PNEUMATIC-HYDRAULIC BRAKE APPARATUS FOR A FOUR-WHEEL TRUCK

摘要

This invention relates to a pneumatically controlled hydraulically actuated brake apparatus of the constant brake shoe clearance type for a two-axle four-wheel vehicle truck wherein a constant brake shoe clearance is obtained by supplying a quantity of hydraulic fluid to a chamber formed between the wall surfaces of a cylinder and an actuating piston slidably disposed in the chamber in accordance with the increase in volume of the chamber as the result of brake shoe wear while a brake application is in effect and thereafter, upon effecting a brake release, always releasing the same quantity of hydraulic fluid from this chamber irrespective of the degree of brake shoe and/or wheel wear occurring while the prior brake application was in effect.