STEERING GEOMETRY

STEERING GEOMETRYThe term "steering geometry" (also known as "front-end

geometry") refers to the angular Relationship between suspension and steering parts, front wheels, and the road surface. Because alignment deals with angles and affects steering, the method of describing alignment measurements is called steering geometry.

There are five steering geometry angles : Camber Caster king pin inclination Toe in & Toe-out on turns

Camber:- Camber angle is the angle between

the vertical line and centre line of the tyre when viewed from the front of the vehicle.

Camber angle is positive when this is outward. This happens when wheels are further apart at top than at bottom. On the contrary, camber angle is negative when angle is inward. This happens when wheels are further apart at bottom than at top.

The camber, should not be more than 2 degree, because this causes uneven or more tyre wear on one side than on other side.

Caster:-

Caster angle is the tilt of king pin centre line towards front of back from the vertical line.

It is the angle between the vertical line and king pin centre line in the wheel plane when looked from side.

King pin inclination

It is the angle between king pin centre line and vertical line when seen from the front of the vehicle.

It is also called steering axle inclination. King pin inclination and caster are used

to improve directional stability in cars. This is also used to reduce steering

effort when steering a stationary it reduces tyre wear. This inclination varies from 4 to 8

degree in modern cars.

TOE IN & TOE OUT In automotive engineering, toe also known as tracking.

 This can be contrasted with steer, which is the anti symmetric angle, i.e. both wheels point to the left or right, in parallel (roughly).

 Positive toe, or toe in, is the front of the wheel pointing in towards the centerline of the vehicle

Negative toe, or toe out, is the front of the wheel pointing away from the centerline of the vehicle.

ACKERMANN STEERING GEOMETRY

Ackermann steering geometry is a geometric arrangement of linkages in the steering of a car or other vehicle designed to solve the problem of wheels on the inside and outside of a turn needing to trace out circles of different radii.

Modern cars do not use pure Ackermann steering partly because it ignores important dynamic and compliant effects.

The use of such geometry helps reduce tyre temperatures during high-speed cornering but compromises performance in low speed maneuvers.

The intention of Ackermann geometry is to avoid the need for tyre to slip sideways when following the path around a curve.

As the rear wheels are fixed, this centre point must be on a line extended from the rear axle.

Intersecting the axes of the front wheels on this line as well requires that the inside front wheel is turned, when steering, through a greater angle than the outside wheel .

Ackerman – Truck Steering System

Straight ahead

Right turn

Left turn

Car Steering SystemsRack and pinion

GearboxRack

Tire rod

Steering arm

Gearbox

Steering arm

Tire rod

Relay linkIdler arm Pitman arm

Truck Steering Systems

Tire rodSteering arm

Drag link

Pitman armGearbox