Drivetrain & Transmission Flashcards
7 cards from real LEC practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Drivetrain & Transmission flashcards as text
In a diesel-hydraulic locomotive drivetrain, what component replaces the traction motors used in diesel-electric designs?
Answer: A hydraulic torque converter and mechanical gearbox
Diesel-hydraulic locomotives use a hydraulic torque converter (and sometimes a fluid coupling) combined with a mechanical gearbox to transmit power to the axles.
What is 'dynamic augment' in the context of locomotive drivetrain forces?
Answer: The cyclic vertical force variation caused by rotating and reciprocating drivetrain components
Dynamic augment is the periodic variation in vertical wheel force caused by rotating wheel/axle imbalance and reciprocating parts, affecting track loading.
What does the term 'gear ratio' refer to in the context of a locomotive axle drive?
Answer: The ratio of traction motor pinion teeth to bull gear teeth on the axle
The axle gear ratio is the number of teeth on the axle-mounted bull gear divided by the number on the motor pinion, determining the speed/torque trade-off.
A locomotive with a higher axle gear ratio compared to a standard unit will MOST likely have:
Answer: Lower top speed but greater starting tractive effort
A higher gear ratio multiplies torque more at the wheels but limits rotational speed, resulting in more pulling power at the cost of maximum speed.
What is the function of the traction motor suspension system (nose suspension) in a locomotive?
Answer: It permits the traction motor to move with the axle over track irregularities while transmitting torque
Nose-suspended traction motors are rigidly attached to the axle bearing housing on one end and pivot from the truck frame on the other, allowing axle movement while maintaining gear mesh.
During a power-off coast, what should a locomotive engineer expect regarding drivetrain behavior?
Answer: The drivetrain will freewheel with no engine braking effect in diesel-electric units
In diesel-electric locomotives with throttle at idle/off, the traction motors are disconnected from the circuit and the drivetrain freewheels with minimal engine braking.
What is the significance of 'continuous tractive effort' rating for a locomotive?
Answer: The sustained pulling force the locomotive can maintain indefinitely without overheating
Continuous tractive effort is the maximum sustained pulling force achievable without causing traction motor overheating, measured at a specific continuous speed.