Heavy Equipment Flashcards
What are the two main types of hydraulic systems?
Open-center systems
Closed-center systems
Explain the seven steps in diagnosing a problem
- Know the system
- ask the operator
- operate the machine
- inspect the machine
- List the possible causes
- Reach a conclusion
- Test your conclusion
What does a service technician do?
- Trouble shooter
- collects facts and pinpoints the trouble before doing any repairs
What does a parts changer do?
Dives into the machine and starts replacing parts until the trouble is found rather than diagnosing the issue first
What are the 4 primary things that require testing in a hydraulic circuit?
- Pressure
- Flow
- Speed (leakage)
- Temperature
What are the simple leakage tests that can be performed without test equipment?
Checking both hydraulic cylinders to see if there is a significant difference in the heat.
Faulty circuit relief valves will affect _______
only pressure readings in the individual circuits
What check should be made before testing or repairing a leak?
You should make sure all hydraulic oil pressure is drained from the system and that all increments are secured to the ground.
What is the principal of the “operational checkout”?
Look, listen, feel
Faulty system relief valves will affect ______
readings in all tests
What is the condition of the machine if the flow readings are the same as the pump readings?
The pump is working fine and all components are okay
What is the condition of the machine if flow drops as maximum pressure us reached with the control valve in all positions?
The system relief valve is probably at fault
There are ________ basic steps in a diagnostic-testing program.
7
The basic checks that can be made with most hydraulic testers is temperature, flow, ___________ and ___________.
pressure and leakage
When high pressure can not be reached in all the circuits of an open-centre system, the problem is most likely _______
a system relief valve
When testing pump and component flow, it is important that _______ and _______ remain constant
temperatures and engine speeds
What are the two general rules for the effect of relief valves on the system?
- Faulty system relief valves will affect readings in all tests
- Faulty circuit relief valves will affect only pressure readings in the individual circuits
Internal leakage in a hydraulic motor can be checked by measuring the amount of oil flowing from __________
the drain line when the motor is at full load
_______ temperature is an important factor to consider when performing hydraulic test
Hydraulic oil
