Patent GB-736713-A (GB)
Title: Improvements in and connected with braking drives embodying hydraulic clutches and particularly intended for motor vehicles
IPC: F16D67/00
Filed: 1953-03-19
Abstract: 736,713. Hydromechanical change-speed gearing. DAIMLER - BENZ AKT. - GES. March 19, 1953 [March 19, 1952], No. 7688/53. Class 80 (2). In countershaft change-speed gearing between driving and driven shafts 110, 120, Fig. 1, particularly for motor vehicles, wherein one or more speed paths, for instance through constantmesh gears 114, 115, 117, 118 rendered operative by engagement of a clutch 119, includes a hydraulic clutch or converter 111, 112, and one or more other speed paths, for instance through a direct-drive clutch 121, by-passes the hydraulic clutch, one speed of each set can be simultaneously brought into action, for instance by engagement of the two clutches 119, 121, so as to produce hydraulic braking. This braking is greater if the two speeds engaged differ considerably, for example second and fourth speeds of a four-speed gear, and it may be varied by controlling the blade inclination, fluid content &c. of the hydraulic clutch. Within a certain range, the braking also varies according to the engine output. A clutch between the engine and shaft 110 may be disengaged simultaneously with the engagement of the two speeds. The gear clutches may be operated by pressure fluid controlled by rotary valves 10, 11, Fig. 3. In the normal position of valve 11, in which ducts 21 ... 24 are in communication with ducts 26... 29 leading to the four gear clutches, pressure fluid supplied at 12 is directed to any one of the ducts 21 ... 24 by turning the valve 10. If, however, valve 11 is turned through 90 degrees, ducts 21 ... 24 are cut off from ducts 26 ... 29 and fluid passes from duct 12 through duct 31 and passages in valve 11 to ducts 27, 29, so as to engage second and fourth speeds, irrespective of the setting of valve 10. Valve 11 may be turned to this braking position by clockwise movement of a lever 40, Fig. 6. Upon further clockwise movement of lever 40, it moves a spring-loaded arm 42 operating, through a rod 45, a cam 46, controlling a valve 47, and, after lost-motion at 48 has been taken up, a lever 49 controlling a plunger 50. A spring 51 is arranged between plunger 50-and a valve 52, the space 53 beneath the latter being supplied with fluid whose pressure increases with the speed of shaft 120. In the position illustrated, with the two speeds engaged but valve 47 'in its upper position, the hydraulic clutch is kept filled from a fluid supply duct 56 through duct 62, passage 61 in valve 47, and duct 63. If lever 40 is moved further clockwise, so as to move valve 47 down, the hydraulic clutch is still kept filled from duct 56 through groove 55 in valve 52, duct 57, passage 61 and duct 63, so long as valve 52 is maintained in its upper position by the pressure in space 53 against the action of spring 51. Below a predetermined low speed of shaft 120, however, valve 52 moves down so that the hydraulic clutch partially or completely empties through duct 59, groove 58 in valve 52, and duct 60, so as partially or completely to suspend the braking action. By still further clockwise movement of lever 40, the plunger 50 is moved down, stressing the spring 51, so that the braking action is suspended below a higher speed.