Abstract: A bolt assembly for interengaging two relatively movable elements. The assembly comprises a first component (1) which is connected to one element, and a second component (11) which is connected to the other element. The first component (1) includes a bolt (4) displaceable between engaged and disengaged positions, and the second component (11) comprises means for engaging the bolt to interengage the elements to which the components (1, 11) are connected when the first component is in a predetermined position relative to the second component and the bolt (4) is in the engaged position. The first component (1) comprises a magnetically (3) releasable latch mechanism arranged to latch the bolt (4) in the disengaged position, and the second component (11) comprises at least one source of magnetic flux (12) arranged to release the latch when the first component (1) is in the predetermined position relative to the second component (11).

Abstract: A valve lock for locking a valve spindle in a selected position corresponding to the valve being for example fully open or fully closed. The lock has a housing which is mounted on the valve body and a hub which engages and rotates with the valve spindle relative to the housing. A latch is provided between the housing and the hub, the latch being actuatable by a key to assume a latched condition in which rotation of the hub relative to the housing is permitted in one direction but prevented in the other direction. A spindle position indicator is coupled by a transmission to the hub as to be displaced as a result of rotation of the spindle, thereby to indicate the spindle position relative to the valve body. The spindle position indicator prevents actuation of the latch by the key except when the spindle is in the selected position as represented by the spindle position indicator.

Abstract: A valve lock for locking a valve spindle in a selected position corresponding to the valve being for example fully open or fully closed. The lock has a housing which is mounted on the valve body and a hub which engages and rotates with the valve spindle relative to the housing. A latch is provided between the housing and the hub, the latch being actuatable by a key to assume a latched condition in which rotation of the hub relative to the housing is permitted in one direction but prevented in the other direction. A spindle position indicator is coupled by a transmission to the hub so as to be displaced as a result of rotation of the spindle, thereby to indicate the spindle position relative to the valve body. The spindle position indicator prevents actuation of the latch by the key except when the spindle is in the selected position as represented by the spindle position indicator.