Patent GB-753577-A (GB)
Title: Improvements in or relating to combined sequence and locking to valves
IPC: F15B13/01
Filed: 1953-07-14
Abstract: 753,577. Hydraulic control systems; valves. BENDIX AVIATION CORPORATION. July 14, 1953 [July 28, 1952], No. 19532/53. Classes 69 (2) and 135. In an hydraulic system for the sequential operation of a pair of motors having a spring- loaded check valve disposed between a manually-actuated cock and one of the motors, the check valve is associated with a pressureresponsive device housed in a chamber on the downstream side of the valve and movable against loading means from a first position resisting valve opening to a second position pormitting valve opening on the reaching of a predetermined pressure in the valve inlet, the pressure-responsive device being subjected on one face to the pressure in the chamber whilst its opposite face is isolated therefrom so that the check valve may be closed by its spring whilst the pressure-responsive device is held in its second position on the pressure in the chamber exceeding the predetermined value. The system comprises single-acting hydraulic motors 16, 19, Fig. 1, a manually-actuated cock 12, a valve body 17 housing a spring-loaded check valve 37 and a pressure-responsive bellows 36 loaded by a spring 40 and secured to a head 35 engageable with the stem 37a of the check valve, and a piston 32 having a stem 32a to engage the check valve. The cock 12 is connected to a pump 11, a tank 10, the motor 16 and ports 23, 24 of the valve body 17. On moving the cock to connect the pump to the motor 16 and to the port 23, the ram 16a first moves upwards to full stroke and thence pressure in the system builds up in opposition to springs 38, 40 which when overcome permit opening of the check valve to connect the pump to the motor 19 and leftward movement of the bellows 36. The ram 19a of the pump 19 then moves upwards and on completion of its stroke the pressure in the system holds the bellows in its leftward position against its spring 40 whilst the spring 38 closes the check valve 37, the rams 16a and 19a being held in their up positions. On moving the cock 12 to connect the pump to the port 24 and the motor 16 to the tank, the piston 32 moves leftward to positively unseat the check valve whence the motor 19 is connected to the tank. In another embodiment, to operate a pair of double-acting motors, two valves are coaxially arranged in a single valve body 63, Fig. 2. Each valve in this case comprises a spring-loaded ball 76 and a spring- loaded plunger 78 whose outer end is subjected to atmospheric pressure and inner end engageable with a seat 84. The piston 32 is replaced by a piston 70 having a pair of stems so that either ball may be positively unseated. On the cock 12 being moved to connect the pump to the lower end of the ram 60 and to the port 64, the rams of the motors 60, 61 move upwards in sequence, pressure at the same time acting on the left-hand side of the piston 70 to unseat the right-hand check valve to open the top end of the motor 61 to tank. To reverse the movement of the rams, the cock 12 is moved to connect the pump to the upper end of the motor 60 and to the port 65.