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Are all Emerson 77646 fan blades supposed to be interchangeable?


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Posted

I have four 77646's. I'm wanting to restore 2 of them using the 2 best (smoothest running) blade sets. I have one stump that's currently functional. One blade set works great, and a second is shaking. The problem comes in when I test with the last 2 blade sets. Both of them cause the fan to stop after it runs about 10-15 seconds. I've figured out that if I slightly untighten the hub on the motor, it'll run again, but stops after the 10-15 seconds. What could be causing this? Again, 2 blade sets run normally, but the other 2 cause the fan to stop. 😕

Posted

You will need to be more specific, what years of 77’s are you referring to? That series fan from 1935 ish until 1960 ish 

Posted

It could be the length of the Drive Shaft interfering with the Oscillating Gears - Try running the fan with the Blade but without the Drive Shaft installed - I've seen different lengths of them - Just a thought - Hope it helps!!

John

Posted
1 hour ago, Lawrence Smith said:

You will need to be more specific, what years of 77’s are you referring to? That series fan from 1935 ish until 1960 ish 

Lawrence, The years of the fans I'm working with include two 49's, a '53, and a '54.

Posted
1 hour ago, John Fengel said:

It could be the length of the Drive Shaft interfering with the Oscillating Gears - Try running the fan with the Blade but without the Drive Shaft installed - I've seen different lengths of them - Just a thought - Hope it helps!!

John

Hey John, I'm trying to get another stump working to help diagnose.  Maybe the drive shafts from 1949-1954 varied in length?  I may just pull all the drive shafts and compare. Will report back if I figure it out.

Posted (edited)

Ok, reporting back after diagnosing/researching the issue of my 77646 stopping after a few seconds of running.

4 fans are involved, but only 2 stumps currently work.  The fans are 2 1949's, a 1953, and a 1954.   The two '49's and the '53 have shafts that are the same length, while the shaft out of the '54 is 8mm longer and includes a spacer next to the worm gear (see pictures 1 & 2 below).

Picture 1 shows the shafts from the 4 fans.

Picture 2 is a closeup of the longer ('54) fan. it is 8mm longer than the other shafts and also has a spacer to the right of the wormgear to account for the deeper well in this oscillator box. Note, the '54 box is 7-8mm deeper inside than the earlier boxes, hence the longer shaft and spacer.

Pictures 3-6 show the earlier oscillator boxes (top & bottom) and the later ('54) oscillator box (top & bottom).

I've confirmed the shorter shafts work fine. The longer shaft is causing the fan to stop because as the fan starts running, the shaft is forced back into the oscillator box 1-2mm and is reaching the back wall of the box. The friction is causing the fan to stop. I've confirmed that by loosening the oscillator box mounting screws ~4mm, leaving a 4mm gap between the box and the back wall of the motor housing. Fan runs fine when I do this. As I start to tighten the 3 screws in an alternating fashion, after 2-3 turns, the fan stops and the gap between the box and the back wall of the fan reduces to ~3 mm.

My solution idea is to shave off ~3mm off the back of the shaft so it won't reach the back of the oscillator box when it's running. If I do that, looks like I'll need to remove the spacer behind the worm gear.  Before I go this route I wanted to lay this out to see if anyone sees an issue with cutting this longer shaft. I have no idea why this problem is happening, but who knows if these are the original internal parts.  Thanks for any input.

 

 

 

 

 

 

Shafts cropped.jpg

'54 shaft.jpg

Earlier osillator box top.jpg

Earlier oscillator box bottom.jpg

'54 Oscillator box top.jpg

'54 Oscillator box bottom.jpg

Edited by Dennis Long
  • 1 month later...
Posted (edited)

Hmmm….i have several 77 of all eras and can’t say I’ve yet encountered this. Are you saying that the 1954 model with the longer shaft is the one having issues? I do believe it is supposed to have the longer shaft because of the differnt gearbox design. 
Measure the depth of the inside of the blade hub. Could be that the blade (hub interior) from that year is also different. Maybe it’s deeper, and if you put another blade/hub on it it’s pushing the shaft too far back. I’m just spitballing at this point. belive my SG or SL is from 1954 cause it has that same gear box. I never measured the shaft though. 

Edited by Marc Sova
Posted

You’re sure the rod is fully inserted into the slot in the blade hub? 
 

Sounds to me like it might not be engaged fully. 

  • Like 1
Posted
On 1/17/2025 at 8:19 PM, Lane Shirey said:

You’re sure the rod is fully inserted into the slot in the blade hub? 
 

Sounds to me like it might not be engaged fully. 

I did that once.So it’s highly possible.

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