A brake mechanism for a beam trolley on a beam has a body member on the beam trolley adjacent the beam. The body member has a recess and axially aligned bores and a rotatable lateral pin extends through the aligned bores. The lateral pin has a rotatable elongate cam portion extending across the recess, and a brake pad is in the recess adjacent to the beam and abutting the cam portion. A handle is connected to the lateral pin for rotating the pin and the cam portion to displace the brake pad against the beam. The brake pad frictionally secures the beam trolley on the beam and locks the rotatable cam in place. Rounded end portions on opposite ends of the lateral pin and sleeve-like bushings between the axially aligned bores and rounded end portions permit rotation of the cam portion by the handle.