Rotary Tensioner Installation Instructions
RT0500, RT1000, RT1600
V-belt, V-ribbed, Synchronous Belt and Roller Chain Drives

Mounting Requirements
Before beginning the installation, review the following:

• Mounting bracket and supporting framework must be sturdy to prevent twisting under load.
• Mounting bracket and rotary tensioner must be located to allow for correct alignment of the idler with the driveR and driveN pulleys or sprockets.
• Rotary tensioner should always be mounted on the slack side of the belt or chain drive. See Fig. 1.
• The preferred location of a rotary tensioner/idler is on the inside of the belt drive. Optimum location would be where the idler provides nearly equal arcs of contact on both the driveR and driveN pulleys.
• As a rule of thumb, the inside idler pulley should be the same diameter as the driveR pulley.
• An outside spring-loaded rotary tensioner may be used, but it imposes a back bend on the belt. Follow the belt manufacturer’s recommendations for diameter and location. Typically, this diameter should be 1/3 larger than the driveR pulley.
• Rotary tensioner and idler sprocket should always be positioned on the outside of the chain. Note: At least three idler sprocket teeth must engage the chain.
• If possible, position the rotary tensioner with idler approximately 1/2, but no less than 1/3, of the center distance from the driveR sprocket.
• Never use a spring-loaded rotary tensioner/idler on a reversing drive.

Assembly Instructions

1. Mount idler pulley/sprocket to rotary tensioner arm.
2. Drill a hole in the mounting bracket, positioned to meet the above Mounting Requirements, corresponding to the mounting bolt size outlined in Table 1.
3. Insert mounting bolt in rotary tensioner body and into the mounting hole. Hand tighten only! Check the alignment with the driveR and driveN pulleys/sprockets. Any misalignment must be corrected!
4. Place belt/chain over all the pulleys/sprockets.
5. Place a 15/16" wrench on the hex nut in the tensioner body and a wrench on the mounting fastener. See Fig. 2.
6. Using the wrench on the tensioner body, apply pressure in the appropriate direction until the belt/chain is properly tensioned. Note: The tensioner body has marks on it, Fig.3, representing the force and degrees per Table 1.
7. With the tensioner securely held in position, tighten the mounting fastener.
8. Before starting the drive, recheck drive alignment and check all mounting fasteners for tightness.

Table 1. Mounting Bolt Selection

Note 1) All forces (lbs.) are nominal.