Help with what hydraulic motor for flail

[lectro88]

Wanted to get some input from you guys about how to, or how you would, for a lack of better words design a auxillary hydraulic circuit on a excavator.
What I want to accomplish is maximum torque and not cause undue stress on the pump. The aux is rated at 15.6 gpm @3000 psi.
My intent is to custom build a flail drum 18" 24" The cutters will be 3"-4"x3/8" or 1/2" angle, whatever I come across first in my steel pile. I think most of the particulars are covered, Except what size hydraulic motor to use.
Thank you in advance.

 

[John C.]

The flow and pressure are easy enough. What is the duty cycle you are going to run? How much would this unit weigh? What kind of mounting are you going to have? All this is to determine the size of the excavator you need. All hydraulic excavators built in the last fifteen years or so have an extra circuit already built in. All you need to do is run the proper sized tubing up the boom.

 

[lectro88]

I basicly use the excavator on the farm. I would use this where the other equipment won't go, around the pond, along some fence line thats in a gully or at the base of an embankment.
And with that being said, the mounting will be quick attach with the ability to twist 180 degrees depending what side of the fence I'm on and where I need to cut close. I plan to keep it well under 500 lbs. Let me say this is not my first fab, but it is my 1st. with hyd. motor drive. I'm building this unit small to be a little Hercules and not be heavy when extended on a incline.

The excavator is a takeuchi tb135 8k. lb. 27.8 kw. hp. 15.6 gpm. @3000 psi.

What hyd. motor would give max performance. Cu. in. ? and gpm. On my machine ?

 

[John C.]

What you need to do is find the local hydraulic components supplier and ask them the question. It has been so long now since I have done something like that I can't bring up any names for manufacturers that make the motors.

Gear motors are probably the least expensive and if you are not running the thing on your excavator all the time should work well enough. They only turn at the speed of the amount of oil you are supplying.

Piston motors are a lot more expensive and complicated but if you are running all the time will give you the best long term service for your dollar. I think you can adjust the shaft speed on some of them also. They do require clean oil.

 

[willie59]

What about renting a typical flail mower for a weekend and give it a good look over. You might get some ideas for your design, might even be able to get some numbers off the motor mounted on it and how the motor drives the mower. Just a though.

 

[lectro88]

As always thank you for the help from all.
If I used it for income I "might" consider buying 1. A rockhound is almost as much as I paid for the excavator. And here again the rockH is about 500 lbs. and without the desired 180 degree pivot and other features I would build in.

Atco. renting 1 is a great idea, I have not as much as seen a flail locally, not even on a trailer going down the road. Dealerships are not stocking anything either. I'll check the rental yards, and try to stop in at the hydraulic shop I use when I need something.

I'm not in a hurry, just asking to see what others think.
I'm sure someone on here knows what I'm looking for. Just a matter of them finding this post.
Again Thank you.

 

[willie59]

As always thank you for the help from all.
If I used it for income I "might" consider buying 1. A rockhound is almost as much as I paid for the excavator. And here again the rockH is about 500 lbs. and without the desired 180 degree pivot and other features I would build in.

Atco. renting 1 is a great idea, I have not as much as seen a flail locally, not even on a trailer going down the road. Dealerships are not stocking anything either. I'll check the rental yards, and try to stop in at the hydraulic shop I use when I need something.

I'm not in a hurry, just asking to see what others think.
I'm sure someone on here knows what I'm looking for. Just a matter of them finding this post.
Again Thank you.

I was just thinking if you could find one at a rental yard to rent for a weekend, for a minimal cost, you would have a whole weekend to look one over, make some notes, noodle with some ideas, and maybe even glean some motor info. Just a thought.

 

[lectro88]

I was just thinking if you could find one at a rental yard to rent for a weekend, for a minimal cost, you would have a whole weekend to look one over, make some notes, noodle with some ideas, and maybe even glean some motor info. Just a thought.

10-4. I got what you meant, I guess I was just rambling in several directions at once, my response said "renting 1 was a great idea" I did not specifically acknowledge the look-over part.
But I understood.
Thanks.

 

[cps]

What about renting a typical flail mower for a weekend and give it a good look over. You might get some ideas for your design, might even be able to get some numbers off the motor mounted on it and how the motor drives the mower. Just a though.

I was just going to say the same thing Atco, thats what id be doing! you may even see a flaw in the design that you could do different etc!

 

[lectro88]

WeLLLLL.
Do you remember me saying I hadn't seen a flail locally.
I called the rental companys today. You are not gonna beleive this, well you might. sunbelt, rsc. etc
Most of the guys didn't even know what a flail unit was, till I described it. Called Cat & Bobcat that rents too, now they knew what I wanted but said in so many words thats not somthing safe to turn loose to just anybody, liability, and damage to your machine, damage to the flail...etc. bystanders, you in the cab, glass on the cab.
and I get and fully understand that. Just somewhat I guess, caught off guard.
oh well. the big girl aint started singing yet.

 

[willie59]

Wow, I was not aware they were so scarce to rent. I do know they are expensive attachments. I'm just a little curious how they drive the flail drum. I know nearly nothing about flail cutters, but I'm near certain they turn at a high speed, maybe not as fast as a tree chipper, but they have some speed to them. I would be surprised if the drum were a direct drive from a motor. But I know so little about those things, I wouldn't know how venture a guess what type of motor would work best. I hope you have some luck finding the info you're searching for lectro.

 

[cps]

I think some of them run from the motor to drum via a set of belts! but not 100% sure! watching this thread with interest now!

 

[John C.]

Here is a mulcher that was down and the local Cat store. I took some picts. for you and pulled the cover off from over the motor. You can see that it has the bent axis piston motor and it has some kind of step down drive between the motor and flail shaft.

Good Luck

 

[willie59]

Nice find John C.

http://hpts.co.kr/rexroth/RE91001.PDF

 

[John C.]

Hey Atco,
Back at ya. That chart lays it all out on the motor with everything but the price.

lectro88,
Does that give you enough to get started with?

 

[willie59]

Hey Atco,
Back at ya. That chart lays it all out on the motor with everything but the price.

lectro88,
Does that give you enough to get started with?

LoL, yeah, just don't have Vg (Cm3) conversion calculator on my home computer to determine flow rate, that's on work computer.

 

[lectro88]

John your almost a saint. LOL
Wow talk about doing the leg work.
Thanks John C.

Piston pump huh ? High $$$ but most effective. Correct ?

Been getting a little feedback and after a little more research I'm changing my thoughts on the drum design, cutting the mass weight by at least 1/2
1 source has given a ball park motor size of 20 cu in.
Don't remember if I posted this, but about the cross over relief, I'm wondering about a magnetic clutch at the unit like on a Z-mower, I've seen double V clutchs, What do you guys think ? clutch engages with aux valve and drops out allowing free wheel.

 

[pondo]

Hey Lectro88
Where you at on flail mower? I kick around idea of trying to build one too.

 

[franklinute]

I occasionally operate a flail mower on my skid steer. It is a Loftness brand mower on a Bobcat with regular hydraulics approx 12.5 gpm
@ 2200psi. When I bought the mower they matched the hydraulic motor of the mower to my Bobcat specs. The motor turns the drum by 3 belts.
There is a hydraulic hose loop with a type of antihammer valve that protects the hydraulic motor. I engage the hydraulics at idle rpm then slowly
raise rpms to about 3/4 throttle to begin mowing. I do the opposite procedure to slow the drum then disengage the aux hydraulics. The mower cuts and mulches really good but it is a slow process.

 

[pondo]

Hi franklinute
What model flail mower do u have?
Do u always run it at 3/4 throttle?
Would that mean that mower is only get 3/4 of 15gpm? Also is the pressure reduced at less than full throttle?
Thxs