Patent ID: 7896102

Claim:
A pneumatic drive system comprising at least one pneumatic drive having a drive housing and an output drive unit able to be shifted in relation to it by the action of compressed air, said output drive unit possessing an output piston, which in the drive housing divides two working chambers from each other, of which one or both is connected with control valve means serving for the controlled action of compressed air, said control valve means being able to be switched over between several switching settings which include an air economy setting defining a choke cross section, wherein, as a further switching setting, the control valve means have a high power setting which sets a flow cross section which is larger than the choke cross section, and wherein actuating means are associated with the control valve means which, during the supply of compressed air into one working chamber, so control the switching over of the control valve means connected to this working chamber in a fashion dependent on the air pressure obtaining in at least one working chamber that a switching over takes place from the normally assumed air economy setting into the high power setting, when and at least as long as the output drive unit is subjected to a increased resistance to motion, and wherein the control valve means, as a further switching setting, have a hold setting predetermining a flow cross section smaller than the choke cross section, and wherein further actuating means are associated with the control valve means which are able to be activated in a fashion dependent on the position of the output drive unit, such further actuating means being able to cause a switch over into the hold setting, when in the course of its working stroke, the output drive unit reaches an end of stroke position or a position just short thereof.