Basic Hydraulics TPC Flashcards
What characteristic of a fluid does the term “specific gravity” describe?
density
Pressure is measured in [BLANK] in the English system
Pounds per square inch
Which of the following is NOT needed in order to calculate the work a hydraulic cylinder can do?
Power (ft-lb/min)
Pascal’s law states that pressure exerted on a confined liquid
is distributed equally throughout the liquid
According to Bernoulli’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 its
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 a filter in a hydraulic system is to
Remove small contaminants
Depth filter do NOT
have a long service life
Surface filter media made of sintered metal powders are used in high-pressure systems because of their
Thick mass
The separation of contaminants from hydraulic fluid in a reservoir 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 the following terms EXCEPT
Pounds per square inch
The ratio of the actual delivery rate of a pump to its displacement is its
Volumetric efficiency
Which of the following is NOT a type of gear pump?
Vane
Internal gear pumps normally are used in applications that have
Pressures of less than 1000 psi
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 noncritical applications having no severe stress, safe working pressures of hydraulic piping are based on 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 a hydraulic system to change the direction of motion of the cylinder?
Directional control valve
A three-way valve is identified any its three
Paths
The closing force of a direct-acting solenoid valve is approximately
15 lbs
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 an
Actuator
Straight-line mechanical force is created by a
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 a
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 [BLANK] gear motors
Internal
Internal leakage in hydraulic gear motor is held to a minimum by the use of
Wear plates
