190303gB

Question 1

As equipment becomes heavier what type of steering is more likely to be seen?

Answer 1

Differential steering, it is less likely to see hydrostatic steering

Question 2

Is there a torque converter involved in the hydrostatic crawler tractor steering system?

Answer 2

No

Question 3

Why would a skid steer creap?

Answer 3

Something is out of adjustment, the swash plates are not in an equal neutral position.

Question 4

What position is a swashplate in when 0 GPM are flowing?

Answer 4

Zero Center (Neutral)

Question 5

What happens in a skid steer when the swashplate is pushed over center?

Answer 5

Reverse, do to the change in outlet port from the pump.

Question 6

What angle should the swashplate be in to get maximum speed (GPM)?

Answer 6

At max angle, allowing pistons to achieve full stroke, pushing max GPM

Question 7

What is max torque in a hydraulic system?

Answer 7

Max Pressure

Question 8

How do you achieve maximum torque (pressure) with a swashplate?

Answer 8

The swashplate must be at minimum angle

Question 9

What is the first rule to remember in Hydrostatic (hydraulic) motors?

Answer 9

Rule 1. The swashplate never EVER goes to zero angle or neutral.

Question 10

What is counter-rotate?

Answer 10

Equipment turns within its own length usually by rotating one track forward and one track in reverse

Question 11

In a dual path hydrostatic system used to control speed and direction, is the system a closed or open circuit?

Answer 11

Closed circuit (2)

Question 12

What type of pumps are used in dual path hydrostatic systems with two closed circuit drive systems?

Answer 12

Two variable displacement reversible pumps, axial type piston pumps

Question 13

What drives the pumps needed for steerng?

Answer 13

“Tractor” Engine

Question 14

What condition is the piece of equipment in when two track motors are rotating at the same speed?

Answer 14

Forward, Straight

Question 15

What is done to the pump and motor to change track speed?

Answer 15

The operator varies the displacement of each pump and motor

Question 16

How is a tight turn achieved with hydrostatic systems?

Answer 16

One track is driven and the other is in a neutral position. (Pivot Turn)

Question 17

What is an advantage of using hydrostatic steering systems compared to clutch steering?

Answer 17

Power is applied to both tracks when the tractor is being turned
Infinitely variable track speed and counter rotation makes the machine more maneuverable
Optimum traction can be achieved, making the machine more productive

Question 18

What type of control system is used on most hydrostatic steering systems?

Answer 18

Electronic Control System

Question 19

What are some components of the hydraulic side of a hydrostatic steering system?

Answer 19

Charge Pump
Neutral Charge Relief Valve
Charge Filter
Hydrostatic Pumps
Hydrostatic Motors
Check Valves
High Pressure Relief Valves
Flushing Valve
Pressure Control Pilot
Operating Charge Relief Valve
Pump Displacement Control Valve
Motor Pressure Control Pilot Valve
Motor Displacement Control Valve
Cooler and Bypass Valve

Question 20

What are some electronic components in a hydrostatic steering system?

Answer 20

Engine Speed Control Sensor
Left/Right Steer Sensor
Decelerator Sensor
Speed Control Sensor
Forward/ Neutral/ Reverse Sensor (FNR)

Question 21

What happens to a torque converter when brakes are applied on equipment with a steering differential?

Answer 21

The torque converter will stall

Question 22

What are the advantages hydrostatic drive has over power shift? (4)

Answer 22

Easy to operate, no learning curve (smoother operation)
Power is applied to both tracks when turning
Infinitely variable track sped, count-rotate
Infinite speed control, ground speed is adjustable to provide optimum traction

Question 23

How is a pivot turn achieved in a dual path hydrostatic system?

Answer 23

One hydrostatic pump is in the neutral position and the other is rotated.

Question 24

What is one way to describe a counter-rotate?

Answer 24

Equipment turning within its own length

Question 25

Describe closed loop systems?

Answer 25

The fluid does not return to “tank” it returns to the inlet of the pump

Question 26

Describe an open loop system

Answer 26

Fluid will return to tank before being picked up by the pump

Question 27

Charge Pump is ran at what speed?

Answer 27

Engine RPM, 100% duty cycle

Question 28

What are the jobs of the charge pump?

Answer 28

1. Replenishes internal leakage
2. Supercharges piston pump inlet (piston pumps cannot draw in oil well)
3. Changes closed loop oil through low pressure side
4. Supplies control pressure

Question 29

How many filters are apart of the closed loop system?

Answer 29

None on average, special equipment can be designed to have them

Question 30

What is pilot pressure also known as?

Answer 30

Charge pump pressure

Question 31

What position does the motor displacement control valve always default too?

Answer 31

Low Speed, High Torque (turtle)

Question 32

What type of hydrostatic motors are used to drive the final drives?

Answer 32

Variable displacement, bent axis

Question 33

What is the basic purpose of the flushing valve?

Answer 33

To change the oil in the closed loop, efficient cooler

Question 34

What is another name or description of a pressure control pilot valve?

Answer 34

Electrohydraulic servo valve

Question 35

In relation to pumps, how many pressure control pilot valves are there in a system?

Answer 35

Most systems have two, one for every pump

Question 36

What operates the pump displacement control valve?

Answer 36

Signal from the ECU to the pressure control pilot valve, changes elect signal to a pressure differential signal