Flat belts, V belts and other belts

[Glenn]

Older equipment use flat belts to transfer power from the engine to the equipment. The ones I have seen have been 8-9 inches wide, leather, and sometimes 40-50 feet in length (20-25 feet from drive wheel to driven wheel).

Today we see *V* belts to powering all sorts of equipment. This can be just one belt or as many as 4 or more side by side on the same pulley.

The *V* belts do not have the same surface area in contact with the pulley. They usually can not be repaired in the field and are usually replaced instead of repaired.

What is the reasoning behind the change.

And why now are we going back to the flat belts to drive the accessories on the car engine via a flat serpentine belt?

[irnsrgn]

Measure the sides of the V belt and see what the actual contact area is, then the V groove in the pulley grips the belt more due to the tapered sides to increase the amount of pull.

Some of the new flat appearing belts on newer vehicles have cogs on the inside of the belt to correspond with notches in the pulley to increase pull and are used as timing belts to keep the engine in time rather than chains as before.

The other which flat appearing belts that you see on modern gas engines which power the accesories (water pump, power steering, AC) actually has many small V's on the inside to correspond to the V's in the pulleys and it is wider than a single V belt so is stronger and it is thinner so more flexible and is lighter so centrifical force doesn't affect it as much.

You forgot the newer notched V belts that have many small notches in the V part, which makes the belt more flexible so it will grip smaller pulleys and regular V belts have a memory. That is after setting wrapped around the pulleys it wants to stay in that configuration, which sets up a vibration in the machine when it runs at speed.

[LarryM]

Jr. is exactlly right on the belts. One other point I would like to add is that when a v belt is bent over a pulley the center of the taper sides of the belt, has a tendency to bulge outward to grip the pulley better. If you picture what happen when you bend a piece of tubing, or hose it flattens out and becomes wider. The old wide B belts would become twisted and roll over in the pulley. That's why we started using narrower belts on machine as well as vehicles. When a heavy load is on the belt we use many small belts to do the work of one.


Happy Hammering
Larry

[welder19]

$$$$
Ever had to buy leather belting, pricey compared to synthetic material, but mainly you can get a lot more torque on a vee belt versus flat, what Larry said about the bulge is dead on, it has a wedging effect, that's how you get more torque w/less surface contact.

welder19

[Chris Pook]

I ditched my 4" flatbelt on little giant and went to a Multiple Vbelt setup when I added a jackshaft to slow it down.

The flat belt worked, I used to pour some warmed up honey on it to keep it from slipping when I need to single hard blows. But no matter how it was setup it would randomly fall off :confused:

The VBelts never fall off, and feels like it pulls the hammer head that much harder for a single hit.

[IronPuppet]

I recently got an old lawn tractor for free. It needed a few parts. After I got it running I went to buy a new belt for the drive train and was told that ordinary "V" belts wont work on a lawn tractor. What I needed was a "fractional horsepower" belt. Much stronger than ordinary "V" belts. The guy at the auto parts store said an ordinary "V" belt would disintegrate in about 5 minuets.

I have since found 2 such belts, but the first was too small and the second one is too big. Seems getting the right belt is going to be the trick and I will have to take my tractor to a small engine type shop to get the right one.

The darn thing has a variable speed pulley on it too. Much like the drive train of a snow mobile. The tractor is 31 years old so I might have to redesign the belt system if I can't find the right belt.

I would also like to point out that on certain machines a flat belt is better than a "V" belt because it will slip if the machine becomes jammed. I am currently building a drive for a mini lathe and I read how if you have positive drive, like chain drive for instance, then parts and tools can explode in your face if something went wrong and the tool became jammed and so it's a good idea to have some form of slippage so if the machine becomes jammed, the belt just slips and things don't get so ugly.

Christopher

[Ten Hammers]

I am going to suggest you visit an implement dealer for drive belts for the mower. The drive belt from motor to deck is one thing and deck belt is another. Sometimes they are one in same, sometimes seperate. Common v belts won't take the backside pressure from idlers (very long normally). The tractor/deck unit should have a serial. Mower shop should have access to belts as well (as I am reading your post as I post ). Same would go for blades. Cheap blades are just that . Good quality blades can be $ 20 each but sure make a difference in long haul. The mower may have used up it's lifetime already or may be still waitin for a few parts to go back into service. A name of the unit might be helpful if you wish any further information. Example is, Cub Cadet belts will last YEARS if driveline is aligned and pullies are in good shape. I have 2 " B " belts (unmatched) off the jackshaft on my power hammer by the way. I will agree on the gripping power of v belts inside pullies. They can be tightened to point of gripping high torque.

[IronPuppet]

Thanks TH for the tip on the implement dealer. This being farm country, I should have no problem finding one.

I have the mower attachment for my tractor, but one of the bearings is bad. It's a duel blade affair and the blades look near new, although they are very rusty. The blade deck itself has a bad crack in it too. At this point I don't think I'll be using the tractor for mowing, but instead I plan to make a parade float out of it.

I got the thing from my friend who is a junk man. He had an old transmission from a yard tractor and I had mentioned to him I would like to use it to build a float. The next time I went to see him, he had this tractor put aside for me. It is a Viking made in '76. Hardly any rust on it's frame and body. Good tiers in almost new condition. The seat has no rips in it and the steering wheel is in perfect shape. Disk brake still has meat on it. The big thing it needed was a carburetor. I got one off another junked tractor along with some other goodies, like an electric starter.

The machine has 2 belts. One runs from the motor shaft to the variable speed pulley and the other goes from the variable speed pulley to the transmission. The transmission changes direction only and runs a chain drive to the back axle.

pic 1- 1976 Viking tractor, I think it was sold by Eaton's or Sears.

pic 2- Tiers are in good shape.

pic 3- This is what I found. Someone had put the wrong belt on and the belt got eaten in the variable speed pulley. The belt at the bottom runs the blades.

pic 4- back axle assembly as it came off. Lots of rust and grease so old it had turned into a jelly like substance, same with the transmission, too.

pic 5- Axle after clean-up and new grease in the differential.

pic 6- Underside of machine. Notice the lack of rust on the body. The only rust has be sanded off and painted black. I would have loved to take the main pulley off the motor, but I need to make a puller first.

I hope you found this interesting.

Christopher

[Neal L]

Another reason you now see flat appearing belt in the automotive industry is one belt, because it is flexible, can power all of the accessories, with the use of spring loaded idlers, where in the past it took many v-groves belts. The belts have mico-grooves on the inside which give the grip and the smooth side runs against the idlers. The belt is also fast and easy to install which I'm sure saves labor in the manufacturing process.

[chainsaw]

Attached is a little belt matrix..

Belt Type.doc

[ThomasPowers]

On the other hand when the belt gives out you are stuck because nothing works. used to be you could often scavange a belt from a non-essential piece and stick it on to get back to town to a shop or parts store.

Of course out here we do have places with no cell phone coverage and a long way to town. (My wife called triple A once and they never showed up and this was in the local town...)

Thomas in Central NM, USA

[Daryl]

Flat belts have specific widths and thicknesses in relation to its ability to transfer horsepower. As well, flat belts must be accurately aligned and have a correct amount of crown in the pulley - as a flat belt will climb to the highest point.
The fractional horsepower belts you speak of can als o be referred to as high torque and there are alos a wrapped belt - these a obvious as you can easily see the fabric around the outside.
As far as farm implements go, there are available single v-belts (quite wide, though) that are rubber and kevlar compounds that are capable of withstanding over 375 horsepower - combines being a good example.