|
|
Posted by Sherman in Idaho [72.47.9.37] on Thursday, December 13, 2012 at 12:22:42 :
In Reply to: 68 W200, 318 alternator quiz question posted by David Hogan [72.93.239.42] on Thursday, December 13, 2012 at 08:35:26 :
If you look at the tables of power transmission capability of various sizes of belts, I'm pretty sure even a single "A" belt is sufficient for a water pump and any reasonable alternator. I've always assumed that belts are doubled for redundancy so that if one breaks you can keep going. It might be possible that if the factory design was such that sometimes a power steering pump or air compressor might be added, with the same belt looping around all four pulleys, the amount of degrees of wrap around one of the pulleys ends up not being enough to positively transmit the needed torque without slippage, or at least not without having to put excessive tension into the belt, and so by going to two belts, they double the amount of torque that can be transmitted for a given size belt and belt tension. This was in the days before serpentine belts so with multiple accessories it would be easy to end up with not much wrap around one of the pulleys.