Module 4 Flashcards
the device used in a hydraulic system to convert mechanical energy into hydraulic energy
Pump
the ratio of a pump’s actual delivery rate to its theoretical displacement
Volumetric efficiency
the ratio of a pump’s hydraulic power output to its mechanical power input
Overall efficiency
A hydraulic pump converts _____ energy into _____ energy.
Mechanical; Hydraulic
Pumps classified by their principle of operation include _____ and _____ types.
Positive-displacement; Nonpositive-displacement
Positive-displacement pumps have either a(n) _____ or _____ displacement.
Fixed; Variable
Fixed-displacement pumps are _____ efficient than variable-displacement pumps.
More
The delivery rate or flow rate of a pump is commonly referred to as its _____.
Capacity
To prevent overheating and internal slippage, a high-pressure pump is limited to a minimum operating _____.
Speed
Name the two ways in which pump efficiency is described.
Volumetric; Overall
The service life of a pump is specified in terms of operating _____.
Hours
External gear pumps can operate at pressures of up to _____ psi.
3000
Internal gear pumps are used in hydraulic systems that have _____ speeds and _____ capacities.
Low; Small
Gerotor pumps are made without an internal gear _____.
Separator
A vane pump in which the rotor is placed off-center is said to be _____.
Unbalanced
Pump vanes that are not spring-loaded are held in contact with the housing by both centrifugal and _____ pressure.
Fluid
The fluid flow in a variable-displacement vane pump is changed by moving the _____.
Cam Ring
The two most common types of piston pumps are _____ and _____ pumps.
Axial-Piston; Radial-Piston
Can piston pumps operate at flow rates over 1000 gym?
Yes
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
d. Produce the working pressure in the system.
Which of the following types of pumps is not a positive-displacement pump?
a. Centrifugal
b. Gear
c. Impeller
d. Vane
a. Centrifugal
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
b. Can be changed by changing the pump’s speed.
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
d. Pounds per square inch.
The efficient operating life of a pump is usually given in terms of
a. days
b. flow rate
c. fluid pressure
d. hours
d. Hours.
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
d. Small capacities and low pressures.
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
c. Off-center rotor.
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
a. A larger contact area to the housing.
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
c. Shifting the cam ring.
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
c. Rotating or stationary block.
