Historical Data David Brown Gearbox?

[InTheField]

Would anyone have information on an old David Brown NH-12 gear box; by old I mean 1940's vintage. I have a client in the Pulp and Paper industry that is looking to increase the horsepower on their existing gear box (and they do not have the $$ to buy and install a new gear box). I am looking for:

a. the thermal horsepower rating
b. the maximum horsepower rating

I am looking for ratings between 900 - 1200 rpm (but I'll take anything anyone has) with a gear reduction of 5.3:1.

After doing extensive searching, I have exhausted my resources. Hopefully someone out there has the information I am looking for. The manufacturer does not have data that goes back to the 1940's. There was some loss of information when Textron bought out David Brown.

 

[diskullman]

If you find this information, and it indicates a bad choice, will he then buy a proper gearbox? Does he just want to go 1 size higher on the motor horsepower? If you were to find this information, you may find it outdated. You will basically just be changing the service factor. My suggestion would be to drain the oil, put in synthetic oil, and use the higher horsepower motor. A few years back, many wormgear manufacturers switched to synthetic oil, and increased all their HP capacities, due to lower operating temperature characteristics of synthetic oil. The most common oil used (in worm gears, I'm assuming this David Brown is) is MOBIL SHC 634.
Even if this is not a worm gear, I would swap the oil for synthetic and use the higher HP motor, what have you got to lose? a 70 year old gearbox? I'm sure it doesn't owe you anything.

Russell Giuliano

 

[unclesyd]

I have to agree with diskullman about changing the oil and going for it.

You might try some of the older gearbox rebuilders about a manual for your box. We had 4 large gearboxes from the 40's and for some reason they required a speed change. A manual for the boxes was located at a rebuilding company. Come to find out we were running the boxes at 1/2 there design speed for our HP.

 

[Tmoose]

What would happen if they suddenly had NO gear box?

I'd probably visually inspect the gear faces closely for pitting or spalling and magnaglow to locate crax first.

Putting the spurs to an old horse may be looking for trouble.

 

[digger200]

Have you contacted DB at Huddersfield?

 

[strokersix]

You could revise lubrication to increase flow and/or cooling. Is it running hot currently? Might give you a clue toward service factor.