juvela

-----

came across this 1937 catalogue page from the French firm of Deprez

one of the gear block images on the page struck me as quite puzzling

perhaps another reader will be able to make sense of it...



the illustration for item Nr. 7-300 shows a block with the two outermost cogs almost touching each other's dentition in such a manner that there would be no possibility of chain engagement on either

the brand of the block in the image is Preference

possibly one of our gear block experts such as pastorbobnlnh will be able to comment...

thank you for looking


-----

oneclick 

Artistic licence - what is depicted is not another (fourth) sprocket, but the imagined (by the artist) reflection on the inner sprocket's dished flange of the outer-most sprocket's teeth.

A similar effect shows a "third sprocket" on the two-speed freewheel to the left.

steelbikeguy

are you talking about this weird row of short "teeth"?




I was thinking that they might be splines for the cogs to slide onto, such as what SunTour used for their large cogs.

When I was reading the original post, I was assuming the question would be about the hubs and axles for trikes.

Steve in Peoria

T-Mar

Preference was a Simplex brand. That's actually a good illustration. The actual cogs have a groove cut into the top of each tooth. What looks like another cog is part of the spacing between the cogs. It may be part of the cog and a shifting aid simlar to Hyperglide's ramps but that's just speculation on my part. See attached photo.

noobinsf 

I'm a regular here, but I still find it remarkable that this kind of esoterica has a very plausible explanation within a couple of hours.

clubman 

IMO, there's a redundant cog inboard of the 16 that's smaller and possibly a thinner gauge that would never contact the chain. Perhaps used as a locknut? I see the split teeth on the 16-19-21 (or whatever they are) but there's definitely an extra set of teeth in there. Artistic license, maybe.

T-Mar

A locknut is a possibilty but it would not appear to be a smaller cog as the pitch appears greater than the 1/2" of the cogs and the teeth aren't tall enough. Also, you can see that it's present on the illustration for the large cog of the 7-100, two speed freewheel and the large cog of the 7-110, 3 speed freewheel. Finally here's another of these freewheels with the same feature. In this one there's a demarcation line with the middle cog, so they do appear to be separate parts. Regardless, given that it's it's in all three illustrations and on both freewheels, it's obviously OEM, whatever the purpose.

pastorbobnlnh 

I like T-Mar's idea of it being a "shifting aid."

I'm pondering whether it is the spacer between the sprockets? If it is, it certainly would catch a good deal of dirt, oil gunk, etc., and would need regular cleaning.

steelbikeguy

disclaimer: until someone actually says they've got one in their hands, this is all speculation.

with that out of the way...
I can't rule out "shifting aid", but if that was the case, wouldn't it appear between all of the cogs, and not just in one place?

I'm leaning towards it being a lock ring of some sort, mostly because I can't think of a better idea. It looks like a hook spanner might be suitable for removing it. The next question would be "why does it have a lock ring?" I guess it would imply that the larger cogs are indeed splined. Of course, it seems obvious that the outboard cog could be threaded and function as the lock ring, so the lock ring hypothesis has problems.

There is some value to the hypothesis that it is a spacer, since chain width might not have been standardized at that time. The only question would be why it wasn't a plain circular/disc spacer instead of a "toothed" spacer.

Steve in Peoria

juvela

-----

thanks so much to all for the many lively responses

all ideas never would have thought of on me own

the only idea i had has to do with the text below the image

it states the block was available as both a 3V and a 4V model

occurred to me that the image provided may have been an artist's attempt at showing both options in a single picture


-----

Bad Lag

Similar features are depicted on all three images.

It appears to me, they are part of the larger cog, not part of the smaller and not in between.

Personally, I really miss the hand-drawn artwork in the old catalogs. Photos are good but,...

oneclick 

Perhaps clearance for the ends of the pivot pins, needed where they ran close to a thicker central portion of the flange abutting the next larger sprocket, but not for some jumps where they were clear of it?

They appear in all cases to match the outer sprocket teeth one-for-one.

Erzulis Boat 

My initial thought was an intermediate "cog" as an aid to shifting. Instead of ramped rings, the intermediate cog has the chain following a set path engaging the rollers of the chain without entering the plates, and would then make a smooth and consistent transition from small/big-big/small. Of course it would need to be indexed to be the most efficient.

Slowride79

Not sure if the description on the box gives us any clues (3 pieces). Found on bay.

C9H13N 

My thought: the small cog is machined with an integral spacer including a lip that overlaps the larger diameter of the body where the other two cogs thread on. The “teeth” on the lip are non-functional and cut as a consequence of cutting the teeth on the small cog.

Somebody needs to buy the one on eBay and disassemble it, for science.

pastorbobnlnh 

...but it won't be me--- with the price north of $100 to purchase and ship it here from Poland.

obrentharris 

I found this Simplex freewheel removing tool on ebay that may shed some light on our mystery.


Brent

T-Mar

I'm aware of this remover and unfortunately it doesn't provide any clues.. The large crescent shaped plate (665/666) that attaches to the handle (654) is slipped behind the small cog, then the handle is attached. Sandwiching the small cog between this plate and the handle prevents the small blocks (656) from slipping out the notches on the freewheel body during freewheel's removal. The extra, stepped blocks (680) attached further down the handle and the smaller elliptical plate plate with the two semi-circular end notchs and a centrral hole (681), are for removing the Simplex single speed freewheel.

pastorbobnlnh 

T-Mar, thanks for posting this diagram.

The instruction sheet should include the warning: KEEP TRACK OF ALL THE SMALL PARTS!

T-Mar

I've only been able to find one piece of Simplex literature showing the freewheels. This literature does not show individual spacers and the cog illustrations appear to depict integral spacers, though none of them show the addional, tooth-like feature. However, the catalogue is from the early 1950s and post dates juvela's literature by about 15 years.

What I found most interesting is that the text mentions a "6 speed" freewheel, though I'm pretty sure that this is a misprint and meant to be 5 speed. Regardless, there were some who would taken this at face value, resulting in a lot of jaws dropping at the time. There were likely many comments the likes of, "who needs 6 speeds, 5 is more than enough", and " real men ride 3 and 4 speeds". I remember when I first joined the forum and all the derogatory comments over 8 speed cassettes (and freewheels) within the C&V membership at that time.