A wheel cylinder is one of the components in a drum brake. When a driver presses a brake pedal, a wheel cylinder pushes brake shoes against the brake drum. This generates friction which decelerates or stops the brake wheel.
A brake pedal produces a force which is converted into hydraulic pressure by the master cylinder. This hydraulic pressure is transmitted into wheel cylinder via brake lines. The hydraulic pressure acts on the pistons inside the wheel cylinders. The pistons, in turn, exert mechanical pressure on the brake shoes. When the diver releases the pedal, brake shoes pull away from the drum pushing the wheel cylinder back to its initial position.
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Components of a wheel cylinder include:
- Compression springs
- Protective caps
A faulty wheel cylinder will lead to braking performance impairment, loss of brake fluid or, worse still, total failure if braking system. A leaking wheel cylinder allows loss of hydraulic pressure in brake circuit. Therefore you should do repairs as soon as as notice a problem.
Wheel cylinders have seals which prevent brake fluid leakage past the piston. Similarly, there is a rubber dust boot at the end of the cylinder to prevent dirt, moisture and dust from getting into the cylinder bore.
Normal wear can cause piston leakage over time. As moisture and corrosion inhibitors build up inside the wheel cylinder, corrosion and pitting occur. Fluid can leak past the pistons to the brake lining and hence causing grabbing and uneven braking. If there is a serious fluid loss past the seals of the wheel cylinder, the braking system is subjected to potential failure.
Another major problem in the wheel cylinder is sticking. Corrosion and dirt can make pistons to stick in its bore. As a result, the brake may fail to release and hence causing shoe drag.
Wheel cylinders are hidden in the brake drum. To inspect them the drum has to be removed. This happens when the cylinders are leaking, or brake shoes have to be replaced.
Eventually, the wheel cylinder will wear out. So it is prudent to inspect the cylinders when doing a serious brake repair, especially for high mileage vehicles. At some point, you may have to replace them.
Here is how to know your wheel cylinder has a problem…
Leakage in the wheel cylinder will compromise their ability to extends pistons and pressurize. The result is a mushy, abnormally soft brake pedal that sinks to the floor when pressed.
Poor Brake Response
Wheel cylinder failure affects the system pressure hence reducing the ability to slow the vehicle. A vehicle that responds poorly to braking will be a hard stop.
Brake fluid leak is a sign that your vehicle’s braking system is damaged. You can easily recognize leaking brake fluid. You will see thin films on the inside of backing plate, drips or pool of brake fluid from the wheel cylinder. A quick inspection can reveal the problems in the wheel cylinder.
If you suspect your wheel cylinders are faulty have the vehicle inspected by a professional mechanic.
Call Chelsee’s A/C & Brake Emporeum now for your FREE check-up! (602) 242-1253
Read more about your car’s brake system: