Flywheel Placement - 6/1

[veggie]

I am planning to move the flywheels further away from the engine on my 6/1 Listeroid.
Are there any guidelines or limits on how far these can be moved?
Currently there is approx. 1/2" between the flywheel hubs and the engine.
I am proposing to slide to flywheels 4" away from the engine to accommodate the mounting of pulleys.
Anyone done this (or even more than 4") ?

thanks,
veggie

[Quinnf]

Well, no, I haven't done that, and here's the reason I wouldn't:

Each flywheel on a 6/1 has a counterweight cast into the flywheel about 30 cm from the center that weighs around 42 ozs, or 2.6 lbs.  So you have two flywheels with 2.6 lb weights spinning around on each end of the crankshaft.  The g-force at 650 rpm calculates out to be about 142 times the force of gravity (142 gs).  

Number of gs = ((650 rev/min * 2pi/ rev * 1 min/60 sec )^2 * 0.30 m )/ 9.8 m/s^2 which is 142 g.

So the 2.6 lb weights each pull on each end of the crankshaft with a force of 370 lbs.  That's 740 lbs total, spinning around at 650 rpm.  To enhance your pucker sensation, consider that every time the piston fires, it pushes down on the center of the crankshaft while the counterweights are pulling UP wherever the fllywheels are placed on the ends of the crankshaft.  The farther the flywheels are placed from the center of the crankshaft, the more bending force is imparted.   So the farther out toward the ends of the crankshaft you place your flywheels, the longer the lever you're providing the counterweights to bend the ends of the crankshaft.  

We've recently been provided with two examples of failures of Indian crankshafts, each of which snapped at the junction of the crank pin and the throw.  In 1930, the 5/1 Lister was introduced with a 1.75" diameter crankshaft.  Many of those crankshafts failed within the first year after introduction, so Dursley increased the crankshaft diameter to 2".  But in those days, the engine turned only 500 rpm, not 650.  And the metal used to make the early crankshafts was virgin iron, not iron of unknown composition scavenged from rusty old ships hauled up on the beach at Alang.  








It's unavoidable that the crankshaft bends a little, and we know that bending causes metal fatigue, and metal fatigue is cumulative.  Eventually the metal WILL fail.  Today, tomorrow, 10 years from now?  Who knows?

When I think of moving the flywheels farther out on the crankshaft, the mental picture springs to mind of Clint Eastwood as Dirty Harry pointing his .44 magnum at a bad guy, and saying, "The question is, do you feel lucky?  Well do you, Punk?"  And we all know how that scene ended.  

q.

[fabricator]

If you need to do that to for accessory drive get a different pulley, mine came with one on it.

[veggie]

Quinnf

Point taken !   
I will leave the wheels where they are.
In my case the crank throws have counterweights and the flywheels are not counterweighted.
Regardless, my sphincter meter moved enough into the red zone to kill the idea.

thanks,
veggie

[veggie]

A beautiful system.
This example illustrates what I was originally trying to achieve...
 9 min: 23 sec  point.  (Inboard flywheel pulley)

http://www.youtube.com/watch?v=NDrEpgHuFBM&feature=channel

[fabricator]

That is nice but that is way far from the main bearing, it's like a lever, even a small amount of imbalance in that wheel will be amplified at the spot where the shaft connects to the throw.

[Tom]

Ah 'roid porn. At first I scoffed when I saw the oil lines going to the trans cooler on the radiator, then it dawned on me that with the cooler at the top of the radiator it will function as a heater. Interesting solution to the cold oil design problem with these engines. I like the air brake compressor too. I think I'll look into one of these for my shop air system.

[Quinnf]

Ok, you must have a GM90 type engine which is internally balanced, so all the fancy arithmetic doesn't apply to your engine.  So long as the flywheels are balanced pretty well, which you can determine by using a bubble balancer like I made to determine the counterweight weights, I would say OK to proceed.  But it's definitely better to keep the flywheels inboard and put the pulley outboard if you can do it. 

q. 

[veggie]

Ok, you must have a GM90 type engine which is internally balanced, so all the fancy arithmetic doesn't apply to your engine.  So long as the flywheels are balanced pretty well, which you can determine by using a bubble balancer like I made to determine the counterweight weights, I would say OK to proceed.  But it's definitely better to keep the flywheels inboard and put the pulley outboard if you can do it. 

q. 

Hi Quinnf,

Nope, the engine is a full sized 6/1 built by GTC (Poweline).
Unweighted flywheels and bolt-on counterweights on the crank throws.
I took a look at the flywheels and they are the same thickness all the way around.

veggie

[Quinnf]

That's a nice innovation on the part of the Indians.  I'd far rather have an engine that's internally balanced than one with all that weight spinning around on the ends of the crankshaft.  When I saw my first GM-90, I thought that was the way it should have been done, and I gave some thought to casting some lead weights and bolting them onto the crankshaft opposite the throw, and then applying weights to the flywheel across from the counterweights to neutralize their effect.  But there's lots of other things that probably need doing more than that. 

Although the balance problem and all the weight whipping around ont he ends of the crankshaft doesn't apply to you, Fabricator's comment about increasing bearing load as you move the flywheel out away from the TRBs does.  It's still best to keep the flywheels as close to the bearings as you can.  But I really LIKE the fact that the crankshaft isn't being whipped around by the rotating forces.

Just for giggles I did a quick calculation from the torque of the engine, (48 ft-lbs) and it looks like the piston and conrod push down on the crank pin with a force of over 900 lbs on each power stroke.  But that's not the peak force, just the force averaged over the 180 degree duration of the power stroke.  The peak force would be more than 3 times that much, but I no longer remember how to actually do that calculation, so just guesstimating.  Point is, there's a lot of stress on the crankshaft, and it's not a good idea to do anything that might increase that stress. 

Quinn

[Hugh Conway]

Ok, you must have a GM90 type engine which is internally balanced, so all the fancy arithmetic doesn't apply to your engine.  So long as the flywheels are balanced pretty well, which you can determine by using a bubble balancer like I made to determine the counterweight weights, I would say OK to proceed.  But it's definitely better to keep the flywheels inboard and put the pulley outboard if you can do it. 

q. 

Quinn, please say more re your bubble balancer. Site search finds nada.
Many thanks,
Hugh