Abstract: A leak-detecting hydraulic system is disclosed for operation of a fluid actuator associated with a front-end loader, a backhoe, or a like implement on a material handling device. Notably, the system includes a leak-detection circuit which normally acts to prevent movement of the implement associated with the actuator by gravity in the event of a failure in one of the hydraulic fluid lines operatively connected with the actuator. Additionally, the system preferably includes a selectively operable float valve which permits fluid flow which bypasses the leak-detection circuit, thus desirably permitting operation of the implement associated with the actuator in a "floating" mode.