Wheelbase

Information about Wheelbase

''For the British TV series of the same name see Wheelbase (BBC).

In both road and rail vehicles, the wheelbase is the distance between the centers of the front and rear wheels.

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Road

In automobiles, the wheelbase is the horizontal distance between the center of the front wheel, and the center of the rear wheel. At equilibrium, the total torque of the forces acting on the car is zero, and thus the wheelbase is related to the weight on each tire by the following formulas:

where $\text{[math]}$ is the weight on the front tire, is the weight on the rear tire, $\text{[math]}$ is the wheelbase, is the distance from the center of gravity (CG) to the rear wheel, $\text{[math]}$ is the distance from the center of gravity to the front wheel, $\text{[math]}$ is the mass of the car, and $\text{[math]}$ is the gravity constant. So, for example, when one loads the trunk with heavy goods, the center of gravity shifts rearward and the weight on the rear tire increases causing it to sink depending upon the stiffness of the suspension. If the automobile is accelerating or decelerating, extra torque is placed on the rear or front tire respectively, and the equation relating the wheelbase, height above the ground of the CG, and the weight on each tire becomes:

where $\text{[math]}$ is the weight on the front tire, is the weight on the rear tire, is the distance from the CG to the rear wheel, $\text{[math]}$ is the distance from the CG to the front wheel, $\text{[math]}$ is the wheelbase, $\text{[math]}$ is the mass of the car, $\text{[math]}$ is the acceleration of gravity (approx. 9.8 m/s²), is the height of the CG above the ground, $\text{[math]}$ is the acceleration (or deceleration if the value is negative). So, as is common experience, when the automobile accelerates, the rear usually sinks and the front rises depending on the suspension. Likewise, when braking the front noses down and the rear rises.:^[1]

Because of the effect the wheelbase has on the weight transfer of the vehicle, wheelbase dimensions are crucial to the balance and steering of the automobile. For example, a car with a much greater weight load on the rear tends to understeer due to the lack of weight and therefore grip from the front tires. This is why it is crucial, when towing a single-axle caravan, to distribute the caravan's weight so that down-thrust on the tow-hook is about 100 pounds force (400 N). Likewise, a car may oversteer or even "spin out" if there is too much weight on the front tires and not enough on the rear tires. Also, when turning there is lateral torque placed upon the tires which imparts a turning force that depends upon the length of the tire distances from the CG. Thus, in a car with a short wheelbase, the short lever arm from the CG to the rear wheel will result in a greater lateral force on the rear tire which means greater acceleration and less time for the driver to adjust and prevent a spin out or worse.

Wheelbases provide the basis for one of the most common vehicle size class systems.

Bikes

Main article: Bicycle and motorcycle geometry

The wheelbase on many commercially available bicycles and motorcycles is so short, relative to the height of their centers of mass, that they are able to perform stoppies and wheelies.

Rail

In rail vehicles, the wheelbase follows a similar concept. It is particularly applied to steam locomotives. Short-wheelbased locomotives can negotiate sharper curves. On some larger wheelbase locomotives, driving wheels may lack flanges in order to pass curves.

References

1. ^ Ruina, Andy; Rudra Pratap (2002). Introduction to Statics and Dynamics (PDF), Oxford University Press, 350. Retrieved on 2007-03-23.

Wheelbase was a BBC television series about cars broadcast on BBC2 between 1964 and 1975.^[1] Amongst its presenters were Cliff Michelmore. The show was replaced by Top Gear.

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Vehicles are non-living means of transport. They are most often man-made (e.g. bicycles, cars, motorcycles, trains, ships, and aircraft), although some other means of transport which are not made by man can also be called vehicles; examples include icebergs and floating tree trunks.
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automobile (from Greek auto, self and Latin mobile moving, a vehicle that moves itself rather than being moved by another vehicle or animal) or motor car (usually shortened to just car) is a wheeled passenger vehicle that carries its own motor.
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torque (or often called a moment) can informally be thought of as "rotational force" or "angular force" which causes a change in rotational motion. This force is defined by linear force multiplied by a radius.

The SI unit for torque is the newton meter (N m). In U.S.
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weight is a measurement of the gravitational force acting on an object. Near the surface of the Earth, the acceleration due to gravity is approximately constant; this means that an object's weight is roughly proportional to its mass.
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center of mass of a system of particles is a specific point at which, for many purposes, the system's mass behaves as if it were concentrated. The center of mass is a function only of the positions and masses of the particles that comprise the system.
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Mass is a fundamental concept in physics, roughly corresponding to the intuitive idea of "how much matter there is in an object". Mass is a central concept of classical mechanics and related subjects, and there are several definitions of mass within the framework of relativistic
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Standard gravity, usually denoted by g₀ or g_n, is the nominal acceleration due to gravity at the Earth's surface at sea level. By definition it is equal to exactly 9.80665 m·s⁻² (approx. 32.174 ft·s⁻²).
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capitalizations in this article need to be corrected: (1) All proper names should be capitalized in the body of the text
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Tires or tyres (see American and British English spelling differences) are pneumatic enclosures used to protect and enhance the effect of wheels.

Tires are used on all types of vehicles, from cars to earthmovers to airplanes.
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Gravitation is a natural phenomenon by which all objects with mass attract each other. In everyday life, gravitation is most familiar as the agency that endows objects with weight.
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Understeer is a term for a car handling condition during cornering in which the circular path of the vehicle's motion is of a markedly greater diameter than the circle indicated by the direction its wheels are pointed.
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Oversteer is a phenomenon that can occur in an automobile which is attempting to turn. The car is said to oversteer when the rear wheels do not track behind the front wheels but instead slide out toward the outside of the turn. Oversteer can throw the car into a spin.
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Wheelbase

Information about Wheelbase

Road

Bikes

Rail

See also

References

References