Abstract: An emergency brake device for stopping the rear wheels of a vehicle comprises a wedge assembly including a frame and a resilient wedge carried by the frame operably secured to the underside of the vehicle. The wedge assembly is movable from a stored position to an operative position such that the wedge is disposed between the rear wheel and the ground thereby to stop the vehicle. The wedge is substantially triangular formed by an inclined arcuate surface for engaging against the wheel and horizontal and vertical planar surfaces. The arcuate surface and the vertical planar surface terminate into a longitudinal projection portion at an upper end portion of the wedge adapted to engage the wheel when the wedge assembly is in the operative position.