Classic cars forum & vehicle restoration.

[HMK]

After spending many years in storage in my 1973 Robin caravan, I've recently unearthed my late fathers green Raleigh (roadster?) 4 speed with dynohub & battery pack bicycle.

I've known this bike from as long back as I can remember & I have used it the odd time in the distant past. I don't think this bike has had a great deal of use during its life as I believe that the tyres are the original July 1958 fitments. They are Dunlop Tourist Sprite white (cream) wall 26 x 1 & 3/8 (Perhaps someone who knows these bikes could confirm if these are in fact original fit tyres). I pumped these tyres up in stages over a few days & half expected them to go bang, but they're now pumped up hard & they seem to be holding up ok. This bike has spent its life stored either in a dark shed or the dark caravan, so this is probably the reason that these tyres have survived, as they shouldn't really have at this age! I've been a couple of miles round the village on it, but I think for any serious cycling, I would need to replace these tyres with new ones for safety & just keep the original ones packed away as part of its history.

I now have a question & I'm wondering if there's anyone on here who knows the answer. I've searched the net & bike forums without success. I've also asked a number of quite knowlegable people & no one knows the answer. As you can see in the picture, this bike is fitted with a hub dynamo & also a 'battery pack'. I don't ever remember this bike having batteries fitted in the battery unit on the frame & not anyone I have spoken to who has owned or remembers this type of bike has ever used the battery facility - well I intend to use it & want it to work properly.

The lighting circuit is a 6 volt system, so I lined up my 4 'D cells' (U2 type) as I've always thought that it must be a 6 volt battery pack. As I looked at the frame tube I thought that it looked a little short to fit 4 'D cells' (1.5 volts each to make up 6 volts). No, it doesn't & also the handbook says that it only takes three, so it is in fact 4.5 volts from the battery which will of course be 'DC' & 6 volts from the dynamo which will be 'AC' as it's an 'alternator', I believe.

All the wiring on the bike is original & as far as I can see hasn't been touched. The switch on the headlamp has three positions, but only one is used as can be seen in the drawing in the handbook - left is off, middle is still off & right is on & the dynamo lights the front & rear lights in this position when the cycle is in motion. When I fit batteries, it's still the right hand switch position that puts both the front & rear lights on with the bike stationary - not very bright at only 4.5 volts, but adequate as 'marker lamps' at night.

What I want to know is how can an AC alternator run 6 volts AC against a 4.5 volt DC battery all at the same time?

At this moment in time & until I can find out how this system actually works, I haven't run the dynamo with the batteries fitted as I don't want to feed DC back into the dynamo & risk possible de-magnetisation of the magnets (it probably wouldn't, but I don't want to provoke a problem anyway). Also, there's no point in ruining the batteries by having the dynamo try to feed them with AC.

There are different versions of these battery pack systems used. One system has a multi-position switch which switches between dynamo & battery. This system has only TWO wires going to the battery pack & is shown on another page of the handbook. The system fitted to THIS particular cycle has a three position switch with only common & one position being used, but it has FOUR wires going to the battery pack.....two are marked + & - which are the output to the lights & the other two are the input from the dynamo. When you remove the chrome top cover of the battery unit, there's nothing to see under it other than the four connections....the batteries go in from the bottom.

As can be seen from the pages from the owners handbook shown below, this is known as a 'Filter Switch'. The circuit drawing does NOT show what this 'Filter Switch' is....it's NOT the headlamp switch, but some sort of 'automatic' switch within the battery unit, I think.

So how does it work - is it a relay of some sort or is it a rectifier? There's very little room in the unit with the batteries in place so I can't imagine it would be a relay & they didn't have SMALL 'solid state' diodes in the 1950s for this sort of job. I thought I'd see if I could find anyone who knew exactly how these things worked BEFORE I 'do-it-the-hard-way' & pull it to pieces & risk spoiling its originality!

[47Jag]

HMK,

I bought this very bike, but with a Triumph badge when I started work in 1955. The difference between the Raleigh and the Triumph was the Raleigh had the steering lock on the forks, a 4 speed Sturmey gear and it had the 'Filter switch' which I believe was a selenium rectifier (sp). It cost about £26 as I recall. My Triumph was £23 odd which I paid of at 8/9d (about 44p) a week for a year. I only got 10/- (50p) a week pocket money. My mum made that up to half a crown' so that I could buy The Autocar 1/- a week (5p) and go to the cafe a couple of times a week with my mates. I loved that bike. OK it was a bit heavy but that only developed bigger muscles I once did a 130 mile day trip on it.

Art

[MVPeters]

Probably your best reference is here:

http://sheldonbrown.com/dynohubs.html

Sheldon is quite a character!

I'm (very slowly) restoring a '49 Raleigh.
_________________
Mike - MVPeters at comcast.net
2002 MINI Cooper 'S'