From Mandatory Appendix 24: Design Rules for Clamp Connection, 24-4

Wm1=0.637 ( H + Hp ) tan (O - u )

Wm2=0.637 ( Hm) tan (O - u )

Wm3=0.637 ( H + Hp ) tan (O + u )


I understand that 0.637 is the percentage of total radial outward force from the hub resolved into the 2 opposite direction which the clamp is being held against. Picture and Formula as follow:-





What i do not understand is how they managed to arrived at :-
( H + Hp ) tan (O - u )

I know the vertical upward force is being resolved into radical outward force through the interaction between the hub and clamp slope.
However i couldnt see how they arrived at that arrangement , my attempts to resolve them result in:-

[a] ( H + Hp ) sin (O - u ) cos (O - u )

[b] ( H + Hp ) / tan (O - u )

Does anyone has any ideas ??

Any discussion on other parts of Mandatory Appendix 24: Design Rules for Clamp Connection are more than welcome..
especially from 24-5:Hub Moments, 24-6:Calculation of Hub Stresses & 24-7:Calculation of Hub Stresses.