When the diesel engine hydraulic governor shown in the illustration is operating at controlled speed, which of the relationships listed will occur between the edges of the pilot valve and the ports of the pilot valve bushings? See illustration MO-0092.
• Hydraulic governor neutral or "in balance" position at controlled speed • Function of the pilot valve plunger and bushing ports in sending oil to or from the power piston • What happens to oil flow and power piston movement when engine speed is steady and load isn’t changing
• When the engine is exactly at the set speed and the load and fuel rack are not moving, what must be happening at the power piston—moving or stationary? How does that condition affect whether oil is flowing to or from the piston? • Look at MO-0092: if the pilot valve edges move up or down past the ports, what specific oil paths open (to high-pressure supply or to sump), and what would that do to the fuel setting? Would that keep speed constant or change it? • In a stable, controlled-speed condition, should the pilot valve be actively changing oil flow, or sitting in a position where no correction is being made? What does that imply about the alignment of the valve edges with the bushing ports?
• Verify which choice describes no net oil flow to or from the power piston (neutral condition). • Check the illustration to see which pilot-valve position would start motion of the power piston; eliminate any options that would obviously cause movement rather than steady state. • Be sure the selected option matches a stable, non‑hunting condition, not one where the valve is constantly opening and closing and causing continual power-piston motion.
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