Do you have room to fit a spring-loaded idler wheel, running against the belt? This, equiped with a switch, should be all you need.

Here's a sketch of the concept:

Note that it is just a sketch - the spring should be as close to the belt as practical to reduce the moment on the bearings, and preferably, the pulley would be between the bearings.

Consider what might move when the belt breaks, and then look for a way to monitor.

So ask yourself "What is different" under the two conditions, then look for a cheap and reliable way to monitor it.

I would think about a micro-switch.

Hello

Just use a stroboscope. For more information about it have a look to http://www.automation.com/resources-tools/articles-white-papers/condition-monitoring/strobe-light-applications-for-machinery-problem-solving.

Hope this helps

This is OK provided you're watching the belt when it breaks.

The belt could be replaced before to fail. That mean the machine could be planned for maintenance with less cost and production is affected less, maintenance time is less.

no doubt a preventitive maint sched would help..proper adjustment at installation is critical whenever the schedule calls for the changing of the belt..

For testing pulley bearings stroboscopes are also used but mainly as a real time diagnostic tool for evaluating potential failure modes rather than preventing the failure from occurring.

in which manor are the belts failing ..? after how manny hours of operation do the belts fail..?

do the " edges " of the belt fray ? do the links shear ?..

if either of these are the problem..one might suspect that the adjustment of the belt at installation is incorrect..

The failure happens after some millions of cycles.

There is no consistency in the failure.

some million of cycles? do the belts come with a recommended lifetime ?

could this be just normal wear ?..

..imho: a pro- active preventative maint sched , aggressively enforced, might reduce the down time ..

imho: to take the time at the beginning of each shift to stop the machine , inspect the belts condition, would help to eliminate the unscheduled downtime...

time spent on the inspection / time spent replace the belts under random conditions. == ??..

thatz my two cents worth.. gl

Just a fragment from suggested article. << Belts on belt driven machinery can be examined for irregular operation using a strobe light. For example, in the case of multiple belts, a loose belt will exhibit more motion than belts that have the proper amount of tension. This condition will cause vibration. The strobe light is tuned to the belt speed. >>

Belt Loosening and Belt Braking is due to following factors

1) Selection of Proper Belt size according to its Load Transfer from Driver Pulley to Driven pulley

2) Vibration due to unbalancing in motor Shaft & driven Unit

3) Proper Center Distance between 2 pulleys according to Length of Belt

4) Misalignment in axel Direction of Drive & Driven Pulleys (Parallel to each other)

5) Proper clamping of motor & driven unit in position

If all above factors are properly done then failure does not take Place in normal working conditions, so instead for monitoring the Failures, kindly look for Solution by corecting the Reasons which make it failure

If you can Send the Details of Drive in term of its Parameters KW of motor details of Driven unit, motor RPM, Center distance Between Two pulleys, & photograph of Present Drive unit , then I can Suggest to ProperTiming Belt Drive system

I think a few people have already mentioned it, the key is vibration. If you attach an accelleration senser to one of the pulley bearing positions and let the vibration level (which is to be determined experimentally) set of the micro switch to turn of the machine then I think you have cracked it. This is the normal method of triggering a test stop for testing pulley bearings. As the life of the belt is normally the limiting factor in these tests the test has to be stopped when the belt starts behaving badly and that before it starts to affect the bearing. Each time a test stop is triggered the belt is checked (i.e. it might have become slack) and the belt is either adjusted or replaced. This is then repeated until the bearing has actually failed (instead of the belt!).

If you control your driving motor with a VFD, you can read out the motor power.

If the belt is broken, the power will go down.

If the motorshaft is locked, power goes up.

The other way is connecting a speed sensor (Tacho generator) at the driven load.

When speeds is out of limit, there is something wrong.

I have noticed all good answers for a broken belt . That is easy. What is a good solution to a loose belt? (Other than periodic observation and maintenance.)

See #1 and #10