Abstract: The present invention involves a hydraulic device for immobilizing the wheel of a stationary trailer. The locking brake is spliced into a brake line of a trailer carrying a surge brake system and allows an individual to manually activate the trailer brake when the trailer is stopped. The brake device includes a housing block with a cylindrical bore and a spring biased piston. A shank is connected to the piston and provides a manual handle for shifting the position between an inner and outer position. In the outer position, brake fluid may flow from the brake system actuating device. In its inner position, brake fluid is prevented from flowing from the actuating device and is pressurized to lock each brake. The housing block also includes a pivotally secured lock pin which engages a hole on the shank to secure the shank to the housing block. In this manner, the brakes of the trailer may be secured in a locked position.