An auxiliary diesel engine on your fishing trawler uses a starting system similar to the one shown in the illustration. The hand pump is capable of charging the accumulator to the pressure necessary to start the engine and the engine successfully starts. While running, the engine driven pump is not capable of maintaining the accumulator in a state of being fully charged. Which of the following is most likely to be the cause? Illustration M0-0049
⢠Hydraulic starting systems: relationship between hand pump, engine-driven pump, and accumulator pressure ⢠How an unloading (relief) valve works when system reaches set pressure ⢠What happens if components like the starter pistons, drive belt, or filter fail or bypass
⢠If the hand pump can fully charge the accumulator and start the engine, what does that tell you about the condition of the accumulator, starter, and filter path? ⢠Once the engine is running, which component is supposed to keep the accumulator charged, and what type of fault would let the engine still start but prevent maintaining full pressure? ⢠For each answer choice, ask yourself: would this fault prevent charging at all, or only affect the engineādriven pumpās ability to keep pressure up?
⢠Confirm which line in the illustration is coming from the engine-driven pump and where it enters the accumulator circuit. ⢠Trace the path of flow past the unloading valve and consider what happens if its set pressure is too high or if it is stuck open. ⢠Verify which failures (worn starter pistons, broken belt, filter bypass) would still allow the hand pump to charge the accumulator and start the engine but limit pressure when relying only on the engine-driven pump.
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