Plot a flexspline profile

Hello,

I would like to draw this blue profile

I do not now much about equations, but I would like to know if it might be possible with Wolfram|Alpha. I compared the equitation with some examples and came up with this

plot (x+la)^2 + (y+hf)^2 = (1.147*0.5)^2,
(x-0.5s)cot y + y - hf = 0,
(x-lf-t)^2 + (y-hf-ef)^2 = (1.307*0.5)^2

pa and pf is given … other values do not. I would be happy about any help.

Best Regards,
Simon

You may find this demonstration useful: Mechanical Involute Gears.