Patent GB-759185-A (GB)
Title: Improvements relating to epicyclic gear assemblies for tractors
Inventor: SENKOWSKI ALEXANDER
IPC: F16H61/02
Filed: 1954-01-18
Abstract: 759,185. Change-speed control. MASSEY-HARRIS-FERGUSON (SALES), Ltd., [formerly FERGUSON, Ltd., H.]. Jan. 17, 1955 [Jan. 18, 1954], No. 1380/54. Class 80(2) [Also in Groups XXVIII, XXXI and XXXIV] An epicyclic gear assembly, interposed between the normal speed gear and the differential of a tractor, comprises an hydraulic actuator 50, 51, Fig. 2, to apply and release a brake 52 on a component of the epicyclic gear, a cylinder and plunger pump 81 supply hydraulic liquid to the actuator, means 90 for imparting suction strokes to the pump, said means being operable from the tractor change speed gear, and a spring device 91 adapted to be stressed by each suction stroke and thereafter to impart a pumping stroke, the arrangement being such that there is generated in the actuator an hydraulic pressure balancing the spring stress following which the work of pumping automatically ceases. In the form shown, the brake 52 consists of a duel band device which is applied to the annulus 46, Fig. 1, of an epicyclic gear having a sun gear 40 fast on the output shaft 20 of the normal change speed gear and planet gears 42 mounted on a carrier 43 which can be connected by a positive clutch 66 to a driven shaft 27. The brake bands 52 are pivoted at 53, Fig. 2, in a gear casing 26, and are pivotally anchorded at 54 by a two armed strut 58, Fig. 7. A fork 62, at the end of a rod 63 engaging the piston 51 in the cylinder 50 of the hydraulic actuator-lies between the two arms of the strut 58 and is pivotally connected at 61 to the end of the brake bands 52. When fluid under pressure is supplied to the cylinder 50, the piston 51 &c. moves to the left of Fig. 2 and engages the brake bands 52 on the annulus 46. The cylinder and plunger pump 81 is situated in the oil sump formed by the gear casing 26. The plunger 81, Fig. 3, reciprocates in a bore in a block 80. The bore is provided with an inlet port 82 and an outlet conduit 85 closed by a spring biased non- return valve 88. The end of the plunger 81 is engaged by a fork 96 on a twoarmed bell-crank lever 93, 94 pivoted at 95. A two humped eccentric 90 is formed on an extension shaft 29 of the countershaft 21 of the normal change speed gear. A cam 92 is formed on the bell-crank arm 93 to engage the eccentric 90. The end 100 of the bell-crank lever 94 is pivotally connected at 99, Fig. 5 to strut 97 having a telescopic pin and slot connection 103, 104 with a link 102. A helical compression spring 91 biases the strut 97 downwardly. The link 102 is pivoted at 106, Fig. 1, to an arm 107 fast on a control shaft 108 turned by the tractor driver on operation of a lever 65, Fig. 11. When the lever 65 is placed in the " brake on" position, the shaft 108 and arm 107 are turned to push the link 102 downwardly and compress the spring 91, thus biasing the cam 92 into engagement with the eccentric 90. On rotation of the eccentric 90, its humped parts compress the spring 91 and withdraw the plunger 81 towards the end of its bore, to suck oil in through the port 82 the pin and slot connection 103, 104 allowing telescoping movements between the link 102 and the strut 97. As a humped part of the eccentric 90 passes beyond the cam 92, the now compressed spring 91 pivots the bell-crank lever 93, 94 and pushes the plunger 81 into its bore. This forces oil past the non-return valve 88 and through the conduit 85 into the cylinder 50 of the hydraulic actuator. As the next hump on the eccentric 90 comes round, it again positively withdraws the plunger 81 towards the end of its bore. While the plunger 81 continues to reciprocate, the pressure in the cylinder 50 builds up as the brake bands are applied. This pressure begins to oppose movement of the plunger 81, so that its strokes gradually become shorter, as the stress in the spring 91 becomes insufficient to move it. When the brake bands 52 are fully applied the plunger 81 stops reciprocating. To release the brake, the control lever 65 is turned to the " brake off position, which turns the shaft 108 and arm 107 to raise the link 102 so that the bell-crank lever 93, 94 is pivoted to disengage the cam 92 from the eccentric 90. This withdraws the plunger 81 to the end of its bore and uncovers the port 82, so that the oil under pressure in the cylinder 50 can flow back through the conduit 85 and through an outlet port 87 to the bore in the pump and then out through the port 82. The positive clutch 66, Fig. 1, which can connect the planet carrier 43 to the output shaft 27, comprises an axially slidable sleeve having teeth 68 which engage teeth on the output shaft 27 and teeth 69 which can be engaged either, as shown, with teeth 37 on an extension shaft 28 of the change speed gear output shaft 20 for direct drive, or with teeth 47 on the planet carrier for reduced drive. The extension shaft 28 has internal splines 33 engaging splines on the end of the shaft 20, and is held in position by a screw 34. The clutch sleeve 66 is slidden axially by a fork engaging a groove 73 therein. The fork is controlled by a lever 70, Fig. 11, provided with an interlock stop 114 which co-operates with an interlock stop 113 on the brake control lever 65. In the position shown, the brake control lever 65 is in the " brake off " position and the clutch sleeve '66 connects the shafts 20, 27 for direct drive. The interlock stops 113, 114 prevent the brake control lever 65 from being turned anti-clockwise to engage the brake until the clutch control lever 70 has been moved to clutch the planet carrier 43 to the output shaft 27. When the clutch control lever 70 has been so moved, and the brake control lever 65 has been turned to apply the brake, the projections 113, 114 again interlock so that the clutch control lever 70 cannot be moved to clutch the shafts 27 and 20 together again until after the brake control lever 65 has been returned to the " brake off " position. The brake control lever 65 carries a projection 110 engaged by a spring biased detent 109 on a fixed part 112 of the tractor. The countershaft 21 of the normal change speed gear has splined connection at 35 with the extension shaft 29 secured in position by a screw 36. A toothed clutch member 30 on the extension shaft 29 can be engaged by an axially slidable clutch member 32B to connect it with a Dower take-off shaft 32. The clutch member 32B is moved axially of the shaft 32 by a control rod 32D. When the power take-off shaft 32 has been clutched to the countershaft 21 and reduced drive has been established in the epicyclic gear, the tractor operator can use the brake bands 52 as a clutch control additional to the main clutch of the tractor. Turning the brake control lever 65 to the " brake off " position releases the brake bands 52 from the annulus 46, so that the epicyclic gear ceases to transmit drive to the differential and the driving road wheels of the tractor. However drive is still transmitted to the power take-off shaft 32 while the main clutch is engaged. On reengaging the brake bands 52 with the annulus 46, the drive to the differential &c. is again taken up.