EHL analysis of your shortlist

Describe the gear pair once and every oil you shortlisted gets its film along the whole tooth, by AGMA 925-B22: the thinnest film, the lambda it gives, the wear risk that implies, and, from the mesh temperatures, the scuffing risk. This is the analysis 9005-F16 says outranks its own tables. It is still a calculation on datasheet numbers, not a test.

No oils in the shortlist. Start on Find my oil, tick the candidates, and send them here.

The gear pair

Pinion teeth

Gear teeth

Normal module, mm

Face width, mm

Pressure angle, °

Helix angle, °

Centre distance, mm

Pinion tip radius, mm

Gear tip radius, mm

Tip and root relief

Tooth finish

Tip radii default to the standard addendum; give them from the drawing when the teeth are profile-shifted. The relief choice selects the load-sharing model of 925 clause 5.4: unmodified teeth carry a third of the load at entry and exit, relieved teeth less.

Speed, load and temperature

Pinion rpm

Power, kW

Pinion torque, N·m

Derating K_D

Sump oil, °C

Lubrication

Take one FZG stage off each oil (925 cl. 10.2.4: oil ages between changes)

K_D is the product of the overload, load-distribution and dynamic factors from AGMA 2101; 1.0 if you do not know them (the standard's own example uses 1.49). The tooth temperature is computed from the sump temperature and the peak flash temperature (925 Eq. 74), and every oil's viscosity is taken at the tooth.

What this is, and is not.

AGMA 925-B22 clause 5 geometry, velocities and loads along the line of action; clause 5.4 load sharing for the relief you chose; the Dowson and Toyoda central film (Eq. 78 to 89) at 25 points; lambda adjusted to the Hertzian width (Eq. 104); wear probability from the Figure 19 fits (Eq. 116 to 120), floored at 5 %. Checked against the standard's own Annex D example to four figures in tests/ehl925-test.php.
Mesh temperatures by clause 8: Blok's flash temperature at each point (Eq. 68) with the constant friction coefficient of Eq. 69 and steel's thermal contact coefficient (16.5 N/[mm s^0.5 K], Annex D's value); tooth temperature by Eq. 74; every oil's viscosity taken at the tooth. Scuffing by clause 10: the oil's scuffing temperature from its FZG stage (Eq. 108, with the base-oil factor of Eq. 109) or, without one, from its viscosity grade (Eq. 105 for R&O, 106 for antiscuff), compared with the peak contact temperature through Eq. 110 to 113, floored at 5 %, graded by Table 9. 925 says the grade formulas are conservative for synthetics. Checked against Annex D: friction 0.109, peak flash 25.6 °C at point 5, scuffing temperature 320 °C, x −4.42.
Isothermal film: no inlet shear heating (cl. 9.3), which lowers the film further at speed; the example's 0.23 µm minimum becomes 0.14 with it.
Steel on steel, external gears. Helical pairs use the clause 5.1.3 minimum contact length. Dynamic viscosity is the D341 value at temperature times the published density; the pressure-viscosity coefficient is 925 Table 4 by base oil type, so an oil whose maker does not state its base stock gets no number.