The difference between an unbalanced vane pump and a balanced vane pump is the
A pneumatic accumulator for most hydraulic systems is commonly pre-charged with
An open center hydraulic system can best be described as one in which
In the illustration below, what type of hydraulic system is being illustrated?
A hydraulic system seems to be functioning normally in all other circuits within the system. However, a noticeably decreased free load hydraulic motor speed would most likely be caused by worn pump housing. What other possible cause must be checked?
To evaluate a hydraulics system, when flow and pressure testing a piece of equipment, the flow rate is best defined as
In a system with a variable displacement pump, the volume of the fluid moved by the pump will
When replacing a hydraulic pump you should
Flow rate is best defined as
The figure below indicates
Causes of a "lack of hydraulic power to do the work" problem might well be the fault of
When testing a hydraulic system, technicians will monitor and test for
Flow meters have a load valve on them. Before starting the equipment to run tests, the load valve should be
On most gear or vane hydraulic pumps, when checking the pumps efficiency, satisfactory pump flow at the rated pressure should be ___________ as high as the pump flow at zero pressure.
If a loader bucket drops slightly while holding a load, with control valve in neutral position, it might be caused by
If pump is cavitating, it may be an indication of
An indication of an internal hydraulic leak caused by an improperly seated main relief valve may show up as
Hydraulic flow is created by:
The device included in many hydraulic systems to help reduce noise, vibrations and shocks to the system is
Most oil-to-water hydraulic coolers use the coolant from engine cooling system.
A certain level of internal leakage is permissible in some components of a hydraulic system.
To make a generalization, fixed displacement pumps are usually used in open-centre systems, while variable displacement pumps are used in closed-centre systems.
In a variable displacement axial piston pump, the distance the pistons can travel back and forth in their bores is controlled by
The three most common types of hydraulic motors are
The technical name for the rotary output of a hydraulic motor is
Which of the following is the most common cause of hydraulic pump and motor failure?
What is the effective area of the rod end of a hydraulic cylinder piston if the the piston diameter is 4 1/2" and the rod diameter is 1.125"?
The function of the bucket kick-out on a wheeled loader is to hold the bucket control lever in the rollback location position until the bucket reaches the correct digging position.
The main disadvantage of electricity controlled hydraulic systems is that they are
Proximity switches are commonly used in wheel loader bucket kick-out and lift height control systems. When the detector plate is in close proximity to the switch, the switch is
The function of input devices in an electronically controlled hydraulic system is to
An example of a typical reference voltage sensor that sends a constant voltage signal when energized is a
Proportional solenoids use a pulse width modulated signal to actuate because it
The main advantage of a pilot operated pressure control valve is that it
A relief valve that limits the pressure in one branch of a hydraulic system is called a
Which of the following components is NOT usually used in a closed centre hydraulic system that is supplied with a variable displacement pump?
One of the primary purposes of a lock valve is to prevent the load from drifting due to leakage.
The flow control valve that splits a single flow among two or more circuits is called a
Auxiliary closed center directional control valves can be connected into an existing circuit closed centre system by connecting the auxiliary valve in
Constant horsepower open centre hydraulic systems maintain a constant power draw from the engine by varying
The identifying characteristic of a closed centre hydraulic system is
Closed centre systems can be designed with either fixed or variable displacement pumps.
The difference between an open and closed circuit HST is that the path of oil flow between the pump and motor is interrupted by the reservoir in the open circuit.
The most commonly used form of HST in mobile equipment is a/an
On HST systems that are equipped with variable displacement motors, motor torque generation will
A pilot control circuit is a low-pressure hydraulic circuit used to remotely operate a directional control valve.
Hydraulic oil temperature is not an important factor to consider when conducting hydraulic tests.
Actuator cycle times that are longer than manufacturers specifications normally indicate
You found that engine speed dropped excessively when performing a hydraulic stall test on an open centre hydraulic system. The cause could be
If you wanted to measure the maximum pressure in a hydraulic system that is designed to operate at a maximum pressure of 18MPa (2610 psig), you should use a pressure gauge with a range of:
Excessively low pressures measured at the pump inlet indicates that
When pressure testing a hydraulic system, you found the working pressures to be abnormally high. One cause for the reading may be
The problem with a cylinder that heats up more rapidly than normal is
When testing pump efficiency with a flow meter, the no-load flow is found to be significantly lower than specifications. The most likely cause is that
Internal leakage in a hydraulic motor can be quickly checked by measuring the amount of oil flowing from the case drain when the motor is at full load.
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