Continuously adjustable rescue strut

A strut or strut system continuously adjustable in length for maintaining two bodies in a spaced relationship with respect to each other. Both the length of the strut and the locking of the strut at a desired length may be remotely controlled by pneumatic pressure. The strut system includes a cylindrical outer member having a cylindrical bore for receiving a cylindrical inner member. The cylindrical inner member is provided with a helical groove for engagement with ball bearings which are retained in a helical pattern in a collar attached to the end of the cylindrical outer member which receives the cylindrical inner member. The collar is adjustable between a first position in which the ball bearings are engaged in the helical groove in the cylindrical inner member and a second position in which they are disengaged from the helical groove in the cylindrical member. When the ball bearings are engaged in the helical groove in the cylindrical inner member, the cylindrical inner and outer members may be rotated with respect to each other to adjust the overall length of the strut. Further, the strut will resist a compressing force applied to the opposite ends of the strut. When the collar is in the second position with the ball bearings disengaged from the helical groove in the cylindrical inner member, the cylindrical inner and outer members may be freely reciprocated with respect to each other. Pneumatic pressure may be used to adjust the collar between the two positions, and to extend the cylindrical inner and outer members with respect to each other.