Puzzler Answer: Crusty's Pulley

Tom: It's time for the spine-tingling puzzler.

Ray: I think I warned you that it is automotive and it concerns our faithful companion of many years: Crusty the Mechanic. This is actually inspired by my friend Murray who put together the mis-information for this puzzler. Here it is: Crusty is at the end of the workday and he is over there at his truck, his '55 Chevy, trying to pry off the pulley for the generator.

And I said to him, "What are you doing?"

He says, "I'm sick and tired of having a dead battery all the time. This generator doesn't turn fast enough and as a result it doesn't charge the battery at low speed. Which is all I do. I drive around town with the headlights on, the heated seat, the radio, you name it, all those accessories are on. The generator doesn't produce enough electricity, the battery gets weaker and weaker, until one morning I come out and the battery is dead. This happens every couple of weeks in the winter. I'm sick of it." He says, "I'm going to replace it with a pulley that is half the size so when this thing is running at idle speed or around town, it will charge my battery. What do ya think?"

Tom: And you say - Go for it!

Ray: Exactly.

Ray: So he does. About a week later he's forced to take a trip on the highway to visit his mother in prison. The State Pen as they call it. On the way back something happens that I and he should have been able to predict as a consequence of this new pulley that he put on.

Here's the answer:

Ray: Because the generator was never meant to turn at very high speeds what he did around town was OK. By making it run faster he did indeed charge up the battery by making the generaor think the truck was running at 50 mph. Except when he got it up to 50, the generator thought the truck was going 100 mph. The commutator -- which is that part of generator with all those slits of copper that send the electricity through the brushes and ultimately to the battery -- flies apart from centrifical force. The generator self-destructed. He came back with a box of melted mush.

Tom: Hey, he could have used that "commutator" to get his mother's sentence "commuted"!

Ray: Okie-dokey.

[ Car Talk Puzzler ]