The actuator device comprises {HEAD ~ a bellows device} defining {TAIL ~ a first chamber} partly bounded by a movable wall and a fixed wall, and communicating with two further chambers defined by associated housings carried by the said fixed wall 
The actuator device comprises { HEAD ~ a bellows device } defining { TAIL ~ a first chamber } partly bounded by a movable wall and a fixed wall , and communicating with two further chambers defined by associated housings carried by the said fixed wall
OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH