SERVICE TIP

Tips of Safe Procedures for:

• Removing worn V-Belts
• Inspecting sheaves and components
• Installing and tensioning new V-belts
  

Removing Worn Belts

Most drives have two sheaves, one on the motor and one on the driven machine. The motor base usually has slotted holes to allow for adjustment toward and away from the driven machine. Loosen the motor hold down bolts and move the motor toward the driven machine to the inner end of the adjustment to release tension on the belts. Use a pry bar against the motor base, if needed. The belts should now be quite loose. If the drive has an idler instead of an adjustable motor base, loosen the hold down bolts and swing the idler away from the belts, allowing them to hang loose. Be sure to use all the adjustment in the drive to loosen belts completely.

Now remove the belts carefully from each sheave. Do not move motor or machine after belt removal.

WARNING-AVOID SERIOUS INJURY

Do not pry belts off drive or attempt to roll them off by rotating sheaves. Doing this can result in serious personal Injury.

Inspecting Sheaves and Components

Check the sheaves carefully for worn grooves or damage. Safety tip: Always use gloves or a cleaning rag when checking the inside of grooves to avoid being cut by nicks or burns.

Sometimes you can actually see the worn areas in the groove sidewall, but a more dependable way is to use the Sheave Gauge (Besser Part Number AL 112541). Select the proper gauge and place it in the groove.

If the sheave is satisfactory, this is a good time to check alignment. Readjust, if needed.

If sheaves are worn excessively, remove them and replace with new ones.

Worn sheaves can seriously shorten the life of V-belts, especially the joined, POLYBAND form. The POLYBAND belts will ride lower in the grooves, forcing the tie band against the sheave land. This will reduce the wedging effect, or if severe enough, cut the tie band, destroying the advantage of a joined belt.

If original sheaves are satisfactory, or if new ones have been installed, put new belts on the drive as explained below.

NOTE: While drive is shut down, inspect all other drive components such as shafts, bearing and guards. Repair or replace damaged and worn parts.

Installing and Tensioning the New V-Belts

With the sheaves or idler moved to minimum center distance for belt removal as described above, the new belts can be easily placed over the sheaves and dropped into the grooves. (If motor has been moved, readjust it to provide slack for easy installation.)

Tension Your Drive Properly

Your final installation step is to tension your drive properly for trouble-free service. In general, a few simply rules will eliminate tension problems.

The best tension for a V-belt is the lowest tension at which the belts will not slip under full load.

Simply take up the drive until the belts are snug in the grooves. Run the drive for about 15 minutes to "seat" the belts. If the belts slip, tighten them until they no longer slip at peak load.

Remember, too much tension shortens belt and bearing life.

Check tension at the end of the first day’s operation. Check it periodically thereafter and make any necessary adjustments.

Although tension of a V-belt drive is usually not critical, accurate tensioning can help assure proper drive performance. We realize that many experienced maintenance personnel have developed a "feel" for belt tension-but because of improved materials mow being used by many manufactures, today’s belt can "feel" considerably different on the drive.

Keep take-up rails and motor base free of dirt, rust and grit, and lubricate them lightly from time to time on your regular maintenance rounds. That way, when you’re ready to install new belts, it’ll be easier to do it the safe way.

Posted 25 June 2001