Patent GB-734556-A (GB)
Title: Change speed and reverse transmission for bulldozing tractors or the like
IPC: F16H37/00
Filed: 1953-07-21
Abstract: 734,556. Change-speed and reverse gearing; toothed gearing. CATERPILLAR TRACTOR CO. July 21, 1953 [Feb. 9, 1953], No. 20194/53. Classes 80 (1) and 80 (2). [Also in Groups XXXI and XXXIV] A power transmission for a bulldozing tractor or like vehicle comprises a set of gears selectably engageable for forward motion at different speed ratios, a second set of gears selectably engageable for reverse motion at different speed ratios, and means operable to impart driving power through either set of gears while each set is engaged for a speed ratio different from the other set. As shown, a driving shaft 22, Fig. 2, carries sun gears 45, 46 meshing stepped planets 50, 51 which engage internally toothed annuli 56, 57, respectively, rotatable on the driving shaft, the planets being mounted in carriers which can be held stationary by brake bands 58, 59 to transmit torque. The annulus 57 is fast with a gear 60 meshing a gear 61 (actually in the position 61a) fast on a layshaft 35 carrying gears 31 ... 34 axially slidable to mesh gears 27 ... 30 on a final driven shaft 26, the gears 31 ... 34 and 27 ... 30 forming the forward drive change speed gear. The annulus 56 is fast with a gear 63 fast on a quill shaft 39 rotatable on the driving shaft and carrying gears 36, 37, 38 axially slidable to mesh selectively with the gears 28, 29, 30, the gears 36, 37, 38 &c. forming the reverse drive changespeed gear. A power take-off 24 is provided. Either the brake band 59 or the brake band 58 is applied to its respective carrier according to whether the tractor is to move forwards or backwards, no 'drive being transmitted when both carriers are free, at which time brake bands 66, 68 can be applied to the quill shaft 39 and layshaft 35 respectively to bring these shafts to rest and facilitate change of mesh of the changespeed gears. The brake bands 58, 59, 66, 68 are operated by a single lever 18, Fig. 5, connected through a link 71 which slides axially for selection to pivot a bell-crank lever 74 and slide a clutch member 78 into mesh with one or other of two sleeves 79, 80, and pivots when the lever 18 is pulled back into one or other of two slots 19, 20 to engage the selected brake, the pivoting motion of the link 71 acting through an overcentre toggle link 84 to rotate the sleeve 79 or 80 and engage either the brake band 59 or 58 with its associated planet carrier. The sleeves are connected to the brake bands through rods 89 and adjusting means 92, 93 which serve to control the distance between the bands and their drums. The brake bands are normally kept disengaged by springs 94. The sleeves 79, 80 carry stops 95 which engage a spring-mounted plate 96 when the brakes are free, to position the clutch members 78 &c. properly for engagement. The brake bands 66, 68 are applied to their drums when the lever 18 is pushed forwardly a little from the position shown to move a link 106 downwards against the force of a spring 107 and thus urge pivoted links 102, 103 together. The sun gears 45, 46 of the two planet gears are splined as at 48, Fig. 4, to engage with splines on the driving shaft and have interengaging axial projections; the two gears are held together by a spring ring 49, the arrangement being such as to permit limited cocking movement of the gears and ensure equality of loading on their teeth where they mesh with the planet gears.