Patent GB-975585-A (GB)
Title: Change-speed power transmission system for a tractor
Inventor: HOWARD ARTHUR CLIFFORD
IPC: F16H37/08
Filed: 1962-06-29
Abstract: 975,585. Change-speed and differential gearing; friction clutches. ROTARY HOES Ltd. June 19, 1963 [June 29, 1962], No. 25001/62. Headings F2C and F2D. [Also in Division B7] A change-speed gear for a tractor, e.g. a walk-type rotary cultivator, comprises an input shaft which may be used with a power take-off clutch to drive directly to the tool, and three layshafts at right angles to the input shaft, one being driven therefrom through a worm and worm-wheel, an arrangement of sliding mesh gears and a pair of " pick-off gear-wheels on the layshafts providing the various ratios. An input shaft 10, Fig. 1, is driven from the tractor engine through a friction clutch 17 &c., and carries at one end a positive clutch sleeve 37 slidden rightwards from the position shown into engagement with a corresponding clutch member to drive the rotor of a cultivator. A worm 40 on the input shaft 10 meshes a wormwheel 41 fast with a first layshaft 45 and bolted to a gearwheel 42. " Pickoff " gears 65, 66, which may be interchanged with spare "pick-off"  gears 69, 70 carried by stub-shafts 67, 68 on a removable casing cover 63, connect the first layshaft 45 to a second layshaft 54 fast upon which are gears 58, 59, the latter meshing a double gear 48 journalled about the first layshaft. A gear pair 80, 81 splined upon a third layshaft 72 can, as shown, mesh directly with the gear 42 for a first forward ratio, or can be slidden rightwards of Fig. 2 into mesh with a gear 49 of the double gear 48 to establish a second forward ratio through the train 45, 65, 66, 59, 48, 49, 81. The gear pair 80, 81 can be slidden still further right into mesh with the gear 58, to establish a reverse ratio through the train 45, 65, 66, 54, 58, 81. The third layshaft 72 also carries an axially slidable output gear cluster 82, 83. Differential gearing.-Gears 84, 85 together with stepped bolts 100 between them, form a cage for intermeshing planet pinions 100 also meshing two output sun gears 95, 97 on shafts 93, 90 thereby driven differentially, and geared through trains 96, 112; 101, 111 to half-shafts 105, 106 and the driving wheels of the tractor. A dog clutch sleeve 117 splined upon the shaft 90 can be slidden axially into engagement with dogs 119 on the gear 85 to lock-up the differential. As shown, the gear 82 of the cluster 82, 83 on the third layshaft 72 meshes the gear 84, but by sliding the cluster along the third layshaft to mesh the gear 83 with the gear 85, a second ratio can be established. Friction clutches.-The flywheel 14, Fig. 1, of the tractor engine carries driving friction discs interleaved with discs 19, 23, 24 rotating with the clutch-driven shaft, which is itself the input shaft 10, compression coil springs 28 surrounding bolts 25 and spacer sleeves 26 biasing the clutch into engagement. Levers 30 act through a thrust bearing 31 and a sleeve 32 for clutch disengagement. The clutch may slip if the tractor tool strikes an obstruction. As described above, the input shaft 10 also carries the power take-off positive clutch sleeve 37 and the differential is locked by a second positive clutch 117, 119.