GB399155A - Improvements in or relating to variable speed gearing and like associated mechanism for the transmission of power - Google Patents

Abstract

399,155. Hydro-mechanical variablespeed gearing. SWAN, J. G., 14, Old Square. Lincoln's Inn, London. Dec. 19, 1931, Nos. 23523/33, 23524/33, and 23525/33. Divided on 398,861. [Class 80 (ii).] Relates to power transmission systems suitable for vehicles comprising a unit of the kind having associated with an hydraulic coupling at least one planetary gear train of which a section is rotatable with one member of the coupling, said gear section and coupling member not being secured either to the power input end or to the power output.end of the unit, said input end being secured with another section of the gear train, the third section being connected to drive the output end, and one of these latter gear sections being rotatable as one with the other hydraulic coupling, member and thus coupled to the first-mentioned gear section. Such units are described in Specifications 172,518, [Class 80 (ii), Gearing, Variable-speed &c.], 393,294, 393,295, and 393,296. According to the invention, there is combined with such a unit a one-way clutch through which power may be transmitted through the unit and also additional planetary gearing with means whereby said additional gearing may, at will, be made operative to cause the driving-part of said one-way clutch to rotate in a reverse direction. Thus, when such a unit is used in series to drive a mechanical change-speed gear, the driving-shaft of the latter is relieved of torque to facilitate gear changing. Arrangements are described with separate planetary trains and with overlapping planetary trains. In the arrangement of Fig. 11, employing a simple planetary gearing, an input shaft 501 is connected by the gear section or carrier 502 of planets 504, 505 to a primary hydraulic member 503. The secondary hydraulic member 514 is connected by a sleeve 513 to a sun gear 511 meshing with the planet gear 505. The one-way clutch 510 according to the invention lies between a sun gear 509 meshing with the planet 504 and the output shaft 507 of the unit. The shaft 507 is normally driven by hydraulic action and passes on power to mechanical change gearing (not shown), but when a drum 512 fast on the sleeve 513 is held by a brake, the sun gear 509 turns loosely backwards so that the shaft 507 is freed from torque. A free-wheel 508 allows forward-drive torque to be transmitted from the shaft 507 to the shaft 501 to allow the engine of a vehicle to be used as a brake. The invention is shown in Fig. 10 with the epicyclic trains in the same housing 500 as the mechanical change gearing, indicated generally at 470. An input shaft 451 carries rigidly a primary hydraulic member 452 and a tubular shaft 453 leading to a planetary gear section or spider 454. A secondary hydraulic member 456 is rigid through a shaft 457 with a sun gear 458. One step 459 of triple planets meshes with the gear 458. Another step 460 of the triple planets meshes with a sun gear 464, which is connected through a forward-driving one-way clutch 465 with the output shaft 466 of the unit. The other step 461 of the triple planets meshes with a larger sun 462 which is loose and adapted to be arrested or held fast by a. brake 467. So long as the hydraulic coupling is operative, the sun gear 464 drives the shaft 466 forwardly, but when the sun 462 is held fast by the brake 467, the sun 464 is driven reversely and the shaft 466 is free of torque. A one-way clutch 468 of opposite sense, between the spider 454 and the shaft 466, permits the engine to be used as a brake. With respect to the gearing 470, the shaft 466 takes the place of the usual clutch shaft. Specifications 375,534 and 385,086, [both in Group XXIX], also are referred to.