Link 1, carrying wedge member b, slides in fixed guides a-a. Latch 3 slides in fixed guides e-e and has at i ts upper end detent f which locks member k of rod 2. Rod 2 slides in link 1. Latch 3 is held in engagement with member k by spring 5, and link 1 is pushed to the left by spring 6. When link 1 is pushed to the right, bevelled surface m of member b slides along inclined surface n of latch 3, withdrawing the latch from engagement with member k. This releases rod 2 which, like link 1, moves to the right (due to the action of spring 4).
$2716$RG,ML$