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Old 07-11-2011, 10:06 PM   #1 (permalink)
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Adding a gear reduction box to engine stand

I've seen a few posts on this but nothing specific that I can find on here or anywhere on google. I'm building my own engine stand using 2X3 1/4" wall square tube and heavy duty locking casters. I am making my own since I cant find one I like thats affordable.

I'd like to add a gear reduction box to make it easier to turn anything from a straight 6 gasser to a 6 cylinder cummins (roughly 1200lbs full weight). From my research a 60:1 box will allow you to turn it over easily by hand and not allow the engine to torque over on its own.

I've considered using a starter gear and flywheel like some have but would rather have a nicely contained box if possible. I'm just not sure on what the minimum specs need to be on the gear box. I'm not sure if it matters but I plan to make a large heavy walled spindle with dual wheel bearings to support the weight of the engine.

Any suggestion on a cheap gear box? I'd like to find a decent used one, seems like you can find heavy duty ones on Ebay for around $100-$150.

I doubt this one would work but figured I'd throw it out there to get input, http://www.surpluscenter.com/item.as...ame=powerTrans

or would I be better off with something like this http://cgi.ebay.com/NEW-TORQUBE-60-1...item5ae14bf89c

I wonder if I could just buy this 2000lb harbor freight winch http://www.harborfreight.com/2000-lb...ake-68146.html remove the spool and cable then attach it to the head of the engine stand? It states 153:1 ratio. I just wonder how well any of these would hold up to a heavy engine.

Thanks

Last edited by carcrafter22; 07-11-2011 at 11:08 PM.
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Old 07-12-2011, 01:48 AM   #2 (permalink)
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After doing some reading I've come up with a few things on gear ratios and forces. It seems that if you take a 60:1 gear box that can handle 445 in.-lbs. max that translates into 37 ft-lbs. With the 60:1 ratio it should be capable of 2220 ft-lbs of tq output, at least I think. Would this be enough to handle turning over a fully dressed diesel engine or would I need to further reduce it using a timing chain setup? Maybe a 2:1 drive from a ford 302?

If I needed the extra gear reduction I could attach the output shaft of the 60:1 box to the crank gear on a timing set and the cam gear from the timing set to the head of the engine stand (timing gears are 2:1) should give 4440 ft-lbs tq again at least I understand it will anyway. Feel free to correct me if I'm wrong.

What I'm wondering.

Will a 60:1 445in-lbs be fine to turn a heavy diesel engine over?

I've never messed with stuff like this before so any help is appreciated.
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Old 07-12-2011, 07:11 AM   #3 (permalink)
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Friend if you're going to have a fully dressed Cummins on it why not go hydraulic set up? Get a electric motor/hydraulic pump assembly (like whats on a tube bender) Then add a valve and motor. It would make it waaaay easier on you.
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Old 07-12-2011, 10:03 AM   #4 (permalink)
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ive seen them with an entire axle spindle assembly as the pivot, and a manual locking hub to lock it in position. throw a handle on there and id bet a 5 year old could spin it.

go find a wrecked axle in a yard and salvage the spindle ~$50 or less
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Old 07-12-2011, 02:55 PM   #5 (permalink)
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ive seen them with an entire axle spindle assembly as the pivot, and a manual locking hub to lock it in position. throw a handle on there and id bet a 5 year old could spin it.

go find a wrecked axle in a yard and salvage the spindle ~$50 or less
If the weight is centered on the axis of the spindle, yes.

On an engine stand it is almost never centered well, and 1200 lbs of iron wanting to spin is something I know I couldn't handle, much less a 5 year old.
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Old 07-12-2011, 02:57 PM   #6 (permalink)
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Here's what to look for. (I am not affiliated with the seller)
http://cgi.ebay.com/GRANT-WORM-REDUC...item415a542a05
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Old 07-12-2011, 05:41 PM   #7 (permalink)
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If the weight is centered on the axis of the spindle, yes.

On an engine stand it is almost never centered well, and 1200 lbs of iron wanting to spin is something I know I couldn't handle, much less a 5 year old.
Thats what I was thinking which is exactly why I'm on the hunt for knowledge on this subject. I just dont think the $300-$500 1000 pound gear driven units available are heavy duty enough and I'm not spending $2500 on a "diesel rated" (their words not mine) unit.

I found this leeson for $40 and is 60:1 ratio, 1 1/8" output shaft, 14mm input shaft.

I like its fairly compact size and the ratio seems about perfect but I wonder if its up to the torque needed to turn the engine over when its not perfectly balanced (cause it never will be). I'd hate to get this thing all setup and seemingly working perfectly only to have it explode allowing a fully dressed cummins engine to spin uncontrolled then doing summer saults across the shop floor.

This one is rated at 445 in-lbs but even the biggest units I see on ebay or surplus stores (weighing in around 90lbs) are only rated to around 1200 in-lbs which still isnt much really.

I'd love to be able to hook up the leeson mentioned above or something like it along with a 1500rpm 1/4hp motor and a reversing relay so I can turn it either way with the push of a button (all for cool factor )
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Old 07-12-2011, 06:14 PM   #8 (permalink)
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You'll need a unit that won't back drive...
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Old 07-12-2011, 07:18 PM   #9 (permalink)
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You'll need a unit that won't back drive...
What does that mean?
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Old 07-13-2011, 04:48 AM   #10 (permalink)
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What does that mean?
Spin the handle due to the torque the engine can generate on the stand.

OTC makes a nice one.

I've worked on some huge engines and never saw the need for such. An engine hoist, a coupla guys, etc. have been able to move some HUGE engines, although, the stands were supporting the engines from the front and back of the block.
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Old 07-13-2011, 12:10 PM   #11 (permalink)
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You'll need a unit that won't back drive...
Worm gears really don't like to do that. I'd go with a worm gear reduction box and put a 3/4" hex on the drive end so you could use a speed wrench [the dealieos that look like old fashioned brace drills] and a 3/4" socket to move it.
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Old 07-13-2011, 07:09 PM   #12 (permalink)
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I think thats what I'm leaning towards to keep it simple. I can pickup complete units on ebay with 60:1 speed reducers, electric brakes and 3/4 hp motors for $125 but the more I think about it I dont think I want to add all the complexity and required extension cord.

I'm thinking just a simple 60:1 reducer but I cant find anyone that can tell me how robust of a box I need. I see most of these boxes are rated at around 445in-lbs and a few rated up to 1200 in-lbs but they weigh around 90lbs.
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Old 07-14-2011, 01:25 AM   #13 (permalink)
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I see most of these boxes are rated at around 445in-lbs and a few rated up to 1200 in-lbs but they weigh around 90lbs.
If that rating is input torque, then go for the 445in/lb one.

Remember the rating is probably for 24/7 use in a production environment or some such shit. The gears won't significantly wear on your application so the rating probably doesn't mean much.

Last edited by [486]; 07-14-2011 at 01:26 AM.
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Old 07-14-2011, 07:31 AM   #14 (permalink)
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Just for S&G - let's say you've got that 1200# cummins on there, and it's center of mass is 12" from the pivot axis. So we're dealing with a moment of 14400 in-lbs. Take that back through the 60:1 reduction, and that only takes 240 in-lbs to move it.

In fact, for the full 445 in-lb input, you could have that engine 22-1/4" out of balance. I've never played with one of those big boys, but I have to assume that you could center the mass better than that.
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Old 07-14-2011, 06:57 PM   #15 (permalink)
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Now we're getting somewhere, thanks guys.

I think I finally found a worm gear box that will work. It's only 40:1 but that should be fine I'd imagine and if I really need to I could always run it through a small set of gears to add 2:1 making it a final ratio of 80:1 but I doubt that will be needed.

Specs.

40:1
Cast Iron case
Weighs 30lbs
Worm gear
tq 1433 lb-in
overhung load 1300 lbs

For its size this is about the beefiest one I've seen.
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Old 07-15-2011, 08:29 AM   #16 (permalink)
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We had some really nice stands at Mercedes school, exactly like what you want. I believe they told us they ran about $10k each. Don't remember who made them, possibly Hazet or Stahl-Willie?

Good luck finding a viable option, they were really really nice to work with.

Edit:

Something very similar to this: http://www.benco.co.uk/engine_stands.htm

Last edited by maslin; 07-15-2011 at 08:33 AM.
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