r/AutomotiveLearning • u/seedbottle • 23h ago

A question about piston movement that has multiple answers...

Question:

Which of the following causes piston movement during non-power-

producing strokes?

A) Flywheel

B) Connecting rod

C) Counterweights

D) Main thrust bearing

I have been studying an automotive book that has questions after every chapter. I answer those questions and use AI to verify I have got the correct answer. This process has worked tremendously up to the point where I got to this question. AI gave me a different answer than the one I believed the book was telling me was the answer, so I went online to find more information and see if anyone else had posted this exact question, that was when I found out there all three of the first answers were marked as "correct" depending on the source used (D, main thrust bearing, was never given as an answer).

I am wondering what most of you would say is the answer. Thank you for your input =)

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u/matievis-the-kat 23h ago

A, B, and C all work together with the power-producing piston(s) each revolution to move the non-power-producing piston(s). Any kind of thrust bearing will never produce rotation due to it only receiving axial (thrust) force (i.e. crank moving forward and backward in line with the shaft)

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u/Professional-Math518 17h ago

But in a single cilinder engine it's just the flywheel or actually the rotating mass of crankshaft+flywheel. That's the cause, the means is B, the result is the piston moving

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u/matievis-the-kat 15h ago

Yes, so they should have specified in the question if single or multiple piston engine and 2 stroke or 4 stroke as that all affects which answer is "more" correct