Gearbox for a hydraulic motor

BarnyardEngineering · Jul 16, 2019

I have one of those "poor man's" bale wrappers that rolls the bale along the ground as it wraps the plastic on the bale.

The problem I'm having is the hydraulic motor is direct coupled to the arm and it is very difficult to control. It's the lowest RPM hydraulic motor money can buy and it's still capable of several hundred RPM. Getting a nice slow consistent rate out if it is very difficult. Either the motor stalls out or it gets to whipping like crazy.

Easiest way to resolve this without major modifications to the machine is with a reduction gearbox. Problem is finding a gearbox.

There are thousands upon thousands of gearboxes out there online, but I can't find what I am looking for. Ideally it will have a 1" keyed input, a 1" keyed output, and a reduction of 5:1 to 10:1.

My google-fu is failing me. Surplus Center has nothing that I can find that will begin to work.

I would appreciate any and all suggestions, either of a better search method, or a source of a gearbox.

Bob 7337 · Jul 16, 2019

don't your bale wrapper have a flow valve in hydralic line. flow valve would probably solve your probably solve situation

BarnyardEngineering · Jul 16, 2019

We have flow valves and restrictors in the lines, and it is still uncontrollable. There is a 1/4 turn difference between the motor flying around wildly and doing nothing at all on the flow restrictor.

It really should be chain driven but that would require cutting the whole thing apart and starting over. I did not build it.

Janicholson · Jul 16, 2019

Boston Gear. Jim

rrman61 · Jul 16, 2019

Look for a gearbox made for conveyers.there some
out there that have pretty low rpm output.a bearing
supply store would be a good place to start

Brendon-KS · Jul 16, 2019

Most styles of hydraulic motors have very
poor "smoothness" of power delivery at
very low rpm. They alternate between zero
and peak torque as the pistons, gears, or
orbital lobes go around. At higher speeds
it all averages out but when rotating slow
things don't work well. Radial piston
motors are an exception in that they have
a flat torque delivery and operate
smoothly down to essentially zero speed.
Changing to one of these motors might be
as easy as adding a reduction gearbox.

Steve@Advance · Jul 16, 2019

Finding a gear box that can handle the torque will be very expensive and big.

Your cheapest route would be the chain and sprocket reduction.

May not be the easiest, but it would be as heavy duty as you design it.

My other thought would be to adapt a hydrostat transmission from a riding mower.

ss55 · Jul 16, 2019

A worm gearbox might give you the speed reduction and torque you are looking for.

caterpillar guy · Jul 16, 2019

Why not drive the motor off from a transmission like in a hydrastat set up. The motor would tunr the trans shaft then inturn would be shifted to the correct speed with the trans while the wrap is put on.

Bob · Jul 16, 2019

(quoted from post at 06:58:56 07/16/19) I have one of those "poor man's" bale wrappers that rolls the bale along the ground as it wraps the plastic on the bale.

The problem I'm having is the hydraulic motor is direct coupled to the arm and it is very difficult to control. It's the lowest RPM hydraulic motor money can buy and it's still capable of several hundred RPM. Getting a nice slow consistent rate out if it is very difficult. Either the motor stalls out or it gets to whipping like crazy.

Easiest way to resolve this without major modifications to the machine is with a reduction gearbox. Problem is finding a gearbox.

There are thousands upon thousands of gearboxes out there online, but I can't find what I am looking for. Ideally it will have a 1" keyed input, a 1" keyed output, and a reduction of 5:1 to 10:1.

My google-fu is failing me. Surplus Center has nothing that I can find that will begin to work.

I would appreciate any and all suggestions, either of a better search method, or a source of a gearbox.

What is the displacement per revolution of the hydraulic motor you are now using?

centash · Jul 16, 2019

Get the drive unit gearbox from an old silo unloader.

Ben

Traditional Farmer · Jul 16, 2019

You need a high torque low RPM motor I got one from Surplus Center to put on a small loader because I wanted to increase the pushing power,over did it a little nothing will stop the loader but it is real slow now.

BarnyardEngineering · Jul 16, 2019

(quoted from post at 08:48:58 07/16/19) A worm gearbox might give you the speed reduction and torque you are looking for.

That's what I'm looking for but I'm having a tough time finding one that has a 1" input and 1" output.

Destroked 450 · Jul 16, 2019

What type of hydraulic motor does it use?
We use Eaton Char-Lynn orbital motors at the mill, depending on the motors size and torque rating they are available from several hundred rpm's down to less than 50 rpm.
I use the same type motors on my litter spreader with a adjustable flow control to set the speed of the floor chains.
The type I'm talking about have 1" keyed output shafts.
One particular motor we use a lot of has a flow rate of 2-15 gpm with a speed variance of 30-245 rpm, torque and speed remain constant once flow is set.

Google Char-lynn H type motor.

If you can't find what you need let me know, I have their product catalog for these motors.
Need to know what you have now and how it's mounted.
Photo would help.

mazemeister · Jul 16, 2019

is this motor run off the tractor hydraulics? if so, can you switch to a different tractor with a smaller displacement pump? or change out the motor you have for a larger displacement motor? other things being equal, doubling the displacement of the motor will half the rpms...

Oliver 500 Wa · Jul 16, 2019

......What is the displacement per revolution of the hydraulic motor you are now using?

This is an important factor in trying get your speed control dialed in. The larger the displacement per rev, the less change in speed will occur for any given adjustment of a flow control.

Also, if you are not using a needle valve type flow control, it would be good to switch to those.

If the motor has a separate case drain line, the needle valve should be on the return line (assuming the motor is uni-directional). This gives you very good speed control.

BarnyardEngineering · Jul 17, 2019

I have no idea what motor it is. It looks like certain Charlynn motors but has no markings on it, just a bar code which does not come up in google. Square base about 3-1/2", mounts with four bolts.

When I bought it the person I bought it from said it had the lowest RPM motor money can buy. He was very specific about that because he bought the wrong motor at first.

Where do you find a motor rated for 50RPM? The lowest I've found is 540.

Bob · Jul 17, 2019

(quoted from post at 06:41:20 07/17/19) I have no idea what motor it is. It looks like certain Charlynn motors but has no markings on it, just a bar code which does not come up in google. Square base about 3-1/2", mounts with four bolts.

When I bought it the person I bought it from said it had the lowest RPM motor money can buy. He was very specific about that because he bought the wrong motor at first.

Where do you find a motor rated for 50RPM? The lowest I've found is 540.

Surplus Center has orbital motors up to 60 cubic inches displacement per revolution.

With a 10 GPM oil flow (as an example), they'd turn under 40 RPM's.

BarnyardEngineering · Jul 17, 2019

Yeah, to the tune of $650 and with a 1-1/2" shaft... That's half of what I paid for the wrapper and requires completely reworking the machine, which I'm trying to avoid.

I just can't believe there isn't a simple gearbox with a 1" female input and a 1" male output. Seems like something that would be extremely common.

Destroked 450 · Jul 17, 2019

How about a photo of the motor, some of the offshore unit's don't have much info on them today.
Char-Lynn H series is what we used a lot of, serval different sizes if they mount similar to yours. They come in several sizes that determine torque and speed.
A photo of the flow control would also help, the needle type as mentioned won't work on a open center system.

This is the type of motor and flow control I'm talking about

Gearbox for a hydraulic motor

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