OBSERVATION
 


CAUSE
 


RECOMENDATION
 

Belt runs true when empty, crooked when loaded.







 		 Off-center loading.


 
Variations in nature, formation of load.
Belt not making good contact with all idlers.		 Adjust chute and other loading devices so load is delivered to center of belt and in line with direction of belt travel
Use notched chute to keep load peak in exact center of belt.
Adjust height so all idlers contact the belt.
Belt runs off as it approaches terminal.


 		 Material build-up on snub pulley or idlers.
Pulley or approaching idlers not square.		 Keep surfaces of pulleys, idlers clean. Consider use of scrapers
Align properly.
 
Belt climbs sideways on some idlers.













 		 Loose idler.
 
Idler sticks or jams and cannot rotate.
 
Idlers or pulleys out of alignment.






 		 Return idler to proper position. Fasten securely.
Lubricate properly. Replace any sticking idlers having worn spots.
Realign idlers while belt is unloaded. Start with second or third idler back of point of run-off and work in direction of belt travel. Make small adjustments initially and to check the effect. Wait for one or two revolutions. Make correction with more than one idler
Part of belt running off idlers is in vicinity of splice.




 		 Improper splice. Ends not cut squarely for a mechanical splice, or steps not properly matched for a vulcanized splice.

 		 Re-splice. make sure ends are square for mechanical type splice. First draw center-line 10 to 15 feet long on belt. Then cut ends at right angles to this line. For vulcanized splice, match ends properly.
Same section of belt repeatedly runs off idlers along entire conveyor. Crooked belt.

 		 Replace with straight belt. (see "belt with worn edge" below.)
 
Belt with worn edge becomes crooked.

 		 Worn edge became stretched because of high friction pull or may shrink from moisture absorption. Eliminate cause of wear. Repair damaged edge

 
Empty or lightly loaded belt does not run straight on carrying idlers but there is no definite pattern in way it runs.







 		 Belt is too stiff transversely to conform well to carrying idler rolls.
 
Belt is new and therefore stiff.

 
Belts increase in stiffness when exposed to cold weather. Effect on some belts is more extreme than others.		 Use a belt construction with more transverse flexibility, or install an extra number of aligning aides.
Allow proper break-in time. Can be hastened by letting belt stand overnight while loaded.
Allow belt to run overnight during extreme cold.

 
Cuts or breaks in belt enlarge quickly. Splices weaken prematurely. Belt stretches excessively.














 		 Too much belt tension. Starting tension my be excessive. Frequent starts under load.














 		 Reduce load by increasing belt speed keeping tonnage the same, or reduce tonnage at same belt speed. Establish controlled loading of belt to produce even rate of feed. Decrease drag by lubricating idlers. Replace worn idlers. Remove spilled material obstructing idlers
Reduce take-up weight applying only enough tension to prevent slippage and keep sag between idlers to a minimum. Increase wrap of belt around drive pulley by using snub pulley, or tandem or dual motor drive, and lag pulleys to permit lower take-up tension.
Belt runs crooked on certain days.


 		 Wind blowing against belt forces it out of line. Sun on one side of steel framing causes uneven expansion in the steel. Erect wind baffles or improve existing belt housing. Use self aligning idlers. Paint framing with aluminum paint to reflect heat.
Convey supports out of line. Proper belt alignment impossible. Conveyor erected on a temporary or insecure foundation. Make foundation more secure. Realign supports and other parts.
[Training problems] Making Conveyor Belts Run Straight