What Is a Brake Wheel Cylinder?

What Is a Brake Wheel Cylinder?

A brake wheel cylinder is an essential part of the drum brake system on your car’s rear axle.brake wheel cylinder It uses hydraulic principles to push a pair of pistons against the brake shoe in the drum, slowing or stopping your vehicle. They are round, cylinder-shaped parts located at the top of the drum brake assembly, and use hydraulic pressure from the master cylinder to actuate them. The fluid used in the system is hydraulic, and the cylinders are made from cast iron or aluminium.

They are similar to a slave cylinder and work in much the same way, internally consisting of just a simple plunger.brake wheel cylinder On older cars, they may begin to leak and limit the performance of the braking system yet they are usually inexpensive and relatively easy to replace.

Located at the top of each drum brake, they bolt to the wheel hub and hold a brake drum on one side and the brake shoe on the other. The cylinders receive brake fluid from the master cylinder and pass it on to the drum brake shoes. The brake fluid is pressurised by the pistons moving outward in the cylinder, with the pistons and rubber cups held in position by a spring. When the cylinders are pressed by the brake pedal, this forces the pistons outward into the drum and creates the necessary friction to stop your vehicle.

These components are exposed to constant exposure to the elements and as they deteriorate over time, they will start to leak hydraulic brake fluid. This is the most common sign that a wheel cylinder needs to be replaced or rebuilt. You may also hear a squeeching noise when you use the brakes if they are failing, and this could be due to dust from the drum that is being constantly in contact with the piston.

Unless you have a good deal of knowledge and experience of working on automotive braking systems, it is best to let a qualified mechanic handle disassembling and replacing your wheel cylinders. It is very easy to break or damage the delicate and sensitive parts, and even if you do manage to remove the old cylinders and clean them correctly, it will take a lot of time and effort.

The circular base of the cylinder projects through a slot in the backplate. A pin prevents it from turning, and outside the backplate two interlocking spring clips pushed on to the projection from opposite sides hold the cylinder in place. There is often a dust cover to seal the slot. Pull off the dust cover and, if there are two spring clips, lever off each of their legs alternately a short way with a screwdriver and a hammer.

The cylinders are normally made from a forged steel casting that is machined to final shape, and the pistons and rubber cups are then installed. They are normally finished in black or gray to reduce the risk of corrosion. Previously they were often made from cast iron, but these are now less popular due to their susceptibility to rusting.

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