Lister start-o-matic flywheel weight

[veggie]

Anyone know the weight of a Start-o-matic flywheel for a 6/1 ?
They look considerably thicker than a standard 6/1CS
Do the SOM's have larger crank bearings than non-SOM's ?

Veggie

[AdeV]

Anyone know the weight of a Start-o-matic flywheel for a 6/1 ?
They look considerably thicker than a standard 6/1CS
Do the SOM's have larger crank bearings than non-SOM's ?

By my calculations, they are approx. 160kg per flywheel. I've got the dimensions written down in the office, I'll dig 'em out & post them up when I get in to work.

[veggie]

By my calculations, they are approx. 160kg per flywheel. I've got the dimensions written down in the office, I'll dig 'em out & post them up when I get in to work.

Wow, if that is correct (350 lbs) then they would be twice the weight of my current wheels.
If the bearings are the same, there would be a huge service factor in the non-SOM engine bearings.

veggie

[AdeV]

Hi Veggie,

Yep, that's about right. The flywheel works out to be about 1200cu/ins (0.7cu/ft) of cast iron, which is about 157kgs or 346lbs...

The major measurements are:

- Max width: 3.75"
- Min width: ~1"
- Overall Diameter: 25"
- Rim depth: 3" (i.e. 22" to 25" of the diameter is rim)
- Hub boss: 4" diameter with 2" hole
- Balancing hole: 4" diameter, circular
- Kidney stone cutouts: 4" diameter, approx 7.5" across

I ignored the "missing" metal from the holes when calculating the weight, so actually they'll be a few lbs less than quoted.

HTH!

EDIT: I just re-did the calculation a bit more accurately; and it's more like 1000 cubic inches, which works out at nearer 300lbs...

EDIT EDIT: Harrumph, another cockup... I didn't account for the thin bit correctly. Nearer 820cu/inches then, so 230lbs. Getting lighter all the time.... Could someone please check my workings? Here's what I did:

Surface area = pi*r²

Entire volume @ 3.75" = pi * (25/2)² = 3.75 * 491in² = 1841
Remove 2.75" worth of volume for 22" of diameter (leaving 1" of "thin" section):  pi * (22/2)² = 380in² * 2.75 = 1045

(subtract to give 796)

Re-add the 4" boss (an extra 2.75" thickness, 2" rad) = 12.6in² * 2.75 = 34.6
Subtract the 2" hole: 11.8in³

Total: 818.8

[Chris]

Don't know for sure, but heavy. I used to be able to get one from the floor to the crankl and install. Don't do that any more. I use a come-A-long attached to the rafters now.

Chris

[veggie]

Sooooooo.....
Just pondering an idea......

I could add another flywheel to each side (20" spare units from a GM90) and increase my flywheel weight to 260 lbs. each side.
Almost identical to an SOM.

I'm assuming the only advantage to this would be less flicker in the lights ?


veggie

[Apogee]

I believe they used different big-end bearings in the SOM.

According to a note on the Stationary Engine page, the CS SOM's used bronze backed bearings and the "normal" ones used all white metal (softer).

http://www.stationaryengineparts.com/-Cylinder-piston-rings-and-con-rod/?page=2

I am planning to run the bronze backed ones even with the lighter flywheels.

Regarding adding the GM 90 flywheels, it would depend if they have balance weights cast in.   You could end up with too much balance weight between the original and the added flywheels if they both have weights or lightened areas EACH of which is designed to balance the crank by itself.  Food for thought...

Steve

[Geno]

My Jkson 6/1 with TRBs has had SOM flywheels on it for at least 1000 hours. I haven't looked at the TRBs but there not making any funny noises. Not only was flicker greatly reduced the engine runs much smoother.  I like them a lot. A few years ago I found a pretty worn out original, electric 6/1 and haven't got around to rebuilding it.

Thanks, Geno

[Crofter]

The TRBs are about the same size as axle bearings on a one ton truck. We load them a lot heavier in that applilcation too. The additional weight of the heavier flywheel is nothing compared to the force of the power strokes which is only very marginally greater with the heavier flywheel. Personally if I were adding flywheel weight I would want to make sure there was not excess end play in The TRBs.