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Heavy Equipment Technician Period 3 Alberta > 190301d Hydraulic actuator fun > Flashcards

190301d Hydraulic actuator fun Flashcards

(76 cards)

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1
Q

Hydraulic cylinders create what type of motion?

A

Linear/ straight line

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2
Q

Single acting cylinders are hydraulically actuated in two directions?

A

Nope

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3
Q

On a ram type cylinder, what are the basic components?

A

Piston Tube, Cylinder barrel, guide rings

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4
Q

How is retraction done on a ram type cylinder?

A

By connecting inlet and outlet ports to the reservoir

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5
Q

On a piston type single acting cylinder, if oil is coming out of the air vent what could be the cause?

A

a piston seal is leaking

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6
Q

What are two types of single acting cylinders?

A

piston or ram type

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7
Q

What causes a piston type cylinder to retract?

A

gravity/weight of the load

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8
Q

How should you adjust the packing nut on a ram type cylinder?

A

Until packing is tight enough to leave a thin film of oil on piston tube when cylinder extends

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9
Q

Why do we use telescoping single acting cylinders?

A

To obtain additional stroke length from a relatively compact retracted package

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10
Q

The first stage on a telescoping single acting cylinder is?

A

largest, develops greatest force, slowest speed

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11
Q

2nd stage and all after, what happens to speed and force

A

Force decreases, speed increases

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12
Q

Double acting cylinders do what?

A

both hydraulically extend and hydraulically retract, oil acts on both sides

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13
Q

In a double acting cylinder, rod end cap is attached to the??

A

Cylinder barrel to prevent external leakage. Threaded together

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14
Q

Double acting cylinder, O-rings and back up rings are used to seal?

A

The cap to the barrel

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15
Q

What are the moving parts in a double acting cylinder?

A

Piston and Piston Rod

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16
Q

Hydraulic cylinders are used to create?

A

Linear (straight) motion to perform work

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17
Q

Pistons are machine grooved in the outer circumference so the piston seals and?

A

Wear rings can be fitted

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18
Q

Seals are used for stopping what?

A

Internal and extend leakage

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19
Q

When selecting a seal you should consider?

A 
Operating pressures and temps
Fluid compatibility
cylinder speed
clearance to be sealed
internal friction
finish of the sealing surface
acceptable seal life
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20
Q

What materials are seals made of?

A

leather, polyurethan, nitrile or viton

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21
Q

What do wipers do for a cylinder?

A

prevent some contamination while cylinder retracts, allowing some leakage to lube seals

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22
Q

Bearings are used to do what in a cylinder?

A

support piston and piston rod

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23
Q

Bearings in a cylinder can be made from?

A

iron, brass, phenolic or composite material

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24
Q

Conventional cylinder, double acting, single rod cylinders are called?

A

Differential cylinders because difference between extension and retraction speed and the forces they produce

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25
If the piston seal starts to leak on a differential cylinder, what will it cause?
reduce cylinder speed and cylinder drift in the hold position
26
Hold position blocks oil flow from?
Both rod and base end of the cylinder | Hydrostatic lock
27
If there is a leak in a double acting cylinder, what can happen?
Oil may flow from the rod end to the base end of the cylinder, may cause drift out to extension direction
28
Single acting cylinders are hydraulically actuated in?
One direction, need gravity or load to make them retract
29
Cylinder drift will only happen in what direction?
Extension
30
If your piston seals on a cylinder leaks where can you see the problem?
Direction control return line
31
Pressure required to support a load doubles when the piston seals are leaky is known as?
Pressure intensification
32
Double acting, double rod cylinder (non-differential cylinder)
Has equal piston area and equal volume or both sides
33
Telescoping cylinders can be?
Single acting or double acting, offers long working stroke from a compact retracted package
34
Double acting telescoping cylinders are used in what applications?
Mining haul trucks, boxes that go over center
35
What are some features that cylinders have?
Piston relief valve cylinder cushions quick drop valves
36
When does the piston relief valves allow oil flow to bypass the piston?
When the piston reaches the end of its stroke
37
Describe a piston relief valve.
Double check valves
38
Cylinder cushions are used to stop a piston?
Nope, they slow down the hydraulically operated implement
39
What creates a cylinder cushion effect?
the effect is accomplished by restricting the return oil from the cylinder, back pressures the piston and resists movement
40
What two types of cylinder cushions are there?
Cushion plunger | Cylinder return drillings
41
Quick drop valves use who's principle?
Bernulli's
42
What do quick drop valves provide?
Faster lowering cycle times on implements
43
The quick drop valve supplements pump flow to the base end of the cylinder with the oil flow from the rod end, what is this principle called?
Regeneration
44
Are quick drop valves normally closed?
Yes
45
Can a slower lowering speed be achieved with a quick drop valve?
Yes, if the operator feathers the direction control valve
46
When does cavitation occur in a cylinder?
When the cylinder drops faster than the oil flows
47
What is a sign of a failing quick drop valve?
No power down | No quick drop (lowering slower than normal
48
What type of energy do hydraulic motors convert?
Hydraulic energy to mechanical energy
49
What do hydraulic motors convert oil flow and pressure into?
Speed and torque
50
What dictates the speed of the motor driveshaft?
The inlet flow rate and capacity of the motor
51
If a motor with a given displacement is given a greater flow rate supply what happens to the driveshaft?
It will rotate faster
52
Motor inlet pressure (max sys pressure) and motor displacement determine what in a hydraulic motor?
The amount of torque generated
53
Motors can convert all hydraulic energy to mechanical energy correct?
No, some is loss to leakage and friction
54
Why is internal leakage necessary?
For lubrication and cooling of moving parts
55
If internal clearances increase (due to normal wear), will oil flow through the drain line increase?
Yes
56
What are three basic types of hydraulic motors?
Gear, Vane and piston motors
57
What are two types of gear motors?
External and gerotor (geroller) motors
58
The gear in an external gear pump that is not connected to the drive shaft is considered?
An idler
59
If you reverse the oil flow through an external gear motor what happens to the output shaft?
It will reverse shaft rotation
60
Do external gears have a lot of working surface area?
No
61
Are external gear pumps balanced or unbalanced?
Unbalanced
62
Do gear pumps create a lot of torque?
Nope
63
Gerotor motors are also know as?
Orbit motor
64
Are gerotor motors low rpm and right torque?
Yeah
65
Which component is splined to the output shaft of a gerotor motor?
Gerotor star, spool valve
66
Does the gerotor star need to be timed?
Yup, must be timed
67
What is different in a geroller motor compared to a gerotor motor?
Gerollers have roller inserts for better wear characteristics, disc type valves instead of spool valves
68
Vane motors have what under the vanes to provide flow when starting up?
Springs
69
Most vane motors are balanced or unbalanced?
Balanced
70
In a balanced vane motor the inlet and outlet ports are located where?
180° from each other
71
Do balanced vane motors operate at higher pressures compared to unbalanced vane motors?
Yes
72
Can vane motors be driven in reverse with oil flow?
yes
73
Are vane motors more volumetrically efficient than external gear motors?
Yes
74
Are balanced vane motors good torque generators?
yes
75
Are piston motors variable displacement?
They can be fixed or variable
76
What are the three types of piston motors?
Axial, Bent Axis or Radial

Heavy Equipment Technician Period 3 Alberta (15 decks)

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