Hi,

I just wanted to pass this idea around with the resident technical gurus on the board. Basically, would it be feasible to manufacture an entire pulley system that uses perpendicular ribs on the inner side of the belt? This would eliminate ANY belt slippage combined with an appropriate tensioner and would wear better in the long term than the current belt designs out there (what I call 'grooved' belts). I have seen these 'ribbed pulley' systems used to great effect in G40/G60 VW Polos and Golfs.

In order for this to work, all the other ancillary pulleys would have to be re-manufactured/ custom fabricated to accommodate the ribbed belt. Would there be any downside to this? Would the AC spin any faster? Theoretically it shouldn't since even with the grooved belt that is not slipping, the AC condenser will not over spin until you go down to 20%+ pulley reductions.

If the outcome of this discussion is favourable, I will be pionering this idea on my own car

I look forward to your feedback.

Henry

 

so am i right in assuming this is ribbed for mutual pleasure?

 

The term is a cogged belt/pulley system. For street driven cars a cogged blower belt is not so good. Much more likely to over spin the blower if you happen to miss a shift or over rev the motor. The current design has a certain amount of slip engineered in to allow for mishaps. Cogged you have no margin for mistakes. No doubt it would be much more effective but a potential danger to your blower.

 

Many cars used cogged belts as timing belts. If they slip, internal engine damage is likely. The the MINI belt appears to have wedge-shaped ridges that ride on the pulleys. I suspect the wed-shape is designed to reduce or eliminate slippage, as is the standard wedge-shape of fan-belts of old. I'd be surprised if the belt/pulley system was designed by the factory to protect some components through slippage.

 

Keep in mind that when a timing belt slips the pistons and the valves get out of sync and if the engine is an interference type they will collide. With an accessory belt like the MINIs, all the components are spinning independantly of one another, and none of them cares how fast the others spin. Unless there is a catastrophic failure of the components themselves, they will never collide regardless of what happens with the belt.

 

The idea is to transfer rotation without slippage or parasitic loss. If you could drive everything with a thread, that would be the best.....

There is deformation in the engagement of the teeth with the gear. This is energy loss. You only do it if you have to.

The current ribbed belts with lots of little ribs allow for increased surface area for traction, while not making the belts thick (remember the old fan belts?). As the belt gets thinner, there is less energy loss in flexing the belt itself.

Matt

 

Everyone,

Thanks for your feedback, it is much appreciated :smile:

Early_Apex

That is what I thought. From what I can gather, since the ancillaries spin at their own rate independent from one another, there would be no drawbacks to a cogged pulley system.

Again, the timing belt is another thing entirely. I was referring to the use of the pulley drive belt only.

I think that this may be a go-er

Henry