Abstract: The invention provides an electrical switch for monitoring stroke adjustment of an air brake as used on heavy wheeled vehicles. The switch has a switch body securable to fixed structure of the air brake, and fixed and moveable electrical switch contacts in which the fixed switch contact is fixed relative to the switch body. A switch actuator moves relative to the body and carries the moveable switch contact into and out of engagement with the fixed switch contact. The switch actuator is selectively responsive to movement of brake mechanism associated with the air brake actuation. A resilient member cooperates with the switch actuator and the body to close the switch contacts. The switch actuator passes through an opening in an air chamber of the brake and, when the brake is properly adjusted, is clear of a diaphragm plate within the chamber.