• A wheel cylinder is a component in a drum brake system. It is located in each wheel and is usually at the top, above the shoes
• Its responsibility is to exert force onto the shoes so they can contact the drum and stop the vehicle with friction.
• It is very similar to a master cylinder and functions in pretty much the same way, consisting of just a simple little plunger on the inside.

Construction:

• Wheel Cylinders consist of the following parts:

  • Two lip seal piston cups
  • Expander spring assembly
  • Two protective dust covers
  • Two pushrods
  • Bleeder valve
  • Inlet Port Cylinder
  • Two pistons
  • Two Rubber Boots

• The expanders prevent air from entering the system when the piston and two cups moving.

• A spring is positioned between the piston cups.
• A rubber boot is mounted on each end of wheel cylinder.
• Pushrods are located between the piston and the brake shoes. The pushrods fit snugly in the dust boot openings.
• The wheel cylinder is bolted to the backing plate and a bleeder screw is mounted in the back of the wheel cylinder.
• Then bleeder screw allows air to be bled from the wheel cylinder and the brake system.

Working:

• When the brakes are applied, the pressurized fluid from the master cylinder is sent to the wheel cylinder.

• The pressurized oil expands or rather forces the pistons out and the pushrods which are in turn connected to the brake shoes.