Alfa selespeed vertical plunger/piston

[Kram]

You could use copper sulphate based layout fluid - that would plate copper onto steel but no effect on chrome.
Wet a tissue with vinegar or weak acid and cover the shaft for a while. If it was steel the part will be etched where as chrome is generally resistant.

If you dont mind me asking, why do you have multiples of this shaft and why do you need multiples, is it a common problem that is replaced often, do you work in repairing these?

Turning is quicker, if I had both machines I'd likely turn the part leaving the seal surfaces slightly oversized. Harden and temper, then chuck up in grinder to get the final size.

Exactly the same if I did it in lathe except instead of grinding, I would simply be polishing starting at 80 grit upto 1000 grit until its as smooth as a babys bum. I do t have one but a toolpost grinder could also be used. I dont think you could tell the difference without fancy measuring equipement.

One thing Im unsure of with grinding, is what grit wheel a shaft grinder would normally use, do they swap a coarse and fine wheel for roughing and finishing?


For the hardening process I suggest the slotted end probably will be a weak point either sould be unhardened or highly tempered due to the sharp corners.
If you file test the original, is that end and the middle section hard?

 

[Agroshield]

Also I'm not convinced the original is plated at all. Still yet to find a way to test this

If it is unplated and just finely finished steel, it will corrode in salt water. A chrome-plated shaft would not do so. Similarly, it would react differently to a dose of acid.

Centreless grinding is a mature trade. The raised portion in the middle is no challenge.

 

[Agroshield]

...do they swap a coarse and fine wheel for roughing and finishing?

Only is there is a mega amount of stock to remove. Like roughing and finishing on a lathe with the same tool, you would alter feed and depth of cut to go from one to another.

The grinding section of Woodbury's History of Machine Tools (https://archive.org/details/studiesinhistory00robe) is rather good.

Sorry, I did not read your distinguishing tests before posting above, which repeats what you said.

 

[Kram]

Thanks for the link but its not showing many pages without registering? I'll have another look later on.

Like roughing and finishing on a lathe with the same tool, you would alter feed and depth of cut to go from one to another.

I rarely would choose the same tool for roughing and finishing and I imagine it is far more important on a grinder.

Ofcourse for a lathe there are tools in the middle that will give an excellent finish and a reasonable depth cut is often superior to a light finishing cut but that does not suit every operation.

 

[bricol]

I think perhaps the way to go would be to use stainless, and have it ground. But how is it ground with the central raised portion in the way, do they have to grind one end at a time? Also I'm not convinced the original is plated at all. Still yet to find a way to test this

The undercuts either side of the raised section allows the grinding to run out. Are there any indentations in the ends for service?

 

[Agroshield]

Are there any indentations in the ends for service?

I think your auto-spell may be playing dirty tricks on you. I think the last word should be 'centres'.

In a production run for an OEM, it would not be economic to grind between centres. The item would likely be ground in a centeless grinder - pour a bucket of unfinished parts into one end of the machine and retrieve round, shiny, precision items from the other end.

 

[bricol]

I think your auto-spell may be playing dirty tricks on you. I think the last word should be 'centres'.

In a production run for an OEM, it would not be economic to grind between centres. The item would likely be ground in a centeless grinder - pour a bucket of unfinished parts into one end of the machine and retrieve round, shiny, precision items from the other end.

No, I did mean "service" - but I'm not fully conversant with grinding process, especially not for large scale production. For my job, large scale production might be 5 off in on go

 

[bricol]

You can plate up to around 0.5mm - depending on the depth of the damage, it might be possible to turn it off, plate and grind back.

Talk to industrial plater - not car bumper platers. If any still exist - we used to spec what thickness plating we wanted, together with paperwork stating it had been achieved - discovered the local place didn't have anything to measure thickness, just relied on estimation from time in the bath - they had grown from plating bumpers etc to more toleranced industrial components but hadn't kept their processes and abilities up to go with it.

 

[markherbert]

I do not run a business repairing these. I have multiple to see if I use get the shaft out of another broken unit

A file marks everywhere on the shaft quite easily

There are indentations in each end of the shaft

I've got the end of the shaft in some saltwater now seeing if it rusts

Thanks for all the help

 

[markherbert]

Filed area

 

[markherbert]

So I've done a drawing. I'm not really sure what I'm doing so if anyone sees any missing information or incorrectly displayed then let me know. I would like to ask this forums advice on tolerances (which I haven't added on yet as haven't a clue on what they should be, and surface finish which I had a go at but unsure if suitable. The shaft I have here definitely isn't plated, tested that, and it appears hardened from its colour but a file marks it no problem. I think I perhaps mistook blueing possibly from the grinding process as a hallmark of hardening? Anyway, any recommendations for material please too. Something that doesn't rust as easily as the one that came in the unit preferably!

 

[Misterg]

I would let somebody re-work that drawing for you before you go out for quotes...

Am I the only one who though that an 'Alfa Selespeed Robot' was some sort of industrial "thing"?

Well, I've just found out that it's a robot gear changer for a car!

I presume that the part in question is the vertical plunger in the bottom right. It just seems to be a double acting actuator that waggles the gear selector between 1/2, 3/4 & 5/R gates without any need for huge precision: Parallel section at each end and a seal in the middle. One end has a notch to engage in the end of the selector. (There is position feedback transducer to hit the right movement.)

Found some info online [EDIT: LInk updated] that gives: "Working pressure between 45 and 55 bar (there is a pressure relief valve to avoid system over-pressure) Working temperature between -30°C and +125°C "

Given that information, and knowing the nominal sizes of the sealing surfaces, it should be possible to figure out suitable dimensional tolerances, surface finish and seal materials with reference to one of the 'Big Books of Orings' - e.g. Eriks (2nd page on - tables on pages 9&10).

I guess the original sliding surfaces will have been ground (the part is designed that way).

It seems quite a few people convert them to manual!

 

[markherbert]

I would let somebody re-work that drawing for you before you go out for quotes...

Am I the only one who though that an 'Alfa Selespeed Robot' was some sort of industrial "thing"?

Well, I've just found out that it's a robot gear changer for a car!

View attachment 467606

I presume that the part in question is the vertical plunger in the bottom right. It just seems to be a double acting actuator that waggles the gear selector between 1/2, 3/4 & 5/R gates without any need for huge precision: Parallel section at each end and a seal in the middle. One end has a notch to engage in the end of the selector. (There is position feedback transducer to hit the right movement.)

Found some info online that gives: "Working pressure between 45 and 55 bar (there is a pressure relief valve to avoid system over-pressure) Working temperature between -30°C and +125°C "

Given that information, and knowing the nominal sizes of the sealing surfaces, it should be possible to figure out suitable dimensional tolerances, surface finish and seal materials with reference to one of the 'Big Books of Orings' - e.g. Eriks (2nd page on - tables on pages 9&10).

I guess the original sliding surfaces will have been ground (the part is designed that way).

It seems quite a few people convert them to manual!

That link doesn't work for me, is it possible you could share some images of the pages here?
The drawing isn't great I know, but not done one other than for my own use before. In terms of tolerance along its length I agree it probably isn't that precise. But the diameters and surface finish I assume need to be quite tight tolerance for 45-55 bar. Will check out that book you have sent.
I think people convert them to manual for this same fault, it would be nice to have a few of these made.

 

[Misterg]

That link doesn't work for me, is it possible you could share some images of the pages here?

Sorry - it was supposed to link to the archived version of that site. I've edited the post above to correct, but try here:

Alfa Romeo Selespeed - hydraulic system

(There are quite a few pages - let me know if you're still struggling).