Innovative Mechanisms Inc. Belt Troubleshooting

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Belt Troubleshooting

V- BELT DRIVE TROUBLESHOOTING

There are many reasons for the failure of a v-belt. When a good quality belt is properly installed on a piece of equipment that has been well designed and is in good condition it should give several years of good service under normal use. We will try to give you some guidelines to use to determine if there is some factor that is causing premature belt failure. V-belts may be thought of as being much like electrical fuses, their unexpected failure is usually a signal that something else in the system is wrong. Even their patterns of gradual wear can often indicate conditions needing corrections or improvements.

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The following is a list of symptoms with the probable cause:

FIG 1	FIG 2	FIG 3	FIG 4	FIG 5	FIG 6	FIG 7
WORN SIDEWALLS	HEAT CRACKS	WORN ON BACKSIDE	SPLIT COVER	BELT SLIPPAGE	ABRASIVE WEAR	A GOOD AND A WORN PULLEY

The sidewall may have a shiny appearance or appear burned or gummy.	The inside surface of the belt is cracked	The back side of the belt is worn and the number is un-readable	The outer cover is torn or cracked	The side of the angled part of the belt is shiny and slick and/ or a portion of the belt is narrowed where a pulley has spun on the belt without the belt turning.	The surfaces of the angled part of the belt appears pitted and scratched.	The belt drops into the pulley groove to the bottom because the sides of the pulley are worn. A new belt will not grip the sides because they are not straight, causing the new belt to slip.

SYMPTOM	CAUSE	SOLUTION
Repeated Breakage	1. Belt tension too high or too low. 2. The belt Pulleys are misaligned.. 3. The belt Load too high. 4. The belt cords have been broken by prying the belt onto the pulleys. 5. A pulley or bearing is out or round or out of balance causing the belt to vibrate. 6. The belt is installed with the belt on the wrong side of the belt guides.	1. Adjust the belt tension. ( See note A below ) 2. Align the belt Pulleys ( See note B below ). 3. Use multiple belts or go to a larger belt and pulleys. 4. loosen the tensioning mechanism before installing the belt. 5. Replace the defective component. 6. Make sure the belt is installed properly. After installation make sure the engine or motor is disabled and put the belt tensioner in the engaged position and check the entire belt route.
Rapid edge wear or burning. ( see FIG 1 above)	1. The belt is hitting a guard. 2. The belt pulleys are misaligned. 3. The belt tension is too low. 4. The belt is the wrong size. 5. Excessive heat. 6. Excessive oil or grease causing the belt to slip. 7. Belt dressing has been used.	1. Adjust guards to assure proper clearance. 2. Align the belt pulleys. 3. Adjust the belt tension. ( See note A below ) 4. Make sure the belt and pulleys are correct. 5. Make sure there is proper ventilation in the area where the belt is used. ( See note C below ) 6. Remove the source of the oil and replace the belt. 7. Replace the belt and never use belt dressing because it softens the surface of the belt. Click here for our Belt Selection Tool.
The belt turns over or jumps off pulleys.	1. Belt cords have been broken by prying the belt onto the pulleys. 2.The belt tension is too low. 3. The belt is the wrong size. 4. Foreign objects are in the pulley groove. 5. The belt retainers are missing or out of adjustment on equipment where the belt tension is released to disengage the equipment.	1. loosen the tensioning mechanism before installing the belt. 2. Adjust the belt tension. ( See note A below ) 3. Make sure the belt and pulleys are correct. 4. Clean out the pulley grooves. 5. replace or adjust the belt retainers as required.
The underside of the belt surface is cracked. ( see FIG 2 above)	1. The pulleys are misaligned. 2.The belt has been subjected to Excessive Heat 3. The system has a backside Idler.	1. Align the belt pulleys. 2. Make sure there is proper ventilation in the area where the belt is used. ( See note C below ) 3. Minimize the amount of wrap on the backside idler. ( See note D below )
The belt vibrates excessively.	1. The belt pulleys are misaligned. 2. The pulleys are worn or damaged. ( see fig 6 above ) 3. The belt tension is too low or too high.. 4. The belt is the wrong size. 5. A pulley or bearing is out or round or out of balance causing the belt to vibrate.	1. Align the belt pulleys ( See note B below ) 2. Replace the belt pulley. 3. Adjust the belt tension ( See note A below ) 4. Replace the belt. Click here for our Belt Selection Tool. 5. Replace the defective components.
Belt slips or squeals. ( See FIG 5 above )	1. The belt tension is too low. 2. Belt pulleys are worn or damaged. ( See FIG 7 above ) 3. The belt is the wrong size. 4. Excessive oil or grease causing the belt to slip.	1. Adjust the belt tension. ( See note A below ) 2. Replace the belt pulleys. 3. Replace the belt. Click here for out Belt Selection Tool. 4. Remove the source of the oil and replace the belt.
Belt soft or swollen.	1. Excessive oil or grease causing the belt to slip. 2. Belt dressing has been used.	1. Remove the source of the oil and replace the belt. 2. Replace the belt and never use belt dressing because it softens the surface of the belt. Click here for our Belt Selection Tool.
Worn Cover on Back	1. The belt cords have been broken by prying the belt onto the pulleys. 2. The system has a backside Idler.	1. loosen the tensioning mechanism before installing the belt. 2. Minimize the amount of wrap on the backside idler. ( See note D below )
The belt cover is split. ( See FIG 4 above )	1. The belt cords have been broken by prying the belt onto the pulleys. 2. Foreign objects are in the pulley groove.	1. loosen the tensioning mechanism before installing the belt. 2. Clean out the pulley grooves.
Repeated adjustment of the belt tension is necessary.	1. Belt pulleys are worn or damaged. ( See FIG 7 above )	1. Replace the belt pulleys.
Bearings are hot	1. Belt pulleys are worn or damaged. ( See FIG 7 above ) 2. The bearings or shafts are damaged. 3. Excessive belt tension.	1. Replace the belt pulleys. 2. Replace the defective components. 3. Adjust the belt tension. ( See note A below )
Pulleys Wobble	1. Belt pulleys are worn or damaged. ( See FIG 7 above ) 2. The bearings or shafts are damaged. 3. Excessive belt tension.	1. Replace the belt pulleys. 2. Replace the defective components. 3. Adjust the belt tension. ( See note A below )
The belts ride too high in the pulleys	1. The belt is the wrong size. 2.Belt dressing has been used.	1. Replace the belt. Click here for our Belt Selection Tool. 2. Replace the belt and never use belt dressing because it softens the surface of the belt.
The belts bottom out in the pulley.	1. The belt is the wrong size. 2. Belt pulleys are worn or damaged. ( See FIG 7 above ) 3. The belts are worn out. ( normal service life )	1. Replace the belt. Click here for our Belt Selection Tool. 2. Replace the belt pulleys. 3. Replace the belt. Click here for our Belt Selection Tool.

Note A: Belts should be tensioned with the minimum amount of tension to keep the belt from slipping on startup or at peak load. When using spring loaded idlers replace the idler spring with a OEM replacement or a matching aftermarket spring of the same specifications.

Note B: Belt pulley misalignment can cause a wide variety of problems. One of the things that is important to check is the spring loaded idler. If the pivot that the idler arm rotates on becomes worn it will cause the pulleys to be out of alignment and the belt will vibrate until it destroys itself. Replace the idler arm, idler arm bushing or the pivot bolt as necessary to correct this condition. The pictures below illustrate the most common types of misalignment and how to check for them with a straightedge. The straightedge should contact the pulleys in all of the areas where the arrows indicate.

ANGULAR MISALIGNMENT		VERTICAL MISALIGNMENT		PARALLEL MISALIGNMENT

Note C: Excessive heat is a symptom that is normally caused by some other factor. if there is something keeping airflow from the belt try to remedy this. If the belt is covered with debris, keep it cleaned off. Look for a overheating bearing or something in the system that is not rotating freely that is overloading the belt. Sometimes the problem is a design issue and cannot be changed. A good rule of thumb is the belt surface should not be over 140 degrees F.

Note D: The amount of wrap on a backside idler determines the amount of bending the belt has to do in the opposite direction that it does when it goes around the pulleys. This bending motion each time the belt goes around causes additional wear and heat, shortening the belt life. Normally we cannot eliminate this as it is designed into the piece of equipment and sometimes it is required to have enough wrap on the pulleys to give sufficient traction to operate the equipment without slippage. In the case of a spring loaded backside idler the amount of back bending can be lessened by shortening the belt length by replacing a stretched belt or using a slightly shorter belt if one is available.

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