The High Speed Freight Vehicle was a generic term for a number of prototype four-wheeled rail vehicles which were fitted with various experimental suspensions developed by the British Rail Research Division in the late 1960s. The development was part of the investigation into the riding of vehicles and the interaction between wheel and rail.
34-554: HSFV1 was intended for fundamental empirical research into wheel-rail interaction and suspension dynamics to be better understood, following from work on wheel tread profiles. It was regularly run at speeds of up to 140 mph (230 km/h) on the Vehicles Laboratory's roller rig. It also performed at 90 mph (140 km/h) whilst under test on the main line. Its suspension had two vertical coil springs and two vertical and one lateral hydraulic damper at each corner of
68-485: A better ride. Examples include the various rear suspensions of Austin-Healey 3000s and Fiat 128s . The earliest known leaf springs began appearing on carriages in France in the mid-17th century in the form of the two-part elbow spring (as the illustrated example from Lisbon), and later migrated to England and Germany, appearing on the carriages of the wealthy in those countries around 1750. Dr. Richard Lovell Edgeworth
102-594: A favourite material for blacksmiths . In countries such as India , Nepal , Bangladesh , Philippines , Myanmar and Pakistan , where traditional blacksmiths still produce a large amount of the country's tools, leaf springs from scrapped cars are frequently used to make knives, kukris , and other tools. They are also commonly used by amateur and hobbyist blacksmiths. Leaf springs have also replaced traditional coil springs in some trampolines (known as soft-edge trampolines), which improves safety for users and reduces risk of concussion. The leaf springs are spaced around
136-512: A leaf spring usually are formed into round eyes or eyelets, through which a fastener connects each end of the spring to the vehicle frame or body . Some springs terminated in a concave end, called a spoon end (seldom used now), to carry a swivelling member instead. One eye is usually fixed but allowed to pivot with the motion of the spring, whereas the other eye is fastened to a hinge mechanism that allows that end to pivot and undergo limited movement. A leaf spring can either be attached directly to
170-413: A long double leaf spring and having hydraulic dampers inclined at 45 degrees to effect both vertical and lateral movement. On test these vehicles were capable of 90 mph (140 km/h) but in service were limited to 75 mph (120 km/h) due to their running with other UIC long-link suspension vans. Ultimately they were converted to standard after a few years, except two examples. One of these
204-707: A medical setting in the early 20th century. Another common needle gauge system is the French catheter scale . Needle wire gauge was derived from the Stubs Iron Wire Gauge. Hypodermic needles are available in a wide variety of outer diameters described by gauge numbers. Smaller gauge numbers indicate larger outer diameters. Inner diameter depends on both gauge and wall thickness. The following chart shows nominal inner diameter and wall thickness for regular-wall needles. Thin-wall needles (not shown) have identical outer diameters but larger inner diameters for
238-475: A traction rod at each corner. Although they were excellent riding vehicles in the railway of the day they were viewed as experimental only and far too expensive for widespread adoption. It was also thought that the sophisticated suspension would not stand up to the daily rigours to which freight vehicles were subjected. However in the early 1970s these experiments resulted in ten covered air-braked vans (COV-AB) being fitted with Taperlite suspension consisting of
272-507: Is characterized by fewer leaves whose thickness varies from centre to ends following a parabolic curve . The intention of this design is to reduce inter-leaf friction, and therefore there is only contact between the leaves at the ends and at the centre, where the axle is connected. Spacers prevent contact at other points. Aside from weight-saving, the main advantage of parabolic springs is their greater flexibility, which translates into improved ride quality , which approaches that of coil springs;
306-415: Is not well controlled, resulting in stiction and irregular suspension motions. For this reason, some manufacturers have used mono-leaf springs. A leaf spring takes the form of a slender arc -shaped length of spring steel of a rectangular cross-section. In the most common configuration, the centre of the arc provides the location for the axle , while loops formed at either end provide for attaching to
340-565: Is one or more narrow, arc-shaped, thin plates that are attached to the axle and chassis in a way that allows the leaf spring to flex vertically in response to irregularities in the road surface. Lateral leaf springs are the most commonly used arrangement, running the length of the vehicle and mounted perpendicular to the wheel axle, but numerous examples of transverse leaf springs exist as well. Leaf springs can serve multiple suspension functions: location, springing, and to some extent damping as well, through interleaf friction. However, this friction
374-480: Is specified by the Stubbs or Birmingham gauge , with typical thicknesses ranging between 0.203 to 0.375 in (5.2 to 9.5 mm) (6 to 3/8 or 00 gauge). The material and dimensions should be selected such that each leaf is capable of being hardened to have a fully martensitic structure throughout the entire section. Suitable spring steel alloys include 55Si7, 60Si7, 65Si7, 50Cr4V2, and 60Cr4V2. The two ends of
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#1732793703476408-608: The Hotchkiss drive . That employed the lower arc, hence its name. "Quarter-elliptic" springs often had the thickest part of the stack of leaves stuck into the rear end of the side pieces of a short ladder frame, with the free end attached to the differential, as in the Austin Seven of the 1920s. As an example of non-elliptic leaf springs, the Ford Model T had multiple leaf springs over its differential that were curved in
442-550: The Stubs Iron Wire Gauge or Birmingham Wire Gauge . It is not the same as, though similar to, the Stubs Steel Wire Gauge . Birmingham gauge is often simply termed Gauge , with the abbreviation G . However, this should not be confused with French gauge . The gauge starts at the lowest gauge number of 5Ø or 00000, corresponding to the largest size of 0.500 inches (12.7 mm), and runs to
476-419: The frame at both eyes or attached directly at one end, usually the front, with the other end attached through a shackle: a short swinging arm. The shackle takes up the tendency of the leaf spring to elongate when compressed and thus makes the suspension softer. The shackle provides some degree of flexibility to the leaf spring so that it does not fail when subjected to heavy loads. The axle is usually fastened to
510-459: The British inventor Obadiah Elliott , referred to two circular arcs linked at their tips. This was joined to the frame at the top centre of the upper arc, the bottom centre was joined to the "live" suspension components, such as a solid front axle. Additional suspension components, such as trailing arms , would usually be needed for this design, but not for "semi-elliptical" leaf springs as used in
544-646: The National Railway Museum chose not to preserve it, but NRM have recently relented and it is now displayed at Shildon alongside the restored APT-E, which after all benefitted from the fundamental research carried out into wheel/rail interaction with HSFV1. HSFV4 is also still extant at the Eden Valley Railway where it is undergoing restoration. A number of vehicles were produced, including HSFV1 and HSFV4, with various tests being carried out between 1975 and 1979. A variant of HSFV1 formed
578-400: The advantage of spreading the load more widely over the vehicle's chassis, whereas coil springs transfer it to a single point. Unlike coil springs, leaf springs also locate the rear axle, eliminating the need for trailing arms and a Panhard rod , thereby saving cost and weight in a simple live axle rear suspension. A further advantage of a leaf spring over a helical spring is that the end of
612-462: The basis for the suspension of the Class 140 Pacer railbus. Leaf spring A leaf spring is a simple form of spring commonly used for suspension in wheeled vehicles . Originally called a laminated or carriage spring , and sometimes referred to as a semi-elliptical spring , elliptical spring , or cart spring , it is one of the oldest forms of vehicle suspension. A leaf spring
646-403: The frame as 'legs' that branch from the base frame to suspend the jumping mat, providing flexibility and resilience. The "diaphragm" common in automotive clutches is a type of leaf spring. Birmingham gauge The Birmingham gauge is a wire gauge system, and is also used to specify thickness or diameter of hypodermic needles and tube products. Birmingham gauge is also known as
680-451: The front suspension of the 1983 Corvette . This arrangement uses a straight leaf spring that is tightly secured to the chassis at the centre; the ends of the spring are bolted to the wheel suspension, allowing the spring to work independently on each wheel. This suspension is smaller, flatter and lighter than a traditional setup. Multi-leaf springs are made as follows. Because leaf springs are made of relatively high quality steel, they are
714-511: The gauge number is used to specify the outside diameter of the product, whereas for larger mechanical tubing the gauge number specifies the wall thickness independent of the overall size of the tube. In medicine , the Birmingham gauge specifies the outside diameter of hypodermic needles , catheters , cannulae and suture wires. It was originally developed in early 19th-century England for use in wire manufacture, and began appearing in
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#1732793703476748-431: The highest gauge number of 36, corresponding to the smallest size of 0.004 inches (0.10 mm). Size steps between gauges range from 0.001 inches (0.025 mm) between high gauge numbers to 0.046 inches (1.2 mm) between the two lowest gauge numbers and do not correspond to a particular mathematical pattern, although for the most part the steps get smaller with increasing gauge number. Concerning wire and fine tubing,
782-504: The latter half of the 19th century as well, making the manufacture of leaf springs more consistent and less expensive. Leaf springs were very common on automobiles until the 1970s when automobile manufacturers shifted primarily to front-wheel drive , and more sophisticated suspension designs were developed using coil springs instead. Today leaf springs are still used in heavy commercial vehicles such as vans and trucks , SUVs , and railway carriages . For heavy vehicles, they have
816-412: The leaf both supports an axle and locates/partially locates the axle. This can lead to handling issues (such as "axle tramp"), as the flexible nature of the spring makes precise control of the unsprung mass of the axle difficult. Some suspension designs use a Watts link (or a Panhard rod ) and radius arms to locate the axle and do not have this drawback. Such designs can use softer springs, resulting in
850-416: The leaf spring is also serving to hold the axle in position, soft springs—i.e. springs with low spring constant—are not suitable. The consequent stiffness, in addition to inter-leaf friction, makes this type of suspension not particularly comfortable for the riders. There are a variety of leaf springs, usually employing the word "elliptical". "Elliptical" or "full elliptical" leaf springs, patented in 1804 by
884-465: The leaf spring may be guided along a definite path. In many late 1990s and early 2000s trucks, the leaf spring is connected to a Hinkle Beam ball joint. The leaf spring also has seen modern applications in cars. For example, the 1963 Chevrolet Corvette Sting Ray uses a transverse leaf spring for its independent rear suspension. Similarly, 2016 Volvo XC90 has a transverse leaf spring using composite materials for its rear suspension, similar in concept to
918-400: The middle of the spring by U-bolts . The leaf spring acts as a linkage to hold the axle in position and thus separate linkages are not necessary. The result is a suspension that is simple and strong. Inter-leaf friction dampens the spring's motion and reduces rebound, which, until shock absorbers were widely adopted, was a very significant advantage over helical springs . However, because
952-613: The other leaves are tapered at each end. Sometimes auxiliary or rebound leaves are part of the main spring pack, in which case the auxiliary leaf closest to the main leaf is No. 1, the next closest is No. 2, etc. The leaves are attached to each other through the centre bolt, which is at or near the mid-point along the length of the leaf spring. To ensure that leaves remain aligned laterally, several methods can be used, including notches and grooves between leaves or external clips. Spring steels were discovered to be most efficient at approximately 1% carbon content. Individual leaf thickness
986-420: The shape of a yoke . As a substitute for dampers ( shock absorbers ), some manufacturers laid non-metallic sheets in between the metal leaves, such as wood. Elliot's invention revolutionized carriage design and construction, removing the need for a heavy perch and making transportation over rough roadways faster, easier, and less expensive. A more modern implementation is the parabolic leaf spring. This design
1020-575: The trade-off is reduced load carrying capability. They are widely used on buses for improved comfort. A further development by the British GKN company and by Chevrolet, with the Corvette, among others, is the move to composite plastic leaf springs. Nevertheless, due to the lack of inter-leaf friction and other internal dampening effects, this type of spring requires more powerful dampers/shock absorbers. Typically when used in automobile suspension
1054-413: The vehicle chassis. For very heavy vehicles, a leaf spring can be made from several leaves stacked on top of each other in several layers, often with progressively shorter leaves. The longest leaf is also known as the main, master, or No. 1 leaf, with leaves numbered in descending order of length. The eyes at the end of the leaf spring are formed into the master leaf. In general, aside from the main leaf,
High Speed Freight Vehicle - Misplaced Pages Continue
1088-443: The vehicle. This was at a time when few freight trains travelled at more than 40 mph (65 km/h) and most passenger trains averaged about 70 mph (110 km/h). It supported theories of vehicle design which led to most later designs of train. A similar converted UIC long-wheelbase four-wheeled ferry van (HSFV4) was utilised for high-speed trials. HSFV4 had two coil springs with two 45-degree-inclined hydraulic dampers and
1122-859: Was awarded three gold medals by the Society of English Arts and Manufacturers in 1768 for demonstrating the superiority of sprung carriages. By 1796, William Felton 's A Treatise on Carriages showed that leaf springs were being marketed regularly by the late 18th century carriage industry. Obadiah Elliot is credited with inventing the modern leaf spring with his 1804 patent on elliptical leaf springs, which brought him significant recognition and revenue, and engineers began studying leaf springs to develop improved designs and manufacturing processes. The mechanics and deflection of leaf springs were developed by Clark (1855), Franz Reuleaux (1861), and G.R. Henderson (1894). Improved steel rolling processes, process instruments, and spring steel alloys were developed during
1156-910: Was used by the R&;DD on the Tribometer train and one by the DM&;EE on their own test trains. HSFV1 survived until recently in Serco stock at the RTC, but in May 2010 was moved out on its way to preservation. It was intended that it would eventually be displayed at the Electric Railway Museum in Coventry, but that museum is now closed. HSFV1 was donated to the APT-E preservation Group by Serco after
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