🔍 Key Concepts

• Study which parts are fixed and which are free to rotate in this rotary vane steering gear (pay close attention to labels O, U, N, P, and the casing). • Think about how hydraulic pressure acting on one side of a vane creates torque and which way that torque will try to move the rotor versus the housing. • Consider what happens when one chamber is pressurized while the adjacent chambers are connected to return (no pressure) – does that cause motion, or can it create a hydraulic lock?

💭 Think About

• Look at the space between N and I: which solid surface does the pressurized oil actually push on, and in which tangential direction is that force applied? • Ask yourself: if oil on the opposite sides of the vanes (mentioned in the answer choices) is being returned to the main pump, are those areas high pressure or low pressure, and will they resist or allow movement? • If the rotor (O) tries to move in one direction, what equal and opposite reaction will the housing (U) experience, and which one is actually held stationary by the ship’s structure?

✅ Before You Answer

• Verify which member is the rotor (driven by oil) and which is the stator/housing (bolted to the ship) by tracing the shaft and mounting bolts. • Confirm which chambers become high-pressure (connected to the pump discharge) and which become low-pressure/return in the situation described. • Check whether there is a continuous oil path around the vanes that would allow rotation, or whether the pressurized areas are trapped on both sides, creating a hydraulic lock.