Question 53 OSE02 - Assistant Engineer - OSV

The Correct Answer is D **Explanation for D (Correct Answer):** Option D is correct because it accurately describes the typical relationship between a mechanical slave remote control station (often a backup or secondary station) and the primary pneumatic master control station in a propulsion control system setup common on vessels like supply vessels. When the mechanical slave control is engaged, it does not typically take over the pneumatic signaling directly. Instead, it mechanically overrides or directly operates the lever or control valve spool of the main **pilot house pneumatic master control station** (the primary control unit) using a physical linkage, such as a chain or cable. By physically shifting the master station's control valve spool, the slave station initiates the standard pneumatic sequence (transmitting air pressure) necessary to shift the clutch actuator 4-way control valve into the desired ahead position. **Explanation of Incorrect Options:** **A) Movement of the mechanical slave remote control station lever directly shifts the pneumatic remote control station lever control valve spool by the action of a chain or cable which results in pneumatic shifting of the clutch actuator 4-way control valve to the ahead direction.** This option is too general and potentially redundant. The "pneumatic remote control station" is the same component as the pilot house master control station mentioned in D. However, the terminology "pneumatic remote control station lever" is less precise than "pilot house pneumatic master control station" in the context of typical systems where the pilot house controls are the primary master. The core mechanism described is similar but D uses the more precise terminology for the primary control point. More importantly, in these systems, the mechanical slave usually acts upon the primary *master* station (Pilot House Master), making D the most accurate description of the control architecture. **B) Movement of the mechanical slave remote control station lever directly shifts the clutch actuator 4-way control valve to the ahead direction by the action of a chain or cable.** This is incorrect. The clutch actuator 4-way control valve is typically located near the engine or gearbox and is actuated by pressurized air (pneumatics), not directly by a long run of chain or cable originating from the bridge/control station. The mechanical link only goes as far as the pneumatic master control station (as described in D). **C) Movement of the mechanical slave remote control station lever directly shifts the engine room control station lever control valve spool by the action of a chain or cable which results in pneumatic shifting of the clutch actuator 4-way control valve to the ahead direction.** This is incorrect. The mechanical slave remote control station (which is typically located on the bridge or near another maneuvering position) links directly to the primary master control station (Pilot House Master), not usually to the engine room control station (which is often a secondary or local station) unless the mechanical control is itself located in the engine room. If the question implies a bridge-based mechanical slave, it acts upon the bridge-based master, making D the correct description of the control flow.