V-belt drive info

[playdiesel]

In my short time here I have learned a lot about belt drives. Here is some good info I found from Reliance/Dodge that realy helps out when your trying to figure out how many and what size amd what legnth V-belts are needed for a given drive. In another part of the book is info on cogged belts, that looks interesting for a no slippage drive but spares wont be found on tha back roads.

The link  http://www.dodge-pt.com/pdf/catalog/pt_components/2004_pdf/vdrive_stock_drive_sel.pdf

[mobile_bob]

that link looks a lot like the engineering material that Browning has had in their catalog for what seems like forever

if one were to follow the engineering and do what is laid out, there is no reason that a V drive need be much less efficient
than a microgroove or any other drive system, provided you use quality products.

a well engineered Vbelt drive can be very efficient and in some cases a better solution than any other option in my opinion.

thanks for the link,

if you would do so, please either duplicate this link down in the "white paper" board or move this one down there.

it is the sort of thing that is very useful reference material and over time folks will find it there much easier.

bob g

[playdiesel]

Done, Imma learn'n

[jimmason]

i've just been through this myself too, and learned much at the feet of a drive guru as a local bearing shop.

the main thing he clarified which i did not realize was the great difference in belts / pulleys between the letter and number series.  the classical v belt is the common A or B , etc belts we all know.  they are a very early industrial standard, not much changed since their origin.   there is also the 3, 5, etc lines that i've previously just fudged in with the rest of them.  turns out these are quite different and allow for much higher drive densities and somewhat higher efficiency.  the 3vx belt was originally designed for automobiles.  i think 50s or 60s in origin, maybe via dodge.  it is a 3/8" wide belt.  ganging them in 2,3,4, etc sheaves gets to surprising drive hp ratings that significantly exceed the letter line.  at typical pulley sizes, (4-6"), they are about 7-8hp per belt.  the drive guru i sat at the feet of repowers letter drives with these number drives constantly with attractive results.

as for the microgroove belts, if you go through the charts properly, you will find them to be about .5hp per ridge.  most of the lister belts we use are 10 ridge, so they are really only rated for 5hp.  but we are also running them over larger pulleys and thus bigger grip surface.  either way, i was surprised how difficult it was to get a rated 20hp drive out of the micro ridge belts, which is the size i need for my current app.  it basically required such a large number of ridges, like 40, that it wasn't realistic to find a belt or pulley to do it.  this was in the J line.  if you go to the L it is much more possible, but in my app i have the engine and genhead inline and offset, with relatively close centers.  the L belt would not work with such close centers. 

this is the problem with the larger higher capacity belts.  they start to not like close distances between the drives.  the 3vx was the only belt i could get to work out in relation to the charts.

you can see the set up i have here:  http://www.gekgasifier.com/forums/showthread.php?p=1316#post1316  actually in this photo i have a fancy 8mm tooth belt drive installed.  this is now changed for a triple stand 3vx.  i was all excited about the toothed belts given their extreme efficiency and very high power ratings over a small belt.  however, at least in my apps i couldn't get it to perform satisfactorily at all.  i had a tremendous problem with resonance, almost like a running a chain.  this got particularly bad if things were not extremely tight.  and if extrmeley tight, or really just properly tight, it whined like a blown hot rod.  the point of the rounded tooth timing belts was partially to get rid of the whine typical of the square ones.  but i still had a huge problem with the round ones.  it makes a whine at a frequency that carries like the dickens.

thus it was back to the v belts.  i tried all the more exotic options, with the general bias that v belts are old, boring, and superceeded.  but after going through all of them, and finally learning how to read the charts, and getting a drive guru to walk through all of it with me, and doing the same again myself in all the catalogs, i realized the elegance of the v belt.  but a very specific belt line, the numbered ones, and with the notches.  the #vx line.  the pulleys that come standard with changfas, listers and st genheads are not these v belt types.

i found all this very interesting.  and somewhat "embarassing" to be back arguing the best total value optimization with a v belt solution.

jim

[jimmason]

i should clarify in this that the reason the number belts like the 3vx are higher power density than the letter A or B belts is due to a deeper groove and thus more gripping surface.  the letter belts were designed at a time of much lower tensile strength materials, so there needed to be more belt to gripping surface to keep the belt together.  the number belts are "cross section to gripping surface" ratioed under the assumption of better tensile strength materials, and thus are much smaller for the grip area used.  the flat ridged belts and toothed belted move even moreso in this direction, given their being later standards.  the tooth belts, for instance, are all engineered on the assumption of carbon fiber strands for their tensile strength.  they are surprisingly thin for the amount of power they will transmit.

you cannot, or at least should not, try to run a number belt in a letter sheave.  the 5 and A belts/sheaves can be mistakently mixed i believe.  nothing will really mix with the 3 line, as they are 3/8" wide and smaller than anything in the letter line. 

note also that there are derates for service factor and engine drive type.  a one cylinder engine will require a bit more pulley than a two cylinder, given the rougher pull.  the charts have all these factors laid out, thus you might find yourself putting together a 20hp drive for a 15hp engine, after you calc out all the service factor issues.

j

[veggie]

For the 650-900 rpm listeroids I use a 2 : 1 service factor.
For the higher RPM changfa's I use 1.5 : 1

The 3V and 5V section belts can withstand a lot more torque than the A and B series.
I also found that the 3V belts fit nicely into the pulley groove of many automotive alternators.

veggie