105-479: Alexander Eric Moulton (9 April 1920 – 9 December 2012) was an English engineer and inventor, specialising in suspension design. Moulton's father, John Coney Moulton , was a naturalist working in the Far East. Alex Moulton was the great-grandson of the rubber pioneer Stephen Moulton , the founder of the family business called George Spencer, Moulton & Co. Ltd, based at Bradford-on-Avon , Wiltshire. Moulton
210-440: 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
315-494: 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
420-633: 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
525-448: 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
630-463: 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,
735-479: 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
840-498: 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 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,
945-400: A suspension system. In 1922, independent front suspension 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
1050-524: 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
1155-507: 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
SECTION 10
#17327879371051260-547: 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 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
1365-416: 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 a vehicle can, and usually, does differ front-to-rear, which allows for
1470-537: A wheel are less severe, if the wheel lifts when the spring reaches its unloaded shape than they are, if travel 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
1575-687: 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
1680-422: 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 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
1785-557: 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
1890-419: 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 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
1995-430: 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,
2100-416: 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
2205-413: 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 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
SECTION 20
#17327879371052310-426: 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,
2415-412: 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
2520-527: 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,
2625-441: 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
2730-617: 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
2835-405: 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 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
2940-437: 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")
3045-410: 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
3150-412: 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 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
3255-660: 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
Alex Moulton - Misplaced Pages Continue
3360-486: 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: 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,
3465-581: The Avon Rubber Company in 1956, Moulton established Moulton Developments Limited to design the suspension system for British Motor Corporation 's new small car, the Mini , that was being designed by Issigonis. The combination of conical rubber springs and small wheels was one of the many innovative developments that allowed Issigonis to achieve the Mini's small overall size. This was later refined into
3570-454: 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 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
3675-608: The Grade I listed Hall – along with investments, land, outbuildings and cottages – was gifted to a charitable trust. In 2020 the trust was reorganised as a charitable incorporated organisation , the Alex Moulton Charitable Trust, which continues to preserve and maintain the Hall and its collections, and promote engineering and design. The Moulton Bicycle name has undergone several changes of ownership. Since 2008
3780-568: 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
3885-506: 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 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)
3990-570: The hydrolastic and hydragas suspension systems used on later British Leyland cars such as the Austin Maxi , Austin Allegro , Princess and Rover Metro , and later on Rover Group 's MG F sports car. Moulton also designed the Moulton bicycle , launched in 1962, again using rubber suspension and small wheels. A factory was built at Bradford-on-Avon, and Moulton Bicycles Ltd soon became
4095-479: 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
4200-529: 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
4305-420: 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
Alex Moulton - Misplaced Pages Continue
4410-630: 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'
4515-479: 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
4620-502: The ability to increase the effective inertia of wheel suspension using 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
4725-414: 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 the ground, which reduces the overall amount of compression available to the suspension, and increases
4830-483: 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 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
4935-522: 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
5040-436: 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 the spring rate. Commonly, springs are mounted on control arms, swing arms or some other pivoting suspension member. Consider
5145-408: 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
5250-428: 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
5355-416: 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
SECTION 50
#17327879371055460-495: 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
5565-415: The development of the superior, but more expensive independent suspension layout has been difficult. Henry Ford 's Model T used 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
5670-528: 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, 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
5775-401: 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
5880-421: 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
5985-503: 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
6090-468: 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), 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
6195-487: 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
6300-414: 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
6405-430: 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
SECTION 60
#17327879371056510-436: 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
6615-419: 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
6720-408: 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
6825-495: 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
6930-457: The mid 1950s, Moulton developed an experimental rubber suspension which was tested on a Morris Minor . His friend Alec Issigonis heard of this work and together they designed a fluid and rubber suspension for a new Alvis car, which did not reach production. Moulton also designed "Flexitor" rubber springs for the 1958 Austin Gipsy , an off-road vehicle. After the family business was acquired by
7035-458: 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
7140-484: The name has been used by a privately held company which has a small modern factory just east of the Hall. Suspension (vehicle) 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
7245-423: 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
7350-449: The platform swing on iron chains attached to 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
7455-402: 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
7560-639: 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
7665-530: 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
7770-461: The right compromise. It is important for the suspension to keep 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
7875-435: 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
7980-605: The second-largest frame builder in the country. Moulton was appointed Commander of the British Empire (CBE) in the 1976 New Year Honours for services to industry. Other honours include: Moulton lived at The Hall, Bradford-on-Avon a 17th-century mansion. He was a member of Brooks's gentlemen's club in London. Moulton died on 9 December 2012 at the Royal United Hospital in Bath. His funeral, which
8085-457: 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 a vehicle. Roll rate is analogous to a vehicle's ride rate, but for actions that include lateral accelerations, causing
8190-472: The sprung center of gravity height is the roll moment arm length. The total sprung weight transfer 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
8295-419: The sum of the vertical force components experienced by suspension links. The resultant force acts to lift 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
8400-431: 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
8505-403: 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
8610-516: 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
8715-476: 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
8820-400: 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
8925-435: 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
9030-414: The top of the suspension stroke (such as when the vehicle's wheel can no longer travel in an upward direction toward 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
9135-461: 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
9240-426: 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
9345-413: 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
9450-507: 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
9555-579: 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 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
9660-429: 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
9765-590: 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
9870-453: The vehicle's sprung weight (total weight less the unsprung weight), the front and rear roll center heights, and 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
9975-468: 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
10080-567: 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
10185-402: 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 is different from what it is under acceleration and braking. This variation in wheel rate may be minimised by locating
10290-533: 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
10395-482: 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, 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
10500-511: Was attended by 'Moultoneers' from all over the world, took place at Holy Trinity Church, Bradford-on-Avon on 19 December, after which he was interred in the family grave at Christ Church in the same town beside his great-grandfather, Stephen Moulton, who founded the Moulton dynasty in the Wiltshire town in 1848. Moulton never married, and had no immediate survivors. Under Moulton's will,
10605-697: 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
10710-536: Was educated at Marlborough College and the University of Cambridge where he was an undergraduate at King's College . During World War II he worked on engine design at the Bristol Aeroplane Company . After the war he joined the family company, which made rubber components such as suspension parts for railway carriages; he turned it towards rubber suspension systems for road vehicles. In
10815-528: 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
10920-410: 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
11025-549: 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
#104895