Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Hydraulic System Components: Pumps, Valves and Cylinders - HET 190103i > Terminology - Hydraulic System Components: Pumps, Valves and Cylinders - HET 190103i > Flashcards

Terminology - Hydraulic System Components: Pumps, Valves and Cylinders - HET 190103i Flashcards

Terms

1
Q

Non-positive Displacement

A
  • inlet and outlet passages connect hydraulically
  • centrifugal force is used to create force
  • outlet is restricted, pressure builds, flow recirculates, therefore reducing flow delivered to pump outlet port
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Positive Displacement

A
  • do not suffer significant flow loss under pressure
  • mechanically seal the path of flow between the pump inlet and outlet ports
  • flow rate changes very little
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Pump Displacement

A

volume of liquid that the pump delivers when the pump input shaft rotates one revolution.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Flow Rate

A
  • amount of liquid that the pump delivers in a given period of time
  • flow delivered is determined by Pump displacement and Input shaft speed
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Imperial gallon contains how many cubic inches?

A

231 in³

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Metric litre contains how many cubic cm?

A

1000 cm³

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Mechanical Efficiency

A

amount of power required to overcome the pump’s internal friction

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Slippage

A

internal leakage oil that provides lubrication for the pump’s moving parts

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Volumetric Efficiency

A
  • amount of flow lost within pump due to internal leakage
  • theoretical delivery vs actual delivery
  • LPM or GPM
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Pressure Rating

A

maximum pressure the pump can safely withstand without damage occurring

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Gear-type Hydraulic Pump

A
  • positive displacement
  • least complex of all hydraulic pumps
  • simple, economical and rugged
  • 2 types: external and internal
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Gear Tooth Pockets

A

spaces between the pairs of gear teeth on the drive and driven gears that carries oil from inlet to outlet side

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Partial Vacuum

A

low pressure

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Internal Gear Pump

A
  • consist of two gears in mesh rotating in a pump housing
  • usually less efficient than external gear pump if missing pressure plates
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

External Gear Pump

A
  • one drive, one driven gear
  • contained in pump housing
  • contains pressure plates
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Pump Inlet Design

A
  • significantly larger than outlet port to ensure adequate oil volume is available
17
Q

Unidirectional Pumps

A

operate in one direction only
always determine the direction of driveshaft rotation to prevent damage when servicing

18
Q

Cavitation

A

pockets of vaporized hydraulic oil form as the oil enters the inlet side of the pump. when carried to the outlet side they are exposed to system pressures and collapse (implode) with tremendous force. will increase oxidation

19
Q

Aeration

A
  • inlet line is leaking, air enters inlet side of the pump.
  • bubbles compress when they reach the pressure side of the pump, generate heat and cause rattling noise.
  • causes system actuators to move with an erratic or jerky motion.
20
Q

Direct-acting Pressure Relief Valve

A
  • normally closed pressure control valve that senses hydraulic system pressure. - commonly located between pump and directional control valve.
  • protects system by limiting the maximum pressure
  • always refer to manufacturer’s recommended procedures when adjusting
21
Q

Cracking Pressure

A

pressure at the inlet port when the ball is initially moved off its seat by hydraulic system pressure

22
Q

Full Flow Pressure

A
  • pressure required to fully open the relief valve
  • greater than cracking pressure to compress valve spring
23
Q

Pressure Override

A

pressure difference between cracking pressure and full flow pressure

24
Q

Poppet Directional Control Valve

A

is a check valve whose function is to allow oil flow in one direction and block flow in the opposite direction

25
Q

Rotary Directional Control Valve

A

employs a rotary action to open and close passageways within the valve

26
Q

Spool Directional Control Valve

A
  • the most common type of directional control valve
    used in heavy equipment
  • employs linear or straight-line, movement to open and close paths of oil flow within the valve
  • has circular grooves to trap oil
27
Q

Feathering

A

partial movement of the spool allows the operator to control the speed of the cylinder

28
Q

Directional Control Valve Actuation Methods (3)

A
  • Mechanical (lever or pedal)
  • Pilot (hydraulic or air)
  • Electrical
29
Q

Pilot Operated Directional Control Valve

A
  • low-pressure hydraulics actuate circuit
  • used on larger hydraulic systems to reduce the amount of operator effort require to activate the valve
  • supplied by low-volume, low-pressure pump, or compressor
30
Q

Electrical Operated Directional Control Valve

A
  • solenoids that actuate the directional control valve.
  • eliminates risk of oil leakage from a pilot circuit
31
Q

Open Centre Directional Control Valve

A

neutral
oil from the pump can flow through the valve and return to reservoir

32
Q

Closed Centre Directional Control Valve

A

blocks the flow of oil from the pump when the valve is in the neutral position

33
Q

Hydraulic Cylinder

A
  • one of the most common actuators in heavy equipment hydraulic systems
  • converts hydraulic power into mechanical power
  • linear actuator
  • single or doubling acting
34
Q

Single-Acting Hydraulic Cylinder

A
  • operated in only one direction
  • acts on the surface area of the rod
  • cylinder rod retracts when the cylinder port is connected to the reservoir
  • an external force is required to retract the cylinder
  • commonly referred to as rams
35
Q

Telescoping Cylinder

A
  • applications that require a longer stroke
  • provides long stroke length while remaining relatively compact when retracted
36
Q

Stages (referring to Telescoping Cylinders)

A
  • nested tubular rod segments
  • most force is required when extending the first stage, less with each additional stage as surface area decreases
37
Q

Double-Acting Hydraulic Cylinder

A
  • hydraulically extend and retract
  • do not require external force
  • aka Differential Cylinders
  • force and speed are different during extension than retraction
  • produce more force during extension

Hydraulic System Components: Pumps, Valves and Cylinders - HET 190103i (2 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions