Brake servo mechanism for vehicle braking, has secondary push rod and secondary spring to reinforce amplification and provide two amplification ratios.

摘要

The brake servo mechanism consists of a valve body (3), which slides within an outer case (2), with the valve stem (8) attached to the input shaft. A primary push rod (24) slides within the tubular part (8A) of the valve stem and is activated by the primary spring (25). A secondary push rod (26) is designed to slide around the periphery of the primary push rod, towards its forward extremity and a second spring (28), with a constant and larger pressure than the primary spring, acts between the second push rod and the valve stem.