Buttress Threads 2

[s1lverfox]

Does anyone know what "Form A" means in relation to buttress thread designations. I have a drawing dated 1992 which states that the thread provided on a shaft is 4 inch buttress thread 6 tpi form 'A'. However I can find no reference to form 'A' in Machinery's Handbook 22nd edition (which contains descriptions of US buttress threads) or BS 1657 which covers UK buttress threads.

Many thanks in anticipation of your replies !!

 

[gr2vessels]

The form A is the standard form, the load face is perpendicular;- form B is the 1 to 5 degrees face angle and the form C is the German metric buttress with 3 degrees face angle. The US Buttress is different.
cheers,
gr2vessels