Home » epicyclics » In the belly of the beast

In the belly of the beast


This one is for hard-core hub-gear fans – epicyclists? – only. It shows the dismantling of my hundred-year-old Sunbeam ‘Newill’ hub, which I did a few years ago. At the moment, the sequence is on Flickr as a set, and some of the shots are a bit dark, though if you blow them up, you can see most detail you might want. They are also labelled, so if you mouse over them you can identify the various components. I hope it may be of some technical interest to perhaps as many as three or four other people in the world.

As you will see from the captions, this is something of a mystery story: the gear slips in direct drive, which in theory should be impossible. Looking over it again, I find I had forgotten the extent of the work I had done on it, and the degree to which I had advanced my understanding.

Any of you who have ever done it will know that while dismantling and reassembling an epicyclic hub can afford a great deal of satisfaction (as long as you get it to work) doing it repeatedly eventually becomes tedious (there are no fewer than seven separate sets of ball bearings in the Newill hub, most of them tiny, to say nothing of six pawls and the little hair springs that actuate them) especially when you are trying to run down the cause of a fault that only becomes evident when the hub is in operation under load, on the bicycle – in other words, every time you put the wheel in place (no small task in itself, though a great deal easier on a Pedersen than a Sunbeam) your heart is high with hope – this time it will surely work! This, time, surely, you have eliminated the fault!

But no, you haven’t, and it doesn’t, but in the end you leave it in place and put up with it (it is an intermittent fault, after all, and you can get by on low gear and high for most purposes) because you cannot face yet another taking off and stripping down…

But now that the passage of time has deadened the pain, and in any case the Pedersen is hors de combat, awaiting a new saddle, I find that my curiosity is sufficiently piqued to give it another go – after all, for any mechanical mystery there must be an explanation – mustn’t there?

So I hope to repeat the exercise some time soon and photograph it better – watch this space. I shall certainly make use again of the original patent drawings as a guide, which I downloaded from the excellent European Patent Office website and printed off. You can view the patent document with drawings here : GB190515579A. Though it might seem daunting, I found it a great aid to understanding when actually working with the hub.

In the mean time, may I invite you to join me  –


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