Pumps & Valves

Question 1

What is the purpose of a piston cushion?

Answer 1

Restricts the outward flow of oil,controlling the speed of an actuator

Needle vv adjust how much oil can leave cylinder

Question 2

Describe the semi rotary actuator

Steering gear

Answer 2

• 6 pressure chambers between rotor & stator
• 2 manifolds connected to the alternate chambers
• Suction & delivery ports in each chamber

Question 3

Rotary acutuators are also known as..

Answer 3

• MOTORS
• Hyd energy to mech work

Used in capstans, stores lifts

Question 4

Where are linear actuators used?

Answer 4

• Stabs
• Davits
• Steering gears
• Gash compactor

Question 5

Name the 2 type of pumps

Answer 5

• Positive displacement (Hydrostatic)
• Non-positive (Hydrodynamic)

Question 7

Describe a Axial piston pump

Answer 7

• Pistons parallel to shaft
• Angle of the swash determines the length of stroke,controlling the capacity of pump

Question 8

What is the procedure for the motor leakage test?

Answer 8

• Isolate return
• Open drain line
• Supply oil to actuator by direction valve
• Collect oil from drain line,timing till got 1 litre
• Temp oil ,repeat test isolating other return line
• Plot results

Question 9

What 2 condition mandate an oil change?

Answer 9

1. Degredation
2. Additive depletion

Question 10

Name 5 malpractices in pumps & motors

Answer 10

• Changing filters
• Too hot
• Incorrect oil
• Filter location
• Not self priming

Question 11

What are the 2 basic methods of flow control?

Answer 11

1. Meter in
2. Meter out

Question 12

Explain the safety supervisor valve

On the steering gear pumps

Answer 12

• 2 solenoid vv connected between hyd supply lines to port & stbd rudder
• Controlled by circuits in each HPU motor starter
• Report to local
• Supply tanks have low & low,low switches
• Protects system from leaks