Mechanical and Electrical Systems 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 Mechanical and Electrical Systems flashcards as text
What is the primary risk of operating a diesel locomotive with a cracked or leaking turbocharger oil seal?
Answer: Engine fire risk due to oil entering the hot exhaust stream
Oil leaking from a turbocharger seal can enter the exhaust system where it ignites, creating a fire risk in the engine compartment.
What does 'DB (Dynamic Brake) Blended with Air' mean on modern locomotives?
Answer: Dynamic brakes supplement the air brake system automatically to achieve desired deceleration
Blended braking automatically combines dynamic and air braking to maintain consistent deceleration while reducing wear on brake shoes and wheels.
What is the purpose of the 'Positive Train Control' (PTC) system interface with locomotive electrical systems?
Answer: Receive speed and signal data and apply brakes automatically if violations are detected
PTC interfaces with locomotive brake and throttle systems to automatically enforce speed limits, signal compliance, and prevent certain accidents.
When performing a 'static test' of the dynamic brakes before a run, what condition must be verified?
Answer: Amperage rises to expected levels in each traction motor/grid circuit
A dynamic brake static test verifies that expected current flows through the grid circuits when the brakes are selected, confirming proper motor and grid function.
What does a 'low oil pressure' alarm on a diesel locomotive engine require the engineer to do according to standard operating rules?
Answer: Reduce to idle and shut down the engine if pressure does not recover
Low oil pressure is an immediate engine-threatening condition; standard procedure is to reduce to idle and shut down if pressure does not recover to prevent bearing damage.
What is the function of the 'isolation switch' (or engine run switch) on a locomotive in a consist?
Answer: Allow the locomotive's engine to run without contributing power to the traction effort
The isolation switch allows a locomotive's engine to run (for heating and auxiliary power) without the unit contributing tractive effort, used when a unit has a traction system fault.
Which electrical protection relay specifically prevents damage from excessive current flow through the traction motors?
Answer: Overload (overcurrent) relay
Overload or overcurrent relays monitor traction motor current and interrupt or reduce power if current exceeds safe limits to prevent motor winding damage.