Patent GB-786933-A (GB)
Abstract: 786,933. Turning-gear. LEECE-NEVILLE CO. Dec..30, 1955 [March 22, 1955], No. 37494/55. Class 7(5) An engine-cranking apparatus for selfmeshing driving engagement with a ring gear 12 comprises a driving motor 14 having a shaft 15 extending adjacent the gear 12, a drive sleeve 31 in which is mounted a pinion 16, a shift sleeve 32 between the drive sleeve and the shaft, the sleeves and the shaft forming a group of co-axial members, and a compression spring 50 surrounding the sleeve 32 and effective between a shift collar 43, connected with that sleeve, and the sleeve 31 for imparting axial movement to the latter for advancing the pinion into engagement with the gear. There is a helical spline connection 33 between a first pair of the said members to cause rotation of the sleeve 32 in response to axial movement thereof, and an axial spline connection 40 between a second pair of those members for transmitting rotative movement to the pinion through the sleeve 31 to facilitate shifting of the pinion into mesh with the gear 12. Construction. As shown in Figs. 1 and 2, the pinion 16 is rotatable and axially movable on the reduced portion 22 of the armature shaft 15 of the electric motor 14, the shaft being provided with helical splines 28a which mesh with corresponding splines 33a formed internally of the sleeve 32. Externally the latter is provided with axially extending splines 34a in engagement with similar internal splines 40a of the sleeve 31, splines affording relative axial sliding movement between the sleeves. The collar 43 has an external, annular groove 45 in which is engaged the forked end 48 of a lever 46 pivotable about a shaft 47; the lever carries a thrust screw 53 which actuates the plunger 54 of a starting switch 55 controlling energization of the motor 14. Complete separation of the telescoped sleeves 31, 32 under the expansive action of the spring 50 is prevented by a ring 51 mounted on the sleeve 32 adjacent the thrust shoulder 37 thereof; the ring is engageable with the splines 40a of the sleeve 31. Normal rotation of the armature shaft 15 is in the direction indicated by the arrow 29. Operation. As the lever 46 is swung to the position 46a the sleeve 32 is moved axially by the collar 43 and axial movement in the same direction is imparted to the pinion 16 through compression of the spring 50; any pressure between the sides of the teeth of both the pinion and gear which resists full axial meshing movement of the teeth is overcome by engagement of the shoulders 37, 38 of the sleeves 31, 32. During movement of the pinion rotation thereof is resisted initially by the gear 12 which is relatively stationary and since the partially meshed pinion is thus held against rotation continuing axial movement of the sleeve 32 will cause the helical splines 33a thereof to react against the splines 28a of the armature shaft 15 and rotate the latter in a direction opposite to that indicated by the arrow 29. In the fully engaged position 16a, the pinion abuts a stop collar 24. The final part of the swinging movement of the lever 46 which results in the position 16a of the pinion causes energization of the motor which rotates the pinion in the direction of the arrow 29. Upon release of the actuating force applied to the lever the latter is returned by a torsion spring 52 to the initial position thereof thereby allowing de-energization of the motor this movement being accompanied by an axial return movement caused by the spring 50 of the sleeve 32 and collar 43, the ring 51 engaging the splines 40a of the sleeve 31 to thereby pull the pinion away from the gear 12. When the movement of the pinion toward the gear 12 results in a condition of abutting engagement of the ends of the teeth of the pinion and gear and axial movement of the pinion is temporarily stopped, the succeeding axial movement of the sleeve 32 occuring while the motor 14 is de-energized results in rotation of the sleeve about the shaft in a direction opposite to that indicated by the arrow 29 and therby imparts a clearing rotation through the spline connection between the two sleeves 31, 32 to the pinion, the latter them being shifted by the action of the spring into mesh with the gear. In a modification, the device incorporates a drive unit 66, Fig. 4, embodying a torqueresponsive clutch means and comprising a housing 67 having coaxial recesses 68, 69, the pinion 16 having a annularly grooved collar 70 retained in the recess 68 by a ring 71, and the drive sleeve 31 being provided with a collar 72 extending into the recess 69. Disposed between the ends of the collars 70, 72 is a clutch ring 73 having on one side ratchet-like teeth 75 cooperating with similar teeth 74 on the collar 70 those teeth being normally maintained in driving engagement by a compression spring 76 and thereby constituting an overunning clutch automatically releasable to permit the pinion 16 to be driven by the gear 12, and without causing rotation of the pinion to be transmitted to the shaft 15; when this abnormal condition subsides the spring 76 causes reengagement of the teeth 74, 75. On the opposite side of the ring 73 are clutch teeth 79 which are normally maintained in engagement with similar teeth 78 of the collar 72 by a group of spring washers 80 effective between the collar and a ring 81; these teeth constitute an overload release which interrupts the drive connection to the pinion and permits the shaft 15 to rotate when the gear 12 is, for example, locked against rotation. A space 82 formed between the teeth 78, 79 is of sufficient axial width to permit movement of the clutch ring 73 to allow the teeth 74 to ratchet over the teeth 75. In a further modification, a device similar to that shown in Fig. 4 incorporates a shift sleeve 32 which has external, helical splines engaging with internal, helical splines of the drive sleeve 31, and internal, axial splines in driving connection with corresponding splines on the shaft 15.