초록 ▼

A parking brake lock-in key switch system for a truck or bus brake system. The system has two parking brake lock-in valves. One parking brake lock-in valve is installed in the air line piping between the primary air tank and the push pull double check valve and the second parking brake lock-in valve

A parking brake lock-in key switch system for a truck or bus brake system. The system has two parking brake lock-in valves. One parking brake lock-in valve is installed in the air line piping between the primary air tank and the push pull double check valve and the second parking brake lock-in valve is in the air line piping between the secondary air tank and the push pull double check valve. The parking brake lock-in valves are air operated valves which when closed will look in actuated parking brakes. The parking brake lock-in valves are operated by a solenoid operated pilot valve which provides air from an air supply to close the lock-in valves when the ignition key is moved to the `off` position. An actuated parking brake will be locked in because new air from the respective tanks will be prevented from flowing to the push pull double check valve and hence the brake chambers. The parking brake lock-in valve does not vent off downstream piping when it closes. Should the ignition key be positioned to the `off` position with the vehicle in motion and the parking brake actuator is not engaged in the park position, air will be locked in the air line piping between the parking brake lock-in valves and the individual brake chambers including the piping in which the push pull double check valve is installed. This locked in air will prevent the brake chambers from locking the wheels, hence preventing inadvertent engagement of the parking brakes. One embodiment of the invention for vehicles with automatic transmissions will include an automatic apply-automatic release parking brake system which operates alone or in parallel with the parking brake lock-in key switch system. The automatic apply-automatic release parking brake system has a valve that acts to operate and engage the parking brake when the automatic transmission is placed in the "Park" position. The valve of the automatic apply-automatic release parking brake system in this embodiment will deactivate and release the parking brake when the transmission shifter is moved out of the "Park" position and the engine of the vehicle is running.

대표청구항 ▼

[ We claim:] [1.]1. A parking brake lock-in key switch system in combination with an automatic apply-release system for an air brake system for a mobile vehicle with an engine, and a key and an ignition with a run position for starting the engine, an off position for stopping the engine and an acces

[ We claim:] [1.]1. A parking brake lock-in key switch system in combination with an automatic apply-release system for an air brake system for a mobile vehicle with an engine, and a key and an ignition with a run position for starting the engine, an off position for stopping the engine and an accessory position, an automatic transmission engaged to the engine, the automatic transmission engaged to be manually operated by a multi-position shifter, the shifter having a PARK position, and a front set of wheel and a rear set of wheels, comprising:(a) a brake assembly engaged to each of one of the set of wheels;(b) each said brake assembly having a spring brake chamber;(c) said spring brake chambers having a spring which expands to apply brake pads to stop rotation of the wheels;(d) said spring being compressible under counter acting air pressure to move and release said brake pads to allow rotation of the wheels;(e) a primary air tank for supplying air to said spring brake chambers;(f) a secondary air tank for supplying air to said spring brake chambers;(g) air lines running from said primary air tank to a push pull double check valve, from said secondary air tank to said push pull double check valve, and from said push pull double check valve to said spring brake chambers;(h) said push pull double check valve having a driver operated parking brake actuator for stopping air flow through and venting said air lines from said push pull double check valve to said spring brake chambers;(i) a primary parking brake lock-in valve operatively engaged in said air lines running from said primary air tank to said push pull double check valve;(j) a secondary parking brake lock-in valve operatively engaged in said air lines running from said secondary air tank to said push pull double check valve;(k) said primary parking brake lock-in valve and said secondary parking brake lock-in valve are operatively engaged to close and not vent downstream air lines when the key of the ignition is turned to the off position and to open when the key is turned to the run or accessory positions;(l) an automatic apply-release valve operatively engaged in said air lines between said push pull double check valve and said spring brake chambers;(m) said apply-release valve operatively engaged to close to vent air through a vent port from between said apply-release valve and said spring brake chambers to allow said springs apply the brake pads when the shifter is moved to the PARK position; and(n) said apply-release valve operatively engaged to open to allow air to pass from said push pull double check valve to said spring brake chambers to release the brake pads when the shifter is moved out of the Park position.