Patent ID: 6933650

Claim:
A wear indicator for a motor carbon brush that is used in association with a commutator having a surface comprising: a housing; a carbon brush slidably mounted within the housing in a sliding direction, wherein the front end of the carbon brush touches the surface of the commutator and the surface of the carbon brush has a contact portion, the contact portion comprising a protrusion protruding from the surface of the carbon brush; a guiding slot in the housing which extends co-directionally with the sliding direction, the protrusion protruding through the guiding slot, an elastic element positioned on the housing which bears against the rear end of the carbon brush; a circuit board which is equipped with an alarm indicator light and is fixed to the housing; and an electric probe disposed on the circuit board which is electrically connected to the alarm indicator light, the electric probe comprising a substantially columnar projection projecting from the circuit board, wherein in use when the carbon brush is in a first operational state, a surface of the electric probe is disconnected from the contact portion of the carbon brush and when the carbon brush is in a second operational state, the surface of the electric probe touches the contact portion of the carbon brush.