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57-460: The dial allows for the quick and simple adjustment of the electronics governing car suspension settings, traction control , electronic differential , and change speed of electronic gearbox . A similar control system was employed on the Ferrari Enzo , but used individual buttons for different settings rather than a single rotary switch. This article about an automotive part or component

114-448: 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

171-463: 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,

228-498: 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,

285-583: A steel chassis and a four-speed transmission that drove the rear wheels via chain drive , and rear-wheel brakes . In 1902, Mors added pneumatic shock absorbers to their cars, which represented a great leap forward given the quality of the roads and racetracks at the time. With this car, Henri Fournier was able to win the highly significant Paris-Berlin race, with the drive chain breaking immediately afterwards. Mors ended racing in 1908. Plans to return to auto racing were cancelled due to World War I . André Citroën became chairman of Mors in 1908 and restored

342-400: 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

399-571: A throttle control. The Mors 11 HP sold for US$ 5000. The St. Louis Car Company also manufactured the American Mors. After manufacturing the St. Louis and Kobusch cars, the latter of which looked like a Mors, in 1906 the St. Louis Car Company acquired an official license , blueprints, and plans from the Parisian factory to manufacture Mors cars in the U.S. After making the American Mors for three years,

456-542: 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

513-416: 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

570-537: 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

627-423: Is a stub . You can help Misplaced Pages by expanding it . Car suspension 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

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684-422: 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

741-419: 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

798-413: 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

855-412: 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

912-441: 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

969-405: 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

1026-410: 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

1083-412: 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

1140-660: 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

1197-486: 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,

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1254-449: 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

1311-564: 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

1368-499: 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)

1425-496: 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

1482-414: 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

1539-483: 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

1596-522: 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

1653-436: 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

1710-566: The bevel drive rear axles from 1914 and a unique feature was the Mors patented clutch, which had a contracting band system which replaced the cone clutch used until 1903. The marque was resurrected briefly when a few small electric cars were made during World War II by a subsidiary electrical company of Émile Mors. Central Automobile Company was the US importer of Mors automobiles in New York, New York in

1767-428: 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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1824-466: The company founder, Émile Mors, in racing's technical and promotional benefits. By the turn of the century, automobile racing had become largely a contest between Mors and Panhard et Levassor . Mors was one of the first automobiles to use the V engine configuration. The Mors 60 horsepower Grand Prix car was powered by a 9.2-litre V4 side valve engine, with magneto ignition and dry sump lubrication , which could reach 950 rpm. The car had

1881-597: The company's viability. In 1925, Citroën bought Mors outright and closed it down, using its factory for the production of his Citroën automobiles. The company produced a number of models which were sold widely in Europe and in the USA. In 1905 these ranged from 2.3 litres to the 8.1 litre 40/52 HP and by 1914 Minerva -built Knight sleeve valve engines replaced side-valve units in the larger cars. Post-1918 only sleeve valve engines were used. Citroën's chevron gears were used for

1938-495: 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

1995-415: 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

2052-516: 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

2109-468: 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

2166-414: 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

2223-430: 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

2280-449: 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

2337-461: 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

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2394-457: 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

2451-467: 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

2508-419: 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

2565-507: 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

2622-476: 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

2679-435: 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

2736-414: 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

2793-407: 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. Mors (automobile) The Mors automobile factory was an early French car manufacturer. It was one of the first to take part in automobile racing , beginning in 1897, due to the belief of

2850-413: 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

2907-579: 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

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2964-429: 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

3021-453: 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

3078-420: The very early part of the 20th century. The 1904 Mors 18 HP was a touring car . Equipped with a tonneau , it could seat 4 to 6 passengers and sold for a high US$ 8000. The vertically mounted water-cooled straight-4 , situated at the front of the car, produced 18 HP (13.4 kW). A 4-speed transmission was fitted. The pressed steel-framed car was quite modern, with a cellular radiator (with fan) and

3135-402: 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

3192-517: 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

3249-477: 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

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