Want to build an 80 inch hydraulic tiller

[SpecElim]

Hi guys. First of all I am new and would like to introduce my self. I am Matt and I would like to build an 80 inch Hydraulic driven tiller as the title says. I want this to hook up to my category II 3pt hitch. I have a New Holland 3010s 65/55 pto horsepower tractor. I have 1 remote outlet @8 GPM. I have found some very basic plans online but would rather base my build on the Woods GTR72 reverse tine tiller. I would also like to use some chain driven parts from agri supply to keep repair as cheap as possible. I now need to figure out how to protect the Hydraulic motor from damage if the tiller hits something. This will be a very heavy tiller as I have to make it as heavy duty as possible. I am thinking about 1200-1500 pounds. Here are the very basic plans that I am basing my design on. LifeTrac - Open Source Ecology
Here is the tiller I would like to base it on but would be more difficult.
Woods Equipment Company - Reverse Rotation Tillers


If anyone could help I would appreciate it a whole lot! Thank you, Matt.

 

[J_J]

Welcome to TBN.

8 GPM does not represent very much HP to drive something as big as 80 in tiller. I would think about 48 in would be your limit, if that much. What is your psi rating on the tractor?

 

[Renze]

Your tractors oil pump doesnt have enough power to drive it. an 80 inch tiller uses 3/4 of the power of your tractor, and this 8 gpm pump will only be able to generate about 10 to 15 Kw, depending on the pressure available.

In most high power hydraulic applications on tractors, a PTO driven hydraulic pump is used... but if you go that route, why put away the existing PTO drive of the tiller ?

By the way, what benefits are you seeking to accomplish with hydro drive anyways ??

 

[J_J]

It takes about 14 HP to drive a pump at 8 GPM, at 2500 psi. So if you are driving a hydraulic motor, with an 85% efficiency, that puts your motor at 11.9 HP.

 

[J_J]

Why would you want a hydraulic tiller ? Your tractors oil pump doesnt have enough power to drive it. an 80 inch tiller uses 3/4 of the power of your tractor, and this 8 gpm pump will only be able to generate about 10 to 15 Kw, depending on the pressure available.

In most high power hydraulic applications on tractors, a PTO driven hydraulic pump is used... but if you go that route, why put away the existing PTO drive of the tiller ?

By the way, what benefits are you seeking to accomplish with hydro drive anyways ??

He might be wanting to do some reverse tilling. They make PTO reverse tine tillers, just select one that matches the PTO HP.

MY hydraulic tiller runs on 15 GPM, and it is 72 in.

 

[SpecElim]

I am just trying to build something that is about half the price of a heavy duty 80 inch tiller from an industry made one. I can get a 23 GPM pump for my pto for $500 from northern tool and still be cheaper at the end. A comparably sized tiller retails for about $2000-2400. Thanks for the quick replies.

 

[Renze]

MY hydraulic tiller runs on 15 GPM, and it is 72 in.

This would be enough to do a well kept garden which is tilled every year, but not "heavy duty" tilling as the OP describes... a 2.30 meter (90") Kuhn tiller takes about 60 hp at 10" depth when cutting horse pasture.

 

[Renze]

I am just trying to build something that is about half the price of a heavy duty 80 inch tiller from an industry made one. I can get a 23 GPM pump for my pto for $500 from northern tool and still be cheaper at the end. A comparably sized tiller retails for about $2000-2400. Thanks for the quick replies.

But why do you insist on hydraulic drive ?

 

[SpecElim]

I don't insist on hydraulic drive but so far it seems like the cheapest and easiest route.

 

[Renze]

I don't insist on hydraulic drive but so far it seems like the cheapest and easiest route.

As a basic rule of engineering, hydraulic drive is only cheaper if it requires continuously variable drive (hydraulics are easier to adjust, but only when you have variable displacement motors) or when hydraulic hoses are easier to route than multiple shafts, pulleys, gearboxes, chain drives. This all at the cost of a way lower efficiency.

So what you're trying to achieve, is to turn your existing Woods standard tiller into an overtop tiller ?

The easiest way to achieve that, is to open the gearbox and move (mirror) the position of the gearwheel of the transversed shaft, along the longitudinal shaft. Then remove ALL your tiller blades and begin reassembling them in reversed order (along the new direction of cut)
You do need to invert the rotational direction of the blades, because otherwise it would have a negative cutting angle or "bite" which means the blades act as ski's