Hydraulic Powered Mower for 1.5 ton mini-ex

[tommott77]

Hi all hydraulic gurus. Looking for some guidance for those way beyond my rudimentary knowledge/skill set of hydraulic power.

I am in the process of purchasing a like new CAT 301.7D mini ex for some work at some property I own and for the neighboring properties of our POA in the NC mountains. I am considering trying to find/build a hydraulic powered mower for the CAT do some light cutting/mowing. Mostly grass and underbrush. Nothing more than 1" thick, or much more than I'd take on with a push mower. Mainly looking to utilize the boom to access hard to reach areas.

Obviously most of what I am finding on the market is for much larger machines with much higher capacities for much larger jobs. The specs of the aux output on my CAT 301.7D a 8gpm at 2465 psi. The total capable flow out of the machine appears to be about 19.3 gpms (the spec sheet I posted below is a bit confusing on how/what all they list for flow rates). I have found a couple heavy duty flail mowers that fit the specs but are insanely expensive, close to half the price of my machine. The smallest capacity rotary cutter I have found calls for a minimum of 10gpm, though they said they can make it work with a direct drive motor for an added cost and I'd need to add a case drain to my excavator.

In doing some searching around here I came across these Power Trac tractors with similar hydraulics specs/output to my CAT mini-ex that run hydraulic powered mowers/brush cuttrers. Their machines spec at 8 gpm at 2500 psi of PTO output. (Here's a link to their website/specs H Class). Other than the metal fabrication needed to allow one of their mowers to mount in place of my bucket on my ex, would their mowers for their machines work hydraulically speaking on my CAT? If so other than the fabrication of the mounting and perhaps some added safety features, hydraulic lines/fittings is there anything else would need to be done to my mini-ex or to the mower to make it all work?

 

[MossRoad]

Hi all hydraulic gurus. Looking for some guidance for those way beyond my rudimentary knowledge/skill set of hydraulic power.

I am in the process of purchasing a like new CAT 301.7D mini ex for some work at some property I own and for the neighboring properties of our POA in the NC mountains. I am considering trying to find/build a hydraulic powered mower for the CAT do some light cutting/mowing. Mostly grass and underbrush. Nothing more than 1" thick, or much more than I'd take on with a push mower. Mainly looking to utilize the boom to access hard to reach areas.

Obviously most of what I am finding on the market is for much larger machines with much higher capacities for much larger jobs. The specs of the aux output on my CAT 301.7D a 8gpm at 2465 psi. The total capable flow out of the machine appears to be about 19.3 gpms (the spec sheet I posted below is a bit confusing on how/what all they list for flow rates). I have found a couple heavy duty flail mowers that fit the specs but are insanely expensive, close to half the price of my machine. The smallest capacity rotary cutter I have found calls for a minimum of 10gpm, though they said they can make it work with a direct drive motor for an added cost and I'd need to add a case drain to my excavator.

In doing some searching around here I came across these Power Trac tractors with similar hydraulics specs/output to my CAT mini-ex that run hydraulic powered mowers/brush cuttrers. Their machines spec at 8 gpm at 2500 psi of PTO output. (Here's a link to their website/specs H Class). Other than the metal fabrication needed to allow one of their mowers to mount in place of my bucket on my ex, would their mowers for their machines work hydraulically speaking on my CAT? If so other than the fabrication of the mounting and perhaps some added safety features, hydraulic lines/fittings is there anything else would need to be done to my mini-ex or to the mower to make it all work?

The PT400 series have 8GPM @2500psi output on their main PTO. I have a 60" three blade finish mower and a 48" brush cutter for my PT425.

I'd be concerned about heat buildup on your mini-ex. The PT425 has a 10 gallon hydraulic reservoir. How large is the hydraulic reservoir on your mini-ex?

 

[MossRoad]

I also think that the 48" brush cutter is THE most dangerous piece of equipment that I own. The blades are huge, heavy, and can get knocked off if you hit the mounting bolt on a rock. Then they fly off and the whole deck shakes violently until you stop the hydraulic flow. Being down on the ground, the blade usually stops a few feet from the deck.

Also, consider this...

If you have it on an excavator arm, you're eventually going to be raising it off the ground at odd angles. It's inevitable. Hey, I think I can reach that branch.... There'd be nothing to stop you from angling the deck so that if you hit a stick, branch, fence post, etc... or something else heavy, you'll be flinging it directly at you, or at other people, or at valued property.

While I frequently lift my brush cutter 6' in the air to bring it down on bushes and shrubs, it's always facing away from me. I can never get it into a position where the spinning blades are in line with my body. With an excavator, nothing stops you from curling it down too far to the point that the blades are spinning in a direct plane with your head and body.

So consider that wisely, before you do anything.

As for the construction of the 48" brush hog, it's fairly tough. However, there was (don't know if it still is) an issue where the deck would start cracking right behind where the front caster mounts. This, in my opinion, is from people accidentally putting down pressure on the FEL arms, lifting their front tires off the ground and putting the entire weight of the front of the machine onto the brush cutter deck. The deck is thin in that location, and eventually it gets a stress crack. An easy fix with some reinforcing steel plate or angle iron. There's some threads on it over in the Power Trac forum here on TBN.

 

[MossRoad]

Oh yeah, forgot to mention that 1" brush is a snack for that brush cutter. :licking:

 

[Dave M7040]

From the posted spec, the reservoir is 5 gal.

I think the caution about heat is valid.

With the cylinders on the excavator, you have a heat radiating surface to help get rid of heat.

With the hydraulic motor on a bush hog, you have nothing to radiate any heat.

Dave M7040

 

[MossRoad]

From the posted spec, the reservoir is 5 gal.

I think the caution about heat is valid.

With the cylinders on the excavator, you have a heat radiating surface to help get rid of heat.

With the hydraulic motor on a bush hog, you have nothing to radiate any heat.

Dave M7040

Also, the cylinders are not in constant load or motion. A hydraulic motor is always moving and fluid is always circulating through it's circuit. Just the friction of the plumbing creates heat, let alone the load.

 

[b7610hsd]

Most Mini Excavators have Hyd oil coolers, mounted in front of radiator.

 

[tommott77]

Thanks for the responses. Mossroad, great having somebody with one of these chiming in so quickly. I had thought I had seen a hydraulic mower on an articulating tractor at some point and double checked the Ventrac but found that they are belt driven. I checked out your site and some of your videos. Very cool machine and it looks like the equivalent specs on your PowerTrac run the bush hog very well on vegetation up to and beyond what I'd be taking on with my machine.

I have thought about and considered some of the safety concerns. I would undoubtedly be curling the mower and am quite aware that curling it inwards with the blades facing me is not a good not just for blades but flying debris as well. My initial thought for a solution is to set up the mount to where the full curl inwards would still keep the mower parallel with the ground surface while allowing the outward curl to point the business end of the mower away from me and the machine. This would also hopefully leave a good stopping point to level the mower with the ground as well. Though I wouldn't plan on riding the mower on the ground all the time I have had some concerns about getting too much weight of the machine on the mower from time to time as well. So some re-engineering of the caster set up would possibly be in order as well.

The heat concern makes sense but is a bit beyond my rudimentary knowledge of hydraulics to know 100% if there would be a potential issue at this point. Like I said I know that there are some very expensive flail mowers that are supposed to work out of the box on my machine. I doubt that there is any type of auxiliary cooler involved with these mowers but there is a gear drive on those mowers and I do wonder if that lessens the heat load on the hydraulics. Also I was not 100% sure why the manufacturer of the rotary cutter said I'd need a case drain to run their mower with a direct drive setup. I thought it had something to do with foaming of the hydraulic fluid but perhaps foaming and heat build up concerns are one in the same thing.

But then again I am not sure I am not exactly understanding what the difference in heat load would be on a Powertrac vs my machine though. Spec-wise the tank capacity the tank capacity is listed at 5.5 gallons on my machine. With all the super long hydraulic lines I would assume an excavator may have the potential to radiate heat a bit better then a Powertrac, but then again I guess there's a possibility that constantly pushing the fluid through the extra length of lines has the potential to build up more heat as opposed to shorter lines on Powertrac as well. I guess we can see that I'm getting a bit over my skis as far as my level of understanding of hydraulics is concerned though.

 

[tommott77]

Most Mini Excavators have Hyd oil coolers, mounted in front of radiator.

I assume I missed your post as I was writing the previous one but sure enough you are correct that a hydraulic oil cooler does come as standard equipment on the excavator I am purchasing.

I guess the question then becomes why the direct drive rotary mower would need a case drain on my excavator and if I would need one to run the PowerTrac mower....

 

[oldnslo]

Tommott77
The motor case drain requirement depends on the hydraulic motor style and what pressure the shaft seal of the motor is rated for. The motor shaft seal is exposed to the return flow pressure of the system.

Piston style motors are typically only rated for 30 PSI case pressure (shaft seal) while some gear style motors have high pressure seals so good for 700-800 PSI

Hopefully this helps you understand the case drain concern