Since gear sets would not function without a proper lubricant, it has been suggested that gear oils be given the status of structural materials. As early as 1942 Almen^1 stated that a gear lubricant in addition to being: “A lubricant in the usual accepted sense of a liquid film separating two rubbing surfaces,” should also be considered as “a structural material in the sense that it is an important factor in determining the size of gears.”
More recently, Blok^7a devoted an entire paper to “Gear Lubricants as Constructural Elements”. This author suggests that the designers of gear sets keep in mind that:
“The lubricant is to be conceived as a constructional material, and thus its constructional properties, such as viscosity and antiscuffing properties, well deserve to be accounted for even in an early design state”.
Consequently, Blok^7a plotted curves connecting power transmitted with speed, showing the barriers which must be raised either by improvement in materials or by the use of special lubricants if load capacity of gears is to be increased
