Question 67 QMED02 - Electrician-Refrigerating Engineer

The Correct Answer is B **Explanation for Option B (Correct):** The hand brake (often referred to as the primary or manual brake) of a lifeboat winch is designed to be failsafe and operator-controlled. It is typically a band brake or disc brake held off the drum by tension against a weighted lever. To apply the brake—for instance, when stopping the boat during lowering—the operator must release or **drop the counterweighted lever**. The weight then rapidly pulls the brake band or caliper tight against the drum, stopping the descent. This design ensures that if the operator loses control of the lever, the weight automatically applies the brake. **Explanation of Incorrect Options:** * **A) manually disengaged when hoisting a boat:** When hoisting (recovering) the lifeboat, the winch is powered by the motor. The brake lever is held in the 'off' position by the operator (or sometimes latched) so the drum can turn freely, but the brake is not primarily designed to be manually *disengaged* for hoisting; it is designed to be manually *engaged* for lowering control. Furthermore, during hoisting, the brake mechanism is often irrelevant as the motor power overcomes any slight residual brake force. * **C) controlled by the centrifugal brake mechanism:** The hand brake is entirely separate from the centrifugal brake. The **centrifugal brake** (or mechanical speed governor) is an automatic brake that controls and limits the maximum lowering speed, operating independently of the hand brake lever. * **D) automatically engaged if lowering speed is excessive:** This function describes the **centrifugal brake** (Option C), not the hand brake. The hand brake is a manual control used by the operator to start, stop, or hold the boat at any point during lowering. It does not automatically react to excessive speed.