🔍 Key Concepts

• 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

💭 Think About

• 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 engine‑driven pump’s ability to keep pressure up?

✅ Before You Answer

• 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.