This animation shows the operation of the Sully escapement in electric clocks which have an electrically impulsed balance wheel. The driving force of these clocks is the electro-magnetic impulse given directly to the balance. There is no other force, weight or spring, to drive the hands of the clock. The escape wheel (in red) is being driven forward by the sloping faces mounted on the balance wheel arbor.
The original escapement was invented by Henry Sully in the eighteenth
century for use with conventional weight and spring powered clocks and
would have worked in the opposite direction to the animation on the left,
i.e. with the escape wheel (in red) driving the sloping faces mounted on
the balance arbor and thereby giving impulse to the balance.