Need help finding a 21 tooth gear for my bedroom slide out

[Fffrank]

It's a martin m1221c gear. They are readily available but do not include the provision for the roll pin (so a machine shop will need to drill them out to match your existing gear.)

I just purchased two of them from BDIExpress and including shipping was almost $100 on the dot. Martin will not sell direct.

Also - I believe almost any miter gear set with the same bore size (3/4") would work but you would need to create new bushings to control the back spacing. The diameter and pitch would dictate of the set would run slower or faster (although who really cares?)

I was not able to find any other gear sets that would be pre-drilled so decided it was best to trust that the original engineers picked the right angles and go with the original spec gear. It's a hassle to need to find a machine shop but once it goes back together should (hopefully) last another 20 years?

[Tindalsj]

fffrank- Thank you for your post, but the part you reference is not the part we are discussing. I think you are referencing part number 521129, which is a miter gear.

Lippert 368967 / DN13747 is a spur gear with a woodruff key to keep it from spinning on the shaft. The bore is 5/8".

See photo at:
https://pdxrvwholesale.com/products/...1-teeth-368967

In any case- I suspect there is an equivalent gear available, perhaps from the manufacturer you mention, but I am not able look through any catalogues and understand the differences in the various catalog specuifications.

[Fffrank]

Sorry about that! I see the specs you are looking for now. I gave the Martin and Boston gear catalogs a pretty thorough review and didn't see ANY gears that have an overall diamater of 1.917, bore of .625 and 21 teeth. I was hoping there would only be a single choice and that would narrow down whether these were 20deg or 14.5deg diametral pitch.

Can you replace both gears that mesh together with some that you know have roughly the same overall dia as well as the correct teeth? For instance, a Boston NB26B-5/8 has an overall dia of 1.917, bore of .625, hub thickness of .44 and a keyway/set-screw already provisioned? It has 24 teeth and a dia pitch of 14.5. It's also only $12 on Amazon. Work out the specs on the matching gear for the other shaft and order one you know will mesh and you should be good to go?

[153stars]

For HWH and Lippert odd flat spur gears with round keyed shafts. I think your best chance find same spec spur gear that has hub with set screw and have the hub machined off.I could probably get close enough with caliper, band saw and grinder. The actual gear widths seems to be pretty standard. Some gear blanks come up in a search as well but needing bore and keying .

[Tindalsj]

Thanks guys for your reply. The idea of finding a similar gear with a hub and then modifying is appealing. I'm going to look into that. I'll update with what I find. The trick is trying to match specs of course.

I have to believe others are going through the same problem.

[DonaC]

The ND21B-5/8 mentioned earlier looks like a match.


https://www.mrosupply.com/gears-gear...SABEgLoDfD_BwE

[153stars]

EDIT never mind OD is got to be wrong not sure how if 21 tooth and pitch is the same as one I was reading listed earlier.
SORRY
This looks like a winner if 3/8" wide??? IDK the key size.. but no hub.
https://www.motionindustries.com/products/sku/02171581

[153stars]

EDIT never mind OD is got to be wrong not sure how if 21 tooth and pitch is the same as one I was reading listed earlier.
Couldn't edit pic in after
https://www.motionindustries.com/products/sku/02171581

[153stars]

I would add that Motion Industries like shared above have stores in Metropolitan areas. These stores after to industries , fabricators , farmers and public that repair their own gear...ect and can be great help. They have fixed me up belts ,bearings and sheaves as well as supply our plant . They maybe able to recommend a good down home machine shop to cut down or bore a gear as well.

[Tindalsj]

Hello all:
Let me summarize what I've learned and what steps I've taken. Today I bought my damaged gear to Machinists, Inc Gear Division (aka Gear Works) in Seattle, WA. The very helpful counterman confirmed all the gear geometry measurements of my original gear, and then looked through a variety of catalogs and online for a match. There is no stock matching part. Below are the details.

2004 Holiday Rambler (Endeavor) / Monaco (Diplomat)
Bedroom slide spur gear damaged

Part #1: Lippert #368967 - obsolete replace by...
Part #2: Power Gear #DN13747 - also obsolete

Gear geometry as measured from my gear (inches, confirmed by Gear Works, Seattle WA):
Outside Diameter: 1.917
Pitch Diameter: 1.750
Total Width: 0.75
Face Width: 0.50
Bore: (5/8") 0.62
Woodruff keyway: (1/8") 0.13
Hub: 1/8" each side
Hub Dimension: 1.3
DP (Diametral Pitch): 12
Pressure Angle: 14.5 degrees

I have not found any exact match, but there are 2 manufacturers of a gear with the same teeth, pitch, bore, and diameter. The width and keyway do not match.
Martin 21221BS 5/8
Boston ND21B-5/8

Both these gears are available from a variety of resellers, but I found the price better at MroSupply: Thank you DonaC!
https://www.mrosupply.com/gears-gear...SABEgLoDfD_BwE

Issues with the replacement gears. These need to be addressed, and as suggested by 123stars most probably by a qualified machinist:
1. The original part has a 1/8" keyway. The replacements are 3/16". The solution will be to cut a larger keyway into the existing shaft, or cut an additional smaller 1/8" keyway into the new gear.
2. The replacements are wider and have a hub. The solution will be to cut the hub off so the exact width is 0.75- same as the original.
3. The original part was 0.50 face width, with two 1/8 shoulders on each side. After cutting of the hub, the new part will be 0.75 face width. I will need to confirm the fit, but I can't see any reason to cut the face down to 0.50. Instead the spur gear will simply be oversize for the rack. As long as there is available clearance I can't see a problem with this, but would appreciate any thoughts.

I've ordered that part and will update this thread once my machine work is complete. At this point I am only $50 into this with the gear ordered. My machine work could easily be $100-$150, so I'm going to keep looking for an exact replacement as well.
Steve

[153stars]

I have picked up full keyed shaft from McMaster Carr , To repair large explosion proof roof fans. New high quality pillow block bearings, belt sheave and full keyed shafts . I could have several made up and install not waste time trying press or pull 20yr old iron belt sheave off then bearings and pull out of fan hub. I just cut shaft and knock stub through fan hub. 5/8" will be very affordable just cut to length dress / bevel the cut with file. Seen similar on amazon
https://www.mcmaster.com/shafts/keyed-rotary-shafts-5/
McMC didn't have the gears unfortunately. We can buy same items cheaper than distributers or manufacture. You just pretty much never know brand name until in you hand.

[Tindalsj]

I did manage to resolve this problem. I am including previous information so that anyone finding this post will have all they need.

2004 Holiday Rambler (Endeavor) / Monaco (Diplomat)
Bedroom slide spur gear damaged

Part #1: Lippert #368967 - obsolete replace by...
Part #2: Power Gear #DN13747 - also obsolete

Gear geometry as measured from my gear (inches, confirmed by Gear Works, Seattle WA):
Outside Diameter: 1.917
Pitch Diameter: 1.750
Total Width: 0.75
Face Width: 0.50
Bore: (5/8") 0.62
Woodruff keyway: (1/8") 0.13
Hub: 1/8" each side
Hub Dimension: 1.3
DP (Diametral Pitch): 12
Pressure Angle: 14.5 degrees

I ordered a similar geometry replacement gear from MRO Supply. It is a softer steel than the original so might wear more but is less brittle.
https://www.mrosupply.com/gears-gear...2_boston-gear/

The new gear had the following problems:
1. Hub on one side,
2. Face width was 3/4" instead of 1/2".
3. Woodruff key slot was 3/16" instead of 1/2".

I took the new gear to a local machinist. Finding a qualified machinist turns out to be difficult because most machine shops are oriented to automotive engine rebuild- not gears. The guy I found specializes in vintage motorcycle restoration where making gears is part of the skill-set. There are specialized tools for cutting woodruff slots, etc. so even if a machinist has the skill- he may not have the exact tools he needs.

The machinist:
1. Cut the hub off so the gear width was 3/4".
2. Cut each side of the gear face down by 1/8" leaving a 1/2" face with a 1/8" shoulder on either side of the gear. This is necessary to fit into the slide-out "gear drive" channel which is barely 1/2" wide.
3. Cut a new 1/8 woodruff key slot. The gear as shipped has a 3/16 slot whereas the original is 1/8". Cutting a new slot in the gear was easier and cheaper than replacing the shaft.

With these changes, the gear was an exact replacement of the original and has now been installed and working for several months without problem.

Hopefully this post helps others find solutions to their problems. My machinist will not allow me to post his contact info, but I will be happy to pass his name on and help make contact if you cannot find a machinist in your area.

Cost: MRO Supply- $50.34 (Aug 2021 price)
Machinist - $150.

Hope this helps!!!
Steve

[153stars]

Glad to hear it worked out . I was just wondering about your outcome, while reading other post about broken roll/shear pins.

[knjobrien]

This same gear was used in many RV's including my old Wilderness by Fleetwood. After I searched the forums with no solution found I was directed to Adobe Precision Gear Inc. in Carlsbad NM. They custom made us a new gear out of hardened steel that is a direct match. We sent him the specs and what was left of the old gear. We provided them with the DN13747 part number in case they wanted to make extra and sell them. Cost to us for the first one Rikki made was $284.93. Repeat customers may get a better price as he did quote me a lower number per gear if I ordered 10 but I didnt pull the trigger on that option. Good luck everyone. There number is 575-885-8322.

http://www.gears.com/Custom%20Parts.html

They make gears for the oil industry and have a great reputation. Turn around was 4 weeks.