Spring brake cylinder having an emergency release device

A spring brake cylinder having an emergency release device, particularly for rail vehicles, comprising:

• a housing;
• a spring piston which can be moved axially within the housing by one of at least one accumulator-type spring for operating a spring brake in the event of a release pressure medium drop and a spring pressure chamber for releasing the spring brake when the chamber is acted upon by a release pressure medium;
• a normally locked, not self-locking threaded screw drive arranged in a transmission of force between the spring piston and an output-side piston rod;
• an outer-radial sliding surface, of the emergency release device, having a detent flank, the outer-radial sliding surface being an element of a rotatable part of the threaded screw drive that rotates with respect to the housing, and the threaded screw drive having a pitch dimensioned such that the rotatable part carries out less than a complete rotation along its maximal axial adjusting stroke, and the detent flank being configured for locking the emergency release device;
• and
• a latch, of the emergency release device, held in contact with the sliding surface, for interacting with the detent flank to lock the emergency release device, and for releasing the spring brake in the absence of the release pressure medium by manually unlocking the not self-locking screw drive and thereby permitting axial movement of the spring piston.