From the Rolls-Royce experimental archive: a quarter of a million communications from Rolls-Royce, 1906 to 1960's. Documents from the Sir Henry Royce Memorial Foundation (SHRMF).
Technical comparison and design breakdown of a Cotal magnetic clutch versus fluid clutches, with details on its construction.
| Identifier | ExFiles\Box 178\2\ img052 | |
| Date | 26th March 1940 | |
| Rm.{William Robotham - Chief Engineer} - page 3 Serial No. 53 OY 13/D/Mar.26.40 At the same time, considers Cotal magnetic clutch in principle is greatly superior to fluid clutches as used on Olds Hydramatic. Trouble with latter is effects of dirt in oil interfering with action of delicate mechanism; and the weight, the two oil pumps weighing 24 lbs., for ex-ample. Olds box weighs 160 lbs. (my guess of February 13 was pretty bad). Packard comes out around 135 lbs. with full equipment. If he uses bronze rings or buttons to prevent actual ferrous con-tact in Cotal clutch, the current consumption is too high. Is working on this problem, but, naturally did not tell me his ideas. (would a de-magnetising kick on release do the job?) I gathered the great clutch problem is to make this Cotal two-way clutch release and engage smoothly under load. Clutches The box is conventional type for this design (four and reverse) with three epicyclic trains, using simple planets, the forward being 1st speed, middle, reverse and rear overgear, with solid drive on 3rd speed. Four clutches have to be used. The forward clutch is Cotal type double acting (scheduled for redesign as above). The center is overgear and second. A roller clutch at the rear permits over-running in fourth speed. Reverse engages with a sliding shift. The center clutch cannot be Cotal type without raising the floor-boards intolerably. Is, therefore, a magnetized multiple plate clutch. It is this feature amongst others that Walter is anxious to keep from G.M. Details The mechanical details are simple and designed for cheap production. All three trains are true plain-pinion epicyclics with planets on plain bearings and the annulus gears designed for through-cutting. No gears will be hardened or ground. It is the intention to heattreat and finish teeth at 40 Rockwell. Helical teeth on some trains being considered. Planet cages are one piece malleable iron castings, with pinions running on plain inserted case hardened pins. Only three ball bearings used in box. Lubrication of plain bearings on center shafts is taken care of by a most ingenious vane pump contrived from a plain/cross-pin [handwritten: sliding] in one shaft running in an eccentric bore on parts rotating with the other shaft. The pin is flattened to form its own valving and results in pump-ing positively a quantity of oil through the center bores of each of the two shafts, whenever there is relative motion between them. Controls Attempts being made to simplify the controls. Shifting on the | ||