Tuesday, March 22, 2011

how to install tension pulley back on,MTD Tiller MOD # 21aa413b129 (287-424)?

The motor drives a belt, and the belt drives a pulley that causes a chain to drive the tines (blades). For the belt to drive the tines, an idler pulley has to put tension on the belt. This is moved into position by a lever that pulls the pulley into tension on the belt, and tension is maintained with a spring when the lever is locked into place.
1. Make sure that the tines will rotate with the belt off. If there is difficulty, check for debris holding the tines (roots, etc.). If necessary, remove the cap covering the chain cover inspection port, and with the machine tilted back, observe for proper operation of the chain while moving the tines by hand. Lubricate the chain according to your manual. If your chain is not working properly, disassemble down to the chain case, and inspect the chain and sprockets. Chain is radily at places like Motion Industries, WW Grangier, or a bicycle shop. Often overlooked, check that the pulley set screws are tight, and causing the shaft attached to it to actually rotate. Check the pins and locking cotter pins in the tines, make sure that they are pinned to the shaft.
2. Check the belt. An old belt can stretch to the point where it will no longer work. The "V" belt can also wear down to where insufficient friction can be applied to the driving or the driven pulleys to cause it to rotate.
3. Check the condition of the idler pulley and spring. Make sure that the lever places tension on the belt. It should be somewhat difficult to engage the idler pulley when the belt is new. You may have an adjustor on the idler that will tighten the belt.

  • Locate the tiller on a suitable work surface, then pull the spark plug wire from the spark plug tip to prevent the engine from starting during the belt replacement process. Remove the 2 torx screws that secure the top of the drive belt cover to the tiller (remove by turning counterclockwise). The belt cover is located on the left side of the machine when you are facing it from the front. On the bottom of the belt cover you will see a hex head nut and flat washer. Remove them both using a socket. Also remove the Phillips screw seen at the very bottom front of the belt cover. The cover may now be removed from the tiller and set asid

  • Remove the 2 hex head bolts along with their respective washers that secure the belt keeper bracket in place. The belt keeper bracket is situated behind the engine drive pulley and allows the belt keeper to keep constant tension on the belt, which prevents it from running off its pulleys during high engine speeds.

  • Ease the static tension on the belt by pulling the idler pulley bracket up firmly with one hand. It's located between the engine drive pulley and the tiller's head pulley. With your other hand, carefully roll the drive belt from the tiller head pulley. Be careful not to pinch your fingers between the pulley and belt. When the belt is completely free from the tiller head pulley, release the idler bracket. Remove the rest of the loose drive belt from the remaining pulley using your fingers. Discard the old drive belt.

  • Install the new drive belt by following the reverse of the belt removal procedures. Because the new belt will be slightly smaller than the worn belt (due to stretching of the old belt), make sure that you have it properly routed, and that all bracket bolts are properly secured. Test the tiller's operation to make sure the belt operates normally. Make sure when purchasing a replacement belt to get the belt specified by MTD as a suitable replacement. Kevlar belts (suggested by MTD) will not stretch much, and improper belt selection may damage the engine if it fits too tightly on the pulleys.

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