Hydraulics TPC Flashcards
What characteristic of a fluid does the term specific gravity describe?
Density
Pressure is measured in ________ in the English system
PSI
Which of the following is not needed in order to calculate the work a hydraulic cylinder can do?
Power (ft-lb/min)
Pascal’s laws states that pressure exerted on a confined liquid:
Is distributed equally throughout the liquid
According to Bournooli’s principle, when fluid flow increases in a system, the pressure:
Decreases
A hydraulic fluid must be able to do all of the following except:
Compress easily
A hydraulic fluid that exhibits little change in viscosity when heated is said to have a high:
Viscosity index
The ability of a fluid to penetrate into small clearances between closely fitted parts is determined by the fluid’s
Viscosity
Which of the following, when added to hydraulic fluid, will limit oxidation?
A chemical inhibitor
The best method of controlling hydraulic fluid contamination is the use of:
Good maintenance procedure
The ability of a filter or strainer to remove 100% of the contaminant particles of a particular size from a hydraulic fluid is called:
Absolute rating
When the maximum allowable pressure drop of a filter is reached, the filter will:
Allow particles to pass through the medium
The purpose of the filter in a hydraulic system is to:
Remove small contaminants
The purpose of the filter in a hydraulic system is to:
Remove small contaminants
Depth filters do not:
Have a long service life
Surface filter media made of sintered metal powders are use in high-pressure systems because of their:
Thick mass
The separation of contaminants from hydraulic fluid in a resovoir is aided by
Slow fluid movement
What is used in a hydraulic reservoir to aid fluid cooling?
A baffle
To maintain the temperature of a hydraulic fluid effectively, the reservoir should have:
Thin walls
An air breather is installed on a fluid reservoir to:
Vent the reservoir
Peak hydraulic system demands are usually met by the use of an:
Accumulator
The resistance of a hydraulic system to fluid flow causes:
Pressure
Pump capacity is rated in all of the following terms except:
Pounds PSI
The ratio fo the actual delivery rate of the pump to its displacement is its:
Volumetric efficiency
Which of the following is not a type of gear pump?
Vane
Internal gear pumps are normally used in applications that have:
Pressures of less than 1000psi
The flow rate of hydraulic fluid through piping or tubing is measured in
GPM
Pressure loss in a hydraulic line depends on the
Flow velocity
Hydraulic lines should NEVER be constructed of
Galvanized pipe
In non critical applications having no severe stress, safe working pressures of hydraulic piping are bases of providing a safety factor of:
6
A disadvantage of using hose in hydraulic systems instead of piping or tubing is that the hose:
Is less permanent
Which of the following kinds of valves should be used in hydraulic system to change the directions of motion of the cylinder?
Directional control valve
A three way valve is identified by its three…
Paths
The closing force of a direct acting solenoid valve is approximately
15lbs
The construction of a spool valve causes it to:
Be partially balanced
A four way valve that can operate in three positions is called a
Closed crossover valve
The operating differential pressure of a relief valve is the difference between its maximum pressure and the
Cracking pressure
The flow from the outlet of a sequence valve is at
Line pressure
Fluid pressure in one section of a hydraulic system is limited by a
Reducing valve
A shock suppressor is used in a hydraulic system as
Protection against pressure surges
A meter-out flow-control valve is used to regulate fluid flow from a(n)
Actuator
Straight line mechanical force is created by
Hydraulic cylinder
The force exerted by a double acting piston is
Less on the rod side
A cylinder in which the retracting stroke is the power stroke is called a
Pull-type cylinder
When a hydraulic cylinder is added to an existing system, be sure that the
Pump capacity is adequate
Mechanical shock is controlled in a Hydraulic cylinder by means of
Cushioning device
Which of the following statements about hydraulic motors is true?
They are all positive displacement types
The pressure range of a hydraulic motor may vary from
100 to 5000 psi
the overall efficiency of a hydraulic motor is defined as the
Output horsepower divided by the input horsepower
A crescent shaped separator is used on some _________ gear motors
Internal
Internal leakage in hydraulic gear motor is held to a minimum by the use of
Wear plates
The amount of matter in an object and its resistance to change in motion is called its
- density
- mass
- volume
- weight
Mass
The Law of Conservation of Energy states that energy cannot be created or destroyed, it can only be
- amplified
-conserved
- diluted
- transformed
Transformed
Turbulent flow conditions:
- can release air suspended in the hydraulic fluid
- conserve power
- cool the hydraulic fluid
- occur when fluid viscosity is too high
Can release air suspended in the hydraulic fluid
A fluid rated at 250 SSU has a ____________ than a fluid rated at 150 SSU
- higher flow rate
- higher viscosity
- lower film strength
- lower pour point temperature
Higher viscosity
The viscosity of a fluid is a measure of its resistance to
Flow
How should cylinders used for heavy-duty pushing or thrust applications be mounted?
Square flanges on the cap end
Which type of motor toque changes with changes in fluid pressure?
Runnning
A counter-balance valve is normally a _________ valve
Double-poppet
The two categories of relief valve are _______ and ________.
Direct acting, and pilot operated
The pressure at which a check valve starts to open is called its ______ pressure
Cracking
In applications using a needle valve that must be shut off frequently, a ________ should be used
Soft seat
Directional valves are sometimes classified by the way the fluid flows when the valve is in the ________ position.
Center
Which of the following connections are suitable for joining 1 1/2” pipe?
Threaded
The most important factor is selecting hydraulic line is the
Flow rate
Pressure loss in a hydraulic line depends on the
Flow velocity
A vane pump with the rotor place off-center is classified as a(n) _________ pump
Unbalanced
Pumps operating at high pressures require a minimum speed to prevent
Overheating
In addition to storing and releasing fluid, accumulators also
Absorb hydraulic shocks
In what part of the hydraulic reservoir tank does the sludge settle?
Sump
What is the reason for installing duplex in-line strainers in a hydraulic system?
Clean one while the other is operating
