How to Adjust Your Motor Base

August 17, 2023

Why would you need to adjust the base of your motor? In electric motor setups where the system is driven by a belt, there are two common issues you’ll likely face. One is belt slippage and the other is excessive tension. Both issues are caused by improper belt tension. In cases where the motor is mounted on a solid base, there isn’t a whole lot you can do to correct the issue. Thankfully, Overly Hautz has developed a great line of adjustable electric motor bases.

In this article, we'll cover:

  1. What Does an Adjustable Base Do
  2. Types of Motor Adjustable Bases
  3. How to Install an Adjustable Base With a Motor
  4. Where to Buy Motor Bases

What Does a Motor Adjustable Base Do?

Adjustable motor bases allow you to correct belt tension. Correcting belt tension in your electric motor setup can help increase the efficiency of the operation and avoid issues that will require additional maintenance. A belt that is either too tight or too loose can lead to frequent belt replacements, damaged bearings, and damage to either the motor or the equipment it drives.

An adjustable motor mounting base will help you avoid unplanned downtime and costs related to unnecessary maintenance.

Types of Motor Adjustable Bases

There are two types of motor adjustablebases that can set belt tension:

  1. Fixed position adjustable bases. This type of adjustable motor base allows you to adjust the belt tension by manually adjusting the distance between the center of the drive pulley and the center of the driven pulley.
  2. Tension-controlling bases. This type of adjustable motor base automatically adjusts the distance between the center of the two pulleys. A tension-controlling base has an additional device that adjusts the tension of the belt based on the load conditions during operation.

Fixed Position Adjustable Bases

Fixed position adjustable bases come in single or dual-screw configurations. After the belt is installed, the adjusting screws can be turned to move the motor into the correct position with the right amount of belt tension. Once the optimal motor position is achieved, the mounting bolts are tightened to hold the motor in place during operation.

You can find many styles and sizes of fixed position bases for electric motors with fractional horsepower ratings and up to over 200 HP. All styles in North America are manufactured to match NEMA motor mounting dimensions.

Single-screw adjustable bases are the most simple and economical style. They allow for belt tension adjustments only. While dual-screw bases allow for an additional adjustment that corrects motor alignment.

There is also a “special” fixed position adjustable base. This style has a mounting plate for the motor that allows adjustments to be made without loosening the mounting bolts. Special fixed position bases allow for easier adjustments that can be completed manually during operation.

In the case of standard fixed position bases, adjustments can’t be made when the system is powered up. So, the belt tension is set to handle the maximum load with minimal slippage. At times when the load isn’t at its maximum value, the belt tension may be too high. When belt tension is too high, there is too much stress on the belt, pulleys, bearings, motor, and driven equipment, which can lead to damage.

Tension Controlling Adjustable Bases

Tension controlling adjustable bases are designed to automatically adjust the tension of the belt based on the load requirements. These adjustments occur while the system is running, no downtime is required to complete adjustments as needed. There are two main types of tension controlling adjustable bases, pivoting bases and spring loaded bases.

In the case of pivoting bases, the motor is mounted to support arms that allow the motor to pivot up and down as needed to adjust tension. The movement of the pivoting arms is based on the weight of the motor and the rotation direction. As belt tension adjustment is required by the load, the arms swing up or down to decrease or increase the tension. Pivoting bases are ideal for operations that only require single-direction rotation and horizontal mounting positions.

Spring loaded adjustable bases, on the other hand, have one or multiple springs built in that control the belt’s tension. The motor is mounted in a “carriage” made of cross members that moves around based on spring tension. The force from the belt tension and the spring tension both act on the carriage in opposition, forcing it to move around to find an equilibrium or neutral position. This allows the belt tension to consistently be exactly what is required by the load.

Spring loaded bases allow for the best possible efficiency of the system and can handle overload situations with ease. The motor will also require less maintenance as the bearings on the load end will experience less stress during operation. Spring loaded bases can be used in horizontal or vertical mounting situations.

How to Install an Adjustable Base With a Motor

Incorrect motor base installation and belt tension can lead to seized bolts, cracked rails, and ultimately motor base failure. A misaligned belt results in excessive vibration and stress on motor and driven equipment components, which will lead to eventual failure. To avoid these common issues, the motor base must be installed correctly. Follow the instructions below to ensure proper adjustable motor mounting base installation.

Before you begin working on the motor and motor base, ensure you have the correct tools and a clean and clear work surface. Clean the motor feet, motor base, and base rails so that the motor sits evenly in the base.

  1. Use a belt alignment tool to ensure the base rails are flat and even with each other. If the base is uneven, you won’t be able to achieve proper alignment and belt tension.
  2. Lubricate the tensioning rods to help reduce friction and make setting belt tension as seamless as possible.
  3. Align the holes in the motor feet with the hold-down bolts on the motor base and place the motor on the base.
  4. Install the motor hold-down nuts on all four bolts. The nuts should be installed loosely so that the motor can easily slide without causing damage to the threads on the hold-down bolts.
  5. Install the belt and create tension by turning the adjusting screws or tensioning rods. Check the belt tension periodically until it reaches the correct tension.
  6. Begin tightening the front motor hold-down nuts. Alternate from side to side as you tighten to ensure the motor feet don’t scrape the threads off of the hold-down bolts.
  7. Once the front hold-down nuts are tight enough to stop the motor from moving, loosen the tensioning rods at the back of the motor to create clearance in the holes of the motor feet.
  8. Tighten the motor hold-down nuts at the back of the motor. Alternate from side to side as you tighten to ensure the motor bolts down evenly.
  9. The rear hold-down nuts should be tight enough to prevent the motor from moving.
    1. The motor is now pulled tight to the base and the motor feet are squared to the hold-down bolts. During this process, the belt tightened as the motor was pulled downwards.
  10. Double-check the belt tension. If adjustment is required, loosen the motor hold-down nuts, adjust the tension by turning the adjusting screws or tensioning rods, and then tighten the hold-down nuts according to the above procedure again.
  11. Double-check the belt tension and repeat the steps until the correct tension is reached.
  12. Torque down the motor hold-down nuts as per the manufacturer's recommendations.

Buy Motor Bases Online

Where can you buy motorbases? It’s as simple as a few clicks online. Navigate to and you’ll find two simple ways to find the right adjustable motor base, whether it’s your first time purchasing or it’s a replacement.

  1. Using the Smart Search bar, type in the catalogue number from your original base and make your selection from the items that appear.
  2. From the Homepage, select “Parts & Accessories” then “Bases.” Using the filters on the left-hand side, narrow the results on the bases page to the selection of bases that could work for your application. Make your selection from the remaining electric motor bases on the page.

eMotors Direct stocks the Overly Hautz brand of motor base. They are a trusted motor base company and commonly used in Canada. Motor bases are distributed from Edmonton, Alberta. Expect 1-5 day shipping within Canada.


When installing an adjustable motor base, getting the alignment and belt tension correct is essential in helping you avoid unexpected wear and tear that could lead to a breakdown in your system. Once you’ve found the correct motor base for your application, follow the above adjustable electric motor base installation procedure.

If you aren’t sure if an adjustable motor base is right for your application or need a hand selecting the correct base, contact our technical support team. Our technical team members would love to learn more about your electric motor project so they can help optimize your operation.

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