Gen drive belt methods

[wagspe208]

Most guys seem to be using v-belts. Others are using serpentine belts.
How much KW can twin v-belts drive? 8/1 Lister engine
Are guys having their flywheels machined for the v-belts/ or serpentine belts?
ow about using a belt like this?
http://www.goodvibesracing.com/moreinfo.php

Reason.. 1) it will handle literally hundreds of hp. (overkill) 2) belts are free from the top fuel guys. 3) Does not have to have rely on tension to prevent slip. 4) I have some pulleys.

I just have to find pulley size to make 1800 rpm. Are there parasitc loss in the belts? If so, why?? Tension? Contact area? What causes the loss?
Thanks
Wags

[wagspe208]

Or a "timing belt" or gilmer belt. Square tooth or round but 1" wide. There goes free belts, but they are cheap enough.
Wags

[TimSR2]

I'm definitely a V belt guy. Old school B section cloth wrapped belt on off the shelf LARGE pulleys. Run the largest pulleys you can find.  Single belt up to 5 kw.  Keep as short as possible, use guide rollers if the belt slaps. Simple, efficient and cheap, and easily absorbs diesel engine punishment.   Many are averse on the losses of V belt drive but if properly designed losses can be kept in the 2-3% range. And they provide a fuse in the system, if not aggressively tensioned. 

Whatever belt drive option you choose remember that larger pulley diameters mean more contact area and larger  belt radius, hence lower loss and less belt tension required to prevent slip. Trying to transfer large amounts of power across small diameter pulleys is a mistake.

[wagspe208]

Tim, so did you have your flywheel machined for v-belts? Or did you get another pulley to slide on the shaft for the engine?
Thanks
Steve

[mobile_bob]

i don't know if i would go with a gilmer, unless i already had all the required pulleys and the cost of the belt wasn't prohibitive.

personally i use v belt drives, mainly because i have tons of pulleys and belts in stock. as mentioned properly engineered they are certainly in the 2-3% range in losses which is acceptable to me. properly sized and applied leads to low belt tensions which reduce
the amount of power required to drive them, extend their life, etc.

for an 8/1 i would recommend going with  the microgroove/serpentine belt and run it on the flywheel as is typical here, no real need for
machining grooves and there is more than enough contact to drive the load, efficiencies ought to be a bit better than a v drive
but probably not much better than 2% in most cases.

fwiw

bob g

[TimSR2]

My generator uses an air cooled twin, a lister SR2. No exposed flywheel on this one so I fitted a keyed stub shaft and 10 and 12 inch pulleys. With a single B series belt I can pull 5 kw with very low belt tension.

    In your case you have all that exposed flywheel rim available....   I'd lean toward ordering a pulley off the net and go with a common automotive style serpentine drive belt.   With a tensioning idler that comes up from below, and gives a bit more wrap on the gen end pulley. That is where the weak spot is, as you are overdriving almost 3 to 1 if an 1800 rpm head and 6 to 1 if a 3600 rpm head. A little more contact area on the gen end pulley wouldn't hurt. And no need to make a sliding base.

But like bob g says sometimes we engineer things around the parts we have on hand :-)

[mbryner]

A serpentine belt around the flywheel with Allmand pulley on gen head is easy, belts readily avail, more than enough contact area on the flywheel.  Doesn't ever slip and it's
efficient.

[Tom Reed]

In fact I setup the serp belt on my system under the fuel tank where the leaky valve dripped fuel onto the belt and it still doesn't slip.

[wagspe208]

So, we are back to getting the grooves in the flywheel. Do you have someone machine them? Just any job shop?  (I can't turn something that big in dameter in my lathe)
Thanks
Wags

[mike90045]

My flywheel came with grooves in it, but it's got casting flaws all over the place obstructing the grooves , wonder if they will clean up wit a 2x4 levered against it, or if I can file them off one at a time, or try to pop them off with a punch ?

[Tom Reed]

No grooves in my flywheel. Unless you want to count the grooves worn in the paint. Yes, the serp belt tracks well enough that there are nice neat grooves worn in the paint!

[slowspeed]

the serp belt works for me.Went to the semi junk yard and found a 8 1/2 inch 10 grove pully off a Big truck.
my belt off ebay ,think its a 6 grove,the 6 out of 10 is good!!
If you go to the yard look for a big alternator you may want one

[TimSR2]

Wagspe208,

If you are keen on going the v belt route you may find it cheaper to install a double pulley on the exposed shaft beyond the flywheel, rather than trying to machine your own groove, which I think will prove expensive unless you know somebody with a huge lathe. The early Lister SOM's used v belt drive, but that was the only thing available in the day.

You might be better off to go with the 6 rib serpentine, as others have done with  good success. Losses will be lower with a serp. belt. The loss in a belt drive is caused by slip, and hysteresis. Slip is just that, no explanation needed. Hysteresis losses refers to the loss as heat from the internal friction of the belt materials deforming and reforming their shape as they absorb power pulses, round corners, etc. Thus my recommendation of large pulleys to minimize loss.

The serp drive has lower hysteresis losses than V section as it's sectional thickness is so small.  That is why it has become the automotive standard.

[mobile_bob]

not to belabor a point, but

serp belts came into their own in automotive applications not because of higher efficiency but because
the engine could be made shorter which was needed for front wheel drive cars, this allowed all driven component
to run in the same plane and save up to 3 inches in the overall length of a fully optioned car.

properly engineered drive and the difference in efficiency is almost unmeasurable without some rather sophisticated
test equipment,

where v drives get a bad rep is when they are under spec's, poorly engineered to save a buck, things like using a single
B belt where two A belts is more appropriate, and undersized pulleys are among many ways to cut cost and encourage
problems later.

bob g

[mbryner]

I have a double-V pulley, maybe 18" diameter, fits on crankshaft outboard of flywheel.  Came with 'road in crate. I'll sell it because I don't see myself changing from serpentine. Forget machining grooves in flywheel.  I can get a more precise measurement in the next few days if you're interested.

Marcus