The tolerance allowed in the endless screw of the governor that allows for a properly operating airbrake. Can be applied to any shaft that employs pivots held between planes.

The removable brass piece atop the governor cock bracket which holds the endstone in place.

The jewel, usually a ruby or garnet, upon which the pivot of the worm or endless screw bears. It is held atop the cock bracket by the endstone cap.

See regulator, reservoir.

See second wheel.