The operation and advantages of the Millam Free-Wheel mechanism, complete with component illustrations.
| Identifier | ExFiles\Box 6\2\ 02-page053 | |
| Date | 3rd April 1929 guessed | |
| Its Operation and Advantages The Millam Free-Wheel is a simple, circular piece of mechanism, which is inserted into the propeller shaft of motor vehicles of all descriptions, and its attachment results in the following advantages :— [Image Captions Left Page] Free-Wheel Body showing Rollers and Wedges in position. Free-Wheel Drum and Back Casing fitted with universal joint. Free-Wheel Drum showing Rollers and Wedges assembled. Sprag showing Rollers and Wedges assembled ready for body. [Main Text Right Page] 1.—FREE-WHEELING. The moment the foot is taken off the accelerator the engine revolutions die away to “ticking-over” speed and the car coasts along. When the accelerator is pressed down the load is once more taken up. 2.—GEAR-CHANGING. In changing gear, it is not necessary to de-clutch, and any gear can be engaged with perfect ease, irrespective of the speed at which the car may be running. 3.—PETROL SAVING. The moment the foot is taken off the accelerator pedal, the engine automatically runs on the pilot jet, using no more petrol than when the car is stationary with the engine “ticking-over.” Due to the conditions above stated, a saving of petrol, averaging about 25 per cent., is gained. This will be obvious when it is recognised that without this free-wheel the moment the foot is taken off the accelerator pedal, the compression of the engine rapidly brings the car to a standstill. 4.—OIL SAVING. Owing to the fact that the engine is never used as a brake, except on the rare occasions when the direct drive is engaged, a vacuum can never be created in the combustion chamber to suck up and burn the lubricant, thereby weakening its lubricating properties. It will be self evident from the above remarks that a saving in oil consumption is bound to occur in any vehicle fitted with this free-wheel. In actual practice, savings have been found to be from 25 per cent. to 60 per cent. From experience it has been found that the period when de-carbonisation becomes necessary has been extended to double the normal time. 5.—EXTRA FACTOR OF SAFETY. The free-wheel and sprag apparatus adds considerably to the factor of safety. In the event of a vehicle getting out of control running down a change into first, second or third gear at any speed, and then cut out the free-wheel by the simple movement of the small handle provided, the powerful engine brake is then available. 6.—EXTRA USE OF BRAKES. It appears to be a popular idea that the brakes are used very much more on a car or bus equipped with a free-wheel, but we have proved this to be a fallacy. It is really just a case of anticipation and practice to obtain the best results. 7.—STRAIN ON THE ENGINE, TRANSMISSION AND DRIVER. It is estimated that 90 per cent. of the reversal strains on the engine and transmission is removed while the vehicle is free-wheeling. In actual practice it is found that on average main roads the period of free-wheeling works out at 25 per cent. of the total distance covered. A very large proportion of the driving strain is taken from the driver. The very fact of the clutch not having to be used in gear-changing is a very much appreciated point. During the period of free-wheeling, the feeling of effortless and noiseless motion has got to be experienced to be appreciated. 8.—LEARNING TO DRIVE. As the Millam Free-Wheel and Sprag is practically automatic and fool-proof, there is no the slightest doubt that from the point of view of the novice learning to drive, it will be of very great assistance in overcoming the old trouble of gear-changing, which is admittedly the principal difficulty the new driver has to master, besides having the additional advantage of making driving much more pleasurable, interesting, and safer. 9.—SPRAG AND ITS OPERATION. The Millam Free-wheel contains an automatic sprag, which prevents a vehicle stopped on a hill from moving backwards, irrespective of the brakes being off or the gears being in neutral. The moment the vehicle stops, the wheels are automatically locked. Starting from stationary on an upward incline has hitherto been a difficult operation to perform. It is a frequent source of accident, due to the difficulty of releasing the brakes, putting in the gear, accelerating the engine, and letting in the clutch all at once. With the Millam Sprag, starting off from stationary on a hill is as simple as starting on the level. No vehicle so fitted can run back except when the gear lever is put into reverse, which operation automatically cuts out both the sprag and the free-wheel. CONCLUSION. Extended trials have been made which go to show that there is practically no depreciation with the Millam Free-wheel and Sprag. When the Free-wheel comes into action it does not do so with a hammer shock, as the double wedged segments have first to squeeze out a film of oil before metal to metal contact takes place, and the squeezing out of the oil gives a time factor which results in its coming into action smoothly and without jar. The moment metal to metal contact takes place there is no further slip or creep, the angles being such that the greater the torque, the greater the grip. The design is very compact and self-contained, and, therefore, readily applicable to any make of private car or commercial motor. | ||
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).