View Full Version : reduction gearbox/transmission

Stephen Sebed
10-29-2012, 6:44 PM
Anyone know of a good way to reduce the rpms on a motor (exploring both gas and electric options) down to about 200 rpm with some degree of speed control say between 150-250rpm?

The end application will be used to wind up electric fence wire back onto spools. So the motor needs enough power to pull about 1/2 mile of light gauge wire with 10 lb weight tied to the end to keep the wire straight.

If I did the math right 200 rpm should be a good speed to turn the spool. I think a 1hp electric motor would have plenty of power (actually a 1/2hp would probably do it) with the needed rpm reduction. So right now I'm considering 3 different approaches: a small gas engine (have an old 5hp briggs) with a reduction gear box. (new gearbox is about $150), an electric motor with reduction gearbox (would need both motor and gearbox ~$200-250) would have to drag around a generator to use and speed control on single phase motors could get complicated, and last a gas over hydraulic setup (small gas engine running a hydraulic pump).

The hydraulic setup would be the easiest to use and also the most expensive (unless I can find the pumps and hoses on some old equipment somewhere). So I think my best route would be the gas engine with a gearbox of some kind. Any suggestions on where to find a gearbox or transmission with a ratio between 10:1 and 20:1? I've been looking at go cart torque converters but I don't think they have the needed ratio. What else would use a ratio like I need?

Does anyone make a gearbox that would bolt up to a 5hp engine (seems like most engines this size use a 3 5/8" bolt circle)?

What ideas do you guys have?

Dan Hintz
10-29-2012, 6:54 PM
Would a car winch be of adequate speed (I have no idea how fast they move)? Harbor Freight sells several, starting at $80 (plus, you can use the 20% off coupon and get it for around $70 out the door).

Stephen Sebed
10-29-2012, 7:35 PM
No, winches seem to have ratios in the hundreds to one ratio area. I looked into using the 12v connection on the back of a pickup and figured even at 30amps at 12v I wouldn't have enough power to pull with any amount of speed. 12v*30a=360watts. 360W/746WperHP=0.48HP. So with 0.48HP of electrical power at the trailer connection, I figured this would be the low side of marginal for my needs. If anyone thinks I ought to explore this option further I'm all ears. I'm really not sure how much power I need to reel in 1/2 mile of wire in a reasonable amount of time (I've been using 10 minutes as a rough figure). Also, I don't have a figure for how much force it takes to pull 1/2 mile of wire with a weight (the weight is an old window sash weight ie long and narrow). So, a lot of my calculations are very rough. I just sort of settled on 1 hp or greater.

Back to the 12v motor run off pickup power, this still might be a viable option. Variable speed control would be a lot easier running a dc motor.

Rod Sheridan
10-29-2012, 9:02 PM
Hi, a small gas engine engine will have about a 3 to 1 range of speed.

So, if you assume 1,200 to 3,600 RPM you would need an 8 to 1 reduction ratio, not difficult at all.

However, I made a cable reel driver for 700 pound lengths of power cable, using a 1/2" heavy duty variable speed drill.

The drill would only need a 2 or 3 to 1 ratio, very simple to achieve..and it could run from an inverter off your car battery..............Rod.

Jerry Bruette
10-29-2012, 10:24 PM
You could gear it down by using a jack shaft and the proper size sheaves. If you use the gas engine method how are you going to clutch the spool?

Most gear boxes are made to bolt up to a C faced electric motor. You could check with surpluscenter.com for a gear box.

The other advantage of the jack shaft and sheaves would be that if you should snag your weight on something you won't deadhead your drive and possibly pull it off whatever your lugging it around on.


Ole Anderson
10-30-2012, 12:18 AM
Grainger sells gear reduction motors.

curtis rosche
10-30-2012, 1:56 AM
We had a cable winch rig set up at school for stacking wrestling mats, a 40:1 worm gear reduction with a 1 inch square drive. We used a right angle drill with a 1 inch socket to turn it. I bet that would work easy

Stephen Sebed
10-31-2012, 9:34 PM
I hadn't thought of using a heavy duty drill. That might work and would be simple also. Would a standard ac inverter (I'm picturing one that plugs into a cigarette lighter) have enough power to run a drill like this or were you thinking a larger inverter hooked directly to the pickups battery?

If I end up using a gas engine, I was planning on a simple belt type clutch. The motor would have a pulley and there would be a pulley on the shaft with the spool, a belt tensioner attached to a lever would tighten or loosen the belt to work like a simple clutch. Right now I'm trying to find a gear box that bolts directly to the engine, commonly sold together for use on small cement mixers with a 6:1 ratio. I haven't been able to find just the gearbox. If I could find one and then use a small reducing ratio with the pulleys on the clutch, I'd be set with this option also.

keep the suggestions coming!

curtis rosche
10-31-2012, 11:51 PM
You could use an air powered tool to run it, just throw the compressor in the truck. Im assuming it will be mounted to either a post or a truck while tensioning?

Larry Edgerton
11-01-2012, 6:33 AM
Try this joint......http://www.surpluscenter.com/

They have a bunch of odd stuff cheap.

How about a old riding lawnmower transaxle? Several speeds, long shaft to mount your pulley, and can be had free. Free is good.


Stephen Sebed
11-03-2012, 12:44 AM
I would need a really large compressor to run an air tool long enough to reel in 1/2 a mile of wire. I'm not using this setup to stretch the wire. It will be used to reel in the wire when the fence is no longer needed.

I'll have to look into the riding lawnmower transaxle, I think there's an old riding mower around here somewhere that might have some good parts on it.

Thanks for the suggestions so far!


Chris Parks
11-03-2012, 4:16 AM
Scale sailplanes use a winch something like this


It is powered by a car/truck starter motor and the speed is variable by a foot control. These are damned powerful things though the fliers use nylon cord instead of wire and anything that can pull a 4 metre scalie should do the job.

There are a few more here

https://www.google.com/search?num=10&hl=en&site=imghp&tbm=isch&source=hp&biw=1362&bih=583&q=scale+glider+winch&oq=scale+glider+winch&gs_l=img.3...3853.9024.0.9748. 09.0j5j7.12.0...0.0...1ac.1.kKM3vhWfI_s

Rich Engelhardt
11-03-2012, 7:59 AM
How about something like this:

Powered by a starter (12V) motor.

Steve Campbell
11-09-2012, 8:49 PM
Stephen. I have to wonder if light guage fence wire is strong enough to pull a half mile of wire? Also if your window weight catches on something solid, and the wire breaks, I sure wouldn't want to be in the way. There is a lot of potential energy. People have been killed when cables have broken. I think you could have it rolled up by now if you just rolled it up by hand. Another thing to think about is when you strech wire too tite it is very hard to get it straight again.
Just some things to think about.


Stephen Cherry
11-09-2012, 10:12 PM
I've seen briggs and stratton engines running car power steering pumps on trotline pullers on crab boats. If you are good at scrounging, this could be put together pretty inexpensively.

Laurent Morand
08-02-2017, 3:25 AM
Thank you for this useful information and thanks for all the suggestions too!

John K Jordan
08-02-2017, 8:10 AM
...Also, I don't have a figure for how much force it takes to pull 1/2 mile of wire with a weight (the weight is an old window sash weight ie long and narrow).

[Ha! I just noticed this was an old thread! Good fun. :)]

You might try pulling the (tensioning?) weight with a spring-loaded hanging scale, such as for luggage or fish. But without a clutch I'd be concerned about it snagging on the ground or something and causing a disaster before I could cut the power - maybe put it on a sled (or have someone walk with it.) Or use another method for tensioning, such as a pulley or two with some rotational tension and a manual idler.

I didn't have time to read all the posts so this may be covered: Do you have a tractor with a PTO? Plenty of power and no problem with the speed control.

Or a powerful variable-speed corded electric drill. I have a big (and old) VS Makita that has so much power it will almost twist your hand off if it gets jammed!


John M Wilson
08-02-2017, 10:54 AM
Before you reply, please note that a first time poster has resurrected a 5 year old thread.

Steve Peterson
08-02-2017, 11:42 AM
Do you have to pull the entire weight of the wire? I assume that you are working from a truck or ATV. Can you drive into the wire and use a battery powered drill to roll it up as you go? The drill only needs to be strong enough to wind the wire.

With your original plan, you have to pull the entire weight of the wire. You should have some mechanical advantage at the beginning because the spool is empty even though it needs to pull the most weight. Near the end, the spool is larger, but the pulling force should be smaller. Not sure if you would need a speed reduction unless the wire starts pulling too fast at the end.


Rick Potter
08-02-2017, 12:09 PM
Perhaps a gate closer. I have an 18' gate and the electric closer is geared down to practically nothing. It has sprockets and chain drive, which could be reconfigured.