Patent GB-741568-A (GB)
Title: Improvements in or relating to reversing gear
IPC: F16H3/14
Filed: 1953-01-09
Abstract: 741,568. Reverse gearing. MAYBACHMOTORENBAU GES. Jan. 9, 1953 [March 24, 1952], No. 778/53. Class 80(2) Reverse gearing for boats includes six gear wheels providing the forward and reverse drive paths according to which of two dog clutches is engaged, a main clutch, and an auxiliary drive by means of which the direction of rotation of the driving half of the disengaged dog-clutch can be re- - versed for synchronization. As shown, a multi-disc main clutch 5 connects a driving shaft 1 to an intermediate shaft 2, on which is fixed a drive gear 31 and on which is rotatable a gear 37 connected to the driving shaft when an auxiliary drive synchronizing clutch 16 is engaged, these clutches being actuated by the admission of pressure fluid through passages 54, 58, respectively. The gear 31 meshes a gear 32 clutchable, by a repelling tooth dog clutch 42, 44, to a countershaft on which is secured a gear 34 meshing a gear 36 fast on a final driven shaft 3; the gear 32 also meshes a gear 33, rotating with a gear 38 meshing the gear 37 and clutchable, by a repelling tooth dog clutch 43, 45, to a gear 35 also meshing the gear 36. One or other of the dog clutches 42, 44; 43, 45 is engaged for forward and reverse drive according to the position of a pivoted lever 46, connected by a link 84 to a servomotor 61 actuated by a slide valve 73 displaced by a control lever 70. The servomotor comprises a piston 81, in a cylinder 62, integral with two slide valves 82, 83, pressure fluid being admitted from a supply pipe 66 to one or other of recesses 85, 86 and thence through passages 99 or 100 to the cylinder 62. Conduits 90, 89, 91 and 96, 95, 97 connect the cylinder to passages 88, 94, respectively, which allow free passage of pressure fluid, according to the position of the piston 81, either through a pipe 65, or direct to the pipe 58 and thence to the synchronizing clutch 16. Orifices 78, 79, 80 communicate with the atmosphere, a passage 68, 87, 67 allows pressure fluid to be supplied from the cylinder 62 to the pipe 54 and main clutch 5 when the piston 81 is in its extreme Tight-hand position, and a similar passage 93 allows pressure fluid to be supplied direct to the pipe 54, &c., when the piston 81 is in its extreme left-hand position. As shown, the control lever 70 and the gear are in the forward drive position. To change over to reverse, the lever 70 is moved to the position R, the slide valve 73 accordingly moving to the left. That part of the cylinder 62 to the left of the piston 81 is thus opened to the atmosphere via the passages 99, 85, 79, and the main clutch 5 is disengaged by the pipe 54 similarly being opened to the atmosphere through the same passages and passages 67, 87, 68, while pressure fluid is now supplied from the pipe 66, through the passages 86, 100, to the right-hand side of the piston 81; the orifice 80 is now to the right of the end of the slide valve 73 and is therefore ineffective. The piston 81 begins to move leftwards and, by means of the links 84, 46, disengages the dog-clutch 42, 44. After a short interval, the dog-clutch members 43, 45 are brought into contact but are revolving in opposite directions to each other, the piston 81 being rather more than halfway along its path to the left. Pressure fluid now goes through the passages 96, 95, 97, 94 to the pipe 58 and engages the synchronizing clutch 16 so that the gear 37 is coupled to the driving shaft 1, and the direction of rotation of the gears 38, 33 is reversed, whereby the clutch members 43, 45 are synchronized. The piston 81 completes its motion to the left and thereby engages the dog-clutch members 43, 45, at the same time venting the pipe 58 to the atmosphere through a passage 64 at the right-hand end of the slide valve 83, to disengage the synchronizing clutch. Simultaneously the main clutch 5 is re-engaged by supplying pressure fluid from the pipe 66 through the passages 86, 100, the space to the right of the piston 81, and the passage 93, to the pipe 54. The change from reverse to forward drive takes place in the same way, the main clutch being disengaged by venting the pipe 54 through a passage 67, etc.; the synchronizing clutch 16 is engaged by pressure fluid supplied through the passages 90, 89, 91 to the pipe 58, until the clutch 42, 44 is synchronized and engaged, the main clutch 5 being finally re-engaged as the synchronizing clutch is disengaged. If the control lever 70 is left in the middle position L, the slide valve 73 closes the supply pipe 66 and vents both sides of the piston 81 to the atmosphere, the pipe 54 therefore being vented either through passages 68, 87, 67 or 93 to the now opened cylindei 62, according to the position of the piston 81, to disengage the main clutch 5 and allow the driving shaft 1 to rotate idly, while leaving either clutch 42, 44, or clutch 43, 45, engaged.