Hydraulic skiddng winch

[Jim Timber]

I got the last one of these motors SC had based on the impressive torque numbers. Now I'm wondering how exactly to implement it?

15.1 CU IN HYDRAULIC MOTOR
New VON RUDEN model MLHPQ250C5A hydraulic motor. Cast iron housing.

SPECIFICATIONS ç–‹isp. 15.1 cu. in. / rev.
ç*†otor Type Gerotor
姫ressure:
2540 PSI cont.
2900 PSI int.
謬orque:
3360 in-lbs. cont.
5160 in-lbs. int.
百peed:
245 RPM cont.
306 RPM int.
彦low:
16 GPM cont.
20 GPM int.
ç´�otation Reversible
ç*†ount 4 bolt Square, 3.25" B.C.
百haft 1" diam. x 1-3/4" keyed
1/4" keyway
ç´�qd. Filtration 25 micron
姫orts 1/2" NPT
匹ase Drain SAE 4
百ize 6-3/4" x 3-1/2" x 4"
百hpg. 19 lbs.


My tractor only produces a little under 12 GPM, but the relief pressure is 2900psi. I know I won't likely see the 300 RPM, but was thinking if I limited the reduction to 5:1 or so I'd account for the spool diameter and would still end up with a 8,000# pulling force and 50 FPM line speed with a 4" drum. Is that close to accurate? I'm not positive I'm doing the math right to get there.

 

[J_J]

3360 in lbs * 5 = 16800 in lbs, / 12 = 1400 ft lbs

 

[Jim Timber]

Right, but the load is being applied at 2.25" from the center of rotation, so it's roughly 5x that 1400 at the cable.

My math says that with a 5:1 reduction and a 4" drum with 1/2" cable, the cable should see 7466 in-lbs of torque on the first wrap at the continuous (lower pressure) rating of my motor at 64fpm.

The next question: is a 4" drum large enough for a 1/2" cable?

 

[Jim Timber]

I should've looked at this before. :laughing: Ramsey built almost exactly the same thing.

HD-P 34,9 - Planetary Hydraulic Winches

 

[Sawyer Rob]

It's going to be a really slooooow skidding winch....if that is important to you...

SR

 

[Jim Timber]

64 feet per minute is slow? Sure, it's not 100+fpm like a PTO driven winch, but my total investment will be <$500 and construction will be a lot easier.

I'm going to get a 3:73 rear end for my gear box and see how it does. I can add reduction on the input if it doesn't meet my needs for pulling later.

 

[Sawyer Rob]

64 feet per minute is slow? Sure, it's not 100+fpm like a PTO driven winch, but my total investment will be <$500 and construction will be a lot easier.

I'm going to get a 3:73 rear end for my gear box and see how it does. I can add reduction on the input if it doesn't meet my needs for pulling later.

Yes, 64 is pretty sloow, unless you have short pulls or won't be pulling many logs out...

My pto winches line speed is 75 to 175 fpm, depending on what I set the RPM of the tractor, and once you get use to the winch, on longer pulls 75fpm isn't fast at all... I always set my RPM faster than that...

Like I said, it all depends on how much skidding you plan to do. I skid out all of my firewood along with my saw logs, so I want it to happen reasonable fast, yet still safe and that's all about getting use to your winch...

SR

 

[Jim Timber]

Maybe someday I can grow up to be like you Rob. I do my wood stuff for pleasure, and part of that includes building my own implements. If you wanted to be truly productive, you'd get a skidder anyway. :thumbsup:

 

[Sawyer Rob]

Come on Jim, you don't have to be rude... I wasn't rude to you, I was just commenting on what you are doing... I've already did the home made winch set up and I was just pointing out what I have learned...

I had no idea that you didn't like to hear about others experiences....

SR

 

[Jim Timber]

Much of what you write here comes off as "I do it better than you can." Whether that's your intention or not, I don't know. You've always been very helpful in the sawing forum on the other site, but your vibe is different on TBN.

My design objective with this winch is to have a reasonable line speed with a capable capacity, have reverse, and keep it under a grand (1/3 the cost of a PTO winch, and those lack reverse). Skidding logs is the primary objective, but I'll also be using it to raise walls/trusses/beams/poles, so having the feather control of hydraulics is more desirable than the brute power of the PTO. If I wanted to knock-off a Farmi or any of their clones I could do it. I have the machinery to build exactly what they make. It wouldn't be a good use of my free time, but I could make one if I chose to.

I'll be the very first person to point out slow performance using a recovery winch for skidding, because those are made for cost effectiveness and extremely short duty cycles - often only being designed to pull a load for 10 feet or less (just enough to get un-stuck). This is a different animal. Getting over 50FPM first wrap is plenty fast for me with a full load. I have no idea how the motor I have will respond to less than full loads and or how that'll relate to being put under pressure. The numbers I'm using are based on the lowest performance values offered. I will have no problem meeting the 2900psi intermittent max pressure, but I probably can't pump the full flow to make the 300RPM - I'll have to use my optical tach to find out what I achieve in use.

When I posted this thread, I wasn't sure how the force numbers of winches were derived. Since then I have learned that it's just the torque available at the cable in relation to the distance from the drum and how much torque is being generated at that axis. Inch pounds vs foot pounds. Granted, there's going to be some mechanical (friction and otherwise) losses in any system, but since I'm not talking about lifting people, or inter-planetary travel; I'm close enough.

It was raining this morning, so I didn't go to the junk yard. There's a couple BMW's that should have the third member I want, but the place doesn't post what's still in the cars in the yard, only when they arrived.