Google Book Search is such a help in learning about past and present manufacturing techniques.
The older books are in the public domain, and so, can be quoted or copied.
Here is the very best (then and probably now) SILENT gear material, which I referenced to above.
It's infinitely tougher than "nylon", though today specialized plastics, moldable like nylon, make the machined laminated cloth gear unnecessarily costly, therefore obsolete. But for strength? This old problem was long ago solved. From: http://tinyurl.com/q2n9s8
840. Bakelite Micarta-D Gears and Pinions. - T. D. Lynch and R. E. Talley. (Elect. J. 13. pp. 368-371, Aug., 1916.)Ã¢â‚¬â€Noise represents in itself a loss of power, but the chief reason for giving it serious consideration is that it is necessarily associated with vibration. Direct loss of energy due to vibration is of particular importance at high speeds. By eliminating noise, the wear and tear on machinery is reduced and the efficiency of workers is increased. A suitable non-metallic gear material must have sufficient strength to keep the face width reasonably narrow ; it must be hard enough, to wear well, and must not shrink or swell. Metallic reinforcement should be unnecessary, so that two muting gears can be made of equal width to obtain uniform wear. A product of heavy duck bonded with bakelite by heating under very high pressure goes by the trade name of Bakelite Micarta-D. This material is as strong as cast iron ; it is proof against oil, atmosphere, and vermin, and, unless conditions arc unusually severe,, it can be used without bush or flange. The teeth need never be shrouded, and the width of the gear is determined only by the power to be transmitted. The physical properties of this material are:Ã¢â‚¬â€ Tensile strength, parallel to laminations, 10,000 Ibs. per sq. in.; compression strength perpendicular/parallel to laminations, 35,000/17,000 Ibs. per sq. in. ; transverse strength, max. fibre stress perpendicular or parallel to laminations, 17,000 Ibs. per sq. in. ; coefficient of expansion (per in. per 1 deg. C., 0-00002 in. parallel to, and 0-000085 in. perpendicular to laminations ; sp. gr., 1-4; weight per cub. in., 005 Ib.; shrinkage practically zero" up to 100Â° C. ; oil absorption practically zero ; water absorption (50 hrs. immersion at 21Â° C.), 0-25 to 2 % by weight, depending on relative amount of edge exposed. The same tools may be used as for steel when cutting teeth, but the cutting speed may be increased 25 % and the feed 50 % ; turning may be done at 400 to 500 ft. per min. with a tool of 30Â° cutting angle and 10Â° clearance. Metal end- plates should be used on heavy Micarta-D gears, and always when the pitch diam. exceeds 4 times the face width. The thickness of the end-plates is governed by the torque at the hub. With light torque the chief function of the end-plates is to act as washers, and J in. to J in. thickness is sufficient. With heavy torque the end-plates must strengthen the keyway, and should be J in. to | in. thick, or even be in the form of flanged bushings. Notes on design and applications of these gears are given in the original. Spur, bevel, spiral, and helical gears can be made from Micarta-D. In order that they may mesh properly with metal gears, both must be cut true, lined up accurately, and properly spaced between centres. The back-lash allowance should be double that usual for steel. Free lubrication with oil or grease is necessary. Generally Micarta-D gears can be substituted for steel (untreated), cast-iron, or bronze gears, and with the same dimensions as the metal gears which they are to replace ; they will outlast raw hide and other non-metallic gear materials, and, in some services, will outlast cast iron.
I hope this was of general interest.
The old tech stuff was generally extremely well thought out by men of long and trained experience:
it was the golden era of the Mechanical Age.
Two corrections at least, are in order:
THANK YOU, Mark, for making me think, even under sedation.
Secondly, the timing gear referenced is not in this thread. I must fetch a link, or just re-describe the gear:
It was a beautiful thing, Westinghouse branded, molded and patent-dated in the face of the gear
and the phenolic-bonded laminations, all hand-laid, many, many layers of cloth, all saturated with thermosetting phenolic resin.
It was a glossy, brown, wonder of workmanship, as was the die it was pressure-cast in, and then the machining of the teeth, beautifully done.
It was a premium product for the demanding Fordist, the man tired of the whine and clatter of the stock, cast iron, half-speed gear.
These things had to be incredibly strong and fatigue resistant, to resist the un-damped, extremely nasty,
hammer-like harmonic vibrations of the slender four-throw Ford crank. Other makers, including Mercedes Benz, used such silent gears in the 20s and 30s, if in lieu of "silent" timing gear chains, which, long term, proved a better method overall.