Spring-loaded brake cylinder

A spring-loaded brake cylinder particularly for a railway vehicle and comprising a housing, a piston slideable within said housing, a threaded shaft and nut carried on said threaded shaft between said piston and a piston rod, said threaded shaft having a non-self-locking thread, one of said shaft and nut being rotatable and the other being non-rotatable, a loading spring within said housing having one end rotatably supportable by a portion of said housing and secured against axial displacement and a second end acting against said piston, means for coupling said spring second end and the rotatable one of said nut and shaft, said rotatable one capable of receiving a load imposed by said spring and of rotating in such a manner to permit torque to be transmitted to said housing, and rotary coupling means in the path of torque resulting from the force exerted by said spring upon said shaft and nut so that said spring and the rotatable one of said nut and shaft are free to rotate upon selective operation of said rotary coupling means.