Pump assembly for hand fork-lift truck

Pump assembly for the lift cylinder of a hand fork-lift truck with the following characteristics:

• A piston pump (24, 80), which is activated by a bar on the hand fork-lift truck and has a piston chamber (26, 86) and an annulus collector (28, 88),
• a three stage control valve (14, 130), which in a lowered lift cylinder (10) position connects with a tank (18), in a neutral piston chamber (26, 86) setting connects with a tank and in a pump setting connects the piston chamber (26, 86) through a first check-valve (56) with the lift cylinder (10) and through a second check-valve (58) with the tank,
• a third check-valve (40) between the piston chamber and the annulus collector (26, 28), which opens up to the piston chamber,
• a reversing valve (42, 98) between the piston chamber and the annulus collector (26, 28, 86, 88), which has its valve element pressed into the closed position by a spring (48, 102) and on the opposite side is pressed by the pressure of the piston chamber (26, 86) whereby the valve element (98) of the reversing valve (42, 98) opens if the pressure in the piston chamber (26, 86) achieves a certain predefined value, whereby
• the valve element (98) seals on the side of the spring (48, 102) and is pressed against with a standard constant pressure.