Hello Shane,

You can determine if the splice is crooked by watching it run on the system or by measuring it.

Belt running method:

[1] choose a convenient spot where you can watch the belt from above the system.

[2] with the belt running observe the mistracking that occurs as it passes an easily identifiable reference point (upright, marked idler, etc.)

[3] if the belt starts to mistrack prior to the splice, stays mistracked as the splice goes by, and gets back on track after the splice goes by and the rest of the belt does not mistrack at this point, the THREE most likely problems with fabric carcass belts are a crooked splice, a bowed belt end, or a poorly cut belt end.

[4] if the splice is centered on this mistracking sequence (i.e. the belt starts to mistrack 15 to 30 feet before the splice passes the reference point and the belt stops mistracking the same distance after the splice has passed), the problem is likely to be a crooked splice.

[5] if the splice is not centered on the mistracking segment, the problem is likely to be either a bowed belt end or a mis-cut belt end. Note that the splice will still be in the mistracked segment - but it will be at either the leading or trailing end of it (normally around a quarter point).

Measurement Method:

[1] Measure on the return run or release the belt tension and measure on the carry run if the return run is too difficult to get at.

[2] Place plywood under the belt for approximately 60 ft, with the splice in the middle. This supports the belt to eliminate any sag considerations.

[3] If you have removed the tension, put belt clamps on either end of this section and apply tension to the section with cable come-alongs. This eliminates any tension considerations.

[4] Mark the center of the belt approximately 30 ft in front of the splice and 30 ft after the splice. Use a chalk line to place a center line through the splice from these two reference points.

[5] Measure the variance from this centerline in the splice area and every six inches from the splice to each end point.

[6] As with the belt moving method, if the splice is crooked the apex of deviation from the master centerline will be in the splice. If the apex is before or after the splice, the problem is likely to be with the belt.

Unfortunately, you can have both a crooked splice and a bowed belt.

Hope this helps. ■

On page 33 of the Foundations book by Martin Engineering there is a diagram of the centerline method for splicing belts. For a complimentary copy please e-mail larryg@martin-eng.com. ■

An added note to Mr. Miller's comments:

Take care with the direction of manufacturing in the factory press. Be consistent with the direction of manufacturing and preferrably with the orientation recommendation of the mfgr.

We specify all belt rolls delivered to site have the direction of travel recommended by the mfgr. stenciled on the reels and at the lead end of each roll.

We have experience with installing multiple rolls of belt that track quite differently from one another. This difference was about a 150 mm offset. We then had to cut the culprit sections of belt out and reverse their orientation. The offset then went away.

Bad splices and bad sections of belt can be detected where the tensile members are misoriented. We setup a side guide roll with the support stem pivoted on a wand attached to a shaft encoder. The shaft encoder signal is fed to a data acquistion system. The assembly is installed at a low belt tension area. This is often the takup region. The belt is rotated and the wand records the belt edge trasverse position in time. Two revolutions of the belt will tell all. All structural defects will be clearly identified as well as splice anomolies. This system can resolve defects below 1 mm of tranverse travel and is repeatable to 0.8 mm over 20 km of belt. Large defects can then be x-rayed for tell tail evidence of bad construction.

Lawrence Nordell

www.conveyor-dynamics.com ■

Dave

Well done, you’ve simplified a very frequently asked question that is generally hard to explain.

;- ) [ I’ll keep this for my own records.] ■