Flail Mower

[Waratah15]

Hello All,

Planning to build a flail mower for my ASV Skid Steer, realise you are PTO kinda guys...if it's any consolation I do have a Kubota BX1800. But reading through the forums there is an absolute wealth of knowledge here and I was hoping you may be able to help me out.

Just after some advise before I get into the 3D drawings stage, I'll be drawing it all up in Solidworks and would be more than happy to share laser cutting files etc once I get to that stage.

Plan to run a hydraulic motor something like this one
Surplus Center - 2.8 cu in CHAR-LYNN 101-1001 HYD MOTOR

This style of motor runs at about 1000rpm

I have 16.3 gpm and a 3000 psi relief pressure on my hydraulics to run the mower

Seems like flail blades need to run at around 8500 fpm, I'm guessing that the overall diameter of the main shaft and blades - cutting tip to cutting tip is about 12 inches. That means that if I run the shaft at 1:1 with the motor (via belts) @ 1000 rpm I will only be getting 1' x 3.14 x 1000 rpm = 3,140 fpm.

So my options seem to be, either 3:1 with the belts or combination of inline gearbox and upping the ratio with the belts. of course I could always increase the diameter of the cutters tip to tip but don't want to make the whole thing too massive considering its a low flow skid steer.

Maybe I need to run a motor like this, with 5000 rpm (scary!) and gear it down with the belts.

http://www.surpluscenter.com/item.asp?item=9-6594&catname=hydraulic

Any suggestions here please?

Next question - the main shaft that the flail blades are attached too, are they solid steel? Maybe 3 or 4" diameter with the ends turned down for the bearings. That's one heavy shaft at 72 inches, couple of hundred pounds right there. I realise this assembly will need to be dynamically balanced.

Hoping I'm not wearing out my welcome here, regarding the hydraulics, if someone with some experience here could chime in I'd really appreciate it. My ASV has controls in the cabin for forward and reverse but I'm looking at what I will need on the mower deck for the circuit. Seems like I need a pressure relief valve to keep the psi in the acceptable range for the motor, is there anything else that I should be putting into this circuit in terms of flow control or cushion valves?

Some of the lower end skid steer flail mowers lack the ability to 'float' in relation to the skid steer. The Bobcat one looks really nice and seems (although I'm not exactly sure) to have a mechanism that lets it articulate up and down as well being able to rock one side higher than the other. At the very least I'd make it free in the up and down plane to follow contours more effectively.

Any thoughts/opinions/advice gladly received, thanks, Jonathan

 

[Localmotion]

Hi Jonathan

Sounds like an interesting (if tricky) project - definately one I'll be following so please be sure to keep us updated with photos :thumbsup:

As a suggestion, you might get more response if you post into the hydraulics thread: Hydraulics - TractorByNet.com

There are a lot of users here that own more than just PTO equipment and would love to get their teeth into your project :laughing:

Cheers, Ian.

 

[MJPetersen]

It sounds like an interesting project for sure. I certainly will be following along. There is a guy who made a flail mower here on the forum not too long ago. It was PTO driven, but the basic concept is the same. http://www.tractorbynet.com/forums/build-yourself/220394-my-homemade-flail-mower-2.html

I would go with the slower motor and get the speed that you need from belt pulleys. The rotor shaft and the riding shaft are not solid. The ends that reduce to bearing size are welded on.

Mike

 

[Waratah15]

Thank you for the responses MJPeterson and Localmotion, I've moved a copy of this to the giant Flail Mower topic in 'Attachments' but once I get started with the design I'll keep posting here with build details.

 

[oldnslo]

Neither of the two hydraulic motors you referenced are rated to 3000 PSI. They are both 1500, 1800 PSI max continuos.

Don't most mulcher heads use cog or gear belt drives. Might consider this as an option also.

 

[Waratah15]

Neither of the two hydraulic motors you referenced are rated to 3000 PSI. They are both 1500, 1800 PSI max continuos.

Don't most mulcher heads use cog or gear belt drives. Might consider this as an option also.

Thanks oldnslo, this looks like a better motor
Surplus Center - 1.80 cu in CROSS HYD MOTOR 40MH18DACSC
Higher speed but not crazy and looks like it would cope well with the output of my hydraulics

 

[Waratah15]

Neither of the two hydraulic motors you referenced are rated to 3000 PSI. They are both 1500, 1800 PSI max continuos.

Don't most mulcher heads use cog or gear belt drives. Might consider this as an option also.

Thanks oldnslo, this looks like a better motor
Surplus Center - 1.80 cu in CROSS HYD MOTOR 40MH18DACSC
Higher speed but not crazy and looks like it would cope well with the output of my hydraulics.

Think I remember reading the I need to allow 5hp per foot of mower so that limits me to 4 feet with this motor that's rated at 20hp at 1800 rpm. Bit narrower than I was hoping for, seems conservative compared to the mowers that are on the market.