Need math help , for my firewood winch build

[dave_dj1]

The differential I have is 3.73-1 gear ratio, I will be powering it with my pto that has a rpm of 540.
540 divided by 3.73 is roughly 145, given a 4" drum for the winch with 1/4" cable and 4-5 wraps so the average length per wrap is approximately 13". If the drum is spinning at 145 rpm's and wrapping 13" per turn, what is my line speed in feet per minute?
I keep tripping up here.
If the line speed is too fast, what should I gear the drum down to? I am going to chain drive the drum so I have the option of using different size sprockets for the gearing.
Thanks for any help.
Dave

 

[brenndatomu]

145 x 13 = 1885" / 12" = 157.08' per minute
sounds a bit fast to me but...I dunno?

 

[Swamp Yankee]

I can help, but need just a bit more info.

Spent 15 years in the winch industry, designed and managed production for applications from small trailers / ATV, off road recovery, to 15 and 50 ton winches for TACOM. (DOD).

From your specs, I'll try for some ballpark numbers. First, line speed numbers are calculated at the "pitch line" of the wire rope, which is a fancy name for the CL of the wire rope.

OK, let's crunch a few numbers.

Your 1st layer diameter is the 4 inch drum dia. plus 1/8 X 2, to get you to the CL of the wire rope or 4-1/4, (4.25 inches). Divide by 12 inches per foot, and your pitch line is .35 ft. Multiplying by pi, 3.14, and you have 1.1 ft./rev. Multiply 1.1 ft/rev X 145 rev/min gets you a line speed of 159-1/2 ft./min bare drum, no load.

For each additional layer add 1/2 inch to the previous layer's pitch line and repeat, For example
your second layer would be (4.25 + .50)in /12 in/ft = .4ft
(.4 ft/rev) X 3.14 X (145 rev/min) = 182 ft/min

Remember, these numbers are calculated and theoretical, they are very close to actual, but will vary slightly in actual measurements, the higher the layer number the greater the difference. As a rule of thumb, add about 10 to 15 % in line speed as you go up a layer.

Also be aware, as layers increase more hp is required to keep line pull constant with the same input rpm. If you have ample hp input you're OK. This is where most 12 / 24 volt winches really slow down as the input hp gets maxed.

Another rule of thumb, if you want to move a load the entire length of the supplied wire rope on a 12 VDC winch multiply the rated line pull by 10 or 15% depending upon winch motor type, electrical cable gauge, drum bearing type etc. IE a 4000 lb 1st layer rated winch with 60 ft. wire rope will pull between 400 and 600 lbs the full rope length.

Hope this helps, any other questions, drop a line.

Take Care

 

[czar800]

I would say you'll never run it at 540.

 

[NCSteveH]

Also remember that's running your tractor at about wide open, cut your rpms in half and your line speed will be half also. Just saying, stuff happens fast at full speed.

 

[Swamp Yankee]

czar800 and NCSteveH are correct

You can throttle down the winch speed by simply cutting the rpm of the prime mover, in this case the tractor pto. No spec is given for the HP output of the PTO, but suffice to say if you're only running 1/4 inch wire rope you won't have need of 15 to 20, or greater, hp input to the winch drive system.

Take Care

 

[Ferguson system]

Also remember that's running your tractor at about wide open, cut your rpms in half and your line speed will be half also. Just saying, stuff happens fast at full speed.

NcSteveH is right. Pto rpm while winching is around 300. Tractor will be idling or just a tad over most of the time.

 

[cmsmoke]

You mention using a differential. Are you using a vehicle differential and if you are will you be holding one of the axles from turning? That will cut your 3.73 in half to 1.865 or twice the speed you are thinking.

 

[dave_dj1]

Thank you all for the input. I was close on my calcs but couldn't/wouldn't believe it would be that fast.
OK, a few more specs on my tractor (and in case any of you are wondering, I am a total newb to tractor pto workings) I have never owned or operated one before.
The tractor is a 40 hp Massey, I didn't realize I guess that I could slow the pto rpm's down by throttling back. I guess that is proportional.
Yes I plan to use the front center section out of a 2000 chevy 4 wd pickup. I will be holding one side (variable) with a disk brake set up and master cylinder, winch spool on the other end.
Swamp Yankee it's good to know we have someone here with the experience and knowledge to help guide us when needed, thank you.
So is the general consensus to gear it down with the chain drive or will the idling be slow enough?
Thanks again and I'm sure I'll have more questions.

 

[farmer steve]

I can help, but need just a bit more info.

Spent 15 years in the winch industry, designed and managed production for applications from small trailers / ATV, off road recovery, and 15 and 50 ton winches for TACOM. (DOD).

From your specs, I'll try for some ballpark numbers. First, line speed numbers are calculated at the "pitch line" of the wire rope, which is a fancy name for the CL of the wire rope.

OK, let's crunch a few numbers.

Your 1st layer diameter is the 4 inch drum dia. plus 1/8 X 2, to get you to the CL of the wire rope or 4-1/4, (4.25 inches). Divide by 12 inches per foot, and your pitch line is .35 ft. Multiplying by pi, 3.14, and you have 1.1 ft./rev. Multiply 1.1 ft/rev X 145 rev/min gets you a line speed of 159-1/2 ft./min bare drum, no load.

For each additional layer add 1/2 inch to the previous layer's pitch line and repeat, For example
your second layer would be (4.25 + .50)in /12 in/ft = .4ft
(.4 ft/rev) X 3.14 X (145 rev/min) = 182 ft/min

Remember, these numbers are calculated and theoretical, they are very close to actual, but will vary slightly in actual measurements, the higher the layer number the greater the difference. As a rule of thumb, add about 10 to 15 % in line speed as you go up a layer.

Also be aware, as layers increase more hp is required to keep line pull constant with the same input rpm. If you have ample hp input you're OK. This is where most 12 / 24 volt winches really slow down as the input hp gets maxed.

Another rule of thumb, if you want to move a load the entire length of the supplied wire rope on a 12 VDC winch multiply the rated line pull by 10 or 15% depending upon winch motor type, electrical cable gauge, drum bearing type etc. IE a 4000 lb 1st layer rated winch with 60 ft. wire rope will pull between 400 and 600 lbs the full rope length.

Hope this helps, any other questions, drop a line.

Take Care

this is why AS is so great. there is always someone there with a good answer. good luck with your build Dave.

 

[midwest_170]

You are going to need to slow it down. Instead of using a chain and sprockets consider using a belt and size the belt slip under the strength of the cable so if you get hung up the belt slips before the cable breaks. If you're set on using a chain consider a shear pin sprocket or a clutch coupling.

 

[Old Doug]

You are going to use the brake as a clutch?

 

[czar800]

You mention using a differential. Are you using a vehicle differential and if you are will you be holding one of the axles from turning? That will cut your 3.73 in half to 1.865 or twice the speed you are thinking.

Cmsmoke is right when you brake one side it splits the ratio in half. If your idling the tractor and slipping the brake when needed you can control line speed.

 

[czar800]

A pto is

Thank you all for the input. I was close on my calcs but couldn't/wouldn't believe it would be that fast.
OK, a few more specs on my tractor (and in case any of you are wondering, I am a total newb to tractor pto workings) I have never owned or operated one before.
The tractor is a 40 hp Massey, I didn't realize I guess that I could slow the pto rpm's down by throttling back. I guess that is proportional.
Yes I plan to use the front center section out of a 2000 chevy 4 wd pickup. I will be holding one side (variable) with a disk brake set up and master cylinder, winch spool on the other end.
Swamp Yankee it's good to know we have someone here with the experience and knowledge to help guide us when needed, thank you.
So is the general consensus to gear it down with the chain drive or will the idling be slow enough?
Thanks again and I'm sure I'll have more questions.

A PTO is a real killer, many of experienced men have been killed by PTOs. It's a Little uneasy reading about how unfamiliar you are with their operation. I don't say this to be a know it all or stop you. Just a word of caution.

 

[Jakers]

I would say you need to be looking at seriously reducing your speed. ive run hydraulic 20,000 lb winches at about 15-20 ft per min. this may seem slow but when a pull gets snagged on something hard or immovable things get hairy quick. this is especially true if you are winching from wet or frozen ground and your anchoring doesnt quite hold. things can go wrong very fast at the 150 ft/min

 

[dave_dj1]

You are going to use the brake as a clutch?

Yes, sort of, by braking one side it forces the other side to have the power.

czar800, I hear what you are saying and thanks for the words of warning.

 

[Marshy]

You mention using a differential. Are you using a vehicle differential and if you are will you be holding one of the axles from turning? That will cut your 3.73 in half to 1.865 or twice the speed you are thinking.

Can you explain this more? I cannot wrap my head around why the ratio would be half... I just don't see how the ratio would change if one side of the axle (output) is held stationary. It should just transmit the power to the other axle... But the ratio wouldn't change...

 

[dave_dj1]

http://web.mit.edu/2.972/www/reports/differential/differential.html
This is about as good of an explanation as I could find however it appears that the other side will actually speed up!
But what do I know? It may slow down when held. I will have to test it and see.

 

[chucker]

you will need to add a secondary clutch system to your pto !! direct connect to the pto is a death warrant! incorporate a limited slip clutch like the ones used on brush cutters for a safety margin for hung up logs during retrieve as the governor on the tractor will engage at low rpm!! like I stated "death warrant".......

 

[Ferguson system]

Like stated earlier in the thread, it is important to have a secondary clutch to engage the winch with. Early Scandinavian logging winches used a wheelbarrow wheel as a clutch (easy to build). Bulldog vinsj and Tunby vinsj are two examples. Logging winches evolved from the wheelbarrow style and to the ones that are used now with a inboard drum clutch. Igland, Farmi and Fransegaard to mention 3 modern logging winch brands.

Bulldog vinsj/winch (wheelbarrow wheel clutch):

https://www.google.no/search?q=bull...v5LgAM:;VBhh8ClQE8EOeM:&imgrc=ZN2Xdq06v5LgAM: