Spur gear help needed

[MMW]

]I'm rebuilding a customers swing boom on his log skidder. The boom was made by Esco who no longer sells or supports them. Parts are n/a.

I need to find or have made a new spur gear & rack. It just swings the boom from side to side. I was quoted $9000.00 by Rush gear to have a replacement made. Can't put that much money into just two pcs. Anyone got any ideas or suggestions before I search for other quotes? I'm assuming that most places would be in the same price range for custom gears. I have searched for something in a "stock" size but coming up empty.

Gear is 3 pitch, 11.8125 od x 3.125 id x 3" wide with a 7.5" x .5" deep counter bore on one face. The rack is 25"+/- long x 2.75"w x 1.875 deep. I think it is just mild steel as it grinds & cuts like it.

As a last resort I may try to have 1/2" thick plates water jet cut & then laminate them to make a gear & do the same for the rack.

gear welded to post.

gear removed.

rack.

rack end detail.

[H80N]

]I'm rebuilding a customers swing boom on his log skidder. The boom was made by Esco who no longer sells or supports them. Parts are n/a.

I need to find or have made a new spur gear & rack. It just swings the boom from side to side. I was quoted $9000.00 by Rush gear to have a replacement made. Can't put that much money into just two pcs. Anyone got any ideas or suggestions before I search for other quotes? I'm assuming that most places would be in the same price range for custom gears. I have searched for something in a "stock" size but coming up empty.

Gear is 3 pitch, 11.8125 od x 3.125 id x 3" wide with a 7.5" x .5" deep counter bore on one face. The rack is 25"+/- long x 2.75"w x 1.875 deep. I think it is just mild steel as it grinds & cuts like it.

As a last resort I may try to have 1/2" thick plates water jet cut & then laminate them to make a gear & do the same for the rack.

gear welded to post.
[ATTACH]35138[/ATTACH]
gear removed.
[ATTACH]35139[/ATTACH]
rack.
[ATTACH]35140[/ATTACH]
rack end detail.
[ATTACH]35141[/ATTACH]

Have you considered looking into having them laser cut?? then finish machined??

a laser would get your gear teeth to a pretty decent tolerance..

It could not be too expensive to have an hour or two of Acad .. Mastercam or some other CAD/Cam system time to generate drawing files..with an experienced draftsman.. especially since you have the old parts as models...

Maybe check with these guys..??

http://precisiongearmanufacturers.com/finishing/laser-cutting/

[gnforge]

Spur gear help needed

My neighbor is a retired machinist. He has a lot of experience in this type repairs.
Looks like could be made from 3" stock but I'm welder & wannabe machinist, he is machinist.
Be glad to ask him tomorrow & get back to you.

[digr]

]I'm rebuilding a customers swing boom on his log skidder. The boom was made by Esco who no longer sells or supports them. Parts are n/a.

I need to find or have made a new spur gear & rack. It just swings the boom from side to side. I was quoted $9000.00 by Rush gear to have a replacement made. Can't put that much money into just two pcs. Anyone got any ideas or suggestions before I search for other quotes? I'm assuming that most places would be in the same price range for custom gears. I have searched for something in a "stock" size but coming up empty.

Gear is 3 pitch, 11.8125 od x 3.125 id x 3" wide with a 7.5" x .5" deep counter bore on one face. The rack is 25"+/- long x 2.75"w x 1.875 deep. I think it is just mild steel as it grinds & cuts like it.

As a last resort I may try to have 1/2" thick plates water jet cut & then laminate them to make a gear & do the same for the rack.

gear welded to post.
[ATTACH]35138[/ATTACH]
gear removed.
[ATTACH]35139[/ATTACH]
rack.
[ATTACH]35140[/ATTACH]
rack end detail.
[ATTACH]35141[/ATTACH]

What's wrong with the old set??? That isn't a 360 degree swing and the teeth on the gear and rack can be built up. I have cut old teeth out of a rack and welded new ones in and ground to fit and I would think that if the gear could be reoriented, it would help. I gave the new teeth 100% weld and heated the rack before welding.

[MMW]

H80N - Yes I thought about laser or water jet cut pcs. I assumed 3" thick would be to much to cut in one pc. or not accurate enough so I thought several 1/2" thick pcs. "laminated" together should work.

Thanks for the lead, I will contact them.

gnforge - Thanks for the offer but I do have two good machine shops I use. Haven't gone there yet as I figured it would be labor intensive for them to make one off gears. I am trying out shops dedicated to gear making first.

digr - The old gear is very worn on both sides as it was spun 180* (reoriented) 17 years ago during last rebuild. A new rack was installed then but now is really bad & has two missing teeth. I do have the original rack which is the better of the two. I thought about welding up teeth & grinding but again that will be very labor intensive so that is a last resort. They need to be accurate as the rack gets shimmed to a pretty close tolerance.

Thanks for the suggestions.

[Sberry]

There may be a generic gear that can either be cut out or have the right hub welded in.

[MMW]

There may be a generic gear that can either be cut out or have the right hub welded in.

I have been looking for a "stock" size gear of the same od & pitch. No luck yet. I can always make the center fit if I found one.

[MMW]

Received this e-mail back from the link H80N posted. Still looking.

Mic, good afternoon. Unfortunately BC Gear is no longer in business. Should you need any precision machining done at your business, let me know as I would like to recommend someone.
Thanks,

Elton Bahnsen
KLSS, Inc.
864-934-9950

[H80N]

Received this e-mail back from the link H80N posted. Still looking.

Mic, good afternoon. Unfortunately BC Gear is no longer in business. Should you need any precision machining done at your business, let me know as I would like to recommend someone.
Thanks,

Elton Bahnsen
KLSS, Inc.
864-934-9950

Sorry to hear that...

[Tryagn5]

Received this e-mail back from the link H80N posted. Still looking.

Mic, good afternoon. Unfortunately BC Gear is no longer in business. Should you need any precision machining done at your business, let me know as I would like to recommend someone.
Thanks,

Elton Bahnsen
KLSS, Inc.
864-934-9950

Looking at the pictures maybe I missed it but the loose gear did not look to bad, most of the wear should be in the rack, that rack should be able to be welded up and reground. Or I would be looking at other manufactures who uses rack and pinion. FYI Vermeer uses a rack and pinion drive in there bore rigs, you might be able to get the Vermeer factory to disclose who makes them. Also depending on the wear the rack can be shimmed in the base to give a tighter grip with the teeth, normally racks wear from the end of the tooth in, so a shim behind the rack will push the teeth to mesh deeper. That would be a last resort.
Kevin

[MMW]

Gear is very worn although the edges look decent as the rack doesn't go all the way to the edges. Gear is 3" wide & the replacement rack was 2.5".

Went to an old friends machine shop today to discuss. He doesn't do this type of stuff but knows all about it. Searched his connections & catalogs but nothing comes up that is exact. So now he is making me cad drawings & once that is done I will get quotes on having it cut in one pc. by an EDM & also get quotes on having thinner pcs. laser or water jet cut, then "laminating" them together.

That's where I'm at. I now have way too many hours in this job just trying to source the gear & rack.

[H80N]

Gear is very worn although the edges look decent as the rack doesn't go all the way to the edges. Gear is 3" wide & the replacement rack was 2.5".

Went to an old friends machine shop today to discuss. He doesn't do this type of stuff but knows all about it. Searched his connections & catalogs but nothing comes up that is exact. So now he is making me cad drawings & once that is done I will get quotes on having it cut in one pc. by an EDM & also get quotes on having thinner pcs. laser or water jet cut, then "laminating" them together.

That's where I'm at. I now have way too many hours in this job just trying to source the gear & rack.

The rest of us will be richer for your experience and willingness to document and share the process of resolving this problem...

I know that is not much solace for all the time and effort you are putting into this.. but hopefully it will greatly help others in the future...

Thanks..

[Don52]

Generally if the gear teeth wear too much, going to a finer pitch will reduce the contact stress and improve gear life. Harder gears also wear better. Gear teeth break for a variety of reasons:

1. The pitch is too fine.
2. The teeth have become thinner and weaker due to wear
3. Some junk got caught in the gear mesh.

Depending on why the rack teeth failed, one option would be to replace the gear and rack with one that had a finer pitch, and then shim under the rack to maintain the correct center distance. This assumes that if you can't find an exact replacement it might be possible to find something close. It does seem that this gear set has a very course pitch and massive face with.

[MMW]

I'm finally back on this job. I decided & was able to have a new rack & gear made which I just received two weeks ago. Long lead time but best price was from Griffin gear. $6200. I was able to get manufacturing drawings which helped immensely.

I need to weld the new gear to the old tower. Gear is 4340 heat treated & tower is mild steel. Looking for another opinion on procedure & wire to use. My research & past experience tells me to preheat to 400-500* with a slow cool. For wire I can use a low hydrogen 70 series as I only need to match the lowest base metal which is the tower. Some dilution will occur which should raise the overall strength of the weld slightly but will remain plenty ductile. I should not have to use a 110ksi rod due to the fact both pcs. are not 4340.

Tower sits on top of gear & gets welded fully around.

[MMW]

Long road to finish this. Started earlier in the year, took awhile to find a gear mfg. then 8 weeks to have it made. The customer by that time had rigged up a pulley set up for the winch as his other skidder went down. By the time he was able to take this off the job & me to schedule it in was awhile. In all it was about seven months total.

We assembled the machine today. Customer just has to finish hooking up a few hoses. We hooked up the swing hoses & rotated it back & forth. At first we didn't have the cylinders fully locked down & it bound up by getting off center. Stupid I know. Pulled it all apart & it only left two small marks inside one of the cylinders that we were able to sand out but hand. Got very lucky there. I really didn't want to make another cylinder. It was tough figuring the whole thing with out any prior knowledge or assembly book. I'm not the first one to work on this so everything was double checked as I went. In my mind it is a weird set up. Everything has to fit just so & there isn't any adjustment to speak of.

first couple passes in.

finished welding

wrapped in insulation for slow cool