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).
The mechanics, development, and fitting of a gyroscopic non-skid device for automobiles.
| Identifier | ExFiles\Box 77\5\ scan0172 | |
| Date | 14th December 1923 guessed | |
| 4 observed the small rollers that are fixed to the frame and that lie close behind the gyro-ring across the horizontal axis. It is these rollers that restrain the precessional action of the gyro-wheel and that take the whole of its reactionary restraining force, so that it will be understood that it all depends as to whether the side-slip is to left or to right, as to whether the gyro-ring tips forward or tips backward, and as to whether in turn the reaction takes place against the right hand roller or the left hand roller. The tipping of the wheel backward or forward also depends upon its direction of rotation. Fig. 4.—A belt-driven form of gyroscopic non-skid mounted in the position usually occupied by the fan between the engine and the radiator. Possibly the improved arrangement illustrated photographically in Fig. 4 and by line drawings in Fig. 5, may make the action of the device even more clear. Here the shaft is carried in substantial frictionless ball-bearings; and the gyro-ring occupies the position usually taken by the fan close up behind the radiator. Our line drawings are, of course, very diagrammatic, but in the central sketch it will be seen how a short spindle, carrying a ball-bearing race around it, is fixed by diagonal brackets to the wheel, so that the spindle remains co-axial with the ring. This ball-race is then mounted between substantial guides that are rendered rigid with the chassis main-frame, and these guides permit a fairly free up and down movement of the ball-race, but prevent any lateral travel. On the extreme left in Fig. 5 is an indication of the position which the gyro-ring assumes at the moment that a side-slip makes its influence felt, the ring having tipped momentarily right over, and having exerted a powerful lateral thrust against its stationary guide. In this latest form of construction small cushion springs are introduced above and below the ball-race to assist in bringing the gyro-wheel back to its normal position more quickly than would otherwise be the case without them, thus rendering it ready to act once more in a series of oft-repeated impulses should the tendency to side-slip still continue. These springs, however, do not materially reduce the rapidity of the “kick” when it first starts, and during the moments when its effect is most needed, so that the quick return action is secured without sacrificing materially the efficacy of the gyro device. Other Mechanical Considerations. For very many reasons it is most desirable that the gyro-wheel should be frictionally driven, and that it should also have the equivalent of a free-wheel device. Its weight is such that it is capable of exerting enormous strains on any intermediate coupling members that may be introduced between it and the engine, while also the fly-wheel effect is sufficient seriously to interfere with the liveliness of the engine if the engine already is equipped with a fly-wheel of exactly suitable weight. It will, of course, have been observed, too, that the gyro-wheel cannot possibly be made to take the place of the ordinary fly-wheel, since no universal-joint could be expected to withstand the enormous strains there would be between it and the crankshaft, if it were called upon to equalise up the positive and negative strokes of the pistons. Thus it comes about that if the wheel is mounted in front of the radiator some form of slip clutch is needed behind it, and also that a free-wheel clutch would to advantage be introduced to permit it to run on quite freely. Speaking of the free-wheel device, or of its equivalent, there is yet another very important reason why it is required, for when one comes to consider it, the very times when sideslip is most to be feared is when a car is travelling fairly slowly in thick traffic, and yet those are the very times when a direct-driven gyro-wheel would probably be revolving much too slowly to be of much use. With a freewheel, however—and those now made remain good and effective for a good five minutes after having been speeded up—the speed remains practically that represented by the maximum rate of travel during quite a considerable previous period, and hence during momentary periods of negotiating awkward places the gyro-wheel is still spinning round sufficiently merrily to fulfil its functions adequately if required. For the reasons just given it is singularly fortunate for the future of this device that a very slack belt running over flat pulleys, or a slack rope running over V pulleys, is capable of meeting the precise all-round requirements of the case. Such a belt or rope absolutely prevents the gyro-wheel from interfering with the liveliness of the engine; and yet, although it permits the wheel to continue revolving for quite a considerable period after the engine has been slowed right up, yet it is quite capable of bringing the wheel up to speed within a reasonable time and without any risk of failing to do so. At the same time the adoption of the belt or rope type of drive facilitates placing the gyro in the most desirable position on most cars, from the point of view that has already been fully explained. In addition, moreover, it lends itself well to gearing-up, say in the ratio of 2 to 1 or thereabouts, so that the size and the weight of the apparatus can be kept down materially in consequence. State of Development. Such then are the principal points connected with this very interesting device at the present time, when the general principles have been fairly well established, and when the practical work of equipping existing cars and of gaining everyday working data has begun. Just for the moment no actual figures are available showing the precise relationship between weight, size and speed, or showing the exact effect of varying the strength of the cushion springs that lie above and below the ball-race in the latest design. These are points, however, with which we hope to deal again at a later period. For the moment it suffices to say that the Company manufacturing and fitting this ingenious apparatus can only determine the precise arrangement that is best in each individual case by taking into full account the exact conditions that happen to hold good. Apart from questions of room and space for fitting and for fixing, the length of wheel-base clearly has some bearing on the outfit needed, besides which, as is well known, some cars have a greater tendency to side-slip than others, and so are apt to need larger or heavier wheels. Some guide, however, may be afforded by the fact that wheels varying in diameter between 10 in. and 18 in. are now made, and that on one of the big 10 ft. wheel-base cars which we recently saw tested a 13 in. wheel weighing about 50 lbs. was employed, and this was driven by a rope with a gear ratio of about 2 to 1. Fig. 5.—Diagrammatic side and front elevations, showing the general arrangement and the action of the device seen in Fig. 4. “Auto.” (Yellow Cover) Copyright. | ||