escapement
es.cape.ment \is-'ka-p-m*nt\ n 1a: a device in a timepiece which controls the motion of the train of wheel work and through which the energy of the power source is delivered to the pendulum or balance by means of impulses that permit a tooth to escape from a pallet at regular intervals 1b: a ratchet device (as the spacing mechanism of a typewriter) that permit s motion in one direction only in equal steps 2a: the act of escaping 2b: a way of escape : VENT