Abstract: The apparatus is a trapped key safety interlock device for use with a coupling that comprises a body provided with a face seal, a rim on one side and a projecting spur on the diametrically opposite side. The safety device includes a coupling part (201) which is complimentary to the said coupling (102) and which comprises a body portion having a rim portion (207) on one side for engagement with the spur of the said coupling and having a spur portion (206) on the diametrically opposite side for engagement with the rim of the said coupling (102). The rim portion accommodates a release mechanism (16, 18) for selectively enabling and disabling a key retention mechanism within the device. The key retention mechanism has a key retention condition and a key releasable condition, wherein the release mechanism comprises a primary release mechanism (16) and a secondary latching mechanism (18) resisting movement of the primary release mechanism until it is actuated itself.

Abstract: A vehicle includes a coupling assembly for connecting first and second sections of a brake supply line, the coupling assembly comprising complementary first and second couplings which fit together. A safety device is complementary to one coupling and which can be fitted to the coupling so that it cannot be connected to the other coupling. The safety device includes a locking device which is operable to prevent removal of the safety device from the coupling; the locking device prevents removal of a key until the locking device is operated. The key removed from the locking device can be used to enable use of a loading bay.

Abstract: An exit door has a security device comprising a flexible member, e.g. a chain, for connecting two locking devices which may be fixed on a door and doorway or on double doors. The first locking device is operable by a first key removable only when the locking device is activated and a second key removable only when the locking device is deactivated. One end of the flexible member is fixed to the second key and the other end is fixed to the second locking device, which is operable by the second key, being removable from the second locking device only when it is activated, and by a third key removable only when the second locking device is deactivated. The security devices are members of a series of such security devices in which the third key of each security device serves as the first key of the next security device in the series. The last key in the series is essential to operation of a control unit permitting use of a building provided with the exit door.