Patent ID: 6848641

Claim:
An actuating valve for a pneumatic cylinder ( 8 ) comprising a first pressure chamber and a second pressure chamber ( 8 . 3 , 8 . 4 ) separated from one another by a piston connected on a piston rod ( 8 . 1 ), the actuating valve comprising: two first 3/2 port directional control valves as relay valves (L 1 , R 1 ) connected to a compressed air source (P); a valve system connected between the relay valves (L 1 , R 1 ) and the pneumatic cylinder ( 8 ) and comprising a venting throttle; wherein the valve system, upon actuation of one of the two relay valves, loads the first pressure chamber with compressed air while the second pressure chamber is relieved of pressure via the venting throttle; wherein the valve system comprises two second 3/2 port directional control valves (L 5 , R 5 ) arranged immediately upstream of the pneumatic cylinder; wherein the valve system further comprises a first branch line (L 3 ) connecting a first one of the relay valve (L 1 ) to a first one of the second 3/2 port directional control valves (L 5 ) and a second branch line (R 3 ) connecting a second one of relay valve (R 1 ) to a second one of the second 3/2 port directional control valves (R 5 ); wherein the branch lines (L 3 , R 3 ) comprise a check valve (L 4 , R 4 ), respectively; wherein the valve system further comprises a first control line (L 7 ) connecting the first branch line (L 3 ) to the second one of the second 3/2 port directional control valve (R 5 ) and a second control line (R 7 ) connecting the second branch line (R 3 ) to the first one of the second 3/2 port directional control valves (L 5 ); wherein the first and second control lines control the first and second ones of the second 3/2 port directional control valves (L 5 , R 5 ) between a first position allowing compressed air to pass and a second position for pressure relief such that a) when the relay valves (L 1 , R 1 ) are not actuated, the first and second ones of the second 3/2 port directional control valves (L 5 , R 5 ) are in the first position and the relay valves vent the first and second branch lines (L 3 , R 3 ); while b) when one of the two relay valves is actuated, respectively, the actuated one of the relay valves assumes a position allowing compressed air to pass to the branch line connected to the actuated one of the relay valves.