This is more a physics than a metalworking question. I'm wanting to unscrew the fan clutch and fan from the water pump pulley of my car. I have a "striking" wrench to fit the big nut on the fan clutch and can clamp the drive belts to restrain the pulley from turning. The belts will probably hold 50-100 ft-lbs of torque, which is unlikely to be enough to free the nut. To what extent will torque from the belts (what I'm calling a strap wrench) add to the torque imparted by a sharp hammer blow to the striking wrench?
At first glance, I expected the restraining torque supplied by the belts to add to whatever torque the hammer blow furnishes, so that applying 50 ft-lbs with a cheater bar and then adding a hammer blow worth, say, 200 ft-lbs should give me 250 ft-lbs on the nut.
On more careful thought, the belts are very elastic compared to the striking wrench, leaving only the inertia of the pulley to restrain rotation. What if any role does the torque applied by the holding mechanism (belts) play in the torque between nut and pulley?
It's still useful to preload the wrench, just to keep it in place, but it's not clear the preload will add to the torque between the nut and pulley.
Has anybody worked this puzzle out accurately?
Thanks for reading,
bob prohaska