Chapter 8 - Hydraulic and Pneumatic Power Systems (B) Flashcards Preview

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Flashcards in Chapter 8 - Hydraulic and Pneumatic Power Systems (B) Deck (28)
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1
Q

On a constant displacement pump, how is the output pressure regulated?

A

It must have some form of regulator or relief valve in the system to relieve the pressure that builds up when the pump moves more fluid that the system can use.

2
Q

What is the safety feature on the micronic filter assembly?

A

Relief valves across both elements to prevent over-pressurizing the return if, for any reason, the pressure drop across the elements become excessive.

3
Q

What is good about the cuno filter?

A

They are able to be used on the pressure side of the system

4
Q

On a variable displacement pump, how is the output pressure regulated?

A

By controlling the amount of fluid that the system will accept

5
Q

What is the main purpose for pressurizing hydraulic reservior?

A

To operate at higher altitudes to compensate for the decrease air pressure.

6
Q

Name some reasons for the quick disconnect coupling.

A
  • Prevents loss of fluid when units are removed
  • It can be used interchagably with other systems
  • Automatically closes when a line has been disconnected from it
7
Q

What pump is connected to the standpipe?

A

Handpump

8
Q

Which three things maintain pressure in a hydraulic system? Which part has the lowest pressure?

A

Thermal relief valve - highest psi

Accumulator - lowest psi

system relief valve - medium psi

9
Q

Name the three types of fluids

A

Vegatable based fluids: MIL-H-7644

  • Not interchagable
  • blue dyed
  • castor oil and alcohol made

Mineral based fluids: MIL-H-5606

  • Kerosene type petroleum
  • Red dyed

Synthetic fluids: Skydrol

  • Non-petroleum based/phosphate easter base
  • Not compatable with neoprene or Buna-N
  • Light purple
10
Q

What is a one way seal?

A

The seal will stop the flow of fluid on one direction only

11
Q

What precaution should be used when removing a pressurized hydraulic reservior cap?

A

All of the pressurizing air must be released before removing the reservior cap

12
Q

On a wet style pump, what else is required?

A

Oil seperator

13
Q

What is a sequence valve used for?

A

To permit actation only when specific prior events have occured

14
Q

What is a priority valve used for?

A

Does not allow flow until a preset pressure is reached. They are opened by a hydraulic pressure rather than by mechanical contact.

15
Q

How do you remove moisture from a compressor?

A

Removed from a moisture seperator with final last traces dried out with a desiccant or chemical dryer

16
Q

What is a moisture seperator?

A

Collects the water that is in the air on a baffle, holds it until the system shuts down, and blows it overboard through a drain valve. An electrical heater prevents water from freezing, and later a chemical dryer removes any last traces of water.

17
Q

Wht is the purpose of a relief valve?

A

Prevents excess pressures from damaging the system through spring tension that can be overcomed to open the valve if pressure is too high

18
Q

What is the purpose of a check valve?

A

A one directional flow-control valve

19
Q

What are some characteristics of the pneumatic system

A

Dual compressor

shuttle valve

moisture sperator - 98%

Desiccant - 2%

20
Q

What are two broad categories of engine driven hydraulic pumps?

A

Constant displacemnt

variable displacement

21
Q

What causes chattering of a hydraulic pump?

A

Air

22
Q

Name the different seal fluid’s base

A

Natural rubber seal

  • vegetable based fluids
  • if combined with petroleum based or phosphate easter base, the seals break down

Neoprene seal MIL-H-5606

  • mineral base fluids

Butyl seals

  • Skydrol phosphate ester base
  • sythetic fluids
23
Q

How is packing protected during installation?

A

Placing tape over the thread

24
Q

What is the most common used two-way seal?

A

The o-ring which may be used as either a gasket or a packing or a packing and needs to squeeze or pinch the groove.

25
Q

What is an unloading valve?

A

A line between the pump and the selector valve that returns fluid back to the reservior

26
Q

What is the characteristics of the open center selector valve?

A
  • It’s an open center poppet type valve used in an open center hydraulic system
  • When in neutral fluid flows straight through the next selector valve and on to the reservior
27
Q

The instruments used to measure
the viscosity of a liquid are known as

A

viscometers or viscosimeters

28
Q
A