Question 586Steam Plants - Assistant Engineer

The correct answer is B) The propeller shaft must be stopped and held stationary until the clutch is engaged. This is correct because engaging the turning gear mechanism while the propeller shaft is still turning can cause significant damage to the turning gear. The propeller shaft must be completely stopped and held stationary before the turning gear can be safely engaged. This prevents the turning gear from being forcibly driven by the rotating propeller shaft, which could lead to mechanical failure. The other options are incorrect because they do not directly address the need to stop the propeller shaft before engaging the turning gear. Setting the brake on the reduction worm shaft (A), having the engine order telegraph on 'stop' (C), or reducing the speed of the astern turbine (D) do not necessarily ensure the propeller shaft is stationary, which is the critical step to prevent damage to the turning gear mechanism.