초록 ▼

A vehicle brake system for operating a spring applied, fluid pressure released brake. In order to assure that the brake is fully released before the vehicle is operated, the system requires the operator to perform two operations. He must move a manually operated hydraulic valve to the brake release

A vehicle brake system for operating a spring applied, fluid pressure released brake. In order to assure that the brake is fully released before the vehicle is operated, the system requires the operator to perform two operations. He must move a manually operated hydraulic valve to the brake release position and in addition must close a normally open, momentary contact switch which actuates a second solenoid operated valve in series with the first valve to the brake release position. When pressure has built up in the brake actuator sufficiently to assure that it is fully released, a pressure sensor causes a hold-in circuit for the solenoid operated valve to be energized whereupon the operator can then release the momentary contact switch.

대표청구항 ▼

A vehicle brake system having a spring applied fluid pressure released actuator, a source supplying pressurized fluid to said actuator for brake release, and a two position valve in the fluid circuit between said source and said actuator having a brake applied position and a brake release position,

A vehicle brake system having a spring applied fluid pressure released actuator, a source supplying pressurized fluid to said actuator for brake release, and a two position valve in the fluid circuit between said source and said actuator having a brake applied position and a brake release position, comprising a solenoid operated valve in said fluid circuit between said source and said two position valve maintaining the circuit normally closed, a momentary contact switch for closing an electrical circuit for energizing said solenoid and moving said solenoid operated valve to pressurize said brake actuator when said two position valve is in the brake release position, a pressure sensor responsive to the fluid pressure in said actuator which closes a second electric switch when a predetermined pressure is reached in said sensor and a connection from said second switch to said solenoid to maintain the solenoid energized even though said momentary contact switch is opened.