Belt Drive Accessories
Guards, hubs, tension gauges, and the hardware that completes a belt drive installation. Browning and Morse accessories are designed around the sheave and belt lines they serve.
A belt drive has to be tensioned after it is built, because belts bed into their grooves and stretch over the first hours of running. There are two ways to do it and this group carries both. An adjustable motor base moves the motor, which changes the center distance and is the preferred method because it adds nothing to the path the belt travels. A tightener or idler presses on the belt instead, and is the answer where the centers cannot move, where the wrap on the small sheave is too short to carry the torque, or where a long span needs damping. The two approaches are not equivalent, and the choice belongs at design time rather than at installation.
Also known as: belt tensioners, motor bases, idler pulleys, drive tensioners
Series in this category
Related guides: V-belt sheave sizes, FHP V-belt sizes, Cross-reference help
| Specification | What it means |
|---|---|
| Belt section | The V-belt cross-section a grooved idler face is cut for. It must match the belt already on the drive. |
| Face type | Grooved for running on the belt side, or flat for running on the back of the belt. The two are not interchangeable. |
| Outside diameter | The working diameter of the idler face. A larger diameter bends the belt less and costs less belt life. |
| Number of grooves | How many belts a grooved idler carries. It has to equal the belt count in the drive it tensions. |
| NEMA frame range and horsepower range | The motor frames an adjustable base bolts to, such as 48 to 56 or 213 to 215, and the horsepower band listed with them. |
For tensioning, usually yes. Moving the motor changes the center distance and adds no extra bending to the belt, whereas every idler adds one more flex per revolution and so costs some belt life. An idler earns its place where the centers cannot move, where the wrap on the small sheave is too short, or where a long span needs damping, and those are design decisions rather than substitutes for adjustment.
The slack side, so that it takes up slack rather than fighting the tight span. An inside idler on the slack side is grooved for the belt section; an outside idler running on the back of the belt is flat faced and bends the belt against its natural curve, which is the harshest duty and calls for the largest diameter the layout will accept.
Enough to install the belts without forcing them over the sheaves, and enough left over to take up the initial tensioning and the stretch that follows. Belts should never be levered onto a drive, because more belts are broken that way than fail in service, so the base travel is checked against both the installation allowance and the take-up allowance for the belt section.
