Clutches And Transmissons

Question 1

What is Viscous Drag

Answer 1

A shearing action between two moving surfaces

Question 2

What are three concerns of Viscous Drag

Answer 2

• Make transmission shifts difficult or impossible
• Make shifts rough in a power shift
• Cause safety concerns in a PTO

Question 3

What are three different configurations of Wet clutches?

Answer 3

• Hydroliclly applied, Spring Released
• Spring applied , hydroliclly released
• Hydrolically operated, Mechanically applied

Question 4

Hydraulic Clutch components are ?

Answer 4

Inner Hub
Friction Plates or Discs
Separator plates,an end plate 
Drum
Piston and seals 
Piston return spring

Question 5

What is the Pressure regulating valve in most systems set between ?

Answer 5

100-300 psi

Question 6

What are Three basic types of PTO’s

Answer 6

Transmission driven
Continuous running
Independent

Question 7

What is viscous drag

Answer 7

The shearing action between 2 moving surfaces

Question 8

What components make up a Hydrolic clutch x6

Answer 8

Inner hub
Friction discs and plates
Seperator and end plates
Drum
Piston and seals 
Piston return spring

Question 9

What is a Disadvantage of a wet clutch and why?

Answer 9

It needs 2 oil sources , pressure and lube and can cause lots of heat

Question 10

What is the purpose of a PTO brake?

Answer 10

To prevent viscous drag for rotating the PTO shaft when the unit is not being used. It is not meant to slow down equipment with high inertial loads. These should be spooled down with the engine before being disengaged.

Question 11

What are three negative effects of viscous drag?

Answer 11

1)makes shifts in transmission rough or impossible. 2)turns outputs when not engaged. 3)rough powershift activation.

Question 12

What is the function of a lube cut off valve?

Answer 12

It prevents lubrication oil from entering a clutch pack so that it will not be effected by viscous drag when a function such as a shift is being performed.

Question 13

How does a transmission brake negate viscous drag?

Answer 13

It is applied by pressurized oil when the clutch pedal is deppressed and stops the transmission input shaft from turning

Question 14

What are the three configurations of hydraulic clutches?

Answer 14

spring applied/hydraulic release, hydraulic applied/spring release, hydraulically actuated mechanically applied

Question 15

What are some functions of hydraulically activated spring released clutches?

Answer 15

main traction clutch, powershift clutch, pto clutch

Question 16

What are some functions of a spring applied hydraulically released clutch?

Answer 16

parking brake, MFD

Question 17

What are some functions of a hydraulically actuated mechanically applied clutch?

Answer 17

Main traction clutch.

Question 18

Why is a spring apllied hydraulically released clutch used on MFD circuits?

Answer 18

Because it acts as part of the braking system in the event that hydraulic pressure is lost the braking stability of the unit is not effected.

Question 19

What factors influence the engagement force of a hydraulic clutch?

Answer 19

surface area of clutch, pressure of oil

Question 20

What is the function of the hub in a hydraulic clutch?

Answer 20

provides a splined connection to the friction discs and commonly ditributes lubrication oil.

Question 21

What is the function of the drum in a hydraulic clutch?

Answer 21

splined to the seperator plates and provides passage and commonly the distrobution seals for the presurized activation oil

Question 22

What is the function of the friction disc in a hydraulic clutch?

Answer 22

provide the a friction surface to allow the engagement of the clutch. Hold a engagement surface material that is capable of holding oil and heat to prevent the friction surface from breaking down.

Question 23

What is the function of seperator plates in a hydraulic clutch?

Answer 23

They provide the second friction suraface required to engage the clutch.

Question 24

What effect does doubling the number of plates have on the torque capacity of the clutch?

Answer 24

it doubles the torque capacity

Question 25

What factors effect the overall torque capacity of a clutch pack

Answer 25

1) oil pressure. 2) piston size. 3) release spring force acting against the piston. 4) coefficient of facing material friction. 5) size of plates. 6) number of plates

Question 26

What is the dfference between a pressure regulating valve and a pressure reducing valve?

Answer 26

a pressure regulating valve is normally closed while a pressure reducing valve is normally open.

Question 27

What is the common pressure range of hrdraulic clutch activation pressure?

Answer 27

100-300psi

Question 28

What are four common modulation devices?

Answer 28

oriface, accumulator, modulation valve, electronic modulation valve.

Question 29

What is the limitation of an oriface as a modulation device

Answer 29

it only controlls the flow of the oil and not the pressure. Therfore when the plates make contact the engagement can still be harsh. It is often used in addition to other forms of modulation

Question 30

What is the function of an accumulator as a modulation device?

Answer 30

It controls the rate of pressure rise within the clutch allowing the clutch to engage at a slower rate

Question 31

What are the two types of accumulators normally found on hydraulic clutches?

Answer 31

Spring or nitrogen

Question 32

What does a modulation valve balance?

Answer 32

hydraulic force with spring force

Question 33

an electrohydraulic PWM valve with 200psi of available pressure is activated to 50% duty cycle. What is the output pressure of the valve?

Answer 33

100psi

Question 34

When a hydraulic clutch's seals are dissasembled should new seals be installed?

Answer 34

yes

Question 35

When installing new seals in a hydraulic clutch what is important to check before reassembly?

Answer 35

That the sealing surface on the drum is not worn out.

Question 36

What are the three configurations of pto's

Answer 36

transmission driven, continuous running, independent

Question 37

in a transmission driven PTO what must happen to operate the pto while stationary?

Answer 37

The unit must be in nuetral with the clutch pedal released.

Question 38

How is the continous running PTO clutch system set up?

Answer 38

There is a two stage clutch that drives the transmission and the PTO. When the clutch pedal is fully deppressed both functions stop. Half way depressed and the pto engages. Fully engaged and both the transmission and the PTO are driven.

Question 39

When does the PTO input shaft rotate on an independent PTO?

Answer 39

Any time the engine is running.

Question 40

What are the three available PTO shaft sizes and their spline numbers?

Answer 40

540 1 3/8" with 6 splines. 1000 1 3/8" with 21 splines. 1000 1 3/4" with 20 splines. The 1 3/8" are fro 150HP and below and the 1 3/4" covers everything else.

Question 41

What are the three common locations for a PTO clutch?

Answer 41

In the flywheel compartment. In the transmission, in a modualar case in the rear of the unit