Belt Burn and Shrinkage Overtension 1

[aliccan]

Hi All ; I have designed generator driven belt and pulley system and used mercedes bus belt tensioner to tension 8 PK 1150 belt at 21 kW load.

The tension is around normal levels as i measured by gates tension meter.
The system has a flywheel shaft with 200 pulley on it and it is driving a 100 mm diameter pulley.

The 100 mm pulley is in the middle of the transfer shaft this shaft is heaving a 15 kW shock load every time the Air condition compressor clutch activates. (6 kW of the load is continous from the alternator)

This power is enough power to stall the engine but engine wins the stall and regenerates the normal 1500 rpm.
In one of the systems today we noticed that one of the Dayco belt was shrinked from 1150 to 1120 mm.
The engine room temperature is 90 Degrees Celcius
We are using cast iron pulleys
The engine room side is well ventilated
There were many signs of burn on the back side of the belt.
Is this normal or do i have system design failure.
You may find several pictures of the system as attached.

 

[GregLocock]

You are regularly stalling (near enough) a diesel engine via a 4 inch pulley. Yes the 1 inch width belt involved will be experiencing grief. Your photos didn't show up.

Cheers

Greg Locock


New here? Try reading these, they might help FAQ731-376

http://eng-tips.com/market.cfm?

 

[electricpete]

You'd think it would stretch rather than shrink, wouldn't you?

=====================================
(2B)+(2B)' ?

 

[electricpete]

There were many signs of burn on the back side of the belt

I guess heating relates to the shrinkage. Maybe got loose first, started slipping, got hot as a result of slipping, then shrunk due to the ehat? ...Or is there some simpler explanation?


=====================================
(2B)+(2B)' ?

 

[electricpete]

Correction: please substitute "slipping excessively" for "slipping" in my previous post.

=====================================
(2B)+(2B)' ?

 

[MikeHalloran]

Now, instead of 'designing' the belt application, 'engineer' it, by reading the back of the catalog and using the appropriate equations or design tables. Pay particular attention to the Service Factor for internal combustion engines.


Mike Halloran
Pembroke Pines, FL, USA

 

[aliccan]

Why the result shall be grief , i didnt get that ?

Thanks for your comments.

 

[GregLocock]

Sorry, Aussie expression, the belt will be unhappy.

Cheers

Greg Locock


New here? Try reading these, they might help FAQ731-376

http://eng-tips.com/market.cfm?

 

[aliccan]

My question is if i buy a 8PK random tensioner from the market and adapt it to my system will i have the necessary tension ?

The Air Condition Compressor is 8 PK and when i calculated the power and take a service a factor of 3 i was still at safe regions so that i designed the complete system with 8 PK

The problem occoured around 40 hours of operation. Some of the other generators are still running at 150 hours but we didnt noticed a similar problem.

Was this our bad chance or will the other systems fail like this one?

Your replies are very important thx

 

[MikeHalloran]

You didn't mention _other_ generators before.

What's different about this one?



Mike Halloran
Pembroke Pines, FL, USA

 

[HowDidYouBreakThat]

I think your pulleys are too small for that kind of load.