no. of vee- belts

Probably cheaper and easier to switch to a timing pulley with kevlar reinforced timing belt. Less slippage, better power transfer.

Vendors of these belts will gladly tell you the proper belts to use. If jamming is an issue a smart motor controller or jam relay in the motor circuit can monitor this.

You can download a belt calculator (Gates DF Pro) from Gates Rubber.

Belt manufactures rate the recommended loads (tension) of their products. Due to the belt specifics it does vary from one product to another. Some simple statics calculations based on the drive arrangement will tell you the belt tension, then you figure out what size and quantity of belts are needed. If you don't install all of the belts on the multi-groove sheave and you drop under the drive margin, the v-belts slip then they melt, or worse.

I would have thought that the answer must be perfectly obvious:-

needed 10, used 6=Broken very quickly again.....

If you had said 5 belts instead of 6, that would be technically seen as a 100% overload......what can possibly happen with a 100% overload!!! How difficult to understand!!! Use your imagination!!!!!

Sajid Ahmad,

Any engineer who is wise will design a power transmission system with a margin of safety. This is particularly true when components of the system can age and wear out (such as V-belts). When the system is in use, the equipment usually is carrying a different load than the specified one when it was designed. Hopefully this different load is not larger than the design load.

V-belt manufacturers will also have a certain margin of safety built into their application tables, because there can be variations in the process controls which can affect the quality of the belts.

Finally, the accuracy of the alignment and wear of the two sheaves (multi-groove pulleys) in the drive will affect how equally the load is divided among the many belts.

With new belts of very good quality, on a system designed with a good margin of safety, installed with good alignment, and under less than full load, it is quite possible for 6 belts to work fine.

However, if the belts are old or have deteriorated, or the design was marginal, or the alignment is poor, or the load is jerking or too big, then failure will occur. Go for safety and use good engineering and maintenance. Cutting corners is not worth it.

Peace be unto you--John M.

You will need to know a bit more information, like:

Motor Power, Motor Speed, Drive Ratio, Input/Output Shaft Diameter, Shaft Centre Distance & Maximum Diameter/Width you can use (if you have existing guards).

It also helps to know the type of motor doing the driving & what the driven machine is, this will help determine how much safety factor to apply.

If you don't need to synchronise the two shafts v-belts are a very cost effective way of transmitting power.