises several components: the tread, bead, sidewall, shoulder, and ply. The tread is the part of the tire that comes in contact with the road surface. The portion that is in contact with the road at a given instant in time is the contact patch . The tread is a thick rubber, or rubber/composite compound formulated to provide an appropriate level of traction that does not wear away too quickly. The tread pattern
17160-568: Was replaced the tooling was shipped to Turkey, where BMC's Turkish subsidiary built it as the "BMC Yavuz" and then as the "Fatih" (with Cummins engines) from 1986 until 1996. The Marathon was Leyland's answer to the booming "max cap" truck fad at the start of the 1970s. Imports such as the Volvo F88 and Scania 110/140 were selling very well in the UK thanks to the previously unheard of levels of driver comfort, reliability, quality and performance. Leyland had insufficient money for development of
17292-562: Was steadily declining. The 1986 closure of Bedford Vehicles ' heavy truck plant further harmed Leyland, as they had been planning on selling axles and other components to the General Motors subsidiary. The bus operations was sold in a management buyout to form Leyland Bus , and was subsequently bought by Volvo in 1988, which then discontinued most of its product range but kept the Olympian . Volvo reengineered and renamed it as
17424-457: Was the most popular rear suspension system used in American cars from the 1930s to the 1970s. The system uses longitudinal leaf springs attached both forward and behind the differential of the live axle . These springs transmit torque to the frame. Although scorned by many European car makers of the time, it was accepted by American car makers, because it was inexpensive to manufacture. Also,
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