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Home Mechanical Engineering Automobile Engineering Lab Dismantling and Assembling of Steering Gear Box and Braking System
Automobile Engineering Lab Lab Experiments

Dismantling and Assembling of Steering Gear Box and Braking System



Aim

To dismantle and assemble the steering gear box.

Tools and equipments:

Given gear box assembly, jack, set of spanners, hammer, slims, pliers, screw drivers, tool kit, gear oil, kerosene, cotton waste etc.

Procedure:

Dismantling

  • Remove the steering wheel, if it refuses to come use puller.
  • Remove drop arm nut and remove the drop arm.
  • With soft hammer push roller sector shaft.
  • Remove the bottom plate then the bearing.
  • Remove the top plate cover and the tube.
  • Remove the outer race, push the steering worm shaft out.

Assembling

  • Fix the roller shaft in with its bushes and tighten the end cover.
  • Fix up worm shaft with taper roller bearing with the bottom cover and top cover.
  • Tight the nuts at the top and bottom plate and fix up steering outer tube.
  • Fix the steering wheel
  • Fix up steering drop arm and the lock nut.
camand double roller steering gear box
rack and pinion steering gear box

Brake System

Working of master cylinder

By pressing the pedal the push rod pushes the piston. When the piston moves forward it closes the by-pass port 'C'.Now the brake fluid in the cylinder is pushed forward and it moves with pressure with pressure valve “B”and reaches all the wheel cylinders through pipes. The wheel cylinder receives the brake oil with pressure and expands the brake shoes against brake drums.

When the pressure on the pedal is removed, the spring in the cylinder pushes back the piston and by suction the brake oil in the line is pushed back in the cylinder. The oil come back through the bypass port “c” when gets opened with the backward stroke of the piston. This way the oil which was forced to wheel cylinders returns back in the reservoir of the master cylinder and again it is ready for braking operation. The push rod which pushes the piston the piston can be adjusted. There must be some play or clearance between bush rod and piston. It keeps in operation the by pass by the primary washer and thrust releasing the pressure. The secondary washer checks the leakage of oil from the piston grooves and the cylinder At the top of the supply tank a filler cap is provided with a vent hole in it. It is vented to the atmosphere because atmospheric causes the flow through the filter part.

Brake Pipes and Hoses

Brake pipes are made of special material which can stand the high pressure that exists when the brakes are applied. Generally steel pipes are used between master cylinder and the frame connection and the rear axle T fitting and rear wheel cylinders. Flexible hose connect the brake pipe to the front wheel cylinder and to the rear axle fitting.

Wheel Cylinder

Hydraulic pressure from master cylinder forces the piston apart. Then the brake shoe actuating pins force the brake-shoes into contact with the brake drum. A bleeder valve is also provided in wheel cylinder to allow the air and liquid to be forced out of the system during the bleeding operation. The piston cups are so formed that the hydraulic pressure forced them tightly against cylinder wall of the wheel cylinder.

Brake Drum

There are generally made of cast iron pressed steel or cast iron and steel. The brake drums are cylindrical members closed from one side and open on the other to house the brake shoe. The drum and wheel rotate together. Cooling ribs or fins are provided around the brake drum rabidly.

Brake Shoes

Generally there are two shoes a primary and secondary. Shoe is made of cast steel or forged steel. The cross section is generally T. Brake lining is fixed on the shoes with the help of rivets. One end of the shoe is fixed in the wheel cylinder and other end is coupled with adjuster Return spring are also fitted on the end.

typical automative breaking system
air brake system
figure

Brake Lining

Brake lining is of two types, molded or woven Is made o specially treated asbestos or other heat and wear of the brake shoes. This lining comes directly in contact with the brake drum to provide braking action. Bonded lining are fixed on the shoe with an adhesive and then backed.

Overhauling of Master Cylinder in Brake System

  • Remove the cylinder from the chassis frame by taking out pipe connections and both from the frame.
  • Remove the push rod piston, spring and valve, open the light switch also
  • Remove the primary and secondary washer from the piston. And clean the cylinder and piston nicely and with brake oil. Remember the petrol should never be used. It spoils the washer.
  • Check the valve and the hole and clean these.
  • Now fit the washers after dipping these in brake oil.
  • It is always advisable to change master cylinder repair kit completely
  • Now assemble the master cylinder and mount it on the chassis frame.
  • Connect the pipes and fill up the reservoir with brake oil.
  • The brake oil should not be filled up to the top but about 6mm lower Remember there must be some play in push rod.

Result:

Thus the dismantling and assembling of steering gear box and brake system have been performed.

Viva Questions:

  1. What is the principle of automotive brake
  2. What do the brakes do to the energy as they stop a moving car
  3. What are the primary and secondary brakes
  4. Why brakes with more than 80% efficiency are not used in automobiles
  5. What is fading of brakes
  6. On what factors does the force of adherion between the road wheels and the road depends
  7. How does skidding takes place
  8. What is leading shoe
  9. What is the difference between power assisted and power operated brakes
  10. What is the advantage of a two shoe trailing brake
  11. Name important components of a disc brake
  12. What is the advantage of a swinging caliper type disc brake
  13. Name important components of a drum brake
  14. What is a split hydraulic brake system
  15. What is steering axis?
  16. What is wheel alignment?
  17. Define Camber, SAI and Castor.