Transmission Service "A"

Question 1

Trans. slip out

Answer 1

Trans moves into neutral when torque is being applied to the driveline. Caused when sliding clutch and mainshaft gears wear.

Question 2

Trans. jump out

Answer 2

Tends to occur during normal driving conditions or rough road. No torque on driveline

Question 3

What are some of the common conditions that contribute to jump out are? (3)

Answer 3

Extra heavy and long shift levers
Excessive movement between the trans and shift linkage (worn motor/trans mounts)
Worn or broken detent springs

Question 4

Hard shifting

Answer 4

When the operator experiences unusually excessive force to get trans into a gear

Question 5

Gear clash

Answer 5

Occurs when the speeds are not properly matched between gears when shifting. Clash that occurs while shifting into 1-R is typically due to a clutch issue

Question 6

Trans whine or squeal

Answer 6

Usually caused by insufficient clearance or backlash. Uneven wear patterns caused by mis-matched gears.
Bearings with insufficient clearance will also cause noise

Question 7

How many shims can be used when installing a PTO?

Answer 7

Up to 4 - ILM

Up to 2 - Class

Question 8

Trans growling

Answer 8

Commonly caused by severely damaged gear teeth. Also caused by improper timing or incorrect install of counter shafts

Question 9

What is considered normal operating temperature of a trans?

Answer 9

100 F above ambient (175-200)

Question 10

At what temp does trans oil breakdown begin to occur?

Answer 10

250 F

Question 11

What is first step when removing trans?

Answer 11

Disconnect battery cables

Question 12

Bearing failures in trans are usually caused by?

Answer 12

Contaminated lube, typically dirt and water in oil

Question 13

What tends to be the root cause of many other trans parts failures?

Answer 13

Bearing failure

Question 14

Frosting

Answer 14

Is a form of micro-pitting that appears as a band of off-white discolouration formed in the middle of the tooth. Caused by loading and unloading at pitch line. Normal from mating of gears, is not a reason for gear replacement

Question 15

Offset-frosting

Answer 15

When frosting appears on one side of the gear tooth and not the other

Question 16

Healing

Answer 16

As mating teeth wear into each other and frosting occurs, the wear rate will decrease until the point is reached where it polishes itself out and frosting is replaced by a very shiny area

Question 17

Initial gear pitting

Answer 17

Mildest form of pitting, consists of definite pits that are about pin hole size (.030”)

Question 18

Moderate gear pitting

Answer 18

About twice the size of initial pitting, when is evenly distributed across face the gear doe not need to be replaced.
When it is concentrated to 50% of pitch line it will make noise and the gear should be replaced

Question 19

Destructive gear pitting

Answer 19

Pits are larger and mainly deeper than those in moderate pitting. Requires replacement

Question 20

Gear spalling

Answer 20

Craters are larger in diameter and shallower in depth. Occurs over a short period of time when a gear is subject to an extreme overload condition

Question 21

Gear scoring/galling

Answer 21

Caused by insufficient oil film between mating gear teeth. High temps result leading to adhesive wear.

Question 22

Burned gear sets

Answer 22

If blue from teeth going inward, this is due to excessive torque combined with lack of lube.
If blue from centre going outward, can be due to lack of clearance on assembly for lack of lube between mainshaft and gears (towing, coasting in neutral)
Should be replaced