Brake cam

[Ivor Collins]

Can anyone help me with a picture or drawing of how/what kind of return spring is fitted to this design of brake cam. Better still, does anyone have an original spring they would part with?
I believe it was an early Leader brake design.
Thanks.

[Nick_Edgley]

Your post prompted me to look at my hubs. My rear hub has a similar cam but as can be seen from the attached photograph there is no spring attached to the cam just the normal springs attached to the brake shoes.

Looking at the parts diagram here I do not see any spring shown either.

[will_curry]

Ivor,

The spring was provided on early brakes with the fulcrum adjusters to help the cam return
after the brakes were used. If memory serves me it was the same as the other two springs.
It wasn't used on later fulcrum brakes or the even later non-fulcrum brakes so presumably
it either didn't work or. more likely, pulled the cam over centre and caused the shoes to
rub slightly. Considering how little change Ariel made to the four-stroke wheels and brakes
hose on the Leader and Arrow came in for a lot of attention.

[Ivor Collins]

Will
Thanks for the reply.
Usually there are 2 holes in the annular rib for anti squeal springs as can be seen in Nicks photo but do you have a third hole for the cam return spring?
It looks as though the cam return was prevented from being pulled over centre by a second tab which must have acted as a stop. I’m guessing that this would have been in use with the cast ally shoes..

Nick
Thanks for the photo
No sign of any attachment hole for the return spring that I can see but maybe we don’t have the correct backplates.
I’m hoping to use this cam on the TLS brake to obviate the addition of an external return springs which they seem to need.

[Ivor Collins]

Thanks for your replies.
This photo has the info I was looking for and shows the spring attachment boss. Looks like it was only used on the fulcrum adjusted backplate which has the ally shoes.