Patent GB-839868-A (GB)
Title: A change-speed gear, particularly for self-propelled machines, í¡í¡ combine harvesters or other agricultural or constructional machines
IPC: A01D41/12
Filed: 1956-08-24
Abstract: 839,868. Variable-speed gearing. AGROSTROJ PROSTEJOV, NARODNI PODNIK, VRANA, V., and PERINA, O. Aug. 24, 1956 [Aug. 27, 1955; (3)], No. 25982/56. Class 80 (2). [Also in Group XXXI] A variable-speed gear for combine harvesters &c. comprises a set of toothed change-speed gearing in parallel with a continuously variable ratio expanding pulley gear, the toothed gearing giving the second, third and fourth ratios while the expanding pulley gearing gives the first ratio. Selection of first, second, third or fourth ratio is made by operation of a single control lever, another control lever operating hydraulic means determining the ratio given by the expanding pulley gearing. As shown, an engine drives through a clutch 2 to an input shaft 4 carrying a gear 5 meshing a gear 6 fast on a countershaft 7. A double gear 8 fast on the countershaft meshes a reverse idler 9, and a gear 10 on the end of the countershaft carries a positive clutch member 14 by which it can be connected to a corresponding positive clutch member 13 at the end of a shaft 11. A second countershaft 16 carries on splines a gear 19 which can be slidden rightwards of Fig. 1 to engage the gear 10 for the second ratio, or leftwards to engage the reverse idler 9. A twin gear 18, also splined on the second countershaft 16, can be slidden rightwards to mesh the gear 8 for the third ratio, or leftwards to engage the gear 6 for the fourth ratio. A gear 17 fast with the second countershaft 16 meshes a gear 22, fast on a third countershaft 23, in turn meshing a gear 36 freely rotatable on a fourth countershaft 32. The gear 36 is integral with an oil impeller 37 which is thus rotated to splash lubricate the gears. A power take-off sprocket 41 and a brake drum 27 are mounted on the end of the third countershaft. A gear 24 fast on the third countershaft 23 carries a positive clutch member 26 by which it can be connected to a freely rotatable gear 25 on the countershaft. The gear 25 meshes the smaller part of a twin gear 31 freely rotatable on the fourth countershaft 32, the larger diameter part of the twin gear 31 meshing a gear 30 at the end of a shaft 29. The shafts 11, 29 carry the flanges 12, 12<SP>1</SP> and 28, 28<SP>1</SP> of two expanding pulleys connected by an endless V-belt 40. When second, third and fourth ratios are disengaged, engagement of the positive clutches 13, 14 and 26 puts in first ratio. Whichever ratio is engaged, drive is transmitted to the gear 24 which meshes the larger part of a twin gear 33 having its smaller part meshing a gear 34 surrounding the differential 35 of the harvester. Selection of the required ratio is obtained by operation of a lever 43, Fig. 2, to move selector forks 15, 20, 21 and 39. The selector forks slide upon three parallel rods 48, Fig. 3, the forks 20, 21 each sliding upon one rod 48 and the forks 15, 39 both sliding upon the third rod 48. The fork 15 controls the engagement of the positive clutch 13, 14, the fork 39 controls the engagement of the positive clutch 26, the fork 20 controls the axial position of the third and fourth ratio gear 18, and the fork 21 controls the axial position of the second ratio and reverse gear-wheel 19. Each of the selector forks is associated with a channel member 44- 47 engaged by the lever 43. A slide 52 mounted in guides 53 is associated with the end of the control lever 43 and carries locking means 49- 51 securing the three forks which are not to be moved. In the position shown in Fig. 3, only the fork 21 is free to move. On displacement of the control lever 43 either left or right, the slide 52 is simultaneously displaced so that the locking means locks the fork 21 but releases the fork now engaged by the end of the control lever. To engage first ratio, and thus introduce the expanding pulley gearing into the torque path, the positive clutches 13, 14 and 26 are engaged. The ratio given by the expanding pulley gearing can be continuously varied by operation of a second control lever (not shown) actuating the valve through which pressure fluid is supplied to a conduit 67, Fig. 5, and thence to a cylinder 65 containing a piston 64. The end of the piston is connected by a lever 57 to a pin 56 controlling the axial position of the flange 12 of the driving expanding pulley, the other end of the lever 57 being pivoted to a draw rod 60 anchored at 61 to the gear casing &c. The piston 64 is normally biased to the right of Fig. 5 by a return spring 68. Admission of pressure fluid to the cylinder 65 moves the piston 64 leftwards against the bias of the spring 68, and, through the lever 57 &c. takes the pulley flange 12 with it. A spring 73 biasing the flanges 28, 28<SP>1</SP> of the driven expanding pulley towards each other is thereby able to reduce the space between these two pulley flanges, and adjust the gear ratio.