Help needed finding a replacement gear

[chucketn]

I need to help an acquaintance find a replacement gear for her fathers lift chair. She describes the gear as plastic, 2 5/16” diameter, 3/8” thick, and 55 teeth. The bore is ¾”. I have tried Stock Drive Products with no help.
She can buy an entire drive assembly replacement for the chair but the cost is prohibitive.
Is there an easy way to enter these specs to find a gear, or am I missing an important descriptor like diametric pitch? Any help in finding a replacement would be greatly appreciated.
Other than the description above, I do have a couple of pictures of the broken gear.

Chuck in E. TN

 

[Jasonb]

Sounds like 1.0MOD as thats 57mm OD and 2 5/16 is 57.93mm depends how accurately its been measured

J

 

[mklotz]

With those parameters (2.3125 OD, 55 teeth), the diametral pitch works out to be an unlikely 24.6486. (DP is usually an integer value.) Perhaps the diameter measurement is in error or the tooth count is off?

OTH, the parameters compute to a module of 1.0305 which is suspiciously close to one. It may be a gear designed to metric standards.

 

[Catminer]

Hi Chuck;
Sounds like you have everything you need to make a reasonable facsimile out of a more durable material.

Peter

 

[chucketn]

http://s571.photobucket.com/albums/ss157/chucketn/Machining/gear%20for%20lift%20chair/

Pictures of gear in question.

Thanks for the help.

Chuck in E. TN

 

[Tin Falcon]

yeah with a rotary table or indexing head you can do it. just grind a tool the shape of the space between the gear teeth and mount in a fly cutter.make it as close as you can to the original and do not worry about definitions or numbers.
Tin

 

[steamer]

As the tooth count is ODD, it may be problematic to measure the OD accurately....

What does the gear go to?...and is it American made?....if it is it is probably a DP gear.....then again.......

Dave

 

[Herbiev]

Hi Chuck. http://www.sdp-si.com/web/html/products.htm could possibly have what you are looking for. Good luck.

 

[bearcar1]

Hi Chuck, if you do not have the facilities to reproduce that gear, perhaps a look at a Boston Gear catalog (sorry, I do not have a web link so you will need to do a web search). They manufacture gears and gearboxes of all sizes and types. I'm certain that would be able to help you out and hopefully at a much better cost that what you have run up against to date.

BC1
Jim

 

[chucketn]

Well, they brought me the broken gear tonight. It has (had) 55 teeth, 2.345 dia, .377 thick with a .750 bore. It meshes nicely with the change gears from my Micromark 7x14 lathe. Thus, I would guess its metric Mod1.
The person needing the gear showed me the webpage for a replacement set of 2 gears for the lift chair as a cost of over $90! Robbery! There has to be somewhere to get a suitable replacement for much less than that.
I’ve checked Boston Gear and Stock Drive Products and they don’t list anything close. Any ideas?
This is for a lift chair for a 83 year young Senior Citizen.

Chuck in E. TN

 

[ShedBoy]

Make one?

Brock

 

[chucketn]

I'd love to make one. But, as it's for something as important as a lift chair, and the ser is 80 years+, I don't trust my ability in a first attempt at gear making...

Chuck in E. TN

 

[ironman]

Chuck, who makes the chair?

Ray

 

[chucketn]

Ironman, the chair is a MedLift with a Hubble motor and gear set as here:

http://www.medicalcentersupply.com/medliftparts.htm

Gear needed is the large one listed as kit #4220.

Chuck in E. TN