Patent GB-190417502-A (GB)
Title: Improvements in Change Speed Gears for Motor Cars.
Inventor: MURRAY KENNETH SUTHERLAND
Filed: 1904-08-11
Granted: 1905-07-27
Abstract: 17,502. Murray, K. S. Aug. 11. Motor road vehicles.-The change-speed gear of a motor car is so constructed that, with the engine running at constant speed, the speed of the car adapts itself automatically, within certain limits, to the varying resistance. This is effected mainly by forming the driving-shaft in two portions with a secondary clutch between them, pressed into engagement by a spring to drive through the higher-speed gear ; and means are described for automatically causing the disengagement of the clutch and driving through the low gear on the occurrence of an excessive load. The engine shaft A, Fig. 1, to which the main clutch (not shown) is attached, has an enlarged part B on which a screw of large pitch is formed. The internal member E of the secondary clutch has a cylindrical extension, which is screwed internally to fit the part B, and is enclosed by a strong spring K resting at one end on the clutch member E and at the other on a sliding ring which can be operated by the car driver. The external clutch member F is carried on a sleeve g to which is screwed the bevel-wheel G, driving the bevel-wheel P of the differential gear. The hollow shaft A' is mounted on an extension of the shaft A, is connected at one end by a feather key to the clutch member E, and carries at its other end the bevel pinion J. The wheel P has a sleeve R formed on its inner side, carrying two bevel-wheels P<1>, S which slide, but cannot turn on the sleeve. Either of these wheels can be put into gear with the pinion J, the wheel S giving reverse motion. The bevel-wheel P<1> has a pawl-and-ratchet movement for allowing the hub to over run the wheel, preferably constructed as shown in Fig. 5. A number of pawls a are pivoted in one of the rotating members b, and the other member c has, in addition to the teeth c<2>, a disc c<3> with cams c<4> operating on the back of the pawls. When the car is started, the secondary clutch E, F is disengaged and the motion is transmitted through the wheels J, P' to the differential gearing. When a high speed is desired, the parts E, F are clutched together and the motion is transmitted through wheels G, P to the differential gear. In this case, the hub or sleeve R must overrun the rim of the wheel P', and, for this purpose, the free-wheel gear described above is used. If the load on the car increase, the portion A of the engine shaft will begin to turn independently of the part A<1>, and the screwed portion B will tend to withdraw the clutch member E, thus allowing slip to occur and diminishing the speed of the car. Under very heavy loads, the clutch is entirely separated and the drive is transmitted through the low-speed gear. Fig. 3 shows a modification of the clutch part of the gear. The screwed part of the shaft A is replaced by a pair of flanges e, B, having inclined teeth. The conical clutch is replaced by a multiple-disc clutch enclosed in a box F forming part of the sleeve g. In another modification, the inclined teeth are replaced by rollers secured in the flange e and adapted to roll against an angular surface on the flange B. The low-speed gear is obtained in this arrangement through spur-wheels, two of which are mounted on a countershaft. One of these wheels is provided with free-wheel gear, while the other can be slid into engagement with a pinion for reverse driving. The two series of discs forming the members of the clutch are arranged respectively to rotate with a sleeve on the shaft A and with a cylindrical continuation of the flange e. Screws are provided to take up the wear in the discs. In this arrangement, two springs K, K<1> are employed, one K acting only on the secondary clutch, the other acting on the engine clutch. A cross shaft L operated by a pedal Y is arranged to bridge over the engine shaft A, and is connected by links M<1>, N' with the sleeve Q and the engine clutch U respectively. When the pedal Y is depressed, its first action is to compress the spring K' and release the spring K. The rods N<1>, owing to their slotted ends N<2>, are not affected by a slight turning of the shaft L. The first movement of the pedal Y gives control of the gears through the secondary clutch, and a further movement de-clutches the engine. The gearing may be arranged to work in a fixed casing constituting the oil reservoir.