401dA Transmission Fundamentals - Part A

Question 1

The function of a transmission is to only provide a means of increasing torque.
T/F

Answer 1

false; The transmission has three functions: to multiply the torque provided from the engine, to reverse the direction of torque delivery and to provide an interruption in torque while the clutch is still engaged.

Question 2

The formula for determining gear ratio is the number of teeth on the driven gear divided by the number of teeth on drive gear.
T/F

Answer 2

true

Question 3

The engine, transmission and other powertrain components must be carefully matched in order to achieve maximum service life in a specific vehicle and operating application.
T/F

Answer 3

true

Question 4

An engine that develops high torque over several hundred rpm can be coupled with a transmission that has fewer gears (within reason).
T/F

Answer 4

true

Question 5

Some vehicles carry loads over short distances at low speeds. Other vehicles pull loads over long distances at high speeds. An identical transmission, in terms of gearing and torque handling capacity, should be used in both applications.
T/F

Answer 5

false; Transmission gearing and torque handling capacities should be matched to each vehicle’s normal operating application.

Question 6

Explain two (2) functions of a synchronizer assembly.

Answer 6

• to match or synchronize the speed of a mainshaft gear with the speed of the mainshaft during the shifting process
• to temporarily connect a selected mainshaft gear to the mainshaft once the speeds of the mating parts have been synchronized

Question 7

Identify three (3) types of commonly used synchronizer assemblies.

Answer 7

• blocktype synchronizers
• pin type synchronizers
• plate and disc synchronizers

Question 8

Multiple countershaft transmissions only have two countershaft assemblies.
T/F

Answer 8

false; Some multiple countershaft transmissions have three countershaft assemblies.

Question 9

Identify three (3) advantages of a multiple countershaft transmission.

Answer 9

• The countershafts,bearings and housings can be lighter because of the smaller forces they are required to withstand.
• Floating design eliminates the need for bearings between the mainshaft and the mainshaft gears.
• The gear width can be half as wide due to the doubled tooth contact area. As well, less expensive spur gears can be used, eliminating the need for thrust control washers.

Question 10

When a multiple countershaft transmission is used, the main transmission section often has five (5) forward gear selections.
T/F

Answer 10

true

Question 11

Multiple countershaft transmissions use several housings. These housings are kept in alignment through the use of:

Answer 11

precise dowelling.

dowel pins

Question 12

The input shaft and gear:

a) deliver torque to the mainshaft gears.
b) are supported on bushings.
c) are driven by the clutch discs.
d) utilize a lip seal for sealing.

Answer 12

c) are driven by the clutch discs.

Question 13

In a single countershaft constant mesh transmission, the countershaft gears:

a) are floating on the countershafts.
b) are in constant mesh with the mainshaft gears.
c) are identical from one countershaft to another.
d) are all individually replaceable.

Answer 13

b) are in constant mesh with the mainshaft gears.

Question 14

The mainshaft gears are located in place on the mainshaft by:

Answer 14

a set of double washers.

Question 15

What is used to reduce transmission noise from being transmitted up into the cab?

Answer 15

an isolator

Question 16

The shift lever directly moves the __________________ in the shift bar housing.

Answer 16

shift rail

Question 17

Identify the function of a detent system.

Answer 17

A detent system helps hold the shift rails in neutral or a selected position during operation.

Question 18

Identify the function of an interlock system.

Answer 18

An interlock system prevents transmission damage by preventing two gears from being selected at once.

Question 19

Identify the function of the spring-loaded plunger.

Answer 19

The spring loaded plunger prevents the operator from selecting first or reverse when the vehicle is moving forward at a great speed.

Question 20

In an overdrive transmission, which of the forward gears would be direct?

Answer 20

fourth