DIN 3975:1976-10

1 Symbols and designations
2 Terms for cylindrical worm gears
      2.1 Cylindrical worm gears; worm, wormwheel
      2.2 Relative shaft position
             2.2.1 Line of centres
             2.2.2 Centre distance alpha
             2.2.3 Shaft angle sigma
      2.3 Speed ratio i, hand
      2.4 Gear ratio u
      2.5 Planes of intersection
      2.6 Pitch surfaces and pitch lines
             2.6.1 Rolling (pitch) circle of the wormwheel
             2.6.2 Pitch cylinder, pitch plane
             2.6.3 Rolling axis
      2.7 Equivalent spur gear pair
      2.8 Reference system for the tooth dimensions
3 Terms and definitions/parameters for a cylindrical worm
      3.1 Sections through a worm
             3.1.1 Axial section of the worm
             3.1.2 Normal section of the worm
             3.1.3 Transverse section of the worm
             3.1.4 Cylinder section
      3.2 Number of teeth z1 in the worm
      3.3 Flank direction; right-hand, left-hand
      3.4 Parameters in the axial section
             3.4.1 Lead pz1
             3.4.2 Reduced lead pz1 red
             3.4.3 Axial pitch px
             3.4.4 Module m (axial module mx)
      3.5 Parameters relating to the various co-axial worm
             cylinders
             3.5.1 Reference cylinder, reference diameter
                      dm
             3.5.2 Diametral quotient q
             3.5.3 Tooth traces, reference cylinder -
                      tooth trace
             3.5.4 Reference lead angle gamma m
             3.5.5 Reference helix angle beta m
             3.5.6 Reference cylinder - normal pitch pmn
             3.5.7 Tooth depths; tip cylinder and root
                      cylinder
             3.5.8 Tooth thickness, spacewidth
      3.6 Worm flank forms
             3.6.1 Shape producing line of the cutter
             3.6.2 Worm tooth flank generator
             3.6.3 Angle of generation alpha o
             3.6.4 Flank Form A (straight sided axial worm
                      - Type ZA)
             3.6.5 Flank Form N (straight sided normal worm
                      - Type ZN)
             3.6.6 Flank Form I (involute helicoid worm
                      - Type ZI)
             3.6.7 Flank Form K (milled helicoid worm
                      - Type ZK)
      3.7 Special parameters for ZI-type worms
             3.7.1 Base cylinder, base diameters db1
             3.7.2 Base lead angle gamma b
             3.7.3 Base cylinder pitch pb
      3.8 Worm facewidth b1
      3.9 Crowning
4 Terms and definitions/parameters for a wormwheel
      4.1 Module m (transverse module mt)
      4.2 Flank direction; right-hand, left-hand
      4.3 Mid-plane
      4.4 Parameters in the mid-plane
             4.4.1 Pitch circle, pitch diameter d2
             4.4.2 Pitch p2 (transverse pitch)
             4.4.3 Addendum modification x.m
             4.4.4 Tooth thickness s2
             4.4.5 Space width e2
      4.5 Axial section of the wormwheel
      4.6 Parameters in the axial section
             4.6.1 Reference toroid, reference toroid
                      radius rm1
             4.6.2 Tooth depths
             4.6.3 Tip surface and root toroid
             4.6.4 Facewidth b2 of the wormwheel
5 Tooth thickness allowance and tolerance
      5.1 Tooth thickness allowances As
      5.2 Tooth thickness tolerance Ts
6 Deviations of individual parameters
      6.1 Worm deviations
             6.1.1 Lead deviation fpz
             6.1.2 Periodic lead deviation fpz per
             6.1.3 Lead angle deviation f gamma
             6.1.4 Pitch deviations
             6.1.5 Total profile deviation Ff1
             6.1.6 Axial run-out (eccentricity fe1,
                      wobble F sigma 1)
      6.2 Wormwheel deviations
             6.2.1 Circular pitch deviations
             6.2.2 Total profile deviation Ff2
             6.2.3 Radial run-out Fr2
      6.3 Rolling deviations