How to Calculate Wheel Cylinder Piston Travel for Drum Brakes?

In summary, the question is whether the wheel cylinder piston travel for a drum brake system should be considered as 8 mm or higher, given an 8 mm liner wear. The answer is that if the top of the lining is at the wheel cylinder level, the piston displacement will also be 8 mm. This is true regardless of whether the adjuster is at the bottom or top of the lining. In the case of an adjuster at the top, there may be a rotation involved, but the lining displacement should still be equal to the piston displacement.
  • #1
Indi Monk
1
0
Hello.
I am in the process of calculating the brake fluid volume in the reservoir. I have a front disc and rear drum brake system. While the piston travel is clear for the disc brake, my question is related to the drum brake wheel cylinder piston travel. Assuming that the liner wear is 8 mm, should I consider the wheel cylinder piston travel to be 8 mm or is it higher considering that the wheel cylinder is usually at the top and might have to travel more in order to compensate? If it is higher, how to calculate the exact travel?
 
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  • #2
If the top of the lining is at the wheel cylinder level, then 8 mm of piston displacement will be 8 mm of lining displacement, no matter what.

Usually there is an adjuster at the bottom to compensate for wear. So 8 mm of wear at the top should be 8 mm everywhere.

Some have the adjuster on top, below the wheel cylinder (the lining self center by sliding down). In this case, there is a fixed pivot point and so there is a rotation where d = θr. But as long as the top of the lining is at the wheel cylinder level, the lining displacement should be the same as the piston.
 

FAQ: How to Calculate Wheel Cylinder Piston Travel for Drum Brakes?

What is brake fluid volume calculation?

Brake fluid volume calculation is the process of determining the amount of brake fluid needed for a specific vehicle or brake system.

Why is brake fluid volume calculation important?

Brake fluid volume calculation is important because having the correct amount of brake fluid is crucial for the proper functioning of a vehicle's braking system. Too much or too little brake fluid can lead to brake failure, which is a safety hazard.

How is brake fluid volume calculated?

Brake fluid volume is typically calculated by taking into account the size of the brake system's components, such as the master cylinder, calipers, and brake lines. The volume of each component is then added together to determine the total brake fluid volume needed.

What factors can affect brake fluid volume calculation?

The type of brake fluid, the size and type of brake components, and the temperature can all affect brake fluid volume calculation. Different types of brake fluid have different compressibility and expansion rates, which can impact the volume needed. Additionally, temperature changes can affect the volume of brake fluid, as it expands when heated and contracts when cooled.

Can brake fluid volume calculation be done manually?

While it is possible to manually calculate the brake fluid volume needed for a vehicle, it is recommended to use a specialized brake fluid volume calculator to ensure accuracy. These calculators take into account various factors that can affect the volume and provide a more precise result.

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