PNA1 Flashcards
Cavitation can be the result of
Hydraulic fluid with low viscosity
Running pump at too high speeds
Increasing inlet flow
Removing inlet stainer
Running pump at too high of speed
An example of a dynamic pump would be
Impeller
Vane
Gear
Piston
Impeller
A spring that extends by force and retracts by spring or Gravity is known as
Single acting
The flow produced by a pressure compensated pump during cylinder extension is at
Load pressure
Relief pressure
Stand by plus load pressure
Stand by pressure
Load pressure
The flow produced by a pressure compensated pump at the end of its stroke is at
Stand by pressure
Load pressure
Relief pressure
No flow produced
Relief pressure
The purpose of a cycling cushion is to
Reduce amount of shock
The pump in a hydraulic system produces
Fluid flow
An unbalanced vane pump can be identified by its
Off Center cam ring
Variable displacement vane pumps control fluid flow by
Shifting the cam ring
The vanes of the vane pump maintain contact with the cam ring by
Sets of inlet outlet ports opposing each other
A pumps input is 15gpm and measured output is 12gpm at 1000 psi. The volumetric efficiency is?
80%
12 div by 15 x 100
The displacement of a bent axis piston can be varied by
Pivoting the cylinder block to change the angle of the shaft
The toque of a hydraulic motor is dependent upon
Inlet pressure, surface area, and radius of rotation
If a cylinder had internal leakage it would effect
Pressure
Hydraulic motors are driven by
Fluid flow and pressure
Balance vane motors maintain vane contact by
Fluid pressure/springs
In an inline axial piston motor, speed can be increased by
Decreasing swash plate angle
The purpose of the stop tube is to
Reduce side load when extended
In a rotary piston pump, the fluid is ported in and out of the cylinder through the
Pintle
The output flow of gear pumps can be adjusted by
Changing rpm or a prime mover
A radial piston motor can be classed as
Low speed/high torque
O-ring boss port connections have what type of threads
Unified national fine
Three main styles of pumps
Piston
Vane
Gear
What is require at the pumps In order for oil to flow into the inlet
Negative pressure
What cylinder style is the most common in hydraulics
Double acting cylinder
What type of cylinder has two Pistons attached to a rod to obtain extra force
Tandem
Used for high force, short stroke
What part of a cylinder contains the load pressure
Barrel
When the main port connections are at the bottom how do you remove entrapped pressure
Bleed port
a symptom of a hot spot would indicate what in a cylinder
Internal leaks
Jerky movement, squealing or rattling sound is a sign of what in a cylinder
Aeration
Or
Misalignment
Hydraulic motors convert what type of power into rotary motion and produce toque to drive
Fluid power
Smooth operation and heavy loads and low speeds of 2rpm describe what type of hydraulic motor
LSHT low speed high torque
Crane hoist, dynamic rollers slow turning vaccume screens all require what type of hydraulic motor
LSHT
Three types of LSHT motors
Radial piston
Cam type
roller vane
Fans generators and compressor all require what type of hydraulic motor
HSLT
What motor cymbal has a half circle with two arrows pointing up
Limited rotation motor
Torque depends on what three 3 key elements
Inlet pressure, surface area, radius of rotation
Motor speed depends on what two factors
Flow rate
Volume
What is the advantage of the roller vane Gerotor design
It reduces the friction between gears by using rollers in place of internal gear teeth.
What do the orbiting gear rotor and roller vane Gerotor have in common
Orbiting star shaped gear
All 4 piston motors operate under the same principle which is…
Pressurized inlet fluid pushes on the piston to produce rotation through either swash plate or a cam
What valve is spring loaded and opens when the filter clogs is hydraulic motors
Spring load check valve
A pressure drop of over 45psi is hard on filter elements and wastes power. A pressure drop of 85 psi at 20gpm consumes about how much HP
1HP
Bypass Indicator colour
Green =
Yellow =
Red =
Green - Full flow is passing through filter
Yellow - bypass valve is beginning to open (yellow is a good indication for filter change)
red - Filter is clogged
What filter has 20% of the total system preset pass through it every minute
Return line filter
What filters are used imidatly after the pump
Pressure line filters
