Camber thrust
Encyclopedia
Camber thrust and camber force are terms used to describe the force generated perpendicular to the direction of travel of a rolling tire
due to its camber angle
and finite contact patch
. Camber thrust is generated when a point on the outer surface of a leaned and rotating tire, that would normally follow a path that is elliptical when projected onto the ground, is forced to follow a straight path due to friction
with the ground. This deviation towards the direction of the lean causes a deformation in the tire tread and carcass that is transmitted to the vehicle as a force in the direction of the lean.
Camber thrust is approximately linearly proportional to camber angle for small angles. Bias-ply tires have been found to generate more camber thrust than radial tires. Camber stiffness is a parameter used to describe the camber thrust generated by a tire and it is influenced by inflation pressure and normal load. The net camber thrust is usually in front of the center of the wheel and so generates a camber torque or twisting torque. The orientation of this torque is such that it tends to steer a tire towards the direction that it is leaned.
s and motorcycle
s, camber thrust contributes to the centripetal force
necessary to cause the vehicle to deviate from a straight path, along with cornering force
due to the slip angle
, can be the largest contributor, and in some cases is the sole contributor. Camber thrust contributes to the ability of bikes to negotiate a turn with the same radius as automobiles but with a smaller steering angle. When a bike is steered and leaned in the same direction, the camber angle of the front tire is greater than that of the rear and so can generate more camber thrust, all else being equal.
s, camber thrust may contribute to or subtract from the total centripetal force generated by the tire, depending on the camber angle. On a well-aligned vehicle, camber thrust from the tires on each side balances out. On a surface rough enough for one front tire to momentarily lose traction, camber thrust from the other front tire can cause the vehicle to wander or feel skittish.
Tire
A tire or tyre is a ring-shaped covering that fits around a wheel rim to protect it and enable better vehicle performance by providing a flexible cushion that absorbs shock while keeping the wheel in close contact with the ground...
due to its camber angle
Camber angle
thumb|100px|From the front of the car, a right wheel with a negative camber angleCamber angle is the angle made by the wheels of a vehicle; specifically, it is the angle between the vertical axis of the wheels used for steering and the vertical axis of the vehicle when viewed from the front or...
and finite contact patch
Contact patch
Contact patch is the portion of a vehicle's tire that is in actual contact with the road surface. It is most commonly used in the discussion of pneumatic tires, , where the term is strictly used to describe the portion of the tire’s tread that touches the road surface...
. Camber thrust is generated when a point on the outer surface of a leaned and rotating tire, that would normally follow a path that is elliptical when projected onto the ground, is forced to follow a straight path due to friction
Friction
Friction is the force resisting the relative motion of solid surfaces, fluid layers, and/or material elements sliding against each other. There are several types of friction:...
with the ground. This deviation towards the direction of the lean causes a deformation in the tire tread and carcass that is transmitted to the vehicle as a force in the direction of the lean.
Camber thrust is approximately linearly proportional to camber angle for small angles. Bias-ply tires have been found to generate more camber thrust than radial tires. Camber stiffness is a parameter used to describe the camber thrust generated by a tire and it is influenced by inflation pressure and normal load. The net camber thrust is usually in front of the center of the wheel and so generates a camber torque or twisting torque. The orientation of this torque is such that it tends to steer a tire towards the direction that it is leaned.
On bikes
On bicycleBicycle
A bicycle, also known as a bike, pushbike or cycle, is a human-powered, pedal-driven, single-track vehicle, having two wheels attached to a frame, one behind the other. A person who rides a bicycle is called a cyclist, or bicyclist....
s and motorcycle
Motorcycle
A motorcycle is a single-track, two-wheeled motor vehicle. Motorcycles vary considerably depending on the task for which they are designed, such as long distance travel, navigating congested urban traffic, cruising, sport and racing, or off-road conditions.Motorcycles are one of the most...
s, camber thrust contributes to the centripetal force
Centripetal force
Centripetal force is a force that makes a body follow a curved path: it is always directed orthogonal to the velocity of the body, toward the instantaneous center of curvature of the path. The mathematical description was derived in 1659 by Dutch physicist Christiaan Huygens...
necessary to cause the vehicle to deviate from a straight path, along with cornering force
Cornering force
Cornering force or side force is the lateral force produced by a vehicle tire during cornering.Cornering force is generated by tire slip and is proportional to slip angle at low slip angles. The rate at which cornering force builds up is described by relaxation length...
due to the slip angle
Slip angle
In vehicle dynamics, slip angle or sideslip angle is the angle between a rolling wheel's actual direction of travel and the direction towards which it is pointing...
, can be the largest contributor, and in some cases is the sole contributor. Camber thrust contributes to the ability of bikes to negotiate a turn with the same radius as automobiles but with a smaller steering angle. When a bike is steered and leaned in the same direction, the camber angle of the front tire is greater than that of the rear and so can generate more camber thrust, all else being equal.
On automobiles
On automobileAutomobile
An automobile, autocar, motor car or car is a wheeled motor vehicle used for transporting passengers, which also carries its own engine or motor...
s, camber thrust may contribute to or subtract from the total centripetal force generated by the tire, depending on the camber angle. On a well-aligned vehicle, camber thrust from the tires on each side balances out. On a surface rough enough for one front tire to momentarily lose traction, camber thrust from the other front tire can cause the vehicle to wander or feel skittish.
See also
- Bicycle and motorcycle dynamicsBicycle and motorcycle dynamicsBicycle and motorcycle dynamics is the science of the motion of bicycles and motorcycles and their components, due to the forces acting on them. Dynamics is a branch of classical mechanics, which in turn is a branch of physics. Bike motions of interest include balancing, steering, braking,...
- Cornering forceCornering forceCornering force or side force is the lateral force produced by a vehicle tire during cornering.Cornering force is generated by tire slip and is proportional to slip angle at low slip angles. The rate at which cornering force builds up is described by relaxation length...
- Motorcycle tires
- Relaxation lengthRelaxation lengthRelaxation length is a dynamic property of pneumatic tires that describes the delay between when a slip angle is introduced and when the cornering force reaches its steady-state value....
- Vehicle dynamicsVehicle dynamicsVehicle dynamics refers to the dynamics of vehicles, here assumed to be ground vehicles. Vehicle dynamics is a part of engineering primarily based on classical mechanics but it may also involve chemistry, solid state physics, electrical engineering, communications, psychology, control theory,...