explain what good the 6 to 1 gear on small single piston gas engines is for.

[burntside bob]

I am in the final planning stage ( drawnings-specifications-components) of a small gravel screen plant. The engine I want is a 12 to 13 HP with 18 to 22 lbs torque.
These engines can come with the expensive option of the 6 to 1 gear.
My question is what does the 6 to 1 gear do? Other then reduce the final shaft rpm by a factor of 6 to 1; meaning if rpm of engine is 3000 then the shaft with the 6 to 1 gears would be turning at 500 rpm.
Does the 6 to 1 gears increase the engines torque?
I have read the posts about small diesel vs small gas engines, the screen plant will not be used all that much over the course of a year, so the more costly diesel engine would not pay to purchase.
Do you believe the difference in price between the China made engine and those made in the USA like Briggs/Stratton, Honda (if made in the USA)!
They do the same thing but cost a lot less, must not be one cent of our hugh government costs included in the China made engines. But our military makes the world safe for world trade, we just do not charge any one for this service, something wrong here?
And theres not that much more torque from a small diesel engine vs small gas engine of the same HP out put, am I wrong on this?
What ever input you present will be greatly appreciated.

 

[/pine]

The smaller B&S engine I have with a similar gear reducer was originally meant to be used on a drum mixer...I think it was for an epoxy/river gravel mixer...

 

[Craig Clayton]

The 6-1 gear reducer is probably an expensive option at the 13 HP range most are 6 HP as stated by Pine . I would work around the problem , chain sprockets # 40 or 50, aka,
1/2 or 5/8 ".
Craig Clayton

 

[zman007007]

The 6 to 1 engines I have used, was used on Hy Pro roller water pumps. It doesn"t take that many rpms to make them work great. If the same engine was hooked too a mortar mixer, you sure wouldn"t want it turning 3000, to 3600 rpms. They would probably fly apart. Same as on the pump. I have hooked engines without the reduction to the same pumps, but only ran them at a little above idle speed and they worked great. Check the implement you want to hook to it and see what the recommended rpm is. zman

 

[J_J]

The torque is increased by 6 , over the torque on the engine without the reduction. The rpm will also be reduced by 6, and therefore the rpm will be 600 rpm.

 

[burntside bob]

The output torque will be increased. These gear reduction engines can be used for roto-tillers, old reel type mowers and pumps.

This is burntside bob, are you communicatiing that a 6 to 1 gear reduction on a small gas engine will multipy the torque by a factor a 6.
Say the 13 HP motor I am looking at has 22 lbs torque with the 6 to 1 option the engine working torque will now be 6 times the 22 or 132 lbs torque from a small single piston engine. Am I understanding this correctly.
I can use the 600 rpm because I will have sproket wheels, one on the out put engine shaft and chain to a sprocket of a difference size to arrive at 400 to 500 final RPM to shake the gravel screen box.

 

[J_J]

This may be deviating from the original a little bit but it will explain torque

Honda Engines - GX390 4-Stroke Engine

This is the data for the 13 HP Honda.

19.5 ft lbs at 2500 rpm. times 6 equals 117 ft lbs of torque

The torque will be multiplied 6 times.

They use little chainsaw engines connected to a winch to pull logs out of woods. They are geared down a good bit. A 7 HP hp chainsaw winch can pull 4000 lbs, and if you double your cable, you can pull 8000 lbs. The gear ratio from engine might be 100 : 1 That is how you can use something little to do big work.

 

[DRL]

Just remember that while torque is multiplied by 6, horsepower is NOT changed.

DRL

 

[burntside bob]

One should be able to get the same increase in torque by using different size sprocket wheels, correct?
Say a 4 inch on engine and 16 inch on other sprocket wheel connected to tool being powered this would result in a 1 to 4 torque increase correct?
From 20 lbs to 80 lbs torque?
The only HP I need is to turn the sprocket wheels and the steel shaft with unblanced weight to shake the gravel screen cloth mounted on springs.
The commercial manuf. gravel screen plants have 12-13 hP small gas engines powering them, so I assume thats what I need to turn the steel shaft, which is mounted tothe screen plant shaker box via two pillow box bushings, one on each end of steel shaft. Two u-joints would connect 16 inch wheel to steel shaft to compensate for movement of shaft as it shakes the screen.

 

[Pops15]

Some, maybe all (?) power trowels have a reduction gear set up.