MMET 401: HYDRAULIC PUMPS QUESTIONS &
ANSWERS
What does a hydraulic pump do? - Answer -converts mechanical energy into hydraulic
energy
What is the pumping theory that all pumps operate on? - Answer -a partial vacuum is
created at the pump inlet due to the internal
What characteristics do non-positive displacement pumps have? - Answer -low
pressure, high-volume applications (250-300 psi)
Do positive or non-positive displacement pumps give out a continuous flow? - Answer -
non-positive
Are non-positive displacement pumps much use in the fluid power field? - Answer -no
What type of pumps are universally used for fluid power systems? - Answer -positive
displacement
What capabilities are of positive displacement pumps? - Answer -high pressure (up to
10,000 psi or higher)
Why do positive displacement pumps have to be protected against overpressure? -
Answer -if the resistance to flow becomes large they can be damaged
What type of pumps are centrifugal (impeller) pumps and axial flow propellor pump? -
Answer -non-positive
What type of pumps are gear, vane, and piston pumps? - Answer -positive
What are the two most common types of dynamic pumps? - Answer -centrifugal and
axial pumps
In dynamic pumps there is a great deal of clearance between the rotating element and
stationary housing allowing what? - Answer -some of the fluid to slip back causing
reduction in discharge flow rate if the resistance starts to increase
What makes up a internal gear pump? - Answer -internal gear, spur gear, crescent-
shaped seal, and external housing
What type of pump are quieter than other types of gear pumps? - Answer -lobe
ANSWERS
What does a hydraulic pump do? - Answer -converts mechanical energy into hydraulic
energy
What is the pumping theory that all pumps operate on? - Answer -a partial vacuum is
created at the pump inlet due to the internal
What characteristics do non-positive displacement pumps have? - Answer -low
pressure, high-volume applications (250-300 psi)
Do positive or non-positive displacement pumps give out a continuous flow? - Answer -
non-positive
Are non-positive displacement pumps much use in the fluid power field? - Answer -no
What type of pumps are universally used for fluid power systems? - Answer -positive
displacement
What capabilities are of positive displacement pumps? - Answer -high pressure (up to
10,000 psi or higher)
Why do positive displacement pumps have to be protected against overpressure? -
Answer -if the resistance to flow becomes large they can be damaged
What type of pumps are centrifugal (impeller) pumps and axial flow propellor pump? -
Answer -non-positive
What type of pumps are gear, vane, and piston pumps? - Answer -positive
What are the two most common types of dynamic pumps? - Answer -centrifugal and
axial pumps
In dynamic pumps there is a great deal of clearance between the rotating element and
stationary housing allowing what? - Answer -some of the fluid to slip back causing
reduction in discharge flow rate if the resistance starts to increase
What makes up a internal gear pump? - Answer -internal gear, spur gear, crescent-
shaped seal, and external housing
What type of pump are quieter than other types of gear pumps? - Answer -lobe
