EVT Chassis & Drivetrain Systems 3

Question 1

What does the term 'axle ratio' refer to in a fire apparatus drivetrain?

Accepted Answer

The number of driveshaft rotations per one axle rotation

Answer

The ratio of front axle load to rear axle load

Answer

The maximum torque output of the axle assembly

Answer

The ratio of tire diameter to axle diameter

Question 2

A technician notices excessive play in the steering wheel of a fire apparatus before the front wheels begin to turn. This symptom is MOST likely caused by:

Accepted Answer

Worn steering gear, ball joints, or tie rod ends

Answer

Incorrect tire inflation

Answer

A misadjusted torque converter

Answer

Low power steering reservoir fluid level

Question 3

NFPA 1901 specifies that the manufacturer must provide a document showing what information about the chassis for each new fire apparatus delivered?

Accepted Answer

Gross vehicle weight rating, front and rear axle ratings, and payload capacity

Answer

Chassis serial number only

Answer

Engine horsepower and torque curves

Answer

Transmission fluid type and change interval only

Question 4

What is the purpose of the inter-axle differential (power divider) on a tandem-axle fire apparatus?

Accepted Answer

To allow the two rear axles to rotate at different speeds when turning without binding

Answer

To lock out the front axle during highway driving

Answer

To increase transmission output pressure to the rear axles

Answer

To automatically switch between 4-high and 4-low modes

Question 5

Which condition would cause a fire apparatus automatic transmission to slip out of gear or hunt between gears during operation?

Accepted Answer

Low or contaminated transmission fluid

Answer

High ambient temperature

Answer

Oversized tires

Answer

Incorrect engine idle speed

Question 6

When replacing a driveshaft on a fire apparatus, what MUST be marked before disassembly to ensure correct reassembly?

Accepted Answer

The phasing relationship and orientation marks of all yokes and slip joints

Answer

The driveshaft paint color code

Answer

The torque specification on the end caps

Answer

The manufacturer date stamp

Question 7

A fire apparatus technician is checking the front axle caster angle. What handling characteristic does insufficient positive caster primarily affect?

Accepted Answer

Straight-line stability and steering returnability

Answer

Vehicle braking distance on wet surfaces

Answer

Maximum turning radius

Answer

Tire wear on the inside shoulder