Question 53 GLI02 - Mate of Unlimited Tonnage

The Correct Answer is B. **Explanation for Option B (Correct):** Option B is correct because nearly all hydraulic systems designed to lift or hold a load (like a winch or crane) incorporate a **load-holding valve** or a **pilot-operated check valve** (sometimes referred to simply as a check valve in this context) within the lifting circuit. If the pump stops (losing pressure), the valve immediately senses the potential for the high pressure on the load side to reverse flow back to the reservoir. The check valve closes instantly, trapping the pressurized fluid beneath the lifting cylinder or motor. This action mechanically locks the load in its current position, preventing it from dropping due to gravity, even if the primary power source fails. **Why the Other Options are Incorrect:** * **A) the control lever will move to the stop position:** While control levers often spring return to neutral (stop) when released, this mechanical action alone does not hydraulically lock a suspended load. The load would only stay suspended if the neutral position activates a positive locking mechanism (like a closed spool valve), but the definitive safety mechanism is the internal hydraulic check valve. * **C) the electric pump motor will cut out:** The motor cutting out is the *cause* of the pump stopping, but it is not the *reason* the load stays suspended. The load stays suspended because of the hydraulic component that reacts to the loss of pump pressure. * **D) a centrifugal counterweight counteracts the force of gravity:** Centrifugal forces are related to rotating motion and are not the primary mechanism used in standard hydraulic systems to lock a static, suspended load. While some mechanical winches might use brake mechanisms, hydraulic winches rely on fluid dynamics and locking valves; a centrifugal counterweight is irrelevant to this hydraulic safety function.