in order for a worker to be able to climb into the shaft pit 3 the car 1 is sent to a higher floor the shaft door 17 at the lowermost floor 16 can be unlatched and opened utilizing either the unlatching and release device 26 which requires rotating the bolt 18 with a standard triangular key or the two stage unlatching and release device 26 39 which requires rotating the bolts 18 and 25 with the key the rotation of the triangular bolt 18 or the triangular bolt 25 moves the latching switch 21 into the detent or set position whereby the safety circuit 39 is interrupted the safety circuit 39 thereby prevents the actuator 12 from extending in response to the disconnecting of the signal lines 21a and 21b from one another by the switch 21 the shaft door 17 can now be opened manually and be maintained in the open setting after the car 1 has moved away from the lowermost floor 16 the swivel buffer 8 or preferably an opposed pair of the swivel buffers tilts automatically into the path of travel 7 and thus blocks the return of the car to the lowermost floor after the worker climbs into the shaft pit 3 he can actuate the control off pit switch 43 see fig1 required by regulation in the.