Crusty and the Pulley

Oct 25, 1996

RAY: Crusty is at the end of the workday. He's at his truck, a '55 Chevy, trying to pry off the generator pulley.

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 the only way I drive. I drive around town with the headlights on, the heated seat, the radio, you name it. 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: You say, "Go for it!"

RAY: Exactly.

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 we should have been able to predict as a consequence of this new pulley that he put on.

What happened?

Answer: 

RAY: Because the generator was never meant to turn at very high speeds, what he did around town was okay. By making it run faster he did indeed charge up the battery by making the generator 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 centrifugal 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"!


Get the Car Talk Newsletter