Single laser belt alignment systems are based on a straight-line measurement that hits two or three targets on a centerline. The targets are placed on the radius of the pulley and a line laser emits from the laser tool. This fan shaped line beam strikes the center lines of the opposing targets, when the laser is on all three center lines, the system is said to be in alignment.
However there is an error in this single laser measurement that is not always detectable to the human eye. The contributing factors are:
- Size of the pulleys
- The distance between the laser and the target
- Width of the laser beam
- Linear size of the target
- Type of target: straight or round
- Environmental conditions
The errors of the single laser systems occur when the laser hits the targets at any distance and the laser beam widens, let’s say 1/8″ and the target line is 1/8th”, thus “spanning” the target line. It is very difficult to visually decipher if the laser line is actually on the target lines or just “bleeding” into or out of the target.
Your system appears to be in alignment, but the sheaves can still be offset and angularly misaligned. This error can only be detected if you reverse the laser and targets and repeat the alignment process, and when this correction move is made, you must then reverse the targets and laser to validate the measurement. Generally another move is required.
This Process may need to be repeated several times, especially on large or temperamental systems. This is very time consuming, costly, and confusing to the technician, also as experience has seen, most technicians do not reverse the laser and targets to validate the alignment, leaving the system in a compromised alignment state.
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