A good steering mechanism is must for a vehicle’s stability at the time of turning. Steering of four wheeler is designed in a manner so that it will not permit lateral slip of front wheels during steering.

There must be true rolling of wheels at the time of steering. The front wheels are mounted on front axles to allow their left and right swing for steering the vehicle.

Steering is done by providing a suitable gearing and linkage between front wheels and steering wheel.

Steering Linkages

Depends on the type of vehicle having Independent Front Suspension or Rigid axle type front suspension.

• Steering linkage for vehicle with rigid axle front suspension.
• Steering linkage for vehicle with rigid Independent front suspension.

The drop arm (also called Pitman arm) is rigidly connected to the cross-shaft of the steering gear at its upper end, while its lower end is connected to the link rod arm through a ball joint.

Stub axle is rigidly attached to the other end of link rod arm. Each stub axle is has a forged track rod arm rigidly bolted to the wheel axis. The other end of track rod arms are connected to track rod by means of ball joints.

Steering linkage for vehicle with rigid Independent front suspension.

In case of conventional rigid axle suspension , the main axle beam ensures the movement of stub axle in the horizontal plane only , there is no vertical deflection of the suspension and hence there is no change in the effective track-rod length.

In case of Independent suspension , the two stub axles can move up or down independent of each other due to which distance between ball-joint ends of the two track rod arms is continuously varying.

Here three piece track rod is used , the centre portion being called relay rod is used , which is connected at one end to the idler arm supported on body structure and to drop arm of steering gear at the other end through ball joints

Applications:

Used in Heavy vehicles such as

• Passenger Bus
• Lorry
• Trucks etc.