Atlas Copco Aktiebolag

Voac Hydraulics Boras Ab

Bo Nilstam

Orjan E Wennerbo

Orjan E Valdemar

Lars P Ericsson

A device for controlling a hydraulic motor (10) comprises a directional valve (15) connected to a pressure fluid pump (11; 50) via a feed passage (17) and a pilot valve (19) activated safety shut-off valve (18) incorporated in the pressure fluid feed passage (17) between the pump (11; 50) and the directional valve (15) and shiftable from a normally open position to a closed position to, thereby, block the fluid communication between the pump (11; 50) and the directional valve (15) in emergency situations. A shunt valve (16) for short circuiting at least a part of the pump flow to a tank or, alternatively a displacement adjusting means (51) of a variable displacement pump (50) are activated by a load sensing pressure derived from a load sensing port (15e) on the directional valve (15), which load sensing pressure is discharged to tank (12) via the shut-off valve (18) as the latter is shifted to its closed position.

Device for controlling a hydraulic motor

Device in a hydraulic power system connected to load driving hydraulic motor (18; 32), comprising a pilot controlled flow regulating directional valve (1; 29) for alternative connection of the service ports of the motor (18; 32) to a pressure medium source and a tank. The directional valve (1; 29) comprises two opposite and by a pilot pressure activatable activating means (3, 4), and a pilot pressure means (84) is arranged to pressurize and activate the activating means (3, 4), alternatively, and drain one of the activating means to the tank through a flow restriction (6, 7) at activation of the other activating means (3, 4). The power system comprises at least one control flow circuit (10-12; 72-83; 37-44) which communicates with one of the activating means (3, 4), and a valve means (11, 12; 71; 31) which is arranged to accomplish a flow through the control flow circuit (10-12; 72-83; 37-44) in relation to the load pressure on the motor such that the counter pressure from the flow restriction (5, 7) generates a compensating force in relation to the load pressure on the motor on the non-activated activating means (3, 4).

Device in a hydraulic power system connected to a load driving hydraulic

Device in a hydraulic power system connected to a load driving hydraulic motor (18; 32), comprising a pilot controlled flow regulating directional valve (1; 29) for alternative connection of the service ports of the motor (18; 32) to a pressure medium source and a tank. The directional valve (1; 29) comprises two opposite and by a pilot pressure activatable activating means (3, 4), and a pilot pressure means (84) is arranged to pressurize and activate the activating means (3, 4), alternatively, and drain one of the activating means to the tank through a flow restriction (5, 7) at activation of the other activating means (3, 4). The power system comprises at least one control flow circuit (10-12; 72-83; 37-44) which communicates with one of the activating means (3, 4), and a valve means (11, 12; 71; 31) which is arranged to accomplish a flow through the control flow circuit (10-12; 72-83; 37-44) in relation to the load pressure on the motor such that the counter pressure from the flow restriction (5, 7) generates a compensating force in relation to the load pressure on the motor on the non-activated activating means (3, 4).

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Boras, Sweden

Bo Nilstam