how to measure belt slippage
how to measure belt slippage
(OP)
Does anyone know of a simple and relative inexpensive device to measure belt slippage between the driver and the driven ( v belts and pulleys)? I want to have an alarm or fault shutdown if the slippage increases to a preset limit. Generally we are dealing with 5V and 8V sheaves and usually 6-12 belts and the power transmitted is 200hp to 1000hp. It seems a manufacturer would provide such a device.
Thanks for any advice or comments.
Thanks for any advice or comments.





RE: how to measure belt slippage
RE: how to measure belt slippage
Cheers
Greg Locock
New here? Try reading these, they might help FAQ731-376: Eng-Tips.com Forum Policies http://eng-tips.com/market.cfm?
RE: how to measure belt slippage
TTFN

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RE: how to measure belt slippage
An odball belt and all bets are off.
B.E.
RE: how to measure belt slippage
Mark pulley and belts.
Get a strobe flash that can be activated by one of the markers - this will work during a full load test -slipage might only occur at full load.
Can a cell phone with an "app" be made to do this ? - along with complete recording video.
RE: how to measure belt slippage
RE: how to measure belt slippage
Then simply easuring driven speed would be pretty close.
Pick your desired output.
http://www.monarchinstrument.com/
Lots of choices, many < $500
RE: how to measure belt slippage
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(2B)+(2B)' ?
RE: how to measure belt slippage
RE: how to measure belt slippage
http://www.redlion.net/products/groups/preset/gemi...
You will need to install a tach/encoder/mag pick-up on each shaft (available from this same company).
RE: how to measure belt slippage
If your pants are down around your knees, you or either a teenager or your belt is obviously slipping. Otherwise, beer gut or up under your arm pits it’s a little tough to call. Suspenders might help.
RE: how to measure belt slippage
Tmoose,
The drivers are induction motors and is not on a VFD.(One motor has soft start) We have two motors on a common shaft and the end users (overseas) do not want to do proper routine maintenance to check belt tension so then they have burned the belts off one motor( that motor will continue to run) and then the second motor will shut down for over amp. So now the customer complains about burning the belts.
We want to compare the two speeds to determine slippage within predetermined limits for each motor and then have a fault to shutdown both motors if either motor runs with no load. We could take a look at amp draw but the motors sometimes are fully loaded and then within perhaps within even seconds will have no load.
Others have provided direction to suppliers and we will take a look.
Thanks
RE: how to measure belt slippage
RE: how to measure belt slippage
Cheers
Greg Locock
New here? Try reading these, they might help FAQ731-376: Eng-Tips.com Forum Policies http://eng-tips.com/market.cfm?
RE: how to measure belt slippage
1 - bearing housing vibration - can find a variety of problems
2 - thermography - as Greg mentioned.
3 - Strobe inspection. Freeze the shaft and inspect. Freeze the belts and inspect. Look for flapping belts. Look for damaged belts.
All of above tools (and qualified people to use them) can be found at any large industrial facility. There are also contractors that specialize in this type of monitoring. It may seem that walking around is a heavy ongoing manpower cost compared to continous monitoring, but balance that against the advantage of having a knowledgeable person gather the data, stand in front of the machine to look/listen/smell/etc for other clues and think about the results.
Also, make sure qualified people are maintaining the machines.
Proper belt tension is of course important (too loose lessens belt life).
When belts are replaced, check the sheave grooves... if they are dished that will rob belt life.
Someone in a hurry may use a screwdriver to pry to belt onto the sheave without having to move the motor... may save some time getting the job done but you'll be back doing the job again very quickly.
I'm sure others can add to the list of "tips". The main point is to have the right guy doing the job, or send him to training, or hire him.
Sorry if all this is a little off topic, obvious, motherhood or whatever. Just seems like it should be mentioned.
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(2B)+(2B)' ?
RE: how to measure belt slippage
Both motors driving a common shaft via belts?
Kind of like this, but with belts in place of the gearboxes?
http://www.freepatentsonline.com/6820707-0-large.j....
"We want to compare the two speeds.."
So the only speed changes when one motor's belts are gone is one motor at full speed, and the other motor is at something greater than full load slip, and the driven shaft may be proportionally and incrementally slower, unless the surviving belts actually slip some more, too?
I guess rather than try to track rpm of at least one of the belts in each set I'd expect if monitoring both motor amps, which are approximately linearly related to speed in the operating range, it would show when one motor was doing even a little less (>rpm), and the other was doing more (<rpm). And provide that indication somewhat Before one set of belts was completely dead, so that would be the trigger for belt maintenance.
http://docs.engineeringtoolbox.com/documents/651/e...
RE: how to measure belt slippage
And when both are running the load can vary from no load to something approaching full load.
If I sense amp draw then I would need to look at the amp draw differential between the two motors. If the belts are gone or slipping excessively on motor A (the motor would be running at or near no load) while motor B would be carrying all of the load (which could be no load, partial load within motor B load rating or most likely
overload on motor B along with the thermals tripping or the breaker tripping.
It would be great to find a module that we could just hook the output of a CT for each motor and have that module control signal a fault to the starters as the control circuits for each motor are in series so if one motor shuts down then the other will also shut down.
Thanks
RE: how to measure belt slippage