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Tightening the Drive Belt on a Treadmill

Before performing any maintenance on your machine, be sure to remove the safety key from the console and to remove the machine from its power source (unplug the machine or remove the batteries).

Over time, your treadmill’s drive belt may stretch with use. If you feel a slipping motion while walking on the treadmill, the drive belt may not be properly tensioned.

Many treadmills are equipped with stretch drive belts that maintain tension as the machine ages. Models that are not equipped with stretch drive belts may use one of two methods to maintain the tension of the drive belt: adjusting the position of the drive motor, or adjusting a component known as the idler arm spring.

Please compare the exploded diagram in your owner’s manual with the diagrams below to determine which method most closely matches your machine. Please note that these methods are not applicable to every treadmill or incline trainer.

Treadmill Drive Belt--Motor Adjustment - Figure 1

Method 1: Adjusting the Drive Motor:

It is recommended that two people work together to complete this method. This method is applicable to models that allow for adjustment of the drive motor. An example of this is shown in Figure 1 (models may vary). The drive motor is held in place on the mounting bracket by a large bolt (Part #18, enclosed in blue). On the other end of the mounting bracket, a large, curved space allows for adjustment of the drive motor by loosening two sets of bolts and nuts. On some models, there may be only one bolt and nut.

Treadmill Drive Belt--Motor Adjustment - Figure 2To adjust the drive motor, you must first remove the motor hood. Please refer to the owner’s manual of your machine for instructions, or reference this step-by-step
video guide.  

After the motor hood has been removed, identify the drive motor (Part #27 in Figure 2). Near the motor, there are a couple of bolts and nuts that need to be loosened. They are enclosed in green and listed as parts 25 and 30 in the example. 
Do not remove the bolts and nuts completely. 

With these bolts loosened, you will notice that the motor is now able to move up and down in the curved space on the mounting bracket. Next, have one person put light pressure on the middle of the motor with their foot. As they press down on the motor, this will increase tension on the drive belt. Once the belt is tight, the second person will then tighten the nuts and bolts again.

After the motor is secured, reattach your motor hood, plug your treadmill in, and test your treadmill by walking on it. The slipping should stop. If it does not, this process may be repeated until the problem stops.

Treadmill Drive Belt--Idler Spring AdjustmentMethod 2: Adjusting the Idler Arm Spring

This method involves units that employ the use of an idler arm and accompanying spring to maintain the tension of the drive belt. The idler arm and spring are enclosed in red and listed as parts 74 and 75 in Figure 3. To perform this adjustment, use a pair of needle nose pliers to grip the end of the spring that is attached to the frame. Then, reattach the spring to the next hole on the holding bracket. This will increase the tension of the spring, and thus tighten the drive belt.

In some cases, another hole for the spring may not be available, or the spring may have stretched to the point where adjusting it will not resolve the problem. To solve this, there may be a replacement spring or a smaller drive belt that will resolve the problem. It may also be possible to tighten the spring by gripping the coil with a pair of pliers and twisting the spring as needed.

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