Patent GB-393294-A (GB)
Title: Improvements in or relating to variable speed gearing and like mechanism for the transmission of power
IPC: F16H61/02
Filed: 1931-11-30
Abstract: 393,294. Variable speed gearing. SWAN, J. G., 14, Old Square, Lincoln's Inn, London. Nov. 30, 1931, No. 33130. [Class 80 (ii).] In combination with mechanical changespeed gearing, which may be of any suitable type and is not described, and between that gearing and an engine as upon a vehicle, there is arranged a coupling device or unit which itself comprises an hydraulic coupling and a three-section planetary gear train, the hydraulic coupling not being connected undisconnectably with both the input and output shafts of the unit but serving to couple together two sections of the gear train one of which sections is neither connected undisconnectably with said input shaft nor so connected with said output shaft. In a simple form of unit shown in Fig. 6, an oiltight casing 49 enclosing the planetary gearing connects a sun gear 13 to an hydraulic coupling element 12 which is in turn fast on the input shaft 11. The driven hydraulic element 14 is connected by a short shaft 50 to an internal gear 24 which meshes with planet gears 20 carried by a spider 19 fast on the output shaft 18. The hydraulic coupling thus serves to connect the driving gear 13 to the free or loose gear 24. In the hydraulic element 14, the usual inner toric partition corresponding to the partition 33 of the driving element 12 is omitted and the vanes extend right across, the object being to diminish the braking effect of the element 14 on the element 12 when the former is rotating backwards. The planetary train 13, 20, 24 may be moved to the right away from the hydraulic coupling 12, 14, the various elements being connected by concentric sleeves so that the planetary gearing can be housed within the fixed casing, not shown, of the mechanical change gearing. A type of coupling unit described and claimed in combination with mechanical change gearing and described and claimed separately in Specification 393,295 is characterized by the use of a brake drum 116, Fig. 3, connected to a gear 113 by a one-way clutch 114 which prevents the gear 113 turning backwards but allows it to turn freely forwards when the drive in the hydraulic coupling rises sufficiently. A planet carrier 105 is fast to a coupling element 104 and to the input shaft 103, a sun gear 112 is fast on the output shaft 111, and the loose gear 110 is connected by a short shaft 120 to the other hydraulic element 109. A brake drum 117 on the shaft 111 is to facilitate gear change in the mechanical change gearing. The coupling element 104 may be connected to the space within the gear casing 105 by ducts similar to ducts 31, 32, Fig. 1, and when the element 109 is restrained by the brake 116, oil will leave the coupling by these ducts for the gear casing and return later by centrifugal force. A type of coupling unit also described and claimed in combination &c. and described and claimed separately in Specification 393,296 is characterized by the presence of a friction clutch such as 16, 17, Fig. 1. Power passes from the input shaft 11 direct to a sun gear 13 fast upon it and also to the loose internal gear 24 across the hydraulic coupling 12, 14 and through the clutch 16, 17. The planet gears 20 are on a spider 19 fast on the output shaft 18. The planetary gearing is in a casing formed in part by a wall of the element 14 and in part by an extension of the gear 24 where it joins a sleeve 25 carrying rigidly a brake cone 26. The clutch 16, 17 is normally held in by a spring 28. A control lever 29 can slide the parts 25, 24, 17 to the right so as to disengage the clutch and to brake the annulus 24 at 27 so as to bring in a positive geared low-speed drive. There is a sliding oil-tight joint at 36 and a spring-loaded seal at 34. Air and froth in an inner toric space 33 escapes inwardly by. a duct 32 to the gear casing, and oil in that casing escapes centrifugally by a duct 31 back to the coupling. A one-way clutch allows the engine to be used as a brake on the vehicle. The control 29 may be interconnected with a brake for a drum 30 on the shaft 18 for facilitating mechanical gear change.