Hydraulic System Types Flashcards
A hydraulic system is defined as:
All of the interconnected hydraulic components mounted on a vehicle or piece of equipment.
Open center hydraulic systems are sometimes called:
a. constant pressure systems.
b. constant flow systems.
c. variable flow systems.
d. variable pressure systems.
b. constant flow systems.
Open center hydraulic systems are most often used in applications where:
a. high system efficiency is required.
b. accurate motion control is a priority.
c. hydraulic operations are not a high percentage of the machine’s duty cycle.
d. the cost of the system components is not a concern.
c. hydraulic operations are not a high percentage of the machine’s duty cycle.
The identifying characteristic of a closed center hydraulic system is:
a. they are always equipped with a fixed displacement pump.
b. they are always equipped with a pressure compensated pump.
c. they are always equipped with an accumulator.
d. the directional control valve always blocks pump flow when it is in neutral.
d. the directional control valve always blocks pump flow when it is in neutral.
Why are closed center systems equipped with pressure compensated pumps often called demand type hydraulic systems?
These type systems are called demand type hydraulic systems because flow is only provided when there is work to perform.
Define the term hydrostatic transmission.
A hydrostatic transmission is a rotary drive system that consists of a hydraulic pump , which is the input component, and a hydraulic motor which is the output component.
The most commonly used HST in mobile heavy equipment is a:
a. open circuit system with a fixed displacement pump.
b. open circuit system with a variable displacement pump.
c. closed circuit system with a variable displacement, reversible pump.
d. closed circuit system with a fixed displacement pump.
c. closed circuit system with a variable displacement, reversible pump.
List 5 advantages of hydrostatic transmissions
a. Infinite motor speed control from maximum to zero in both directions of rotation.
b. accurate motor speed can be maintained regardless of the load on the motor shaft.
c. Quick response to speed and directional changes.
d. provides a hydrostatic lock on the motor, when the output shaft speed is zero.
e. The load cannot overrun the motor when load is decelerating.
A group of interconnected components within a hydraulic system that are intended to perform a specific function is called a:
Hydraulic circuit.
One characteristic of open center systems is is high system pressure when the directional control valve is in the neutral position.
False.
Constant horsepower open center hydraulic systems maintain a constant power draw from the engine by varying:
a. pump displacement proportional to the load on the system.
b. the pressure proportional to the load on the system.
c. the speed of the engine proportional to the load on the system.
d. pump flow rate proportional to actuator speed.
a. pump displacement proportional to the load on the system
Closed Center systems may be supplied with either a fixed or variable displacement pump.
True
False
True
Why are load sensing hydraulic systems more efficient than other types of systems?
They provide the precise amount of flow and pressure to perform the work demanded by the systems actuators.
The difference between an open and closed circuit HST is the path of oil flow between the pump and motor is interrupted by the reservoir in the open circuit.
True
False
True
On HST systems that are equipp with variable displacement motors, motor torque generation will:
a. remain the same regardless of motor displacement.
b. be reduced as motor displacement is reduced.
c. be increased as motor displacement is reduced.
d. be reduced as motor displacement is increased.
b. be reduced as motor displacement is reduced.
