Cylinders: Horizontal vs. Vertical

[lesorubcheek]

I've been curious about this point for a while now and hope someone can add some insight. Very early chainsaws seemed to predominately use vertical cylinders. Then, by the 70's and 80's it seemed the majority of saws used a horizontal orientation. Present day, and for the past 10-15 years or so, it seems vertical cylinders are used on almost all saws. Besides the location of center of gravity, are there performance aspects that vary based upon orientation of the cylinder? Why the transitions from vertical to horizontal and back to vertical?

Thanks for any input,
Dan

 

[eyolf]

This is just my opinion, and worth what you're paying for it...

In the early days, people expected the spark plug on top, so the saw makers supplied...

In the early 1960's Homelite pioneered the laydown setup with the XL saws. Eventually saws appeared with all components including tanks as part of the same die casting, but one other feature was the reed-valve fuel system. Reed valves are useful for making mid-range power, but for all-out top-end piston-porting has a bit more potential, and it's easier to design a piston-port engine in a compact, lightweight design with a vertical (more or less, as in Stihl) cylinder layout. Heat flow issues into the fuel tanks was problematic, vapor-lock, etc. with laydown piston-port, modular-design saws.

 

[Crofter]

eyolf, I wonder if vibration imput to the hands had anything to do with cylinder orientation. I had several of those old Homelites and they were real hand numbers. Vibration is usually less in one direction than the other.

Frank

 

[16gauge]

Interesting question. Echo still uses the horizontal engine in its smaller saws, but gets vertical with the larger ones...HMMM.

 

[Lawn Masters]

Pretty much EVERY tophandle saw is a horizontal cylinder saw, while the larger saws, cs440 and larger anyhow, are vertical cyl models.

 

[16gauge]

LM,

Your facts are not in dispute...but why? Small saws = horizontal, bigger saws = vertical...there must be some reason...HMMM

 

[Lawn Masters]

I too must wonder this. there IS a reason I think, but I'm not sure what it is. maybe its that on small saws where the motor is directly below the handle, the vibrations arent felt as greatly. I'm not quite sure.

 

[pbtree]

Hmmmmmm......

 

[bugfart]

I think the vertical design once tough on chains in the cut - benefitted greatly once these guys tuned that counterweight on the crank. And my hat goes off to those guys, even the old schoolers.

What puzzles me in all of this is the effect of gravity on the cylinder. I mean, horizontal it doesn't matter which side has the plug, but ... do we wear out one side of the rings faster creating a flat-spot? I don't have enough experience to speak on that yet. But logic says it happens.

I am intrigued by what effect on timing could be realized with a bottom mounted plug on the verticle. Also; would it not be somewhat easier on a bearing to support an uphill throw with a downhill return? Think about the explosion pushing a piece of metal downhill as opposed to up-hill. Kind of scavenging power like a satelite slinghot around Uranis (we'll see how smart the profanity checker is) and this is the kind of math neccesary to play with it. We're just using inertia in place of the deliberately decayed orbit.

The whole thing from a maintenence stand point to me would be ring wear VS bearing/seal wear.

I say we put a sparkplug at each end... dual carbs... replace the piston with a plate and have a post come out of the side. Connect that to a wheel (clutch) like they did with old locomotives. As the wheel spins it covers one exhaust or the other. Electronic propane injection? How about a pressurized tank with check-valves?

 

[pinus]

IMO
Vertical cyl. advantages
1. Saw engine lenght (dimensions)
2. Location of the gravity center of saw.
3 Cooling
4. Fuel system (carb-filter position and serviceability)
5. AV advantage

 

[PWB]

LM,

Your facts are not in dispute...but why? Small saws = horizontal, bigger saws = vertical...there must be some reason...HMMM

Take one of your vertical saws and try to picture it with a top handle.

Get the picture?

 

[Lawn Masters]

I thought about that myself. a wee bit tricky to do.

 

[Bob Wright]

I was told by Echo when i sold their saws from '72-'85 that the horizontal engine had less vibration, but only the CS-60s had vertical. But it was designed in the early 60's, the rest came after it. Maybe they changed their mind? However as already said the new bigger Echo's use vertical, maybe it has to do with size, go up instead of long, making the distance between the handle's shorter...Bob

 

[lesorubcheek]

There are many factors to consider, but I still can't understand the trend. In regards to piston porting vs. reeds, the Homelite 360/45/550/650/750s were horizontal without reeds, yet the 410 was vertical with reeds, so I can't be sure there's an inherent advantage in one orientation over the other. In regards to smaller saws, especially the top handle types, it makes sense that only a horizontal layout would work. Again, why are all the larger saws of today vertical? What was wrong with the Pioneer P60's or the Homelite 750's with their horizontal layout?

Dan