190301d

Question 1

What do hydraulic motors convert hydraulic energy into?.

Answer 1

rotary mechanical energy

Question 2

Over time, internal clearances in a motor increase due to wear. What else does this increase?

Answer 2

leakage and oil flow through the drain line

Question 3

Name three categories of hydraulic motors.

Answer 3

• gear motors, including external gear motors and gerotor and geroller motors,
• vane motors and
• piston motors.

Question 4

The construction between hydraulic pumps and hydraulic motors is significantly different. T/F

Answer 4

False; In most cases, the construction of hydraulic motors is very similar to the construction of hydraulic pumps.

Question 5

What does reversing oil flow through a hydraulic motor do?

Answer 5

Reversing the oil flow through the motor reverses output shaft rotation.

Question 6

Why are gear type motors not commonly used?

Answer 6

Their design makes them poor torque generators.

Question 7

Pressurized oil is allowed to flow past the piston to the rod side of a ram type
cylinder T/F

Answer 7

true

Question 8

Telescoping cylinders offer the following advantage.

Answer 8

additional stroke length is gained from a relatively compact retracted package

Question 9

Double-acting cylinders are often referred to as differential cylinders because

Answer 9

There is a difference in the speed and forces generated by extension versus retraction

Question 10

The difference between a differential and non-differential cylinders is that

Answer 10

nondifferential cylinders have equal piston area and equal volume on both sides of the
cylinder.

Question 11

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.

Answer 11

all of the above responses are correct.

Question 12

The function of a cylinder rod wiper is to:

Answer 12

prevent contamination from entering the cylinder.

Question 13

The purpose of a piston relief valve is to

Answer 13

allow pump oil flow to bypass the piston

when the piston reaches the end of its stroke, reducing heat generation.

Question 14

In reference to hydraulic cylinder operation, the term regeneration refers to

Answer 14

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.

Question 15

The quick drop valve used on dozer cylinders provides regeneration when the
operator selects:

Answer 15

the full lower position.

Question 16

The speed of a motor driveshaft depends upon:

Answer 16

a) inlet flow rate

b) motor displacement (capacity)

Question 17

One factor that does not influence motor torque generation is:

a) inlet flow rate.
b) inlet pressure.
c) motor displacement

Answer 17

inlet flow rate.

Question 18

Most motors are equipped with a drain line that carries:

Answer 18

leakage oil from the motor to the reservoir

Question 19

Why are external gear motors such poor torque generators?

Answer 19

Due to counteracting forces, torque is generated by inlet pressure acting on the
surface area of just one tooth.

Question 20

Gerotor motors are considered to be high-speed low torque motors.T/F

Answer 20

false;

Question 21

Gerotor motors require a spool valve to:

Answer 21

direct the flow of oil to and from the valleys in the gerotor element.

Question 22

Balanced vane motors are good torque generators because:

Answer 22

they can operate at higher pressures than other types of vane motors.

Question 23

Why must some vane motors be equipped with spring-loaded vanes?

Answer 23

Spring-loaded vanes are used to ensure good vane-to-cam ring contact at start-up.

Question 24

The main difference between variable and fixed displacement motors is that their
speed and torque characteristics will change as their displacement changes.T/F

Answer 24

true

Question 25

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:

Answer 25

increases.

Question 26

Why are variable displacement motors prevented from reaching the zero
displacement position?

Answer 26

The motor will hydrostatically lock and stall (freewheel) in the zero displacement
position.

Question 27

In a piston motor the cylinder barrel and pistons are often referred to as?

Answer 27

Rotating group

Question 28

Three types of piston motors?

Answer 28

Axial
Bent
Radial

Question 29

In a piston motor leakage oil is returned to tank using?

Answer 29

A drain port/line

Question 30

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?

Answer 30

Torque arm

Question 31

What are the 2 most common set angles that can be set as swash plate displacement?

Answer 31

6.5 and 19

Question 32

If a motors swash plate goes into a perpendicular position, what could happen?

Answer 32

The circuit would go into a hydrostatically locked situation allowing motor to freewheel.

Question 33

Pressure compensation allows for the motor to have what?

Answer 33

It allows the motor to have a swash plate that is automatically adjusted according to load on he motors output shaft.

Question 34

How is maximum torque achieved in a piston pump?

Answer 34

With the swash plate at minimum flow angle.

Least speed. Maximum torque

Question 35

A bent axis piston motor cannot be made to bend at 6.5 or 19 degrees? T/F

Answer 35

False. A bent axis piston motor will use the rotating group as the swash plate.

Question 36

How does a bent axis piston motor become a fixed displacement motor?

Answer 36

The motor housing holds the rotating group in a bent shape.

Question 37

How does the bent axis piston motor become a variable displacement motor?

Answer 37

This is achieved by using the rotating block as a swash plate.