General Rule: Operate the Rubber Belt (RB) with as little tension or stretch as possible. Excessive tension requires an increase of compression on the RB in order to achieve the same amount of shrinkage. It also increases the stress on the RB and on the machine, causing premature wear on both.


Remove all tension from the RB.

Confirm that there are two marks, 12" (30.5cm) apart, on both sides of the RB.* If not, use a straight edge pushed against the belt's face, between the bottom idler roll and the tension roll (see diagram below), to straighten the curvature of the RB. Now, draw two thin lines exactly 12" (30.5cm) apart on the flat edge (perpendicular surface to the face) of the belt. Make these lines on both edges of the RB.

Increase the tension evenly on both sides of the RB until the lines are the recommended distance apart. (Note: To insure accuracy, the belt should be rotated several times (4 - 5) before measuring the stretch). The recommended settings are as follows:

For a 2 5/8" (67mm) SHIELD I or SHIELD I-C Belt - Stretch preferably 1/8" (0.32 cm) to a maximum of 1/4" (0.65 cm). Note: The 12" (30.5 cm) mark located on the side of the Belt* should now preferably read 12 1/8" (30.8 cm) to a maximum of 12 1/4" (31.11 cm).

For a 2" (51mm) SHIELD Ior SHIELD I-C Belt - Stretch preferably 1/4" (0.65 cm) to a maximum of 1/2" (1.27 cm). Note: The 12" (30.5 cm) mark located on the side of the Belt* should now preferably read 12 1/4" (31.11 cm) to 12 1/2" (31.8 cm) maximum.

* UNITED STATES SUPPLY CO., INC. places these marks on all New Rubber Belt's shipped. With age, however, these marks will fade and will need to be reapplied. Obviously, the marks should be placed as accurately as possible to help insure the proper tensioning of the RB.

Continue checking the distance between the lines until it remains constant.

If the fabric's appearance is desirable, the tension is now correct. The RB should not require further adjustment until ground. For possible exceptions to this rule, please see below.


If a particular fabric corrugates after setting the tension as described above, it generally means a little more tension is necessary to successfully run this particular fabric.

Have someone positioned on both sides of the tension roll (if manual). Tighten the tension roll uniformly (each side at the same time and same amount) a single turn at a time, while watching the fabric as it runs. As soon as the corrugation stops, tighten the tension roll one more turn. (This extra turn allows for slight variances in the fabric from roll to roll).

This should be a perfect setting for this particular fabric. Subsequent fabrics may need similar adjustment.

Should you have any questions concerning this process, the products used in this process (Rubber Belt Maintenance Products), or have Difficulty in Tensioning, please contact us via or Fax 704-393-5628 or Tel 704-399-4276.

Copyright 1997,1999 United States Supply Co., Inc. All Rights Reserved


Related Information:

Procedure For Installing A Rubber Belt
Procedure For Tensioning A Rubber Belt
Procedure For Cleaning A Rubber Belt
Rubber Belt Maintenance Products
Cross Sectional Rubber Belt Unit Diagram
Difficulty In Grinding (Trouble-Shooting).
SHIELD Belt Record

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United States Supply Co., Inc.
2651 Bagby Ln Charlotte, NC 28208 PO PO Box 668945 Charlotte, NC 28266
Ph: (704) 399 - 4276 · Fax: (704) 393 - 5628

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