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olf20
09-29-2016, 08:18 PM
We have a grain truck that has a hydraulic pump to lift the grain
bed. The pump has a electric clutch that is driven by the serpentine
belt that drives the water pump, alternator, etc.
The problem is the pump pulley does not have very much wrap
on the pulley and it will slip sometimes.

Are these belts made for different applications similar to v belts?
I can not improve the wrap on the pump pulley and I have the
belt extremely tight.

Any help would be appreciated.

Thanks
olf20 / Bob

Doozer
09-29-2016, 08:39 PM
Instead of giving it more wrap,
could you pinch it to the pulley
with a rubber idler wheel that
presses on the back of the belt
directly pressuring the belt
right to the pulley?


-D

enl
09-29-2016, 08:53 PM
Increasing the wrap is the best bet. Overtight belts don't help. They just destroy bearings and shaft seals.

If you look at the capstan equation (https://en.wikipedia.org/wiki/Capstan_equation) you see that the wrap is by far the most significant factor. A belt with double the friction won't have the same effect as a fairly small wrap increase, and I doubt you will get double the friction no matter what you do. A pinch idler might do it, but I would guess that to get sufficient force, you will be at a load that destroys bearings in the pump quickly.

The question is WHY do you think you can't get more wrap? is there too much in the way? You can't shift an idler or put in another one?

If it was me (and it has been a few times), I would find a way to increase wrap. Move an idler, add one, or move the pump. Yes, you will need a different length belt. But too much tension will cost you much more in blown bearings and shaft seals. The other option, for me, would be a secondary belt or move the pump to another drive such as PTO. Again, more up front cost, but a major saving in down time and repair up the road.

paul463
09-29-2016, 09:01 PM
Post a picture of the pump setup if you can. Ideas will come rolling in after that.

Arcane
09-29-2016, 09:24 PM
Post a pic of the hoist too when it's in the extended position.

Willy
09-29-2016, 10:13 PM
Increasing the wrap is the best bet. Overtight belts don't help. They just destroy bearings and shaft seals.

If you look at the capstan equation (https://en.wikipedia.org/wiki/Capstan_equation) you see that the wrap is by far the most significant factor. A belt with double the friction won't have the same effect as a fairly small wrap increase, and I doubt you will get double the friction no matter what you do. A pinch idler might do it, but I would guess that to get sufficient force, you will be at a load that destroys bearings in the pump quickly.

The question is WHY do you think you can't get more wrap? is there too much in the way? You can't shift an idler or put in another one?

If it was me (and it has been a few times), I would find a way to increase wrap. Move an idler, add one, or move the pump. Yes, you will need a different length belt. But too much tension will cost you much more in blown bearings and shaft seals. The other option, for me, would be a secondary belt or move the pump to another drive such as PTO. Again, more up front cost, but a major saving in down time and repair up the road.


This is very well put. You are in effect trying to put a bandaid on an ill conceived assembly of parts and hoping it might work. In order for a belt to transmit the required amount of power in the limited time available it is imperative that it has an ample amount of surface area contact between belt and pulley. A pinch idler while sounding good only increases pressure in a very small spot thus requiring all of the necessary power to be transmitted by a very small segment of belt/pulley interface, just not going to work.

You have to change you current drive setup, making the best of a bad situation still leaves you with a bad situation. A properly designed belt drive system is a thing of beauty in that it does what's required and is almost forgotten due to it being almost transparent in that little to no maintenance is needed.
Get help from someone qualified if you must.

Below is a link to a pdf file that I always recommend for guidance in belt driven power transmission applications.
Have a look, it may give you some insight.
Good luck, as I know this is the time of year when that grain truck needs to be working, but if you can't get it up you may have to change your strategy.:o

Carlisle Power Transmission Products, Industrial V-Belt Drives Design Guide. (http://www.c-rproducts.com/downloads/pdfs/Industrial_vbelt_drives_design%20_guide.pdf)

Guido
09-30-2016, 12:37 PM
Pull up 'minibooster' per Mr. Google, or go to a multiple stage lift cylinder. __G

Paul Alciatore
09-30-2016, 12:46 PM
Would belt dressing help?

https://www.grainger.com/product/SPRAYON-Belt-Dressing-6KHF7?functionCode=P2IDP2PCP

OKChipmaker
09-30-2016, 01:54 PM
If you can stand a slower rate,a larger pulley would allow more wrap and also more leverage between the belt and pump shaft.