Horizontal to Vertical & Back

[mikem]

The MCS(?) as I understand it, was Homelites first attempt at a one man saw. This saw appears to have a horizontal cylinder and the saw is pretty compact for one that age. The next generation of saws (EZs,ZIPS, Buz's) went to a vertical cylinder followed by the saws of the 70s where the cylinder was horizontal again Does anyone know, or care to speculate why Homelite abandoned the original vertical design and went to an upright cylinder then back to vertical ?Was it engineering, cost of production, competition or something else....one of lifes unsolved mysteries maybe

[billg]

That is a interesting question. I would be interested in what others think.

Bill

[lesorubcheek]

I asked this question years ago over at AS. Didn't get any decisive answers, but there was some interesting thoughts.
One answer regarding the trend of going from horizontal to vertical was concerning the muffler layout. Appearantly some fires were started with mufflers being so close to the ground on horizontal saws, so a vertical saw with a muffler up and clear of dry grass and stuff is safer. Don't know if there is true, but it makes sense.

Dan

[mikem]

Jul 16, 2009 6:50:07 GMT -5 lesorubcheek said:

I asked this question years ago over at AS. Didn't get any decisive answers, but there was some interesting thoughts.
One answer regarding the trend of going from horizontal to vertical was concerning the muffler layout. Appearantly some fires were started with mufflers being so close to the ground on horizontal saws, so a vertical saw with a muffler up and clear of dry grass and stuff is safer. Don't know if there is true, but it makes sense.

Dan

Seems like the addition of a spark arrestor would be much cheaper than re-engineering the saw but you could be right.

[lesorubcheek]

Jul 16, 2009 7:27:41 GMT -5 mikem said:

Seems like the addition of a spark arrestor would be much cheaper than re-engineering the saw but you could be right.

The way I understood it, the issue wasn't as much with the outlet of the muffler, but dry grass and stuff that would get hot enough just touching the muffler housing itself. Again, I sure don't know if this was fact, but its what I remembered someone saying.

Dan

[MCS]

The 20 MCS, Homelites first Motorized Chain Saw, was created using an existing engine, the model 20. At the time, I'd guess that most saws were reduction drive and reduction drive requires a design where the clutch is mounted on the crankshaft and the chain sprocket is mounted on the output shaft. To keep the saw somewhat compact, having the crankshaft toward the rear allowed the output shaft to be tucked in close to the cylinder. On the MCS, the carburetor (existing engine design) comes in under the crankcase so the saw body is high from the ground and there is room to put the muffler and chain sprocket. Later, when Homelite designed an engine specifically for gear drives, they used the sloped cylinder design. In a rear pointing horizontal design the body gets a little longer with the gear case extending forward from the front mounted crankcase. For the direct drives, some of you like the balance of the vertical cylinder design but they are not compact in size. When the cute little box carburetors became available, saws like the "little" EZ showed up. They had to be appealing to the customer.
So if you look at everything that makes up a saw, the horizontal engine is quite efficient for the direct drives. The fuel tank wraps around the crankcase and, in the C family, it is quite large. Everything else seems to fit in quite nicely too.
The reduction drive has three variations: the forward horizontal cylinder, the sloped cylinder, and the rear pointing cylinder. The direct drives went from vertical to a rear pointing horizontal cylinder and never went back.