How to tension conveyor belt?

Once the belt has been pulled onto the conveyor system, it must be tensioned prior to splicing to facilitate correct positioning of the take-up and to eliminate sag. The tensioning operation takes place at the location where the last splice will be made. After final tensioning, clamps are placed on each end of the belt.

Tension is applied by means of a power device, which is used to pretension the belt before "clamping off."

When tension measuring load cells or scales are used, they are rigged to measure the pull on the take-up pulley. The belt is pulled until the load cells or scales register a tension equal to Tension Clamp for Splicing or slightly greater than the recommended take-up force. Make allowance for an amount of belt necessary to correctly position the counterweight from this point.

Certain basic statements and recommendations can be made about tensioning for splicing:

› Check the belt frequently during tensioning to ensure that the belt is free and not binding at any place.
› During the final tensioning pull, be sure the ends of the belt are lined up properly.
› Belts which are tensioned by pulling in only one direction require more splicing tension than those pulled in both directions.
› Slope belts spliced at the top of the slope require more splicing tension than those spliced at the bottom.
› Slope belts with an anti-rollback device that cannot be released must be tensioned by pulling only in the direction of belt travel.

Conveyor installations having limited take-up travel should be spliced to a tension based on the loaded running tension. This tension should be specified by our engineers and measured by suitable load cells or dynamometers. Where it is practical, fabric belts should be run for several weeks with mechanical fasteners before making the final vulcanized splice.

Obtaining the required tension depends heavily on the experience of the individual making the splice. It is possible for a gravity type take-up to severely damage the conveyor structure if it is positioned too close to the forward or upward stop. Too much tension applied to a relatively short belt may thus have a harmful effect on the pulley shafts and bearings as well as the belt.

The belt may be tensioned with a suitable take-up device as follows:

When the counterweight is on: Tie the take-up off 6" to 8" (150mm to 200mm) above the desired running position (consideration may have to be made for excessive sag). Next, pull the belt until the take-up starts to lift and the tie-off ropes become slack. Make the final splice, allowing a minimum of belt slack.

When the counterweight is not on: Splicing without the counterweight installed is undesirable; however, the following procedure should be employed if necessary: Use suitable belt clamps to hold the take-up pulley 6" to 8" (150mm to 200mm) above the desired running position (consideration may have to be made for excessive sag). Pull the belt to its running tension, which can only be estimated in this situation. Judgment in estimating this tension will improve with the experience of the splicer.

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