Lego Clock Escapement W4.3. As W4, but with wheels rotating the other direction. This allows a better contact with the pendulum, and a smaller amplitude. Note that, at the moment of impulsing, the contactpoint, the pendulum-axis, and the scapewheel-axis, are nearly on a straight line (tangential impulstransfer). This applies to 'entry', as well as to 'exit'; it is not possible with a single scapewheel.