# Converting a 6" tow behind chipper to pto



## fourwheelinj1 (Oct 6, 2011)

I just bought and old gravely 6" tow behind chipper really cheap because it is missing the engine. It originally had a 25 hp Kohler engine. I was planning on just buying a another 25 hp engine but the 25 hp seem underpowered and expensive so I am contemplating converting it to run off a tractor pto. I have a 35 and 60 hp tractor I could run it off. Does this seem feasible? I would need to make some sort of adapter with a belt pulley to hook the pto shaft to. The chipper originally had a clutch mounted on the engine. Would I need some sort of clutch if it is pto powered? Any other things I need to take into consideration? Here are some pics of the chipper.


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## RC Wells (Dec 26, 2008)

The cost of converting to PTO operation will most certainly exceed the cost of a 25 horse engine. 

Your chipper is hydraulically driven, so will need a PTO gearbox that steps up the tractor's PTO speed to the original engine's rated rpm to operate the chipper's pump. The cost of that gearbox will exceed the price of the new engine alone, and you still will need the PTO shaft and connections, and the safety shields.

The last one of those old beasts that I saw used a Kohler Command engine that would likely be compatible with the current 25HP KOHLER COMMAND ENGINE CH730PS, that is made to operate a hydraulic pump. I would guess that engine would be around $2,200 to your door, and the step up gearbox to get from 540 rpm to the rated rpm of that Kohler engine would run about $3,700 and that is without the work of welding brackets, etc.

If you have a hydraulic spool system that has a constant flow option on your tractor, it is possible that you could adapt the hydraulic hoses from the chipper drive motor to the tractor's hydraulic system, but you will need pressure and flow information for both the tractor and the chipper to know if that is feasible.

Unfortunately I do not have any specifications on flow rate and pressure requirements of the Gravely 04108953 hydraulic motor that I suspect powers that chipper.

A hydraulic repair shop may be able to provide you with the flow details on the hydraulic motor, but would likely need to see the motor itself to do so.


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## bcp (Apr 25, 2011)

A couple of ideas, and one more. 

1. 22 hp $699 at http://www.harborfreight.com/22-hp-670cc-v-twin-horizontal-shaft-gas-engine-epa-61614.html

2. Hydraulic tank on the trailer, PTO pump on the tractor

3. Old air-cooled VW engine on the chipper.

Bruce


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