Hydraulics

Question 1

What is the definition of a fluid?

Answer 1

1) A substance that will readily take the shape of its container.
2) It is capable of transmitting power.
3) It can be liquid or gas.

Question 2

What do A, F and P stand for in the hydraulic equation?

Answer 2

A = Area - Area of the piston face.

F = Force - Force acting on a piston / Force transmitted by a piston.

P = Pressure - Pressure exerted on the system fluid.

Question 3

What are the 8 advantages of hydraulics?

Answer 3

1) Reliability
2) Simple and easy to understand
3) Infinite speed range
4) Easily reversed
5) Ability to withstand overload
6) No spark risks
7) High torque at low speeds
8) 1/12 size of equivalent electric motor

Question 4

What are the four disadvantages of hydraulics?

Answer 4

1) Fire risk with mineral oil systems
2) Noise
3) Risk of contamination
4) Less efficient (85 - 95%)

Question 5

What is the hazard associated with O-Rings containing fluorocarbon elastomers?

Answer 5

At extreme temperatures above 300 degrees, they will give off toxic gasses including hydrogen fluoride.

Question 6

What PPE must you wear when working with fluorocarbon elastomers.

Answer 6

PVC gauntlets
Rubber boots
PVC coveralls
Full-face visor

Question 7

What are the two types of hydraulics fluid?

Answer 7

Petroleum based - General purpose mineral oils.
Synthetic based - Man-made for specific purposes.

Question 8

What oils used for hydraulics are in use in the Royal Navy? What are their colours?

Answer 8

OX30 - Red

OM33 - Yellow / Orange

OX40 - Green

Question 9

What are the six requirements of hydraulic fluids?

Answer 9

1) Transmission of power
2) Must flow easily through lines
3) Must be as incompressible as possible.
4) must provide Lubrication
5) Sealing properties
6) Cooling properties

Question 10

What are the five most common causes of contamination in hydraulic oil?

Answer 10

1) Airborne particles and moisture
2) Construction dirt
3) Dirt in new fluid
4) Dirt produced by wearing of new system.
5) Dirt from human sources.

Question 11

What are the seven methods used for reducing contamination?

Answer 11

1) Good system design
2) Filtration and filter maintenance
3) Operation of filter and clogging indicators
4) Good working practices
5) Use of guardian filter pack
6) Caps should be fitted to open pipework
7) Clean working area

Question 12

What are the three sets of pipework in a hydraulic system?

Answer 12

Pressure supply, return, and drain.

Question 13

What is the purpose of the drain leg?

Answer 13

Allows oil that has been specifically used for cooling and Sealing the Actuator/motor to return to the tank.

Question 14

What are the six different types of positive displacement pumps used for hydraulic systems?

Answer 14

1) Internal gearwheel type
2) External gearwheel type
3) Vane type
4) Lobe type
5) Radial piston type
6) Axial piston pump (using swash plate)

Question 15

What are the applications of an Axial Piston Pump?

Answer 15

Stabiliser systems
CPP systems
Steering systems

Question 16

What is an Actuator?

Answer 16

Converts hydraulic energy (system pressure) into mechanical motion.

Linear and Rotary types.

Linear actuators can be either single or double acting.

Question 17

What is an accumulator?

Answer 17

A device that stores energy and smooths out pulsations. Used as a surge/pulsation dampener/absorber.

Question 18

What is the equation used in hydraulics to work out pressure, force or area?

Answer 18

F = A x P

Question 19

Where is denso tape used? Where is it stored? What is the hazard associated with it?

Answer 19

Used on the upper deck for hydraulic fittings to protect them from corrosion.
Stored in the flammable stores.
Gives off toxic gas when heated.

Question 20

What is demulsibility?

Answer 20

The ability of oil to separate out from water.

Question 21

What is the purpose of a control valve in a hydraulic system?

Answer 21

Controls oil flow and direction.

Question 22

What are the two types of accumulator?

Answer 22

Piston type
Bag type