Question 1

Technician A says that when excessive metal contamination has occurred in an Allison hydromechanical transmission,ALL the bearings should be changed.Technician B says that metal contamination in an Allison transmission requires that the external heat exchanger circuit be entirely replaced.Who is correct?

Accepted Answer

Technician A is correct because excessive metal contamination requires replacement of all bearings. Technician B is incorrect because the external heat exchanger circuit does not need to be replaced unless it is also contaminated.

Question 2

Technician A says that a valve body and governor test stand can be used to check both governor and modulator pressure.Technician B says that a valve body and governor test stand can be used to check shift points and trimmer regulator operation.Who is correct?

Accepted Answer

A valve body and governor test stand is designed to test various functions of the transmission's hydraulic system, including governor and modulator pressures, shift points, and trimmer regulator operation. Both Technician A and Technician B are correct in their statements.

Question 3

When a stall test is performed and the results are within specification but the transmission overheats,what is the likely problem?

Accepted Answer

The torque converter stator is responsible for transferring power from the engine to the transmission. If the stator is stuck, it will cause the transmission to overheat.

Question 4

Technician A says that a high transmission oil level in an Allison transmission can cause the oil to aerate.Technician B says that low transmission oil level in Allison transmissions can cause aeration.Who is correct?

Accepted Answer

Both high and low transmission oil levels can cause the oil to aerate in Allison transmissions. High levels can lead to the oil being churned by moving parts, introducing air, while low levels can cause the pickup to ingest air along with the oil.

Question 5

When an Allison retarder on a hydromechanical transmission fails to operate at high speeds,what is the most likely source of the problem?

Accepted Answer

An air supply problem is the most likely source of the problem because the Allison retarder is an air-actuated device. If there is not enough air pressure, the retarder will not be able to operate properly.

Question 6

If the engine is accelerated while checking the oil level in an Allison transmission,what will happen to the oil level?

Accepted Answer

When the engine is accelerated, the oil is distributed throughout the transmission system, causing the oil level in the pan to decrease.

Question 7

Which of the following conditions would be more likely to cause harsh upshifts in an Allison hydromechanical transmission?

Accepted Answer

A mechanical modulator out of adjustment in an Allison hydromechanical transmission can cause harsh upshifts because it improperly regulates hydraulic pressure, affecting shift smoothness.

Question 8

When should a governor filter on an Allison hydromechanical transmission be inspected?

Accepted Answer

The governor filter on an Allison hydromechanical transmission should be inspected every oil and transmission filter change to ensure proper function and prevent potential issues.

Question 9

Technician A says that any metal particles regardless of size on the magnetic drain plug can indicate an imminent transmission failure in an Allison.Technician B says that when coolant is present in Allision transmission fluid,the source is usually the oil cooler.Who is correct?

Accepted Answer

Technician B is correct because coolant in the transmission fluid often indicates a problem with the oil cooler, which is a common source of such contamination in many types of transmissions, including Allison. Technician A's statement is not entirely accurate because not all metal particles indicate an imminent transmission failure; some amount of fine metallic particles can be normal, especially in a new or recently rebuilt transmission as it wears in.

Question 10

Which of the following conditions could cause low main pressure in an Allison hydromechanical transmission?

Accepted Answer

The answer of Which of the following conditions could cause...

Question 11

Technician A says that a clogged breather can cause an inaccurate oil level reading on an Allison dipstick.Technician B says that when the transmission oil is cold,a high dipstick reading will result.Who is correct?

Accepted Answer

A clogged breather can cause pressure issues in the transmission, leading to inaccurate oil level readings on the dipstick.

Question 12

Which of the following would be the more likely cause of an Allison hydromechanical transmission that downshifts when the accelerator pedal is at full travel?

Accepted Answer

The answer of Which of the following would be the...

Quiz 19: Automatic Transmission Maintenance