Sturmey X-RD5 pinion timing marks. - why?

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Geoff.D
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Sturmey X-RD5 pinion timing marks. - why?

Post by Geoff.D »

I'm not asking a question about a problem. It's really information for my own satisfaction that I'm after.

I've recently stripped and rebuilt two of these hubs. There's plenty of help on the internet and in the SA literature. It clearly says that lining up the timing marks on the planet pinions is essential.

One of the pleasures (not to say frustrations!) of delving into the mysteries of an IGH for the first time has been tracing the drive train through the gears and getting an understanding of the function of each cage, set of pawls, clutch, etc. But, for the life of me, I can't understand why these pinions need to be "timed",

Can anyone explain?
rogerzilla
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Re: Sturmey X-RD5 pinion timing marks. - why?

Post by rogerzilla »

They have to mesh exactly with two other parts, that's why. I'm assuming these are stepped (compound) planets as in an old AM hub.
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531colin
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Re: Sturmey X-RD5 pinion timing marks. - why?

Post by 531colin »

"worn in" to a particular orientation?
....as in no other orientation will be EXACTLY the same?
Geoff.D
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Re: Sturmey X-RD5 pinion timing marks. - why?

Post by Geoff.D »

rogerzilla wrote: 9 Aug 2022, 6:07pm They have to mesh exactly with two other parts, that's why. I'm assuming these are stepped (compound) planets as in an old AM hub.
I agree they have to mesh with other parts, Roger. But, assuming each pinion is machined to the same pattern, why don't they mesh whatever the orientation? That's what puzzles me.
Could it be that, because the two sun pinions are at a set orientation to one another (determined by the angle of the ball locking orientation) the planets must also be at a particular orientation to mesh.

Ah....even as I write I'm having a eureka moment. If it were one sun and one planet it wouldn't matter. They'd just mesh. And if it were two sun and a compound planet, but both of same diameter, it also wouldn't matter. But, because the compound planet is of different diameters, the teeth don't line up opposite each other. The angular difference between the teeth must match the difference in the orientation determined by the ball locking mechanism.

I don't think words can explain it well enough. But I think I'm on the right track. Thanks for the prompt.
Geoff.D
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Re: Sturmey X-RD5 pinion timing marks. - why?

Post by Geoff.D »

531colin wrote: 9 Aug 2022, 6:24pm "worn in" to a particular orientation?
....as in no other orientation will be EXACTLY the same?
I'm not sure about this idea, Colin. I can't see Sunrace spending time "wearing it in" on a manufactured gearbox. And then dismantling it to carefully punch the timing marks.

I think I'm onto the right track in my reply to Roger (above). It's all about the orientation of the ball locks (ie the orientation of the small sun gear to the large sun, and the variation of orientation of the smaller cogs of the compound planet to the larger. Each planet pinion must "present" the exactly same variation to mesh with the variation between the large and small suns, which (in turn) is determined by the ball locking mechanism.
Carlton green
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Re: Sturmey X-RD5 pinion timing marks. - why?

Post by Carlton green »

In the late ‘80’s I had a Sturmey five speed hub, ***** awful things, it broke a lot and used three planets instead of four. I had that hub apart several times and aligning the gears was essential to ensure that loads where properly and equally transmitted through the planets. IIRC the planets were two different sized gears on the same axle so getting all the teeth in sync with each other is an issue. I didn’t have the special tool and did alignment by eye … that might not have been good enough, I don’t know if that was a factor or not but these days I’d make some temporary tool. IIRC the timing marks on the gears weren’t brilliant either.

TLDR; whatever you might think still make sure that you get the timing completely right.

For what it’s worth I’m a big fan of SA AW gears.
Last edited by Carlton green on 10 Aug 2022, 10:33am, edited 2 times in total.
Don’t fret, it’s OK to: ride a simple old bike; ride slowly, walk, rest and admire the view; ride off-road; ride in your raincoat; ride by yourself; ride in the dark; and ride one hundred yards or one hundred miles. Your bike and your choices to suit you.
Geoff.D
Posts: 1982
Joined: 12 Mar 2010, 9:20pm

Re: Sturmey X-RD5 pinion timing marks. - why?

Post by Geoff.D »

Carlton green wrote: 9 Aug 2022, 8:51pm ............ IIRC the timing marks on the gears weren’t brilliant either.

TLDR; whatever you might think still make sure that you get the timing completely right.

For what it’s worth I’m a big fan of SA AW gears.

I agree. The timing marks aren't brilliant. They're small (but there's little space, I admit) and invisible if there's any residue of grease about.
Stradageek
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Joined: 17 Jan 2011, 1:07pm

Re: Sturmey X-RD5 pinion timing marks. - why?

Post by Stradageek »

Geoff.D wrote: 9 Aug 2022, 5:45pm I'm not asking a question about a problem. It's really information for my own satisfaction that I'm after.

I've recently stripped and rebuilt two of these hubs. There's plenty of help on the internet and in the SA literature. It clearly says that lining up the timing marks on the planet pinions is essential.

One of the pleasures (not to say frustrations!) of delving into the mysteries of an IGH for the first time has been tracing the drive train through the gears and getting an understanding of the function of each cage, set of pawls, clutch, etc. But, for the life of me, I can't understand why these pinions need to be "timed",

Can anyone explain?
I asked the same question of the much missed guru (Brucey) and got this excellent answer viewtopic.php?t=125712&hilit=timing.

And as I observed in the link, if you rebuild a hub ignoring these marks it definitely runs rough.
SA_SA_SA
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Re: Sturmey X-RD5 pinion timing marks. - why?

Post by SA_SA_SA »

Carlton green wrote: 9 Aug 2022, 8:51pm In the late ‘80’s I had a Sturmey five speed hub, ***** awful things, it broke a lot and used three suns instead of four....
Do you mean planets?

I think all Nottingham SA 5 speeds have had two suns?
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squeaker
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Re: Sturmey X-RD5 pinion timing marks. - why?

Post by squeaker »

Geoff.D wrote: 9 Aug 2022, 8:31pmI'm not sure about this idea, Colin. I can't see Sunrace spending time "wearing it in" on a manufactured gearbox. And then dismantling it to carefully punch the timing marks.
The marks would be made on initial assembly... :roll:
"42"
Carlton green
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Re: Sturmey X-RD5 pinion timing marks. - why?

Post by Carlton green »

SA_SA_SA wrote: 9 Aug 2022, 11:45pm
Carlton green wrote: 9 Aug 2022, 8:51pm In the late ‘80’s I had a Sturmey five speed hub, ***** awful things, it broke a lot and used three suns instead of four....
Do you mean planets?

I think all Nottingham SA 5 speeds have had two suns?
Yes I did mean planets and have corrected my post, thanks for helpfully pointing that mistake out. I still have a couple of old SA shafts and they do have two suns on them.

Here’s the definitive stuff:
http://www.sturmey-archerheritage.com/i ... -131.1.jpg
http://www.sturmey-archerheritage.com/i ... il&id=1062
Last edited by Carlton green on 10 Aug 2022, 3:23pm, edited 2 times in total.
Don’t fret, it’s OK to: ride a simple old bike; ride slowly, walk, rest and admire the view; ride off-road; ride in your raincoat; ride by yourself; ride in the dark; and ride one hundred yards or one hundred miles. Your bike and your choices to suit you.
jb
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Re: Sturmey X-RD5 pinion timing marks. - why?

Post by jb »

Timing marks are needed on all compound planet gears. As the gear teeth need to all be in the same position to mate with the compound gears 'sun' gear. If they are not aligned more likely than not you wont be able to assemble it or if you do it will feel very stiff to turn.
Cheers
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Geoff.D
Posts: 1982
Joined: 12 Mar 2010, 9:20pm

Re: Sturmey X-RD5 pinion timing marks. - why?

Post by Geoff.D »

squeaker wrote: 10 Aug 2022, 9:49am
Geoff.D wrote: 9 Aug 2022, 8:31pmI'm not sure about this idea, Colin. I can't see Sunrace spending time "wearing it in" on a manufactured gearbox. And then dismantling it to carefully punch the timing marks.
The marks would be made on initial assembly... :roll:
Yes, my point exactly, Squeaker. But my question is why? Why does the orientation (timing) matter when each compound pinion is manufactured exactly the same as the next?

I believe I'm on the right track to link the orientation of the cogs on the smaller planet compared to the larger with the orientation of the ball lock of the smaller sun gear compared to the ball lock of the larger. If we were to say that the sun gears were "x" degrees advanced (one to the other) then the cogs of the planets must also be "x" degrees advanced when they mesh with the suns.. There must be only one orientation when they line up exactly with this "x" advance (signified by the timing mark). So, for all three planets to line up with "x" degrees advance they must all show the timing mark at the same time.

I haven't quite worked out the maths of it. It's all because there are fewer cogs on the smaller planet. So there may be only one position in which they offer the right "advance" to match the ball locking advance (sun gear advance). Were I better at maths (and knew the ball locking advance) II might be able to demonstrate it. But the idea seems OK.
Stradageek
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Re: Sturmey X-RD5 pinion timing marks. - why?

Post by Stradageek »

It must be because my mind works 'visually' that Brucey's explanation viewtopic.php?t=125712&hilit=timing. makes most sense to me
Geoff.D
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Re: Sturmey X-RD5 pinion timing marks. - why?

Post by Geoff.D »

Stradageek wrote: 9 Aug 2022, 10:16pm
I asked the same question of the much missed guru (Brucey) and got this excellent answer viewtopic.php?t=125712&hilit=timing.

And as I observed in the link, if you rebuild a hub ignoring these marks it definitely runs rough.
Thanks for the link, Stradageek.

I had to read it a couple of times for it to sink in, and I'm not sure it quite answers my question. It explains why, given the layout of the planets and suns, the planets must be in that particular orientation to ensure that the larger planet tooth fits comfortably in the smaller sun pinion. He goes on to say that if one planet were adrift (say just one tooth out of sync) the the sun couldn't sit quite concentrically. I can see that. I can see (as you affirm) that being out of sync would make it run rough, or not at all.

But, I'm still struggling.

Does this mean that the need for timing stems purely from the ratio between the diameters of the smaller and larger planets? If so, then my previous idea (above) is a load of bunkum.
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