Module 4

Question 1

the device used in a hydraulic system to convert mechanical energy into hydraulic energy

Answer 1

Pump

Question 2

the ratio of a pump’s actual delivery rate to its theoretical displacement

Answer 2

Volumetric efficiency

Question 3

the ratio of a pump’s hydraulic power output to its mechanical power input

Answer 3

Overall efficiency

Question 4

A hydraulic pump converts _____ energy into _____ energy.

Answer 4

Mechanical; Hydraulic

Question 5

Pumps classified by their principle of operation include _____ and _____ types.

Answer 5

Positive-displacement; Nonpositive-displacement

Question 6

Positive-displacement pumps have either a(n) _____ or _____ displacement.

Answer 6

Fixed; Variable

Question 7

Fixed-displacement pumps are _____ efficient than variable-displacement pumps.

Answer 7

More

Question 8

The delivery rate or flow rate of a pump is commonly referred to as its _____.

Answer 8

Capacity

Question 9

To prevent overheating and internal slippage, a high-pressure pump is limited to a minimum operating _____.

Answer 9

Speed

Question 10

Name the two ways in which pump efficiency is described.

Answer 10

Volumetric; Overall

Question 11

The service life of a pump is specified in terms of operating _____.

Answer 11

Hours

Question 12

External gear pumps can operate at pressures of up to _____ psi.

Answer 12

3000

Question 13

Internal gear pumps are used in hydraulic systems that have _____ speeds and _____ capacities.

Answer 13

Low; Small

Question 14

Gerotor pumps are made without an internal gear _____.

Answer 14

Separator

Question 15

A vane pump in which the rotor is placed off-center is said to be _____.

Answer 15

Unbalanced

Question 16

Pump vanes that are not spring-loaded are held in contact with the housing by both centrifugal and _____ pressure.

Answer 16

Fluid

Question 17

The fluid flow in a variable-displacement vane pump is changed by moving the _____.

Answer 17

Cam Ring

Question 18

The two most common types of piston pumps are _____ and _____ pumps.

Answer 18

Axial-Piston; Radial-Piston

Question 19

Can piston pumps operate at flow rates over 1000 gym?

Answer 19

Yes

Question 20

A hydraulic pump does all of the following except

a. convert mechanical energy into hydraulic energy
b. create a partial vacuum at the inlet
c. deliver the fluid to the outlet
d. produce the working pressure in the system

Answer 20

d. Produce the working pressure in the system.

Question 21

Which of the following types of pumps is not a positive-displacement pump?

a. Centrifugal
b. Gear
c. Impeller
d. Vane

Answer 21

a. Centrifugal

Question 22

The volume of delivery of a fixed-displacement pump

a. can be changed by changing the physical arrangement of the pumping mechanism
b. can be changed by changing the pump’s speed
c. cannot be changed
d. changes with variations in system pressure

Answer 22

b. Can be changed by changing the pump’s speed.

Question 23

The capacity of a pump may be specified in all of the following except

a. cubic inches per minute
b. cubic inches per revolution
c. gallons per minute
d. pounds per square inch

Answer 23

d. Pounds per square inch.

Question 24

The efficient operating life of a pump is usually given in terms of

a. days
b. flow rate
c. fluid pressure
d. hours

Answer 24

d. Hours.

Question 25

Because of their design, internal gear pumps are limited to applications having a. low pressures and high speed b. low speeds and high pressures c. small capacities and high speeds d. small capacities and low pressures

Answer 25

d. Small capacities and low pressures.

Question 26

A vane pump of the unbalanced design can be identified by its a. counterweights b. dual inlet ports c. off-center rotor d. special drive motor

Answer 26

c. Off-center rotor.

Question 27

The vane tips of a vane pump are usually grooved or split to permit all of the following except a. a larger contact area at the housing b. better lubrication c. free movement of the vanes d. longer vane life

Answer 27

a. A larger contact area to the housing.

Question 28

Variable-displacement vane pumps control fluid flow by a. changing the discharge port b. changing the inlet port c. shifting the cam ring d. shifting the housing

Answer 28

c. Shifting the cam ring.

Question 29

Radial-piston pumps are generally designed and manufactured with a a. bent shaft b. double check valve c. rotating or stationary block d. straight shaft

Answer 29

c. Rotating or stationary block.