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Old Welch 1400 reassembly

Posted: Thu Oct 26, 2017 8:05 pm
by Filippo_Passeri
Hello, all.

Recently I have been accumulating parts for my Welch (probably 1400) head to rebuild it. I have everything except the smaller pulley for the motor. I'm planning to lathe the previous pulley to a smaller diameter to fit the RPM rating of the pump.
The motor rating is 500W and 1430 RPM (although I measured it without load to be close to 1500 RMP).

It's written on the pump head that the optimal RPM is from 400 to 475. From rough calculations, the necessary ratio for the Vacuum pump pulley to the motor pulley is 3.5:1. So I need to reduce the previous pulley to 50mm to achieve optimal RPM.

Any suggestions or corrections?
View from the side
IMAG0203 (1).jpg
The smaller motor pulley to be lathed
View from top

Re: Old Welch 1400 reassembly

Posted: Sat Oct 28, 2017 7:47 am
by Richard Hull
All Welch belt drives are slow winders. This gives them their long life reputation and quiet drive noise. You can go to sleep listening to that quiet lub-lub-lub, just like the railroad track joints click-click putting you to sleep in an old Pullman sleeper car.

Good luck on getting the pump going.

Richard Hull

Re: Old Welch 1400 reassembly

Posted: Sat Oct 28, 2017 6:44 pm
by Dennis P Brown
Those are really great pumps that will give you many years of excellent service. I love their internal simplicity - they are so easy to open and then clean!

Really nice how you are partly rebuilding it and making the system "like - new" again. I prefer the belt drives (with a safety cage installed) since it makes service easier compared to current single piece systems - when the motor goes on these newer type pumps, only that exact motor type can be used.