190301d Flashcards
What do hydraulic motors convert hydraulic energy into?.
rotary mechanical energy
Over time, internal clearances in a motor increase due to wear. What else does this increase?
leakage and oil flow through the drain line
Name three categories of hydraulic motors.
- gear motors, including external gear motors and gerotor and geroller motors,
- vane motors and
- piston motors.
The construction between hydraulic pumps and hydraulic motors is significantly different. T/F
False; In most cases, the construction of hydraulic motors is very similar to the construction of hydraulic pumps.
What does reversing oil flow through a hydraulic motor do?
Reversing the oil flow through the motor reverses output shaft rotation.
Why are gear type motors not commonly used?
Their design makes them poor torque generators.
Pressurized oil is allowed to flow past the piston to the rod side of a ram type
cylinder T/F
true
Telescoping cylinders offer the following advantage.
additional stroke length is gained from a relatively compact retracted package
Double-acting cylinders are often referred to as differential cylinders because
There is a difference in the speed and forces generated by extension versus retraction
The difference between a differential and non-differential cylinders is that
nondifferential cylinders have equal piston area and equal volume on both sides of the
cylinder.
Leaking piston seals in a differential cylinder result in:
a) increased cylinder cycle times.
b) cylinder drifting in the extension direction.
c) pressure intensification when in the hold position.
all of the above responses are correct.
The function of a cylinder rod wiper is to:
prevent contamination from entering the cylinder.
The purpose of a piston relief valve is to
allow pump oil flow to bypass the piston
when the piston reaches the end of its stroke, reducing heat generation.
In reference to hydraulic cylinder operation, the term regeneration refers to
supplementing pump oil flow to the base end of a double-acting cylinder with oil
flow from the rod end which increases cylinder extension speed.
The quick drop valve used on dozer cylinders provides regeneration when the
operator selects:
the full lower position.
The speed of a motor driveshaft depends upon:
a) inlet flow rate
b) motor displacement (capacity)
One factor that does not influence motor torque generation is:
a) inlet flow rate.
b) inlet pressure.
c) motor displacement
inlet flow rate.
Most motors are equipped with a drain line that carries:
leakage oil from the motor to the reservoir
Why are external gear motors such poor torque generators?
Due to counteracting forces, torque is generated by inlet pressure acting on the
surface area of just one tooth.
Gerotor motors are considered to be high-speed low torque motors.T/F
false;
Gerotor motors require a spool valve to:
direct the flow of oil to and from the valleys in the gerotor element.
Balanced vane motors are good torque generators because:
they can operate at higher pressures than other types of vane motors.
Why must some vane motors be equipped with spring-loaded vanes?
Spring-loaded vanes are used to ensure good vane-to-cam ring contact at start-up.
The main difference between variable and fixed displacement motors is that their
speed and torque characteristics will change as their displacement changes.T/F
true
Pressure compensated, variable displacement motors vary their displacement in
response to changes in motor load. As the load on the motor output shaft increases,
the motor displacement:
increases.
Why are variable displacement motors prevented from reaching the zero
displacement position?
The motor will hydrostatically lock and stall (freewheel) in the zero displacement
position.
In a piston motor the cylinder barrel and pistons are often referred to as?
Rotating group
Three types of piston motors?
Axial
Bent
Radial
In a piston motor leakage oil is returned to tank using?
A drain port/line
In a piston motor the amount of Tourque generated is determined by the force generated by the Pistons and distance between the centreline of the Pistons and centre line of driveshaft referred to as?
Torque arm
What are the 2 most common set angles that can be set as swash plate displacement?
6.5 and 19
If a motors swash plate goes into a perpendicular position, what could happen?
The circuit would go into a hydrostatically locked situation allowing motor to freewheel.
Pressure compensation allows for the motor to have what?
It allows the motor to have a swash plate that is automatically adjusted according to load on he motors output shaft.
How is maximum torque achieved in a piston pump?
With the swash plate at minimum flow angle.
Least speed. Maximum torque
A bent axis piston motor cannot be made to bend at 6.5 or 19 degrees? T/F
False. A bent axis piston motor will use the rotating group as the swash plate.
How does a bent axis piston motor become a fixed displacement motor?
The motor housing holds the rotating group in a bent shape.
How does the bent axis piston motor become a variable displacement motor?
This is achieved by using the rotating block as a swash plate.
