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 function of the 'alerter' (or vigilance device) on a locomotive?
Answer: Ensure the engineer is alert by requiring periodic acknowledgment
The alerter requires the engineer to periodically press a button or move a control to confirm alertness; failure to respond triggers a penalty brake application.
In a diesel-electric locomotive, what causes 'wheel slip' and how is it initially detected?
Answer: Traction motors drawing unequal current detected by wheelslip relays or sensors
Wheel slip occurs when traction motor torque overcomes rail adhesion; it is detected by current imbalance between motors or by axle speed sensors.
What is the role of the 'main reservoir' in a locomotive's air system?
Answer: Provide the primary compressed air supply for all pneumatic systems
The main reservoir stores compressed air from the compressor and supplies all locomotive pneumatic systems including brakes, controls, and auxiliaries.
When a locomotive's cooling water temperature exceeds safe limits, what protective action typically occurs?
Answer: The engine automatically reduces power or shuts down to prevent damage
High coolant temperature triggers a power reduction or engine shutdown to protect the diesel engine from thermal damage.
What does 'motoring' mean in locomotive operation terminology?
Answer: Using traction motors to propel the locomotive forward
Motoring describes the mode where traction motors receive electrical power and convert it to mechanical energy to move the locomotive.
Which component in the brake system equalizes brake cylinder pressure across all cars when the engineer makes a service brake application?
Answer: Distributing valve (control valve)
The distributing valve (control valve) on each car senses brake pipe pressure reduction and proportionally applies brake cylinder pressure to that car's brakes.
What is the purpose of the 'fuel prime' switch or priming pump on a diesel locomotive?
Answer: Remove air from the fuel system to ensure reliable starting
The fuel prime switch activates a pump to fill fuel lines and remove air, which is necessary for reliable diesel engine starting after shutdown or fuel system work.