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Need 9A clutch photos or prints

swells

Stainless
Joined
Dec 29, 2004
Location
Indiana
I have an e-mail request for help on the clutch assembly of a 9A, photos or assembly
prints. The clutch came apart while he was cleaning his apron. I have searched and I don't
have photos of the clutch apart or in assembly. He has PL-902D, and would like clearer
assembly instructions.

Thanks,
Steve
 

swells

Stainless
Joined
Dec 29, 2004
Location
Indiana
Thanks Bob,
I've never ha a 9A clutch apart, so I'm in the dark cept for the PL prints.
Am I guessing correctly that the expanders sit in a groove and at a slight angle pushed
by the spring behind it. When pulled forward the expanders pivot and push on the shoes?
Does the expander retaining spring clip just set free on the shaft? held in place just by tension
or does it set in a groove also? Where does the #26 pin go and do?

Steve
 

Webb Wyman

Stainless
Joined
Oct 18, 2001
Location
Lewes, DE.
Hi There,

Steve, as you surmise, the half-moon shaped
expanders (#23) fit in the angled slots of the
clutch shaft (the "screw #24") and when the
star knob (#37) is tightened, it pulls the two
expanders (#23) in and against the inside of
the shoes (#22). These in turn push against
the inside of the worm gear (#21).

It has been awhile since I have been inside an
apron but IIRC, the clutch pinion gear (#19)
has two square-like projections on one end.
These are the driving "dogs" of the clutch. The
shoes (#22) fit on either side of these dogs.

The coil spring (#20) pushes the inside of the
clutch pinion gear (#19) and against the cross
pin (#26) in the clutch shaft screw (#24). This
gives pressure (to open) in the clutch by pushing
the expanders (#23) away from the shoes (#22).

Remember, the worm gear (#21) is constantly
turning (so long as the leadscrew is turning). When
the clutch is disengaged, the clutch pinion gear (#19),
shoes (#22), expanders (#23), shaft (screw #24),
etc. are NOT turning with the worm gear (#21).

When the star knob (#37) is tightened, the clutch
shaft (#24) is pulled in. The expanders (#23) push
against the shoes (#22) and force them outward,
locking them with the worm gear (#21). These
shoes (#22) in turn are mechanically engaged with
the dogs on pinion gear (#19). So, with the clutch
engaged, the clutch pinion gear (#19) is locked with
the worm gear (#21) and in turn, will power the rest
of the apron (depending on the selector lever on the
apron).

The two pins (#26) are a later addition to the clutch.
Or maybe I should say, when the clutch shaft (screw
#24) was modified, the two pins (#26) became
necessary. Older versions of the clutch shaft (screw
#24) had 4 projections formed on the outside in two
pairs (and hence no pins were necessary). Their pur-
pose is to keep the clutch shaft and expanders co-
ordinated with the shoes and give something for the
coil spring (#20) can push against

Lastly, the "hair pin" spring (#25) is placed on the end
of the clutch shaft (#24) and the ends are "tucked in"
between the two expanders (#23). And the star knob
retaining screw (#30) is screwed on (left hand threads).

Good Luck!
-Blue Chips-
Webb
 

Paula

Titanium
Joined
Sep 16, 2005
Location
Indiana, USA
Steve,

Here is a page about assembling a 9" apron. It's a Hercus, though I believe identical to SB (FWIW):

http://steammachine.com/hercus/page5.html

Webb, great explanation! I think that the "hair pin" spring was also a later addition to the design. Mine didn't come with one, and it seems that it could use it. My later model 10K had the spring and the clutch action was very smooth and reliable. The 9A without the spring has kind of an indistinct action, and will sometimes "grab" with the knob loosened (:eek:)

Paula
 

swells

Stainless
Joined
Dec 29, 2004
Location
Indiana
Webb, that was absoultly perfect, I'll save that in the "From the Experts" files.
I copied the text and have e-mailed it to Harrison.

Steve
 

swells

Stainless
Joined
Dec 29, 2004
Location
Indiana
Thanks Paula, I can see the spring, spring pin and the outer pins in the photo.
I had seen that link some time ago, but did'nt have it saved, thanks for posting it.
I sent it to him also, from the photos and Webbs description he should be fine.

Steve
 

Webb Wyman

Stainless
Joined
Oct 18, 2001
Location
Lewes, DE.
Hi There,


Thanks for the kind words!

Paula, My first lathe was a 9 inch horizontal drive
model A w/ 4 ft. bed made in Oct. 1942. When
I took it apart, it had the "hair pin" spring. It ap-
peared that I was the first to be inside the apron
since new (but I cannot be sure). I always as-
sumed the hair pin spring was present since new
and had always been part of the clutch design.
It did have the older clutch shaft (screw #24)
with the formed projections instead of the pins.

The hair pin spring is a small part and its use isn't
clearly apparent to many that tear-down their
aprons for the first time. Hence, I think they got
left out sometimes.

Good Luck!
-Blue Chips-
Webb
 

swells

Stainless
Joined
Dec 29, 2004
Location
Indiana
For Webb:

"Steve,
Thank you. Please give my regards and thanks to Mr. Wyman. You both have been very generous with your time and very helpful.
Based on the detailed explanation provided I have confirmed that I had reassembled the clutch correctly. Probably because of dumb luck and the fact there were only a few pieces, more than anything else.
Mr. Wyman’s reference to pins Piece 26 was an extra benefit. I have an earlier version clutch. [“Older versions of the clutch shaft (screw #24) had 4 projections formed on the outside in two pairs (and hence no pins were necessary)]. So this cleared up the difference between what I was seeing and the pictorial I was using.
Thanks again. If I can some how return the favor, let me know. I plan on sending you some “after clean up” pictures of the SB 9A.

Harrison Solt"
 








 
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