Hydraulic Accumulators

Question 1

Hydraulic accumulators are often used as a protection against failure of the _____________.

Answer 1

oil supply

Question 2

When the power brakes on large machines, If the system oil supply fails, the _________________ traps enough oil for several brake applications, thus providing emergency braking

Answer 2

accumulator

Question 3

How does a hydraulic accumulator absorb shock?

Answer 3

Accumulators take in excess oil during peak pressures and let it out again after the surge is past.

Question 4

Why would an accumulator use a gas instead of a fluid?

Answer 4

Fluids do not compress, but gases do compress.
This means you can charge the oil and to provide a cushion for shock loads.

Question 5

Pneumatic means operated by _________________

Answer 5

compressed gas.

Question 6

In pneumatic accumulators, the gas is separated from the oil by: _____________

Answer 6

a piston, a bladder, or a diaphragm

Question 7

What is the function of the a piston, a bladder, or a diaphragm in a pneumatic accumulator?

Answer 7

This prevents mixing
of the gas and oil and keeps gas out of the hydraulic system.

Question 8

Some accumulators used for ______________ or fairly static applications do not have a
separator between the gas and oil.

Answer 8

low-pressure

Question 9

In a piston-type accumulator, a free-floating piston separates the _________________

Answer 9

gas from the oil

Question 10

In a piston-type accumulator, a bleed hole is needed to make certain the _______________

Answer 10

top O-ring is lubricated.

Question 11

In a ____________-type accumulator, a flexible bag made of synthetic rubber contains the gas and separates it from the hydraulic oil.

Answer 11

bladder-type

Question 12

In a bladder-type accumulator, when system hydraulic oil pressure drops, protection is needed to prevent the bladder from being forced into the oil passage. How is this prevented?

Answer 12

To prevent damage to the bladder, a valve, a protective button, or a screen is used.

Question 13

The ______________ is the gas pressure in the accumulator before
any oil is admitted.

Answer 13

precharge

Question 14

The accumulator will not accept oil until the hydraulic pressure exceeds the _______________

Answer 14

gas pressure.

Question 15

You should never fill an accumulator with __________or _________

Answer 15

oxygen or compressed air

Question 16

Why should you never fill an accumulator with oxygen?

Answer 16

An explosion could result if oil and oxygen mix under pressure.

Question 17

Why should you never fill an accumulator with compressed air?

Answer 17

An explosion could result if oil and oxygen mix under pressure. and
When air is compressed, water vapor in the air condenses and can cause rust. This in turn may damage seals and ruin the accumulator.

Question 18

Always fill an accumulator with _____________. This gas is inert and free of both water vapor and oxygen.

Answer 18

dry nitrogen

Question 19

Never charge an accumulator to a pressure more than ______________

Answer 19

that recommended by the manufacturer.

Question 20

Before removing an accumulator from a hydraulic system, _________________

Answer 20

release all hydraulic pressure.

Question 21

Before you disassemble an accumulator, ____________

Answer 21

release both gas and hydraulic pressures.

Question 22

When you disassemble an accumulator, make sure that dirt and abrasive material does not _______________

Answer 22

enter any of the openings.

Question 23

Before Removing Accumulator From Machine be sure all hydraulic pressure is released. To do this ______________

Answer 23

Shut down the pump and cycle a priority function within the hydraulic circuit that contains the accumulator until all pressure is relieved.

Question 24

Why is air not recommended for use in a pneumatic accumulator?

Answer 24

An explosion could result if oil and oxygen mix under pressure. and
When air is compressed, water vapor in the air condenses and can cause rust. This in turn may damage seals and ruin the accumulator.

Question 25

What are the four major uses of accumulators?

Answer 25

1. Store energy
2. Absorb shock
3. Provide emergency power
4. Maintain system pressure