I have a Farmi logging winch that I would like to be able to switch between my tractor and Dresser TD7G. I found a Danfoss hydraulic motor in Surplus Center that I can drive with my dozers hydraulic pump and get acceptable torque and rpm for the winch. To start I have two questions. 1) Will doing this put undue stress or other wise shorten the life of the pump ? The winch would probably run 1 minute continuously max and have a lot of idle time. The pump should run at about 3/4 max pressure or less most of the time ( I think ) and the engine at 2000 rpm. 2) Will the dozer hydraulic filter system be clean enough for a motor that requires contamination level 20/16 (ISO 4406). The filter is a Wix 51493. Thanks for any help or comments.
Hmmmmm....... Quiet is scary...... or maybe I am beyond help. Nobody has any thoughts or experience doing this ??? gg
I'll put in my opinion. No problem running anything off the dozer hydraulics as long as fluid levels are compensated for. Filtering adequate for the dozer will be fine for the winch motor. The hydraulically powered winch is a great asset. I converted a 20k Braden PTO winch from an army truck into a hydraulic by adding a hydraulic motor and chain driving the winch input shaft. This method gains you reverse, that is, power out. (Most PTO's don't have reverse). As for the motor specs, as long as the motor will handle the max pressure out of the dozer pump, no problem. Volume is easy, too because as long as the motor is spec'ed big enough, whatever volume of fluid comes out of the dozer, dependent on it's rating and engine speed, the additional motor will use. A big displacement motor may not run full speed but you will get the power as soon as the winch builds resistance and hydraulic pressure builds. What to avoid: using a motor that cannot handle the max pressure (bypassed pressure) from the dozer, and using a motor that's so small that minimum flow from the hydraulic pump over pressures it. If the motor you buy has a 'case drain', be sure to plumb it for low pressure return to reservoir otherwise the motor could be damaged. BTW, every hydraulic system I've ever seen has a relief valve that protects the pump. Most will protest loudly (but not self-destructively) if over pressured. The system takes care of itself. In my case, my Unimog has a 12 gpm system up to 2200 psi, or thereabouts, and that's at 1800 rpm. I used a motor to handle those maximums. The winch drive, being made for PTO, runs up to about 500 rpm. Most of the time the 'Mog engine runs at much lower speed, therefore gpm pumped is lower, and pressure is slower to build. The only negative of those conditions is that the winch runs slower, normally a good thing. Now, if you want to have a high speed winch and pull logs from 500 feet away, you'll need to spec the pump a little differently to achieve maximum rpm on the winch, otherwise you'll be waiting a long time for those logs to arrive. Build it, you'll like it. Bob
I should have mentioned that you'll need a spool valve to control the winch, that is if the dozer does not have a spare valve section. The winch motor can't just be hooked straight to the pump output, of course. And, if the dozer hydraulics do not provide a spare spool valve, you also have the challenge of inserting your added spool into the flow of the dozer system. Most dozers would provide for that, no doubt.
Bob, Thanks very much for the help. That is the reassurance I need. I have worked with adding valves and cylinders and can do the plumbing, but I have never worked with a motor or motor control valve and when I saw those specs I did not know if it required something special or just normal filtering. My dozer can supply 13.5 gpm at 2500 rpm and the relief pressure is set at 2000 psi. I plan on running at 1800 or 2000 rpm for about 10 gpm out of the pump. The motor I am looking at is good for 2000 psi continuous, 2500 psi intermittant and 15.9 gpm continuous, 19.8 intermittant. The clutch on the winch should slip before I get to 2000 psi. But like you said I should be able to hear it if it doesn't. So I think I am good there but if you think not let me know. Thanks
Those Farmi Forestry Winches are very nice and can be standard equipment on some Unimogs (which I use as tractors, trucks, trail riding, camping ). Here's a video of a Farmi on the back of a Unimog (not mine). That appears to be a fast winch! http://www.youtube.com/watch?v=eshR8y8LEKI Bob My dozer is a JD650G, a recent purchase.
They can be really fast if you run the pto at 540 rpm. Up to 200 feet per minute or so. OK for across a field like the video, but to fast for in the woods, at least for me. I usually run my tractor pto at about 280 rpm or less. On the dozer with the hydraulic motor it will be less than that. The old rpm vs torque trade-off on the motor.
Another option to give you fast and slow control of the hyd motor on the winch would be to add a flow control ahead of the winch. That way you could speed it up to let the line out or reel in excess cable. Slow it down when you need to. Flow controls come in a variety of flow rates and pressures, so check that before buying. Also, I don't know what throttling the hyd motor down would do to the torque of the motor - maybe someone else on here knows... Andrew
It's my belief that reducing the volume of the fluid going to the winch does not reduce the available pressure, and therefore does not reduce torque. The torque would be applied more slowly, and that means less horsepower, but the winch pulls as high a load. A simple way to say it: the winch would pull just as hard but not as fast. Where that theory falls apart is if flow gets so low that leakage or bypasses within the system causes the loss of efficiency (all systems have loses). Ultimately there would be some very low flow level that would be entirely lost (zero efficiency) and no work gets done. Hopefully we will not ever experience that, LOL. Bob