# Cylindrical gears

 Normal module = mn = = mt.cosb = .cosb Transverse module = mt = Normal pitch in mm = pn = pt.cosb = mn.p Transverse module in mm = pt = Normal base pitch in mm = pbn = pn.cosan = pt. cosan.cosb Transverse pitch in mm = pbt = pt. cosat Number of teeth = z = or or Virtual number of teeth = zv = Pitch diameter in mm = d = z.mt of or Tip diameter in mm = da = d+2.mn Facewidth in mm = b = 10.mn Tooth depth in mm = h = 2,16.mn or 2,16. for a= 14°30’ = h =2,25.mn or 2,25. for a= 20° Addendum in mm = ha = mn or Dedendum in mm = hf = 1,16.mn (1,25.mn) Thickness below the tooth in mm = H = approx 1,6.mn minimum Centre distance in mm = a = Helix angle = cosb = = = Base helix angle = tgb b = tgb .cosa t Transverse pressure angle = tga t =

## NOTES:

Cylindrical gears are used in transmissions between parallel or crossed shafts. For the crossed shafts the case of having an angle different from 90° are omitted; after all this hardly occurs. The abovementioned formulas apply on cylindrical gears for parallel and / or crossed shafts; for the size and direction of the tooth angles there are, however, separate rules we will explain below.