Abstract: Heavy duty hydraulic surge brakes for carrying high front end loads includes a fixed section for mounting on the tailer draw bar or frame and a movable section connected to the coupler. The fixed section has a frame for mounting to a trailer frame and a pair of end plates. A pair of rigid rods extend between the end plates. The hydraulic master cylinder mounts on the fixed section and has a push rod which is operated by the movable section. The movable section includes a pair of slide tubes on the rods guided by low friction bearings. A cross member joins the tubes to the draw bar, and a brake adjusting screw is carried on the tubes for coaction with the cylinder push rod. Springs urge the tubes forward on the rods, and bumpers cushion the forward position of the tubes. In another embodiment, automotive-type shock absorbers add further control of the surge-induced movement of the movable section to the fixed section.

Abstract: A trailer brake actuator and method of operation in which the actuator is interposed between a towing vehicle and a trailing vehicle and is operable upon a change in the distance between the vehicles to displace actuating fluid to the trailer brakes. The actuator is effective in both directions of relative movement between the vehicles, and in each direction of movement, the development of pressure above a predetermined minimum pressure or relative movement of the actuator parts beyond a predetermined amount will cause the pressure in the brake system to be released.