Author Topic: 1913 rear brake details  (Read 1610 times)

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Offline Steph1960

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1913 rear brake details
« on: 12 Mar 2023 at 14:13 »
I need a rear brake block assembly for my 1913 model N and if I can find one would be perfect, but if not, does any one have a good drawing that I can manufacture one from or even better one I can look at near Norfolk, England.

Offline Tim OConnor

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Re: 1913 rear brake details
« Reply #1 on: 14 Mar 2023 at 19:49 »
I have photos a friend sent me of his 1920 W-20 if that helps.

1920 2 3/4 W-20

Offline EW-Ron

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Re: 1913 rear brake details
« Reply #2 on: 14 Mar 2023 at 22:22 »
A quick google shows this 1913  with brake bits visible


But, what is a Model N
And why is there a chain on the pic above.
My ignorance is showing here ...

Offline Hutch

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Re: 1913 rear brake details
« Reply #3 on: 14 Mar 2023 at 23:30 »
Hi Steph1960,

Welcome to the forum!

Attached are some pictures of a rear brake "shoe" that I think is correct for 1913 Model N. It is not for sale and destined to go on one of my projects. It would not appear to be "handed" so should be the correct design to go on either the left hand side (i.e. near side on Model N) or on the more common right hand side of the other veteran 2 3/4HP bikes.

(Edit: Mounting bolt for 1912/13 models as shown in pictures, 1914-19 is different and goes in an oval hole in the frame)

If one doesn't turn up in the near future, let me know and I will do up a drawing of the one I have for you.


Cheers

Hutch
« Last Edit: 14 Mar 2023 at 23:45 by Hutch »

Offline Hutch

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Re: 1913 rear brake details
« Reply #4 on: 15 Mar 2023 at 10:47 »
I am wondering if the three holes in the shoe I have are original? All the pictures I have found so far don't have holes but I think in the past I have seen at least one other with holes. Does anyone else know the answer? I'm fairly sure the later veteran rear brake shoes don't have holes but not sure about the early ones.

cheers

Hutch

Offline eddie

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Re: 1913 rear brake details
« Reply #5 on: 15 Mar 2023 at 13:48 »
Steph 1960, your original photo shows one of the early 'peddlers' with the belt drive on the LH side. I am surprised it is listed as a 'model N' - it looks to be more in the E-G range.

Hutch, the brake shoe you have shown - if the pivot bolt is as originally fitted, would appear to be from one of the later models with the cross over gearbox and belt on the RH side. I would assume that the same brake shoe was used for both models (just the pivot bolt being reversed). This then begs the question -'were other options available' as i have seen mention of different diameter belt rims being used - thus altering the geometry of the brake shoe? - there being no provision on the frame for adjusting the position of the brake shoe.

  Regards,
                Eddie.

Offline Steph1960

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Re: 1913 rear brake details
« Reply #6 on: 16 Mar 2023 at 10:07 »
UPDATE.
I am now in possession of two rear brake block holders, thanks Geoff. There are some other items that came with them but the only item that looks relevant is the mounting bolt.

The next question is, what shape do I make the block and what is the spring arrangement?


Offline cardan

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Re: 1913 rear brake details
« Reply #7 on: 16 Mar 2023 at 10:37 »
The spring might be something like this?

Leon

Offline Steph1960

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Re: 1913 rear brake details
« Reply #8 on: 16 Mar 2023 at 10:40 »
Thanks everyone for your replies.

Hutch. It looks like the one you have with holes in is correct but now I have one of each which one is correct for 1912/3? I have offered both up to my bike and they line up perfectly.

Eddie. I am no expert but the models E & D look to carry their engine higher in the frame and didn't have a counter shaft for the pedal gear, the N range had the counter shaft arrangement and was not dissimilar to the two speed models of the same era but without foot boards and with the drive belt and brake on the left. I have attached a picture of mine as found.

EW Ron. This is an extract from classic-motorbikes.net explaining the model N.  "Douglas renowned for the quality and reliability of their machines, presented this model N in 1912. It is equipped with chain drive to a countershaft and secondary belt drive. The horizontally opposed twin has been improved by the addition of mechanically operated intake valves (up to and including 1911 the intake valves had been automatic). The improvements were crowned by a victory in the 1912 Junior TT Race. Starting is by means of pedals the rear wheel is equipped with a free wheel. Gear ratio of this single speed machine is 5 1/2 : 1."

Offline Steph1960

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Re: 1913 rear brake details
« Reply #9 on: 16 Mar 2023 at 10:48 »
The spring might be something like this?

Leon

What year is that Leon?

Offline cardan

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Re: 1913 rear brake details
« Reply #10 on: 16 Mar 2023 at 10:53 »
1914, I think.

Offline cardan

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Re: 1913 rear brake details
« Reply #11 on: 16 Mar 2023 at 11:34 »
It's hard to see the brake spring in period illustrations used by Douglas in their catalogues etc. - the artist usually touches up the photographs and tidies out small, messy details. In period photos 1912-14 I fancy I can see the spring as in my photo above.

Not sure if this link will work, but if you zoom in you can see the spring on this 1914 Douglas racer:

https://www.stilltimecollection.co.uk/collection/starbike-tpt-transport-bike-douglas-racing-prix-motor-sport-raceway-race-tt-rider-wf-newsome-1913#Property%20

No doubt someone will have one - sorry I don't.

Leon

Offline Hutch

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Re: 1913 rear brake details
« Reply #12 on: 16 Mar 2023 at 23:11 »
Hi All,

Here is a picture of the spring for the rear brake shoe. I'm fairly sure I bought it from the LDMCC about 10 years ago......how time flies! Also shown are the holes in the frame where the end of the spring goes. This frame is 1915 and has the "eccentric" bolt (122D) for the brake shoe and as such has two positions for the shoe relative to the belt rim. I would say that is why there are two holes in the frame for the spring end. (Edit: interestingly the "artist" who produced the picture of the spring in the 1916 parts list has "cut" the little end off that goes in the hole in the frame! As the spring will be on the left hand side rather than the right hand side on the 1913 Model N, then the spring spiral i.e. direction of operation, will need to be reversed? )

Steph - there may be a hole for the spring on the inside of your left hand chain stay? Thanks for the info regarding the 3 holes in the brake shoe being original - I was pretty sure I had seen them before but couldn't find a picture to confirm. I'm fairly (?) sure the ones without the holes are later - say 1914 onwards (the brake shoe - 122D - shown in the 1922 onwards parts lists don't have holes in them) but will see what I can find to confirm this. The 1916 parts lists only shows a side view of the brake shoe unfortunately.

Cheers

Hutch

« Last Edit: 16 Mar 2023 at 23:37 by Hutch »

Offline Steph1960

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Re: 1913 rear brake details
« Reply #13 on: 18 Mar 2023 at 17:58 »
Can you let me know the dimensions of the spring please Hutch and I'll get one made to the opposite hand. Thanks.

Offline Hutch

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Re: 1913 rear brake details
« Reply #14 on: 19 Mar 2023 at 06:09 »
Steph 1960, your original photo shows one of the early 'peddlers' with the belt drive on the LH side. I am surprised it is listed as a 'model N' - it looks to be more in the E-G range.

Hutch, the brake shoe you have shown - if the pivot bolt is as originally fitted, would appear to be from one of the later models with the cross over gearbox and belt on the RH side. I would assume that the same brake shoe was used for both models (just the pivot bolt being reversed). This then begs the question -'were other options available' as i have seen mention of different diameter belt rims being used - thus altering the geometry of the brake shoe? - there being no provision on the frame for adjusting the position of the brake shoe.

  Regards,
                Eddie.

Hi Steph and Eddie,

Good question Eddie, re the different diameter belt rims and no adjustment for the rear brake block on the frame (except for the two positions on the 1914-1919 ones). I went looking through the early parts list and could only find the one part number describing the belt rim diameter for the 2 3/4 hp so far. So I can only assume that Douglas only supplied one size ? (I'm sure tho' Douglas would have supplied different diameters on request and there were probably also after market ones avail. in period) Different overall gearing ratios could be altered tho' by a selection of different primary gears for the flywheel and gearbox and also an optional variable belt pulley on the output of the gearbox was avail. from Douglas and listed in their parts lists, so maybe they didn't feel the need to supply different diameter rear wheel belt pulley's? Not sure - but will keep looking.

In my investigations I dug up some pictures of the 1913 Model N and its predecessor to, the 1912 Model H from the Douglas specifications and Price list booklets. As usual this opened up the typical "Douglas can of worms" :-)  I must admit I know very little about these models and had not really looked at their specifications in any detail before.

Interestingly the pivot point on the frame for the rear brake shoe of the model H  appears to be slightly different to the model N but hard to tell accurately from the pictures.  Also the brake block on the 1913 appears to have either two holes, or bolts through it? Maybe made up of two pieces of friction material bolted together or maybe the brake shoe is a different design (i.e. no slot for the block but a "T" section?? No idea and I have not found any more information so far )

Anyway, I think the rear brake system design was in a state of flux circa 1912 to 1913 and what we are seeing is most likely "pre production prototypes" ??. I say this because the way the brake operating rod attaches to the brake shoe also seems to have changed only for the 1913 model N (two adjusting nuts on the rod?) compared to the 1912 model H and all other 2 3/4hp's (the "square" type non adjustable end brazed to the rod). I'm not sure how much emphasis to place on the Model N brake picture from the Douglas Literature until more period information can be found.

After looking at the pictures I am now intrigued as to how the rear brake pedal at the bottom of the frame front downtube operates!

Steph,

I have marked up a drawing showing the dimensions of the rear brake spring I have. I did not have any accurate angle measuring equipment with me but I have estimated the position of the "spigot" to go in the frame as shown in the picture with the yellow combination square. I can get a better measurement of this if required.

If you need any more information please let me know.

Cheers

Hutch
« Last Edit: 19 Mar 2023 at 10:55 by Hutch »

Offline Hutch

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Re: 1913 rear brake details
« Reply #15 on: 19 Mar 2023 at 06:14 »
Having problems uploading the marked up pictures - here they are.

Edit: The 9/64" dimension refers to the maximum diameter of a circular rod that would pass through the hole created by bending over the wire. I assume the screw that goes into the brake shoe and block has a 1/8" shank.
« Last Edit: 19 Mar 2023 at 06:23 by Hutch »

Offline Hutch

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Re: 1913 rear brake details
« Reply #16 on: 19 Mar 2023 at 06:17 »
I'm still having issues with this last picture - one more go....

Offline Steph1960

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Re: 1913 rear brake details
« Reply #17 on: 19 Mar 2023 at 13:25 »
Thanks for all that info Hutch, it is very much appreciated. I have holes in my frame that correspond with what you are saying. One thing I noticed is that both yours and my frame has another hole further back from the brake, I wonder what that is for?

Offline Hutch

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Re: 1913 rear brake details
« Reply #18 on: 19 Mar 2023 at 21:59 »
Hi Steph,

The other small hole is a vent that is there to allow hot gas to escape when the frames are brazed together (and, I guess, also to equalise the pressure inside the tubes when it cools down). You may find another one on the inside of the other chain stay as well and there are also usually some on the insides of the fork tubes as well.

Cheers

Hutch