Which statement best describes DP (DPU) trains in terms of stall risk?

Which statement best describes DP (DPU) trains in terms of stall risk?

• A. They are immune to stalls
• B. They are less likely to stall, but issues can still cause a stall and manned helpers will be used
• C. They never stall
• D. They always stall and require DP

Answer: (B)

DP trains use distributed power units to spread traction across multiple locomotives, which smooths power application and reduces wheel slip. This coordinated, multi-unit control makes starts and climbs more reliable and lowers the overall chance of a stall compared to a single-power setup. Yet they aren’t immune—under heavy loads, on grades, or if grip conditions or equipment faults degrade traction, a stall can still occur. When that happens, additional, manned helpers are often brought in to provide extra traction and assist with restarting or moving the train.

DP trains use distributed power units to spread traction across multiple locomotives, which smooths power application and reduces wheel slip. This coordinated, multi-unit control makes starts and climbs more reliable and lowers the overall chance of a stall compared to a single-power setup. Yet they aren’t immune—under heavy loads, on grades, or if grip conditions or equipment faults degrade traction, a stall can still occur. When that happens, additional, manned helpers are often brought in to provide extra traction and assist with restarting or moving the train.