Introduction to Steering Gear

What is Steering Gear?

• Steering Gear is a gear that couples the steering wheel to the steering linkage of a motor vehicle.
• A steering wheel manages the directional movement of a vehicle. This wheel is connected to a special rod, which uses a steering gear to turn the axles in the car. When the steering wheel is turned, the rod rotates the gear, which then pulls or pushes the axle in the required direction.
• Rack-and-pinion steering, manual steering, and power steering. Each form of steering requires a steering gear to manage the directional changes of the automobile.

Functions of Steering Gears:

• It helps to multiply a small effort applied on the steering wheel by driver into a greater force on the dragging link.
• It functions to transform the rotary motion of the steering wheel into the to-and-from motion of the drag link.

Types of Steering Gears:

1. The Pit-man-arm type and
2. The Rack-and-Pinion type

Types of Steering Gearbox:

     1. Worm and Roller

• The bearing are designed to resist both radial and end trust.
• The threads of the worm gear are meshed with roller shaft at the end of the steering tube.

     2. Worm and Sector

• The worm is attached with the inner column of the bearing block.
• The worm at the end of the steering shaft meshes with a sector mounted on a sector shaft.

     3. Cam and Roller

• The cam and roller boxes are very efficient.
• The cam is carried by the steering shaft connected with rollers.

    4. Cam and Peg

• The peg is moved along the groove for rotating the rocker shaft by rotating the cam.
• An adjusting screw on the side cover is connected for governing the backlash and end float of the rocker shaft. 

    5. Cam and Turn Lever

• The cam is mounted at the lower end of the steering shaft. It consist of variable pitch worm.
• A twin lever carrying studs messes in the groove of the cam.

    6. Screw and Nut

• These types of steering boxes are commonly used.
• Screw and nut gear has a phosphor-bronze of steel nut which is screwed on to a multi-star Acme thread.

    7. Worm and Ball

• Steel balls are circulating for obtaining friction-less drive between the worm and nut.
• If the steering shaft is turned to left, the ball nut is moved downward by rolling action.

    8. Rack and Pinion

• This type of gear is mainly used in cars having independent front suspension.
• The pinion is mounted at the end of the steering shaft.

    9. Recirculating Ball

• It consist of a worm at the end of the steering rod, half nut and transfer tube containing the balls.
• The balls are fed back to the nut connected by half nut with the transfer tube.

When a steering gear fails it causes the wheels of the vehicle to rotate freely without control from the steering wheel. This is a dangerous situation that typically occurs when the steering gear wears out. The most obvious sign of gear failure is the reduction of wheel movement with turns in the steering wheel. If this happens during driving conditions the operator should slow down as quickly as possible.

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