Morse #3, 1 16' 26'' , DIN4550 and 17/4 or 17-4 Taper?

apolkhanov said:

I have, perhaps, strange question but I was unable to find an answer to it despite my pretty good Googling skills.

Air cylinder in my office chair has failed so I started looking for replacement. I have learned that original cylinder was made by company called DANT in accordance with DIN 4550 standard which is a German standard for these cylinders. Now when I looked at numerous drawings I found that top side has a taper which is 1 26''16 or 1.4377 degrees which I later found is exactly same taper angle as in Morse #3. But when I was looking for replacement cylinder I found that many specify same taper as "17/4" or "17-4". My question is WHY? What notation is 17/4? Is this even related to the size of taper? I am just really really curious where "17/4" came from?

If anyone know please share!

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Heavey Metal said:

Ratio

4 inch taper in 17 inches

4mm taper in 17mm........

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WILLEO6709 said:

That taper has been used in office chairs for decades. In the old days was the 17/2- you could use a morse 3 reamer. They had issues snapping the neck off the cylinders, so it became the 17/4- same taper per inch as a morse 3 but closer in size to a stub morse 4. as I rcall 1.102 inches is the od of those cylinders. Most makers use interchangeable gas cylinders that I am aware of.

No idea the origins of the names.

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