Drum brake howl

[David Damerell]

We were off from Whitby to Grosmont a few days ago with a shiny new drum
brake. On the final hill down into Grosmont - narrow, steep, and be-caged
- Clare suggested we get off and walk, and I agreed.

Of course, pushing a fully laden tandem down a 1 in 5 is quite a bit of
work, so I put the drum brake on a bit. It then produced the most
amazingly loud steady note as long as I was walking. Slowing down made it
die out; I can't tell if the tone changed.

Anyone else encountered this?
--
David Damerell <[email protected]> Kill the tomato!
Today is Gloucesterday, October.

 

[Clive George]

"David Damerell" <[email protected]> wrote in message
news:Cow*[email protected]...
> We were off from Whitby to Grosmont a few days ago with a shiny new drum
> brake. On the final hill down into Grosmont - narrow, steep, and be-caged
> - Clare suggested we get off and walk, and I agreed.
>
> Of course, pushing a fully laden tandem down a 1 in 5 is quite a bit of
> work, so I put the drum brake on a bit. It then produced the most
> amazingly loud steady note as long as I was walking. Slowing down made it
> die out; I can't tell if the tone changed.
>
> Anyone else encountered this?

No, because I don't walk down hills (on road...)

cheers,
clive

 

[Membrane]

David Damerell <[email protected]> wrote:

>We were off from Whitby to Grosmont a few days ago with a shiny new drum
>brake.

I didn't knew they were still being produced (or are you referring to
roller brakes?).

>On the final hill down into Grosmont - narrow, steep, and be-caged
>- Clare suggested we get off and walk, and I agreed.
>
>Of course, pushing a fully laden tandem down a 1 in 5 is quite a bit of
>work, so I put the drum brake on a bit. It then produced the most
>amazingly loud steady note as long as I was walking. Slowing down made it
>die out; I can't tell if the tone changed.
>
>Anyone else encountered this?

Resonance in drum brakes can be caused by the brake shoes being glazed
over, at certain speeds and brake force this can result in resonance.
I'd say that on a tandem that is being ridden in hilly terrain there is
significant chance of brake shoes glazing over.

If on the other hand you are referring to roller brakes, then it is a
sign that they need re-greasing.

--
Membrane

 

[Clive George]

"Membrane" <[email protected]> wrote in message
news:[email protected]...
> David Damerell <[email protected]> wrote:
>
>>We were off from Whitby to Grosmont a few days ago with a shiny new drum
>>brake.
>
> I didn't knew they were still being produced (or are you referring to
> roller brakes?).

On a tandem, it'll be an Arai drum brake. Which are still being produced,
and if you want a drag brake, are still the best thing to have.

cheers,
clive

 

[Peter Clinch]

Membrane wrote:
> David Damerell <[email protected]> wrote:
>
>> We were off from Whitby to Grosmont a few days ago with a shiny new drum
>> brake.
>
> I didn't knew they were still being produced (or are you referring to
> roller brakes?).

My 8 Freight has SRAM drums, Sturmey/Sunrace make them too, and you'll
see plenty in NL. Standard on ICE trikes and Windcheetahs too.

Pete.
--
Peter Clinch Medical Physics IT Officer
Tel 44 1382 660111 ext. 33637 Univ. of Dundee, Ninewells Hospital
Fax 44 1382 640177 Dundee DD1 9SY Scotland UK
net [email protected] http://www.dundee.ac.uk/~pjclinch/

 

[David Damerell]

Quoting Membrane <[email protected]>:
>David Damerell <[email protected]> wrote:
>>We were off from Whitby to Grosmont a few days ago with a shiny new drum
>>brake.
>I didn't knew they were still being produced

The Arai drum brake is still made and very commonly fitted to tandems,
and that is what I mean. It's not a roller brake.

The new Sturmey-Archer also still make what they describe as drum brake
hubs.

>Resonance in drum brakes can be caused by the brake shoes being glazed
>over, at certain speeds and brake force this can result in resonance.

That would be a bit unfortunate after only 3 descents on an otherwise
completely new brake. I might take a look inside.
--
David Damerell <[email protected]> Kill the tomato!
Today is Gloucesterday, October.

 

[Membrane]

David Damerell <[email protected]> wrote:

>>Resonance in drum brakes can be caused by the brake shoes being glazed
>>over, at certain speeds and brake force this can result in resonance.
>
>That would be a bit unfortunate after only 3 descents on an otherwise
>completely new brake. I might take a look inside.

Glazing typically occurs due to overheating, for example continues use
of the brakes on longer downhill stretches. If that doesn't apply then
it seems unlikely that glazed brake shoes are the cause.

Alternatively it could be that the brake shoe hasn't yet had time to
wear so that it matches the shape of the drum and evenly presses against
the drum. If that is the case then it should resolve itself after a bit
more use.

--
Membrane

 

[Membrane]

Membrane <[email protected]> wrote:

>Alternatively it could be that the brake shoe hasn't yet had time to
>wear so that it matches the shape of the drum and evenly presses against
>the drum. If that is the case then it should resolve itself after a bit
>more use.

Forgot to add another option: the new brake material might have a thin
hard outer skin due to the production process and/or be too smooth.
Roughing it up with sandpaper will help in that case.

--
Membrane

 

[David Damerell]

Quoting Membrane <[email protected]>:
>Glazing typically occurs due to overheating, for example continues use
>of the brakes on longer downhill stretches.

That seems rather unlikely, this being the exact intended use of the Arai
drum. The previous one has been LEJOG twice and goodness knows what else
without making this howl.

The "not quite bedded in" scenario seems more likely; I'll keep an eye on
it.
--
David Damerell <[email protected]> Kill the tomato!
Today is Gloucesterday, October.