Flat Belts vs. V-Belts

A V-belt tracks in a V in the pulley wheel, and minor misalignments are permissible.

A flat belt relies on a high standard of alignment between the pulley wheels, and at least one one of them will have a convex surface so as to maintain the tracking.

"Horses for courses".

Advantage of a flat drive is that you can do a 180deg flip and it is generally more adaptable to situations.

I don't know about newer material but a flat is less efficient than a v-drive.

If possible see about installing timing belts instead.

Yes, timing belts, as well called 'toothed belts' are more efficient than simple flat belts and v-belts.

Yes, timing belts, as well called 'toothed belts' are more efficient than simple flat belts and v-belts.

Is it possible to use timming belts in grinding mills on high speed and high load.

But they are much louder and a lot more expensive.

I agree with what has been said and would like to add:

V belts develop more friction with the sheave they are gripping than flat belts. That is if all else is the same such as belt tension, Cf of the materials etc. That is because the V shape wedges into the sheave and causes higher "normal" forces. This allows V belts to carry more load if all other things are the same. This wedging is possibly also the source of the a lower efficiency.

Flat belt manufacturers can make up for the lower load carrying ability by upping the belt tension or increasing the Cf etc. When you make the switch to a flat belt just make sure the application is within the manufactures limits of load carrying ability.

If after looking at your application and a flat smooth belt (if that is what you want) can not carry the load, switch to a cogged belt as suggested. The pulleys for flat belts often have side guides that keep the belt on under slight misalignments.

Good answer: I think others on the thread have misinterpreted "efficiency".

don't know what the average loss of timing belts is considered to be, but some manufacturer literature may help. (My wild guess: 3-4% ??)

Typically, more like 2%.

Cogged v belts (which are different from timing belts) in which the cogs reduce the thickness of the material which must flex, are often claimed to be 97-98% efficient if properly tensioned and maintained.

At one time "Goodyear" were promoting there "Eagle" brand of flat belts. These had a herring bone pattern. It looked like a good idea, but cost and alignment were the killer.

What about multi-Vee belts? They stay aligned, the vees are a greater angle than a simple Vee belt and the bending material is thinner with commensurate reduction of losses. I'm no mech eng so I cannot quote figures.

Chas

Dear all,

I thank you for your in valuable comments.

But i have a doubt with respect to the ability of the flat belts to withstand the starting torque / jerk experienced by the motor while sudden starting.

Is there any limitation of flat belts based on this factor also?

Regards

If you are worried about the jerk on start up. You might want to consider using a variable frequency drive, with a soft start option.