What was the reasoning behind gear reduction saws?

[Andy1234]

Hi all,
A few questions foe some of the more knowledgable folks out there: (and, yes, I already used the search engine ).
1.) What were the gear driven saws for?
2.) Was the 090g designed and marketted for different uses then the 090av?
3.) Are there any gear reduction saws currently manufactured?

Thanks,
Andy

 

[Lawn Masters]

to answer your questions.

1.) What were the gear driven saws for? to make an already powerful saw even MORE capable of pulling HUGE bars in Pacific Northwest giant trees
2.) Was the 090g designed and marketted for different uses then the 090av? See #1
3.) Are there any gear reduction saws currently manufactured? not to my knowledge.

note this may not be exactly correct, but it is why I believe that geardrives were made.

 

[spacemule]

If I'm not mistaken, they were popular in the virgin big timbers that are less common now. They work well with obscenely-long bars, since they effectively multiply the torque of the engine.

 

[Andy1234]

What was the rpm range? I believe that an 090av spins out at approx 7000 rpm, does the 090g rev that high or does the gear train limit the revs?
Thanks,
Andy

 

[spacemule]

I don't know what the rpm ratings were on the saws, but they shouldn't be any different, or if they are, one would think the g would run at a higher engine speed (pure speculation on my part). However, the 090 and 090g used different sized engines--the g was substantially smaller.

 

[Andy1234]

Any idea what the size difference was?

Also, would a gear reduction saw work better for milling? Has anybody tried that?

Thanks,
Andy

 

[Big Woody]

The 090g was the same engine as the 070 which was 107 cc and a 58 mm piston diameter. The 090 was a 66 mm diameter and 137 cc.

 

[TimberPig]

090AV
090G

Milling is more about torque than chain speed. The gear reduction of a gear drive, multiplies the torque, normally at a 2:1 gear ratio, so the chain sees twice the torque (and half the speed) that the engine produces, instead of being 1:1 as in a direct drive saw. The high torque of a gear drive makes it virtually impossible to bog the saw down, so it will keep chewing through virtually anything, but it won't do it quickly. If the torque of the direct drive saw is adequate to the load the wood and chain are applying to it, the higher chain speed will allow it to cut faster due to the higher chain speed. If the torque is not adequate, the gear drive may maintain a faster cut rate by maintaining chain speed better. Once concern I have heard regarding gear drives, is that the gears may not be adequately lubed, while sitting on the side for extended periods while milling, because the oil is sitting below the gears in the case.

Be aware that since most gear drives were made well over 25 years ago, most even longer than that, parts are getting more difficult to find.

 

[Andy1234]

Thanks to all for the info, this is one of the reasons that i love this site!

A few more questions:

Were there any other LARGE saws besides the 090g that were gear reduction saws?
If so, how common were they?
How about mid-range saws?
Did Stihl make any other gear reduction saws? I saw the pic of the 041(?) gear saw on Gypo's post on HOS, but are there any others? If so, I am guessing that they are not very common, correct?

Thanks,
Andy

 

[Andy1234]

Did anybody actually use a 090 with the 18" bars that they are pictured with? Seems like a bit of overkill to me...
Andy

 

[TimberPig]

McCulloch and Homelite, and a few others also made gear drive saws many years ago, when they were used for driving monster bars, for felling massive old growth timber on the west coast from California to Alaska.

To my knowledge, Stihl only made the 041G and 090G, before that was the Contra G, and going way back, some of their very early ones were gear drives as well, but you're unlikely to encounter them due to their age.

Most gear drives were on large powerheads, to maximize the ability to pull bars from 48" and up. Only a few medium size ones, like the 041G were produced to my knowledge.

Some people probably did and do use short little bars like an 18" on an 090, but for all practical purposes, if the wood is that small, a lighter saw will probably cut it. The advantage of the 090 is in its ability to pull a long bar through big wood, why not make use of it. If not, there are lighter, more modern saws that will be much nicer to run with a short bar. These days, outside of milling, or where a monster bar is needed, few people use saws of that size and weight anymore.

 

[Andy1234]

Thanks again!

Again, another question: Was there any saws produced larger then the 090? Semi-modern saws, less then 30 years old? If so, by who?

Thanks,
Andy

 

[Big Woody]

Keep in mind that if you double the torque you are also doubling the possible tension force in the chain as long as the sprocket radius remains the same. Hence those saws used .404 or often 1/2" pitch chain. I think you could break 3/8" chain on those saws if you wanted too.

 

[RaisedByWolves]

I have 2 Homelite 700g's a 4-20g and a really cool C-91 Convertable.

The C-91 is 5hp without the gear drive attached but has the torque of a 12hp saw with the gear drive on (2.3:1ratio). The motor is similar to the SXL-925 but the saw is way bigger due to the fact that it holds 2.5 quarts of fuel and a quart of bar oil.

I guess they planned on some really long cuts.

 

[Bill G]

The 090g was the same engine as the 070 which was 107 cc and a 58 mm piston diameter. The 090 was a 66 mm diameter and 137 cc.

Not all,

I have 090G's with 66mm/137cc engines.

As for the later questions regarding small gear drives

Homelite SXL and C Series (RARE)
Mac -10 series (RARE)
Mac BP-1 (GOSH DARN RARE)
tons of older saws

Bill

 

[Big Woody]

Were those 090g's factory or did someone switch the jug and piston? Just curious since I have always read the g was an 070 saw. Acres website also says 106 cc.

 

[Lee Bradley]

Usually those old chains did not work as well at high chain speeds as today's chains. Also no roller tips and the lubricates were not as good so lower chain speed extended the bar life. And those engines just didn’t have the grunt of today’s saws.

 

[turnkey4099]

Back as late as the 50s, all saws of all sizes that I am aware of were gear drive and very low rpm. I doubt if any of them would have turned 8-9,000. The families first saw was a Mac with a 24" bar, gear drive and we even had the posthole digger attachment for it as wwell as an outboard helper handle.

When I retired in 1976 from the AF I was surprised to find that there were no longer gear drives being made with very few exceptions.

Harry K

 

[canguy21]

A mill I serviced saws for used 090's with 24" bars on the barker. They supplied the fallers with saws which was unusual and only wanted one model to simplify inventory. I cut the mechanical governors back to keep them from over revving, couldn't stall the saw with the short bar.
A number of the early saws like my Mac 35 were gear drive because the crank was parallel to the bar. Rewind was at the back of the saw.

 

[hoss]

Those old gear drives did use 1/2 and .404 chain, wich took a bigger bite out of the wood. This does not completley mitigate the slower chain speed but helps speed things up a bit. Remember, if the engine rpm on a saw is 6,000 and it has a 3-1 or 2-1 gear reduction the chain speed will only be 2,000-3,000 rpm. I have 4 gear drives, a homelite 990g, a homelite 770gs and a mcculloch g70. I use all three and i'll tell you that 990(112cc converted to .404) cannot be stopped and is faster than you might think. The 770(95cc) works great also though not as strong as the 990. The g70(72cc) spins a little more rpm than the homelites but it's smaller displacement is apparent in the harder woods. Ialso have a mcculloch model 73(120cc) but still haven't found a carb kit for it, so I cant say how it runs. Homelite made a few very big gear drive saws back in the day, the 7-29,8-29 and model 23 were all over 120cc. I also would not want to run a 3/8 chain on one of those big gear drives.(especially with a very long bar, 40+ inches) I have direct drive saws and gear drives and use them both. The direct drives definatley have more chain speed, but once in a while it's nice to feel that unstoppable torque.