Abstract: A portable security lock of the "U-bar" type includes a rigid "U" or "C" shaped security bar (8), and a flexible security loop (14) and a generally tubular cross member (2). The cross member has a pair of sockets each of which is adapted to cooperate with a suitably shaped end of the security bar or loop, and an internal rotatable barrel member (26) having keyhole slots (28, 30, 32) which receive the shaped ends in a first rotational position. The barrel member is then rotated to a second position in which the shaped ends are locked into the cross-member. Electrical contacts connect the barrel to an alarm via the security loop so that the alarm is triggered if the security loop is removed or broken while the alarm is set.

Abstract: An alarm lock particularly suitable for use with a bicycle or similar article to be secured, comprising a casing having an integral clamping device and containing an alarm siren which can be actuated either by an internal motion sensitive device, or by breaking or disconnecting a security loop which is connected around the article. Both of the alarm devices are connected to an automatically resettable detector circuit which includes a timer for resetting after a predetermined period. A battery for the circuit is contained in a compartment which is closed by abutment of the alarm lock against the body of the article, when it is attached by the integral clamping device.