Two marks questions and answers

TWO MARKS QUESTIONS AND ANSWERS

1. List four basic requirements on which the life of the fluid power systems depend?

The four basic requirements are:

(i) Properly installed equipments,

(ii) Properly trained personnel,

(iii) Planned preventive maintenance, and

(iv) Efficient troubleshooting.

2. List any four common types of faults that can be found in hydraulic systems.

1. Reduced speed of travel of machine tool elements.

2. Slow response to control.

3. Excessive loss of system pressure.

4. Excessive leakage in the system.

3. List any four common causes of hydraulic system breakdown. 

1. Inadequate supply of oil in the reservoir.

2. Clogged or dirty oil filters.

3. Leaking seals.

4. Loose inlet lines that cause the pump to take in air.

4. Define troubleshooting?

The term troubleshooting refers to an organised and systematic study of the problem and a logical approach to the difficulty faced in a system.

5. What is the purpose of a tree-branching chart ?

A tree-branching chart is a fault finding chart which can be used to simplify the complex fault finding process in a fluid power circuit. This chart helps the maintenance personnel in developing a logical and rapid approach to fault diagnosis.

6. List any four common types of pump faults.

1. Pump may deliver insufficient or no oil.

2. Pump may make more noise.

3. Pump may develop unstable or zero pressure.

4. Pump oil may get overheated.

7. If a pump is delivering insufficient or no oil, what are all the possible causes and also give remedies for them.

Probable Causes

1. Wrong direction of shaft.

2. Pump shaft turning too slowly to prime itself.

3. Clogged strainer or suction pipeline.

4. Air leak in suction line.

Remedies

1. Must be reversed immediately to prevent seizure.

2. Check minimum speed recommendation and momentarily increase rpm, to rectify.

3. Clean strainer or suction pipeline. Remove foreign matter.

4. Add oil and check oil level in reservoir. Check for leaks and repair.

8. List any four causes for a pump making more noise.

1. Misalignment of pump and prime mover.

2. Strainer capacity insufficient.

3. Air remains in pump casing.

4. Small size of suction pump.

9. List any two types of faults that can be found in each of the following hydraulic valves:(a) Directional control valve, and (ii) Flow control valve.

Faults in a DC valve may be:

1. Faulty or incomplete shifting, or

2. Cylinder creeping or drifting.

Faults in a flow control valve may be:

1. Variation in feed, or

2. External leakage.

10. If a hydraulic motor does not provide the proper speed and torque, what could be the possible causes for it ?

Probable causes are :

1. System overload, relief valve adjustment not set high enough.

2. Relief valve sticking open.

3. Free recirculation of oil to reservoir.

4. Pump not delivering sufficient volume or pressure.

11. What will you do to reduce/prevent excessive heating of oil in a hydraulic system? Remedial actions are :

1. Follow manufacturer's instructions while trying to reassemble.

2. Use artificial cooling.,

3. Provide large reservoir or install cooler.

4. Check and repair the leaking check valves and relief valves in the pump.

12. List any two types of faults that can be found in each of the components of a FRC unit.

Faults in a filter:

1. Excessive pressure drop through filter.

2. Contaminants carried through the filter. 

Faults in a regulator :

1. Air often escaping from vent hole.

2. Chatter and vibration.

Faults in a lubricator :

1. Oil not delivered from the lubricator.

2. Delayed oil delivery.

13. If an air cylinder produces erratic cylinder action, identify the probable causes and also give remedies for them.

14. List the probable causes for the problem of leakage of compressed air in pneumatic systems.

1. Loose joints, fittings or glands.

2. Ruptured pipes and hoses.