Hydraulic Brush Cutter Connections?

[J_J]

I am sorry I didn't see this post before now. I have something to add. Although you said you used 3/4 in hose, I believe the inside of those QD's will measure out to about 1/2 in. The rule is that you are supposed to go one size larger when using QD's. Since it seems to be running OK, leave it as is. Taking a quick look at a nomogram for flow rates and velocities, It is close to 3/4, so I think you are good with that setup. You might notice a little more speed with one size larger QD's. It will also depend on the size of the motor. I have often wondered if the engineers really think about the smallest orifice in a valve, or fitting, etc, when computing things like ports, hose size, etc.

I am about to convert a PTO bush hog into hydraulic drive for my Case skidsteer. I will probably lose some energy through the gear box, but I am going to give it a try.

 

[J_J]

I'm not really good at calculating flow and pressure drop, but my gut instinct is that a 1/2" hose should work well. We sell tons of quick disconnect couplers for Bobcats and such. The size that almost everyone uses? 1/2" couplers with 1/2" NPT thread connected to 1/2" hoses. It seems unlikely that this attachment would require larger than that, especially considering the last guy had it running (although poorly) on 1/4" hoses.

By the way, if you still can't make up mind between 1/2" and 3/4"? There's always 5/8" available.

Ken

You can not forget about those skid-steers with high flow capability. I am talking about 25 to 40 GPM. They should be using 1.0 in and greater, and next size up QD's. 1/2 in hose with 3/4 in QD may be alright for low flow. The high flow attachments will run, but at a reduced capacity. Conversely, if you run a low flow attachment at high flow by mistake, it will sure kick it up in speed, but life cycle of the motor might be decreased.

 

[franklinute]

Mark glad you got the mower working to your satisfaction. I run a 72" flail mower on my skidsteer on the lowflow side which is about 22 gal/min. I do have high flow on the machine but have never hooked it up that way. If I run the mower hard for about an hour the hydraulic temp light comes on. Have you noticed anything like this with your machine? Before I use the machine I give the radiator and hydraulic cooler a good rinsing off so there will be good air flow. BTW I have 1/2" hydraulic lines to my mower.

 

[GATC35]

JJ,

Thanks for your input. I'm going to change my QD's from the 1/2 NPTF with the 3/4 to 1/2 bushing to a 3/4 NPTF coupler. I need another set of QD's for my grapple, so I'll order the correct ones for the mower, and use the one's I remove for the grapple. It probably won't make much difference, but will elminate one less joint to leak. The couplers were the same price so swapping them out is not a big deal since I need another set anyway.

My machine is a standard flow only, no high flow, 16.9 GPM.


Frank,

I really havn't used the machine enought to see if it will overheat. I ran it about 30 minutes the day I took the pictures. The motor and hoses were warm to the touch, but not close to being hot or uncomfortable to touch. I have a big job coming up next week, I'll let you know how it does.

Thanks.....

 

[J_J]

GATC35,

Have you used your machine with any other hyd motor on it? If so, what temp does your hyd fluid temp light come on? If not, I recommend that if you have a temp gun, take a reading after you have completed a big cut, or ran it for about an hour. If no temp gun, use a candy thermometer in the reservoir . I believe the ideal max temp for hyd oil should be around 180 degrees. Keep the hyd radiator clean as has been suggested. I would go beyond just blowing with a good soak with detergent and then rinse with water jet. Small nozzle. If I am not being nosy, how good a deal did you get on it?

Good luck and keep them blades sharp. Don't let the bush hog people know that you sharpen blades. By the way, how about a picture of the underside. I would love to come across one of these real cheap. The blade housing can slide out and cover the blades or retract for some serious work.

 

[GATC35]

JJ,

I've only had this Bobcat for about 6 weeks. All I've done with it so far is move dirt. I haven't run it with any other hydraulic attachment, so I don't know what the hydraulic temps are doing. I do have a temp gun, one of the best tools I own. I'll shoot the motor, lines, and tank after a good workout and see what the temps are doing. I rountinely use a leaf blower to clean the screens/radiators on both tractors and now will do the same with the Bobcat. About twice a year I wash the radiators with a low pressure water hose and "Simple Green."

I had a hard time finding one of these things used. My local Bobcat dealer in Atlanta wanted $5400.00 for a new Bobcat brand. The local Kubota/New Holland dealer could get me a Bradco RC60 for $4200.00. The local Caterpillar dealer in Atlanta was talking something over $6000.00. I know their stuff is good, but it's not that good. The Bobcat dealer in Oxford, Alabama could get a Bush Master for $3800.00. So I kept watching Craigslist and found a used one In Spartanburg, South Carolina listed for $2700.00. After a couple of phone calls and a lil wheelin and dealin I gave the guy $2300.00 for the used cutter. So add in $50.00 in diesel fuel, breakfast at Waffle House $7.00, and $100.00 in hoses and fittings I have less than $2500.00 in it.

I'm at the airport at my real job now, when I get home I'll try and get a pic of the bottom of the unit.

I agree with you on sharpening the bush hog blades. I have a small landscaping/tractor business as a side job. Most of my customers have pastures ranging from a couple of acres up to 10 or 12. So I'm mainly just cutting grass. I have a 8 foot dual spindle Kodiak cutter that will leave a finish mower look when I sharpen the blades.

 

[J_J]

GATC35,

Thanks. Yes, take lots of temp readings when cool, and hot to have a reference for all future problems. As soon as you can, get yourself a good set of manuals. Somewhere in there, it will tell you at what temp the hyd temp light comes on, or you may have the digital readout . If you can get in good with the service people for your Bobcat, you might get him to copy that CD,DVD for you. You might start out by having him copying several pages out of the CD at first, then hint that you surely would like to have a copy of that CD. Maybe a case of adult beverage might help.

 

[Ken45101]

I am about to convert a PTO bush hog into hydraulic drive for my Case skidsteer. I will probably lose some energy through the gear box, but I am going to give it a try.

THAT sounds interesting

Ken

 

[Eagleview]

Mark , does that motor have a cross port relief ? If not i think you should be running a case drain hose .

 

[J_J]

Mark , does that motor have a cross port relief ? If not i think you should be running a case drain hose .

As an additional safety feature I would say yes, but,

I believe that just about all skid-steers have a motor spool for the aux hydraulics, and will let the hydraulic motor spin down. About the only time I would see a problem is if the operator popped off the return line QD's, and the motor was still winding down, and the fluid would have no place to go. The motor would then act like a pump, and maybe destroy something.

Another thought, that if the motor was winding down, and you popped off the pressure line, that you might be safe enough, because the hydraulic motor acting as a pump might be able to draw a vacuum and pop the seat inside the QD. Never tried it, just an educated guess.

As far as case drains, if a hydraulic motor has a case drain, the hydraulic motor was designed for it, and I believe that is to circulate some fluid through the case for lubrication, and to take some of the heat away, because most case drains collect at a junction and then go through a cooler/radiator before returning to tank.