Knocking around a Skidding Winch build.

mike paulson

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Been thinking of an old 8000 lb Braden PTO winch. Tractor is a B2620 with about 19 hp at the PTO. I'm seeing here most guys are recommending a hydraulic Motor powered by the tractors hydraulics to turn the winch. The 2620 gives me 4.7 GPM pump flow, and around 1500 to 1800 psi at around 2000 rpm. What hydraulic Motor should I use. Anyone with Hydraulics knowledge who could help me with a make and model hydro motor would be great.
 

North Idaho Wolfman

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You don't have enough GPM flow to run a hydraulic motor to run a PTO winch.

The flow you do have would only give you 4.5HP and very little torque if I remember right.
 

mike paulson

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You don't have enough GPM flow to run a hydraulic motor to run a PTO winch.

The flow you do have would only give you 4.5HP and very little torque if I remember right.
I was afraid of that. What about powering it with the PTO. I do realize that introduces a whole set of additional factors like a shaft, a clutch and tractor PTO gear protection. Or should I just go to a capstan winch driven by an hydraulic Motor like others here have done.
 

North Idaho Wolfman

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I was afraid of that. What about powering it with the PTO. I do realize that introduces a whole set of additional factors like a shaft, a clutch and tractor PTO gear protection. Or should I just go to a capstan winch driven by an hydraulic Motor like others here have done.
A PTO driven winch with a clutch is about the strongest you can get, you'll safely outpull just about anything else set up right.
You want a clutch that has a brake setup in it, or it will unspool the line too easily under tension.
You can do it with electric, mechanical or hydraulic.
 

mike paulson

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I was considering a Capstan setup and was wondering how Stomper made out with his build which I've been following. I'm a 40yr truck/ diesel mechanic by trade, just retired, and can handle about any fabricating project at hand. My weak point is hydraulic mathematics. With my tractors hydraulic pressure and GPM and revolutions (60 RPM)needed at the Capstan ,I called a hydraulic Motor supplier mentioned here for what motor I would need for a Capstan setup but the sales rep wanted torgue/ HP requirements I would need. I went thru some calculations provided using online calculators to figure this and came up with a torque spec of 4900 in lbs and around 5 HP. My pump flow is 4.7 GPM with roughly 1800 PSI. Do these numbers jive and would they work a Capstan to pull medium size maybe 1500lb max logs. I did try to contact Stomper on what make and model motor he eventually used but haven't heard back. His tractors hydraulic specs are similar to mine. I still would consider going this route for simplicity and I'm only looking at cutting 5 or 6 cord per season for my home
 

North Idaho Wolfman

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I was considering a Capstan setup and was wondering how Stomper made out with his build which I've been following. I'm a 40yr truck/ diesel mechanic by trade, just retired, and can handle about any fabricating project at hand. My weak point is hydraulic mathematics. With my tractors hydraulic pressure and GPM and revolutions (60 RPM)needed at the Capstan ,I called a hydraulic Motor supplier mentioned here for what motor I would need for a Capstan setup but the sales rep wanted torgue/ HP requirements I would need. I went thru some calculations provided using online calculators to figure this and came up with a torque spec of 4900 in lbs and around 5 HP. My pump flow is 4.7 GPM with roughly 1800 PSI. Do these numbers jive and would they work a Capstan to pull medium size maybe 1500lb max logs. I did try to contact Stomper on what make and model motor he eventually used but haven't heard back. His tractors hydraulic specs are similar to mine. I still would consider going this route for simplicity and I'm only looking at cutting 5 or 6 cord per season for my home
Yea sounds right, that motor would run a capstan winch no problem. ;)
 

mike paulson

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I followed Crmorse's Capstan thread and great videos but have to say I was alittle discouraged at the problems he faced. I might just wait to see Stompers results. Problem is I have someone who's selling a Barden Winch, PTO drivin at 8000 lbs for 100 bucks. Kinda at a crossroad for the moment.
 

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Go check out this thread, they are running the PTO winch off of a hydraulic drive motor.


So it does look to be quite workable, I was thinking about only direct driving it, they are using chan reduction to pull it off.

Egg in my face! :eek:

And with a hydraulic motor running the winch you get the best of every world!

http://forestryforum.com/board/index.php?topic=66545.0
 
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mike paulson

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Stomper

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Hey mike sorry for not getting back to you earlier but I have been busy and havent been on here much lately. As you have seen in my thread I havent had much time to work on my capstan winch either but I did find some time to build the motor mount and I will be picking up the valve for my rear remotes this weekend so thing should start moving along now. I personally think that the issues that crmorse is having with rope slippage and binding is only a rope issue. The capstan is a simple concept and there isnt much that could go wrong. I have watched countless capstan videos and they all seem to work fine without issue. As far as motor selection I think he has nailed it right. It seems to have good rpm and torque. Mine is still to be determined as I havent had a chance to try it. I wish I could help out more on the motor selection but my hydraulic skills are very limited so I am in no position to give advice. I will keep posting in my thread as I continue my build nd will keep an eye on yours as well
 

mike paulson

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Hey mike sorry for not getting back to you earlier but I have been busy and havent been on here much lately. As you have seen in my thread I havent had much time to work on my capstan winch either but I did find some time to build the motor mount and I will be picking up the valve for my rear remotes this weekend so thing should start moving along now. I personally think that the issues that crmorse is having with rope slippage and binding is only a rope issue. The capstan is a simple concept and there isnt much that could go wrong. I have watched countless capstan videos and they all seem to work fine without issue. As far as motor selection I think he has nailed it right. It seems to have good rpm and torque. Mine is still to be determined as I havent had a chance to try it. I wish I could help out more on the motor selection but my hydraulic skills are very limited so I am in no position to give advice. I will keep posting in my thread as I continue my build nd will keep an eye on yours as well
I've watched every available video out there on capstan winch's and can honestly say pulling technique has alot to do with it. Looks like a slow but very steady pull keeps the pulley working against the rope. Looks like a lot of operators are jerking on the line in an almost pull release fashion. Steady non stop tension that matches winch speed I think is key.
 

Stomper

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Agreed on the technique but having said that I have no real world experience to back that statement.........yet! Time will tell I guess.
I really hope I can get this system working because the capstan is the perfect setup for my needs of personal logging of around 6 or 7 cords a year.
 
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crmorse

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Motor selection is surprisingly easy if you're using a 2" diameter capstan. A 2" diameter capstan (standard) has a 1" lever arm (the radius). If you allow a little bit of rounding in the formulas a 1" lever arm turns inch-pounds of torque into pounds of direct force.

In other words, a motor/hydraulics combination that gives 4000 in-lbs of torque into a 1" radius capstan will give 4000 pounds of theoretical pulling force. The theoretical here is because all motors have losses, the rope slipping [or hopefully not] on the capstan has loss, and the log dragging across the ground adds friction. If you add all that up you definitely don't get 1:1 log weight to pull force. I don't know what the real ratio is, but you seem to already have that idea and in my actual setup I've not hit any motor lack of torque problems. I sized my system for a max of 60fpm (that determines your RPMS) and 8000 lbs (that determines your motor's torque requirements).

Before we get to the actual motor sizing selections there's one more thing to consider. Most hydraulic motors are NOT designed for side torque (the rope pulling perpendicular to the output shaft). Luckily, most motors do specify the allowable torque in their spec sheets. Most of them specify that value at something like 80% of max RPMs. Since we won't be using these motors anywhere near the max RPM and we're not looking for thousands of hours of use, you can safely go up to max side torque and probably beyond. However, since I was looking for a very beefy system I chose a "drive wheel motor" since those are designed for heavy direct side torque.

Ok, here's the "nutshell" of hydraulic theory. I'm greatly over-simplifying here so real engineers in the house please don't crucify me.

PSI = torque, GPM = speed aka rpms

You can't really affect the max PSI of your tractor's system so you can almost* treat that as a constant.

*Two exceptions here:
a) your tractor won't actually generate max PSI unless your engine is near PTO RPMs AND the hydraulic system is actually under load.
b) the hydraulic motor's torque & rpm curves are not linear. The motor's datasheet will have tables for a series of max PSI values and RPMS. Don't overthink this.

You also can't really change your tractor's max GPMs. However, you can change how fast your target motor will spin based on that GPM. The value you will select for is the motor displacement, measured in cubic inches (cu in) in imperial measurements. Generally speaking, the larger the displacement the slower the motor will turn for a given GPM and the higher the torque. That is, until you drop below a minimum useful RPM and the motor actually stalls out.

There's a few different hydraulic motor designs out there that have different rpm/torque curves. I'm not an expert on them. I did enough research to determine that a "Gerotor" was the right style for me and gave the best torque-speed combination. I am very happy with my motor selection so I'd suggest you do the same.

So here was my process:
a) I knew I wanted 8000 lbs so I needed 8000 in-lbs of output torque.
b) I wanted 60fpm of pull rate at max RPM.
c) With a 2" diameter capstan that's a circumference of 6.28" or 0.523' (2*Pi*R) so I need 60' / 0.523' = ~115 rpm
d) my tractor can do ~3000psi @ ~11gpm of flow
e) 11gpm / 115rpm = 0.09 gallons/revolution
f) 1 gallon = ~231 cubic inches so 0.09 * 231 = 22.1
g) then I searched through all the drive motor on surpluscenter.com until I found one that was an affordable price, near enough to 22.1 cu-in and had at least the desired torque at 3000psi.
h) I ended up picking https://www.surpluscenter.com/Hydra...355320A8321BAAAA-HYDRAULIC-MOTOR-9-8675-D.axd which yielded an expected 8231 in-lb of torque with 79 rpm at 11gpm/3000psi

For final plumbping, on advice from a thread on from TBN I also added a flow control valve. I *STRONGLY* recommend that you also add one as well. I don't actually use it much for flow control as I find that the tractor's throttle is far more useful for that. However, it has saved my butt several times as a quick way to cut off rotation.

As has been discussed before, my rope likes to climb over itself. If this happens with any load on the line the capstan's slip design no longer works and you can't release the load. If you can't stop the rotation it's going to continue until something breaks. I also found out this same condition can happen if you have a heavy load on the line. For example, if you're pulling a log up a hill, even a very small one. So definitely have some kind of quick cut-off in easy reach.

Other than that, it's a simple design and I'm fairly happy with mine now. I'll definitely try some other ropes in the future.
 

crmorse

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Mike Paulson, since you specified you have 1500 to 1800 psi at around 2000 rpm and 4.5GPM flow we can work this backwards.

e) 4.5gpm / 115rpm = 0.039gal/rev
f) 0.039gal/rev * 231 = 9.09 cu-in
g) this motor looks like a good fit https://www.surpluscenter.com/Hydra...55160A1316AAAAA-Hydraulic-Motor-9-8632-EE.axd Its specs claim 2142 in-lbs of torque at 1500psi/4gpm

Cautions about the above motor:
* it has a 25mm shaft instead of the 1" common in US capstans. This is "probably" close enough but YMMV
* It has BSPP ports. This will require adapters to use with NPT hoses. These can be hard and/or expensive to find. You might want to search further for a motor with either ORB or NPT fittings. YMMV, however, in my case, I needed 90 elbows anyway so I just got a combo elbow BSPP to NPT and I'm fine with that.
* It has a 2 bolt pattern. That might or might work for you. Mine is 2-bolt and worked fine. IIRC, stomper had to do some fab work to make his bolts fit (but I don't remember what pattern he has)
* This is a White "Light Duty" motor. The datasheet says it's only rated for a max of 1250 in-lbs of side load torque up to 200 rpms. If you ever used it to the full expected 2000 lbs of pull you'd likely damage the bearings.
* I checked the 281 series motor (https://www.surpluscenter.com/Hydra...281160A6821BAAAA-Hydraulic-Motor-9-8672-F.axd) on Surplus Center which is a "medium duty." It is spec'd for 1997in-lb@84rpm and it has 5500lbs of side load but the shaft is 32mm which would require a custom capstan. Perhaps you could custom order one that has the 1" shaft necessary.
* There are plenty of other manufacturers of motors and one might suit you but I'm only familiar with the White line from my research.
 
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mike paulson

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Thanks CR, I will look into those suggestions. I would like to find a motor with a one inch shaft so I can order a capstan from Portable Winch. I did come across this unit which should generate somewhere in the neighborhood of 4500 in lbs of torgue if my calcs are right. The price is OK and it should work with my GPM ,but is out of stock at this time.
https://www.surpluscenter.com/Hydra...ic-BMPH315H2KP-Hydraulic-Motor-9-7077-315.axd
So it should be in stock this week. If you have the chance maybe you can look it over.
 

crmorse

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I found the datasheet here: http://dynamicfc.com/documents/2016DynamicFullCatalog_Motors_BMPH.pdf

At tractor WOT and max load you're only going to be getting 28rpm or roughly 15fpm. That'll be painfully slow. The no load speed is 47rpm or ~25fpm. That's still pretty slow.

This looks like a good line of motors, the side load is rated at 88,000lbs but I think I'd drop the displacement in favor of a little more speed at the cost of some torque.

Their 9.5ci would give you half the torque (1903) but triple the rpms (85). It costs a little bit more but looks to be a much better match for your tractor.
https://www.surpluscenter.com/Brand...ic-BMPH160H2KP-Hydraulic-Motor-9-7077-160.axd

Think of it this way, your tractor has to resist the pulling force (Newton's third law) and may not weigh enough to anchor a 4500# pull anyway. If you're dead-set for more torque you could go half-way between and pick the 14.1ci. It would give 2894ft-lbs @ 50rpm and 60rpm at no load.
https://www.surpluscenter.com/Brand...ic-BMPH250H2KP-Hydraulic-Motor-9-7077-250.axd
 

Stomper

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Again Im not a hydraulic guy by no means but hopefully someone will chime in to correct me if Im wrong. A few things that I took into consideration when I chose my motor was the mounting flange. Being that there was going to be all side torque on the motor I chose a motor that had a 4 bolt mount instead of the 2 bolt to help give that little bit extra resistance to wanting to torque on mount.
Another was the operating pressure of the motor. My tractor hydraulic system operates at around 2200psi, even at idle its very close to 2200. I chose a motor that had a continuous operating pressure at or above the 2200 psi. Not sure what your system pressure is but I would guess its somewhere around the same. The below link helps understand this
https://youtu.be/ruLOjlyiTmI
I also looked at how much side load the shaft could take simply because in this situation its going to be all side load.
The manual for my motor had a chart that showed the different rpm in comparison to flow. I chose a motor that would give me the rpm I wanted as compared to flow.
Hopefully this helps
 
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mike paulson

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I found the datasheet here: http://dynamicfc.com/documents/2016DynamicFullCatalog_Motors_BMPH.pdf

At tractor WOT and max load you're only going to be getting 28rpm or roughly 15fpm. That'll be painfully slow. The no load speed is 47rpm or ~25fpm. That's still pretty slow.

This looks like a good line of motors, the side load is rated at 88,000lbs but I think I'd drop the displacement in favor of a little more speed at the cost of some torque.

Their 9.5ci would give you half the torque (1903) but triple the rpms (85). It costs a little bit more but looks to be a much better match for your tractor.
https://www.surpluscenter.com/Brand...ic-BMPH160H2KP-Hydraulic-Motor-9-7077-160.axd

Think of it this way, your tractor has to resist the pulling force (Newton's third law) and may not weigh enough to anchor a 4500# pull anyway. If you're dead-set for more torque you could go half-way between and pick the 14.1ci. It would give 2894ft-lbs @ 50rpm and 60rpm at no load.
https://www.surpluscenter.com/Brand...ic-BMPH250H2KP-Hydraulic-Motor-9-7077-250.axd
I just spoke to Mike at Surplus and he pretty much verified exactly what you said. The 9.5 cu in is what I'll need to move a load at a decent RPM. I'll be giving up torque but let's face it my little Kubota is only going to anchor so much weight and backing up to stumps or chaining it to a tree is something I don't want to do. So I ordered the 9.5 and see what happens. The tech at Surplus was very non committal on load or what size logs I'll be able to pull and I understand this. It is only a two bolt but if it doesn't work out I'll go from there. I will learn the limitations and cut logs accordingly. I'm a 40 yr retired diesel mechanic who can rip an engine down, pull and replace transmission's etc ,but the mathematics of hydraulics is mind boggling.
 

crmorse

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So I ordered the 9.5 and see what happens. The tech at Surplus was very non committal on load or what size logs I'll be able to pull and I understand this. It is only a two bolt but if it doesn't work out I'll go from there. I will learn the limitations and cut logs accordingly.
I honestly believe you will be just fine. I have a pressure gauge on mine and I made a little chart that matches PSI to pounds of pull and I'm pretty sure you won't be able to pull the rope hard enough long before you hit enough torque to max out your motor. (not saying the rope won't work, saying that you'll have plenty of torque for anything you want to attempt with rope)