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只看楼主 倒序阅读 楼主  发表于: 2009-03-17
— 本帖被 摇摇 执行加亮操作(2009-03-18) —
图片很多,随便看看
原贴:http://www.velovision.co.uk/cgi-bin/show_comments.pl?storynum=715

Inside the Sunrace-Sturmey 8-speed

The new one is fab, but the old one broke. We take it apart, find the fault and reassemble. Warning for dial-up readers: report contains 46 images...


As some of you may already have read over in the VV Forum and as hinted at in VV18, the third of the Sturmey-Archer 8-speed hubs I've tried broke recently.

I know a number of readers have been following the ongoing reports in the magazine about my experiences with the Sturmey-Archer 8-speed hub with interest. It seems I was sent a number of hubs which weren't really fully-developed - and I've broken three so far. But fingers crossed, it looks like they might have cracked it now...

The good news is that the new one they sent, which I built into a wheel for my town bike and have been using for a few weeks now, is MUCH better. Shifting is far more precise than ever before, it's still lovely and silent, and feels pretty efficient too. I've also heard similar very positive reports from Tony Hadland who also has a latest-generation Sturmey 8-speed. Apparently someone who tried his, a Rohloff user usually, compared the Sturmey's shifting favourably...

If the hub is now mature, many people are holding out hope that it'll be squeezed into a Brompton rear triangle before long... finally giving that bike a decent range of gears at a feasible price.

Anyway, in the meantime I thought I'd have a go at taking one of the old ones apart - Sturmey didn't want it back, as it failed from a cause already known by then. I don't think they should mind me showing detailed pics of the innards - any competitor wanting to copy the hub will simply have bought one. But realistically, there's such a tooling cost involved anyway that this is pretty unlikely.

Please note this is not an 'official' guide about how to do it. No doubt, expecially when reassembling, there are alignments to be observed and torque settings to be adhered to. It's for interest only.

We'll start with the hub, with sprocket and axle nuts removed:



First stage is to remove the circlip:



This releases the shifter cable support plate and a washer:



This exposes the drum which the gearchange cable wraps around and rotates to change gear. Remove the nut, and this and a few spacers are released:

Another plate is exposed:



This just pulls off, revealing the first set of bearings.



The hub had been used hard for six months or more, but the bearing races look like new:



Pull off another plate and you can see the spring which tensions the gear change cable. Note also the still-clean grease on the ball race.



These parts also just pull off now. The ballrace is secured behind a press-fitted sealing ring, so I couldn't remove it. There was also a thin cylinder-ring type seal in a groove around the outside, seen below the part.




Inboard of this ring is another bearing surface, again gleaming as new.





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只看该作者 沙发  发表于: 2009-03-17
图片很多,随便看看

Next pop off a plastic shield and you can unscrew (left-hand thread) the large-diameter outer race. This screws into the hub with a fine thread. You really need a large pin spanner to remove this, or a special tool. Again, bearing surfaces pristine:

 

At this point the hub innards are ready to come out:

 

But first you need to flip the hub round and release the hub brake parts:

 

Just undo a few nuts and it all pulls off:

 

Just the cone left:



and you can pull the innards out leaving the hub shell:




Inside there's a freewheel ratchet ring and axle bearings, again with clean grease:




The innards are one solid lump:





And a reverse view:








The reason for the hub's failure is now revealed, too:


 

The ring gear has burst in two places:












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只看该作者 板凳  发表于: 2009-03-17
图片很多,随便看看

Removing the circlip from the end allows the damaged part to be removed:



A number of gear fragments fell out at this point. One of the planet gears was missing, with just the pin remaining.




Leaving that for now, we can continue to disassemble: the various stages of the transmission simply pull off the axle:





The largest stage, all greasy. The grease was mostly pretty clean still.






Each stage has three freewheel pawls on its outside, which engage with a ratchet ring at the back of the previous stage.


 
Looking at the axle with some stages removed, we start to get an idea of how the shifting works:



There are three wee spring-loaded shifter levers, recessed into the axle, and controlled by the three rings on the other end. When raised, the levers engage with the splined bore of the planet gears rather like the pawl of a freewheel:

 






The shifter levers can now drop out:








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只看该作者 地板  发表于: 2009-03-17
图片很多,随便看看

Removing a circlip lets the controller rings slide off. These have a cam-like profile, which clearly controls the shifting sequence:











小图 | 大图 图片

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只看该作者 4楼 发表于: 2009-03-17
图片很多,随便看看
[ 此贴被lixuela在2009-03-17 23:23重新编辑 ]

小图 | 大图 图片

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1条评分
摇摇 贡献值 +3 经典教学片 2009-03-17

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只看该作者 5楼 发表于: 2009-03-17
才看到一个!哈哈,插一个。

77,我回来啦。

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只看该作者 6楼 发表于: 2009-03-17
简直是个大铁坨。。。

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只看该作者 7楼 发表于: 2009-03-17
没这个功力看明白。

77,我回来啦。

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只看该作者 8楼 发表于: 2009-03-17
功力深厚的。。。。。
骑电摩的结果就是.....越来越胖
减肥  减肥  减减肥

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只看该作者 9楼 发表于: 2009-03-17
个刹车蹄块强大  

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只看该作者 10楼 发表于: 2009-03-18
超复杂啊!!!
evolution of perfection

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只看该作者 11楼 发表于: 2009-03-18
有行星齒輪和齒輪架很強大
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只看该作者 12楼 发表于: 2009-03-18
看了就不敢拆了
沒準裝不回去
呵呵
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只看该作者 13楼 发表于: 2009-03-18
看了就不敢拆了
沒準裝不回去
呵呵
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只看该作者 14楼 发表于: 2009-03-18
有装配图的话就好了。

大三的时候去某职校拆过通用的5速自动变速器,难以完全看懂。不过照着装配图拆装就很简单了。
haha haha  haahaha

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只看该作者 15楼 发表于: 2009-03-18
那裂缝是拆坏了?
WECYCLE
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只看该作者 16楼 发表于: 2009-03-18
lz蠢蠢欲动了
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只看该作者 17楼 发表于: 2009-03-18
小时候老拆东西,装上后总是会有零件多出来的飘过
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只看该作者 18楼 发表于: 2009-03-18
里面好黑好复杂呀……
虽说内变不用保养……
但内变速坏了没有高人就基本上修不了了……
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只看该作者 19楼 发表于: 2009-03-18
又黑又重又复杂的一大坨……
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只看该作者 20楼 发表于: 2010-05-06
这个难度很高啊
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只看该作者 21楼 发表于: 2010-05-06
有简单的原理图参照下就好了,这样完全看不明白

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只看该作者 22楼 发表于: 2010-05-07
这玩意太复杂了。。。居然还能装回去
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只看该作者 23楼 发表于: 2010-05-07
都快比得上汽车的变速箱了
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只看该作者 24楼 发表于: 2010-05-08
捡到了!
穷人玩车,穷有穷玩,一样精彩!
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只看该作者 25楼 发表于: 2010-05-08
终于见识了内变的内部结构
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只看该作者 26楼 发表于: 2010-05-08
卧槽的,这个忒复杂了。
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只看该作者 27楼 发表于: 2010-05-08
坏了    
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只看该作者 28楼 发表于: 2010-05-08
是个拆开修理的过程嘛
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只看该作者 29楼 发表于: 2010-05-12
功力深厚的。。。。。