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Air Compressor Belts Guide – Tightness, 2 Belts, Replacement & Where To Buy

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Air compressor belts are instrumental parts of air compressors that transfer power from the motor to the pump in order for the system to compress air. This article will provide you with all the relevant information about air compressor belts and how to inspect and replace them.

Table of Contents

What are Air Compressor Belts?

Air compressor belts connect the air pump to the motor on belt-driven air compressors. The belt turns when the motor operates, in turn running the air compressor’s pump. Typically, the pressure and speed of the air compressor are determined by the pulley sizes that the belt runs through in the pump.

By using the pulleys to transfer power between the motor and pump, belt-driven air compressors offer advantages of control and flexibility. But, they’re not always suitable for all applications and users. The most significant benefit of using belt-driven air compressors is the flexibility of being able to change the pressure or speed by simply adjusting or replacing the pulleys.

Though belt-driven compressors have pulleys and a belt, their general maintenance tends to be a lot easier and cost-effective than other models. The pulley and belt alignment is crucial for air compressor efficiency. If the pulley or belt is not perfectly positioned and aligned, the air compressor won’t be able to operate as it should, which will waste time and reduce productivity. So, let’s take a look at how to inspect an air compressor belt!

Air Compressor Belt Inspection & Replacement

Air compressors need to be maintained in order to work at their best. This maintenance includes inspecting the belt to ensure it is under the right tension or still in working order. Maintaining your air compressor belt can help improve the performance and even extend the life of your air compressor!

Improper tension is the number one cause of power transmission belt failure. Therefore, learning how to properly tension a belt is ever so important. If there is too much tension on the belt, the excess strain on not only the belts but the bearings and shafts will cause premature wear of these components. On the contrary, if the belts are too loose, there will be slippage, rapid belt or sheave wear, and, ultimately, loss of both energy and productivity.

The following steps are a guide on how to replace, or re-tension, your air compressor belt. It is generally advised to inspect your belt and adjust the tension every 90 days.

Air Compressor Belt Inspection & Replacement Guide

  1. Remove the Belt Guard

    The belt guard is typically held together by screws or pressure snaps. You must carefully remove the screws or twist and separate the pressure snaps to take the belt guard off. Make sure you store the screws in a safe place so that you can reattach the belt guard later on.

  2. Inspect the Belt

    Now you should inspect the belt for breaks or signs of fraying. If the belt shows any signs of damage and needs replaced then continue to step 3. If the belt appears to be in great condition and shows no signs of damage then proceed to step 4.

  3. Remove & Replace the Belt

    First, you should loosen the bolts holding the motor in its place (do not remove) before shifting the motor towards the pump. After doing this, the belt should become loose and easily removable. You should refer to your user’s manual for your compressor to determine the correct sized belt for your compressor if you’re buying a replacement. Replace the belt and move the motor back to its original position to create proper tension on the belt, before tightening the motor bolts.

  4. Aligning & Tensioning the Belt

    Start laying a straightedge against the face of the flywheel touching the rim at two places (measurements should be within 1/16 of an inch in both places). Then adjust the motor pulley so that the belt runs parallel to the straight edge and use the gear pulley to move the pulley on the motor shaft. When in position, tighten the setscrew.

    Belt tension is typically decided by how much the belt moves when weight is applied to it. How tight should air compressor belts be? You ideally want a belt that doesn’t move more than 1/4″ to 3/8″ downward under normal thumb pressure. Your compressor’s user manual will provide you with a recommendation on the ideal tension for your compressor.

    Adjust the motor’s distance from the pump by slightly adjusting the motor position to the pump. Now tighten the motor bolts & roll the belt back in place. You may need to repeat the process of adjusting and testing the tension several times.

  5. Reattach the Belt Guard

    Finally, place the belt guard back on and either snap pressure snaps back in place or replace the screws and tighten them. Ensure the screws are tightened properly because you do not want the vibrations of the compressor loosening them!

It’s very difficult to be any more specific than that as the process may vary slightly depending on the make and model of your air compressor. Use these steps as a guideline, but refer to your compressor’s user manual or contact your manufacturer where necessary to get the best advice possible.

Tensioning Belt Alternative Methods

Many people recommend against tensioning a belt using the “thumb test” as there are methods available that will provide you with far more precision and better operational efficiency. One of these methods is using a belt tension meter which is quick, easy, and accurate. Though this method has the initial cost of purchasing the belt tension meter, it is worth the investment.

The hand-held device has two elements to it: an optical sensor and a meter. It’s designed to detect the vibration of a belt using an invisible infrared beam and a light. It is typically advised to take three successive readings for consistency purposes to ensure you’re getting a correct reading. If the readings vary by more than 10%, reassess your measurement technique!

The meter does not give a measurement reading for any belt that is under extremely low tension. If the meter does not respond, you should simply increase the drive tensioning until the meter responds.

Another method is using a pencil gauge tool to conduct the force/deflection method. This can be very time-consuming and tedious but will provide you with inexpensive and precise reading.

Air Compressor Replacement Belts

So who sells replacement air compressor belts? You should immediately refer to your compressor’s user manual or contact the manufacturer for guidance on purchasing a replacement belt, otherwise, you can visit a local compressor store or search online – if you know the exact belt you need.

There are multiple replacement belts readily available on Amazon too, which can help speed up your process. I have picked out a couple of examples here which appear to be some of the most popular on Amazon.

Tools Needed to Align an Air Compressor Belt

Typically, the tools required for conducting the alignment of an air compressor belt include:

  • Ratchet
  • Sockets
  • Box Wrenches
  • Allen Wrenches
  • Straight-edge (at least 3 foot long)
  • Ruler

Useful YouTube Demonstrations

This YouTube video below is a useful demonstration of checking the belt tension and alignment!

Here’s another useful YouTube demonstration on aligning the sheave to the flywheel in order to set proper V-Belt Tension.

Further Reading

Ingersoll Rand SS-5 belt slipping.

Craftsman 1.6 HP 33 gallon compressor burning rubber belt

Repair a Sanborn Model 500A60 belt drive air compressor.

Sears craftsman 5 hp 20 gallon tank belt drive plug wiring

If you have any questions regarding air compressor belts, please leave a comment below, with a photo if applicable, so that someone can help you!

By Aidan Weeks

A passionate Mechanical Engineer with endless enthusiasm for fluid power - building off the back of over 18 years of high quality contribution and discussion stimulated by Bill Wade here at About Air Compressors. With both practical and theoretical experience in pneumatics and hydraulics, I'm putting my knowledge to work - and working my grey-matter through my research, assistance and publishing work here at About Air Compressors. Feel free to reach out any time! P.S. A HUGE shout out to Doug who really offers such great value to all visitors to About Air Compressors - once again, feeling like I'm standing on the shoulders of GIANTS by getting to work alongside such a great community

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