Involute spline 9H Formula 2

[Phlegyas]

I have a Din 5480 Spline on my Blue Print N50 X 2 X 24 X 9H.
the 9H is where I can use some assistance. Is 9H the Space width tolerance? is 9 the class? (my 25 hand book only list 4-7) What is the formula that is used to calculate 9H . Any help is much appreciated

 

[gearcutter]

You are correct 9H is the tooth space tolerance.
To figure out how it relates to the actual measurments needed for a given pitch, pressure angle, diameter & number of teeth you'll need to get hold of the DIN5480 part 14 standard, easily obtainable via the web.
Here is a link to a calculator that may help you understand the DIN fit tolerancing system, you'll need Java to be enabled in your browser -

http://www.tecnologix.net/en/tools/passungsrechner/passungsrechner_v05.html

In this case the BTL across 5 spaces would be 26.644 - 26.682 and across 3.5mm pins would be 42.673 - 42.762.