TOH

Dave8N in Pa · Apr 28, 2018

Hello again, I'm building a log winch for the tractor and I need advice on hyd. motors. The winch is 30 to 1 and I want a hyd. motor to power it. How do I choose the
right motor?

TheOldHokie · Apr 28, 2018

(quoted from post at 09:05:02 04/28/18) Hello again, I'm building a log winch for the tractor and I need advice on hyd. motors. The winch is 30 to 1 and I want a hyd. motor to power it. How do I choose the
right motor?

My first question would be what is the size and source of the hydraulic power you will using to power the winch motor? Can't size a motor without the input power numbers.

TOH

Dave8N in Pa · Apr 28, 2018

12 gpm. Input shaft on winch is 1 inch keyed.

Dave8N in Pa · Apr 28, 2018

That's on a 40hp tractor

TheOldHokie · Apr 28, 2018

(quoted from post at 10:45:25 04/28/18) That's on a 40hp tractor

OK - we are not talking an N-series :shock:

The next issue is what speed and torque do you want out of the motor. That is not a single simple calculation with a single correct result and requires some other design parameters - e.g. what line speed and pull do you want out of the winch? Here is a link to some simple calculators to run some combinations of those numbers.

Your knowns are 12 GPM @ 1500 (???) PSI flow rate.

From that you can calculate various motor speeds, torques and and displacement combinations.

Then use those results to calculate the corresponding line pulls and speeds based on your winch's 30:1 mechanical advantage.

The tradeoff you are dealing with is line speed versus pull. If it were me I'd start by deciding on what my minimum acceptable line pull is and work backwards from there. That maximizes your line speed which would seem to be the primary goal. You may have to make several iterations through that process to find the combination that best fits your needs. In other words you may have to trade off some pull to get an acceptable line speed or vice versa.

Hydraulic Motor Calcuators

TOH

Dave8N in Pa · Apr 28, 2018

Thanks a lot, I think I'm going to go with 5 cid and hope fore the best. Surplus Center has them for around 130.00 but I don't know If the quality is good. Thanks again.

TheOldHokie · Apr 28, 2018

(quoted from post at 13:38:35 04/28/18) Thanks a lot, I think I'm going to go with 5 cid and hope fore the best. Surplus Center has them for around 130.00 but I don't know If the quality is good. Thanks again.

Given tractor hydraulics of 12 GPM @ 1500 PSI a 5 CID motor gets you 100 lb-ft of motor torque at 550 shaft RPM. With a 30:1 winch ratio that gets you a drum speed of 18 RPM. Give me the drum diameter and I can give you line speed and pull.

TOH

Dave8N in Pa · Apr 28, 2018

Drum diameter is 5 inches. But that is the empty drum. When it's full it would be 10 inches.

Dave8N in Pa · Apr 28, 2018

I tried to figure it myself and I got 24 feet per minute. I don't have any idea how to figure pull.

TheOldHokie · Apr 28, 2018

(quoted from post at 18:03:56 04/28/18) I tried to figure it myself and I got 24 feet per minute. I don't have any idea how to figure pull.

Let me start by saying I know very little about winches and the following is to the best of my understanding but is anything but definitive.

If you look at winch specifications they will give you multiple line speed and pull specifications which vary "by layer".

Layer 1 specifications are for an empty (e.g. minimum diameter) drum and will have the lowest line speed and highest pull.

Layer N is a drum with N-1 wraps of cable on it (e.g. a larger drum) and will have the fastest line speed, and lowest pull.

Layers 2 through N-1 specifications will be incremental steps through those outer ranges.

A 5" drum on a 1" input shaft is a 5:1 loss of torque so if your winch has a 30:1 gear advantage in the middle it is reduced to 6:1 at the drum. A 100 lb-ft shaft input torque gets you 600 lb-ft of torque at layer 1 on the drum and will decrease as the wraps on the drum increase.

TOH

Dave8N in Pa · Apr 28, 2018

You said you know very about winches.........?
Again, thank you very much!

TOH

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