Troy Built Hydraulic Chipper Shredder Project

[MossRoad]

I want to take a gasoline powered chipper shredder and convert it to hydraulic to run off of my tractor hydraulics. The hydraulic stuff is pretty straight forward. It's the chipper shredder stuff that I am hoping all of you can help me with, so here's a few questions to chew on....

One of the donor machines that I am looking at is an 8HP Troy Built Super Tomahawk. Does anybody have experience with this machine?

I want to be able to chip branches 3 inches or less in diameter and shred garden refuse for compost. Will this machine do a good job?

 

[Steve_in_Ont]

Hydraulics could certainly be made to work... But... For something that runs a constant speed, like a chipper, why wouldn't you drive it off the PTO? It would be more efficient and probably cheaper. You would probably still need to belt drive it though, as I think that chippers like to run faster than 540 rpm (unless you have a two speed PTO).

 

[Charlie_Iliff]

Steve:
He's planning to run it with his Power Trac which only has a hydraulic PTO setup. Do you know the best working RPM for the chipper?

 

[DVerbarg]

MossRoad,

The Super Tomohawk chipper is pretty nice. My parents have one that we (siblings) bought for them 12 years ago. Does not get extensive use but has taken everything they have given it. Like many of the Troy-Bilt items it seems to be engineered pretty well. Parts are heavy duty and there's nothing flimsy about it.

The only thing I did not like about it was the engine. It needed more power, IMHO. Just not sure if they had a reason for not using a more powerful engine. When feeding wet material (green wood) it could bog down pretty easily (but it still had more ummph then other similarly sized chipper/shredders).

Sounds like a fun project.

 

[MossRoad]

The RPMs of the gasoline engine that runs it is 3600 RPM. I don't have a PTO, so to speak, just really good hydraulics /w3tcompact/icons/smile.gif. Getting the proper sized hydraulic motor to run it at that RPM won't be a problem. I am more interested in the performance of this model chipper shredder. It is already a belt driven unit, so hooking up a hydraulic motor will be pretty easy.

 

[MossRoad]

Thanks.

 

[AndyR]

How is your conversion project coming? I have the TB Super-Tomahawk 8hp as well. My concern with a hydraulic motor would be the direct drive vs. belt drive issue - as the belt absorbs some of the shock. I would make sure you have the large grate mounted for anything slightly green or damp. Check the flails and cutter blade for chipping - I turn and/or sharpen them at least once a year (otherwise the branch chipper just kinda nibbles things to death). I wouldn't count on this unit for anything over 2". If it isn't pretty straight, you have a tough time getting things into the chute. That said, it has performed very well for yard trash and trimmings and is really good at regrinding commercial tree shreddings.

 

[MossRoad]

Thanks for asking.

Haven't found a reasonably priced donor machine yet. The two that I found they guy wants $500.00 each or $350.00 each without the 8HP gas engine. A new hydraulic motor will cost me at least $150.00 saved. So until I can get one very cheap, I am not going to do it.

I was considering putting a pulley on the hydraulic motor and keeping the belt drive for a slip safety in case of jam.

Assuming a 1:1 drive I now have to figure out how to size a hydraulic motor to spin at 3600 RPM with 8GPM input @ 2500PSI.

Or get one to spin 1800 RPM with 8GPM @ 2500PSI and increase the size of the drive pulley by 2. That might be the better option.

Anyway, I (my wife /w3tcompact/icons/tongue.gif) have other projects that are more important, but I will keep my eye open for a donor machine.

Now, anyone got a formula for figuring out what hydraulic motor to use? Just for fun.

 

[Charlie_Iliff]

MossRoad:
Since it's just for fun, and you certainly wouldn't select anything hydraulic based on information from me, I will not remind you of the vastness of my ignorance of things hydraulic. In the course of recent reading, however, some formulas have recurred. They appear not to account for friction, so will be optimistic:
When
T is motor torque (in lb)
HP is horsepower
D is motor displacement (cu in)
RPM is motor speed in revolutions per minute
GPM is flow in gallons per minute
T=DxPSI/6.28
HP=TxRPM/63025
RPM=GPMx231/D

Assuming those are right, you can deliver over 10 hp turning a 1 cu in motor at 1800 with your hydraulic PTO. That match your calculations?

 

[king_black_shoes]

In regards to converting your chipper I have an 8hp yardman with a frozen engine. I'm sorry it's not for sale but you might not know that it has a tapered shaft like a generator motor so your hydraulic motor may need one too. I'll let you know if I find one for mine. See ya.

 

[king_black_shoes]

Me again. I went back and read the rest of the thread so here is a little more info. I recommend the Yardman 8 hp machine (for conversion to hydraulic) because before mine frooze up (my fault) it was great. Consumer Reports magazine liked it enough to top rate it. I put 3" pine and oak in mine and it chipped it without any problem. I think Yardman has a lot of other brands so it may be easy to find a similar one. Mine had an 8 hp Tecumseh and was direct drive via tapered shaft. The cutter head looks like an auto flywheel with 3 (I think) straight blades each bolted over a hole. The other side has centrifical hammers for chopping brush and leaves. The main motor output bearing served double duty as bearing for the cutter head so a direct drive hydraulic motor would need sturdy bearings. Surplus Center (800 488 3407 no web page) has good prices on new and used hydraulic motors. Hope this is of help. I hope to convert my gas generator to hydraulic also. I'm tired of maintaining (or not) small engines that get only occasional use.

 

[MossRoad]

I hadn't seen the formula for T, thanks.

 

[MossRoad]

That's why I was looking at the belt drive units. The slip factor if it jams would just be another safety valve for expensive repairs.

And you are thinking exactly like me when it comes to gas engines to maintain. I have quite a few that could be converted to hydraulic. I've already eliminated the need for two snowblowers, my yard tractor and a push mower with the PT425. And a gas can for the gas/oil mix for the blowers.

I think I'll leave the gerator stand alone, though. When there is a power outage, there is usually storm damage to clean up and I'd have to disconnect the PT425 from the generator to do the cleanup.

 

[fractal]

How long does it take you to get the Yardman unit apart to sharpen the blades? I looked at taking my 5hp mtd apart to sharpen the blades last time I changed the oil (what a pain in the arse what was as drain plug was flush with the mounting plate and all the oil flowed over the plate) and changed my mind.

Access to the cutting edges and replacement blades should be high on the consideration list when looking for a doner machine.

 

[s1120]

<font color=red>I looked at taking my 5hp mtd apart to sharpen the blades last time I changed the oil (what a pain in the arse what was as drain plug was flush with the mounting plate and all the oil flowed over the plate) and changed my mind.</font color=red>

I had my MTD apart, and it not THAT bad. There is about a zillion bolts holding the halfs together, but other than that its simple. Ya that oil tube is a PITA! /w3tcompact/icons/crazy.gif They only had to extend it anouther 1/2 inch and it would have been perfict. I am going to replace mine with a longer one one of these days.