Patent GB-968544-A (GB)
Title: Improvements in or relating to power transmissions
IPC: B62D11/10
Filed: 1960-02-17
Abstract: 968,544. Change-speed gear. EIMCO CORPORATION. Feb. 17, 1961 [June 20, 1960], No. 5919/61. Heading F2D. Two output shafts 110, 110<SP>1</SP>, driving the crawler tracks 109, 109<SP>1</SP> or wheels on opposite sides of a tractor, are driven at selectively and independently variable speeds forward or reverse, for normal travel and for graduated or full-spin steering, by constant mesh gear trains rendered effective by selectively engageable fluid-pressure actuated friction clutches and arranged to connect a single input shaft 104 to the output shafts 110, 1101 through at least a first countershaft 106, split into two parts 122, 124. The gear shown provides four equal ratios forward and reverse with four different spin turn ratios either way in either direction, and twelve different geared turns, together with, if desired, the usual de-clutch and brake turns. Clutchable wheels 114, 116 on the input shaft 104 selectively drive the first counter-shaft 106, which comprises the two axially aligned sections 122, 124 connectable by a clutch 126 and carrying three fast wheels. A second countershaft carries a fast wheel 184 and three freely mounted wheels one, 136 of which can be clutched at 145 to the shaft 108 whilst the others 156, 172, are clutchable only to adjacent wheels by clutches 160, 174, 182. Each output shaft 110, 110<SP>1</SP> carries two freely mounted wheels 190, 196 meshing respectively directly and through an idler 194, 194<SP>1</SP> with the countershaft wheels 156, 184, and clutchable to their respective output shafts 110, 1101 by clutches 192, 200, which are the forward and reverse clutches. Power paths from the input shaft 104 in the four ratios to the output shaft 110, are as follows. FIRST-as shown in Fig. 7, clutch 120, wheels 116, 132, 134, 136, clutch 160, wheels 156, 190 and clutch 192 for forward; or for reverse from wheel 136 through clutch 145, shaft 108 wheel 178, idler 194, wheel 196 and clutch 200. SECOND-clutch 118, wheels 114, 128, clutch 126, wheels 134, 136, then as for first. THIRD-clutch 120, wheels 116, 132, clutch 126, wheels 128, 172, clutch 174, wheels 156, 190 and clutch 192 for forward; or clutch 182, wheels 184, 194, 196 and clutch 200 for reverse. FOURTH-as for third but using clutch 118 and wheel 114 instead of clutches 120 and 126. The clutches are used to provide differentially geared or spin turns one example of which is as follows-to drive one output shaft 110 in first forward or fourth reverse, whilst the other output shaft 110 is driven in fourth forward or first reverse (or vice versa). Both input clutches 118, 120 are engaged together and the clutch 126 is released. Power passes in first ratio through wheels 116, 132, 134, 136, and clutch 160 to the forward wheels 190 on both output shafts 110, 110<SP>1</SP> and at the same time in fourth ratio through wheels 114, 128, 172 clutch 182 and wheels 184, 194 to the reverse wheels 196. Thus by engaging the forward clutch 192 on the output shaft 110 and the reverse clutch 200 on the other output shaft 110<SP>1</SP>, the former is driven forward in first and the latter reversely in fourth, and vice versa. The other geared and spin turns are similarly obtained by suitable combinations of the clutches. A simple form, Figs. 1-4, not shown, provides only two ratios, using a split countershaft comprising two concentric shaft parts.