Cogged V-belts are more efficient than wrapped V-belts
Cogged V-belts are more efficient than standard V-belts due to reduced slip and the resultant friction losses. In addition, cogged V-belts have increased flexibility compared to the standard V-belts which also produces less friction and associated high temperatures. Average V-belt percent efficiencies are shown below for both wrap and cog belts. Note that belt efficiencies can vary, and if belts are not periodically re-tensioned their efficiency can drop by as much as 5% due to additional slip. A cogged belt is not as sensitive to correct tension and will not greatly increase its slip due to the tension lessening. They do need to be kept tight to prevent premature damage/failure.
2% Savings…. Who Cares?
Two percent savings is nothing, so why bother? Here’s why. How many motors in a facility use belt drives? How long do those motors run? The $ Savings table shows how quickly the dollars start adding up.
Is it really as easy as putting on a new belt?
No, but almost. A cogged belt will require a sheave designed for a cogged belt. In addition, for many applications, such as fans, switching to a cogged belt will increase their speed and thus their flow. This will increase the energy usage of the system unless the speed is reduced. If the fan or pump is controlled by a variable frequency drive (VFD) with automatic controls (not fixed speeds), the VFD will automatically reduce to the correct speed. Without a VFD, sheaves will have to be resized to achieve the desired fan speed.
Drawbacks
A cogged belt will not work for every application. They do not work well in instant start applications and are also noisier than V-belts. Cogged belts do work in wet and oily environments and with any variable speed drive that can be used as a “soft” start. If a cogged belt won’t fit your application, a notched belt may work. They don’t reduce slip like a cogged belt but are an improvement over a standard V-belt.
