Wheel cylinder: pressure becomes movement of the brake shoes

Useful to know

The wheel brake cylinder transmits the hydraulic pressure to the drum brake shoes. Bosch explains this principle in its technical catalogue for the respective applications. [1]

Do not confuse the wheeled with the main cylinder: they occupy different places in the chain. With a trace of a leak around a drum node, an accurate inspection is required, not a conclusion only on the color of the contamination. Dimensions and seals are specific. The principle helps to understand the function, but the sample catalogue does not define the spare part for each passenger car.