Question 44 UFIV02 - Assistant Engineer - UFIV

The Correct Answer is C **Explanation for C (Correct Option):** Option C states: "The manual shutdown lever is operated by means of a remote pull cable and uses the over speed trip mechanism to accomplish engine shutdown." In most large diesel engines (like those used on fishing industry line vessels), especially those equipped with overspeed protection, the primary manual emergency shutdown system utilizes the existing overspeed trip mechanism. This mechanism is designed to instantly cut fuel to the injectors or intake air, bringing the engine to a rapid stop. 1. **Remote Pull Cable:** Since the engine itself may be inaccessible or hazardous during an emergency, the physical shutdown lever on the engine is almost always connected to a remote control station (often on the bridge or in the engine room control area) via a heavy-duty **remote pull cable** (or sometimes a hydraulic/pneumatic system, but a mechanical cable is common for emergency trips). 2. **Over Speed Trip Mechanism:** Utilizing the overspeed trip mechanism for emergency shutdown is efficient because this system is inherently designed for rapid, positive fuel cut-off, ensuring the engine stops quickly, regardless of the governor setting. Pulling the remote cable mechanically triggers the same mechanism that would activate if the engine exceeded its maximum safe RPM. **Explanation of Incorrect Options:** **A) The manual shutdown lever is operated by means of a remote pull cable and uses the governor fuel control linkage to accomplish engine shutdown.** * **Incorrect:** While a remote pull cable is used, emergency or manual shutdown should bypass the normal governor control. Using the governor linkage for an emergency stop risks a slower, less positive shutdown, as the governor might attempt to maintain minimum idle speed or fight the shutdown command, especially if the linkage is sticky or damaged. Emergency stops must be instant and decisive. **B) The manual shutdown lever is operated by means of the over speed trip reset lever and uses the over speed trip mechanism to accomplish engine shutdown.** * **Incorrect:** The shutdown mechanism uses the over speed trip mechanism, but the manual operation is achieved by pulling a dedicated **shutdown lever/cable**, not by operating the **reset lever**. The reset lever is specifically for re-arming the trip mechanism *after* it has been activated and the engine has stopped, not for initiating the trip itself. **D) The manual shutdown lever is operated by means of the emergency trip reset lever and uses the governor fuel control linkage.** * **Incorrect:** This option is incorrect on two counts. First, it incorrectly identifies the operating component as the "reset lever" (see B). Second, it incorrectly identifies the mechanism used as the "governor fuel control linkage" (see A). Emergency shutdown bypasses the governor linkage.