1956 July 1, James Reston, "Washington: It's Not the Whistle that Pulls the Train," New York Times, p. E8:
“In the words of the nursery rhyme,” says Mr. Green, “‘it isn't the whistle that pulls the train.’”
1962, American Flint, American Flint Glass Workers' Union, vol. 62, p. 17:
Until then, remember, don't brag, it's not the whistle that pulls the train.
2005, Eve-Lyn Woodard, Resounding Echoes, →ISBN, p. 113:
The shiny aluminum body of the 1928 Peerless race car with its rumble seat and purchase price of 50 dollars must have put Kenwood in a boastful mood because Grandma Proper immediately stated, “Kenwood you must remember that it is not the whistle that pulls the train.”