mark chandler
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| posted on 1/9/13 at 06:31 PM |
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Reverse gear pulleys
Hello chaps
I need to put an electric reverse on my car, the transmission tunnel is very narrow so I am looking at fitting a camshaft gear onto the sierra diff
output shaft and grafting a crank gear onto the winch motor (slow turning, lots of torque 12v, target price £50 including the winch.
The winch has now been purchased, £30 so I now need some pulleys, has anyone got some old camshaft pulleys? The question I need answering, although
these are made for toothed belts will a small crank pulley mesh with a cam pulley directly? If so I now have a cheap gear option 
Failing that some old lathe gear change cogs should do the job.
Longevity and noise are not an issues, it will only be pass scrutineering.
Cheers Mark
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Volvorsport
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| posted on 1/9/13 at 07:02 PM |
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have you worked the gear ratio out ? 1:2 doesnt sound like a lot ?
how do you engage the gear also ?
sounds like a good idea tho, never thought about a winch motor
www.dbsmotorsport.co.uk
getting dirty under a bus
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steve m
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| posted on 1/9/13 at 07:25 PM |
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what about a xflow cam pulley? its about 5" and toothed for a chain
I might have a spare one knocking about
Thats was probably spelt wrong, or had some grammer, that the "grammer police have to have a moan at
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dave_424
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| posted on 1/9/13 at 07:39 PM |
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I'm sure you probably know already, but I'm pretty sure winch motors have a planetary reduction gear between the motor shaft and the winch
drum, the motors actually turn pretty fast.
Dave
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mark chandler
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| posted on 1/9/13 at 07:58 PM |
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I,ll be modifying the cable drum on the winch to take a gear, I guess it spins at around 100rpm with a 250kg pull load.
To work I just need a bracket so it drops into mesh when in use, some kind of lever affair should be fine.
Old cam gears are just a cheap thought, looking at eBay I can get some lathe gear change cogs which will give me a much greater range
Has anyone got any old larger lathe cogs catching dust? Harrison etc, maybe a 5" and 1.5" pair of gears.
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dhutch
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| posted on 2/9/13 at 06:07 AM |
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I cant see using tooth pulleys, meshed as gears, without a belt, its going to be other then hideous. A lot of tooth belts are less than 50% too as
well, meaning the pulley cannot mesh, as per the below image.
Lathe gears sounds a much better idea, although you can/could by off the shelf pulleys new for very reasonable prices, or as said, you could go with a
chain drive solution, or even belt drive, which my be less fussy on mesh, if you have the space to get something in which can handle the torque.
That said, before making anything, I would do a few more sums than you appear to have done, 100rpm sounds faster than I would expect a winch drum to
run, and with a four to one (roughly) on the diff, I have a feeling you might be far too slow.
- But if you have the lift rate, drum dia, diff ratio, and tyre dia, you can calculate it all in a speadsheet in about 10minutes..
Daniel
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mark chandler
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| posted on 2/9/13 at 09:29 AM |
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Looks like lathe gears or similar will be the solution then
The drive gear will be on the output shaft, 13" wheels with 60 profile tyres so one revolution is around 5 1/2 feet.
Google tells me 5280 feet in a mile so devided down gives around 1.5mph turning it will then be fast, maybe 10mph with 2:1 gears on the output but its
only for going back enough so I can enter my car for sprints in a road going class.
I had better paint a strip on the winch drum and count out the revolutions.
It should be more powerful than say a bike starter solution although a little heavier but more accessible and as I like locost using new parts for
under £50 
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mjkh
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| posted on 3/9/13 at 12:55 PM |
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I've made a few BEC winch reverses for lcost race car over here in Finland. We must have working reverse gears in our race series.
I've used 1:1 gear ratio and gear OD is 102mm. Gear is big enough for the gear to mesh over the sprocket adapter and small enough to have a bit
of clearance to engine casing. I've used a lever to push the winch forwad to mesh the gears and I have a push button on the lever to spin the
motor.
Here's one
http://3.bp.blogspot.com/-_yKnhU7NLJs/UguDPl-n4LI/AAAAAAAAFyg/KqEdUX8V7sA/s1600/WP_20130804_008.jpg
An other one being test fitted
https://picasaweb.google.com/lh/photo/QnDZQaHSEQbaIwKpMOO6uNMTjNZETYmyPJy0liipFm0?feat=directlink
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stevio73
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| posted on 3/9/13 at 09:07 PM |
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Why not just have a cog lazer cut? Then size, pitch,etc wont be an issue. Use the right material and then case harden maybe? Real easy solution.
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dexion7
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| posted on 10/9/13 at 06:14 PM |
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watching this with interest!
could you use a clutch off an air con compressor to engage when you press a switch?
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