GB785511A - Improvements in or relating to control mechanism for reversing gears - Google Patents

Abstract

785,511. Reversing gearing. MAYBACHMOTORENBAU GES. Jan. 13, 1956 [Jan. 20, 1955; Feb. 28, 1955], No. 1275/56. Class 80 (2). In a reversing gear for marine use driven through a main progressive clutch and positive clutches for each direction of rotation, including an auxiliary drive through a progressive clutch from the main drive for synchronizing the driving halves of the positive clutches, the control means comprise a selector slide valve controlling a change-over slide valve directing pressure to a reversing clutch slide valve which temporarily engages the synchronizing clutch and at the end of the operation directs pressure through the selector valve to engage the main clutch, and including a device to cut off pressure flow to the selector valve during synchronization. A main driving shaft 1 is connected to a driving shaft 2 through an hydraulically engaged friction clutch 4, the gear 5 on the shaft 2 driving a gear 8 on a driven shaft 3 through gears 5, 6, 9, 8 for the forward direction and gears 5, 6, 7, 10, 8 for the reverse direction. The gears are engaged by repelling tooth dog clutches 11F/12F and 11R/12R for forward and reverse respectively, the clutches being engaged by a lever 13 actuated by a reversing clutch slide valve 18 working in a cylinder 19 and being urged by a spring 20 to the neutral position at mid-stroke. An auxiliary friction clutch 15 can connect a gear 16, concentric with shaft 2, to the driving shaft 1 to drive the gear 7 in the reverse direction for synchronizing purposes. Engaging lock valves 27F, 27R are connected through drag rings 77, 78 (F and R) to the dog clutches to prevent attempted engagement when the clutch elements are rotating in the same direction but at different speeds, i.e. when the repelling faces of the clutch teeth are not able to function. Manual selection of Forward, Neutral or Reverse, F, N, R, by lever 21 moves the selector valve 22 which passes pressure from line 30 to a change-over valve 24 and unloads the main clutch servo valve 25 to open the clutch. The change-over valve 24 passes pressure to the reversing valve 18 through shut-off valves 28F, 28R controlled by the engaging locks which are fed through a servo-valve 26. Initial movement of the valve 18 pressurizes the auxiliary clutch 15 to effect synchronization and at the same time moves slide-valve 23 to cut-off pressure from valve 22 during this period. Further movement of valve 18 vents the auxiliary clutch and moves the lever 13 to the appropriate clutch-engaged position. Valve 23 is then released and pressure is fed via valve 25 under the control of selector valve 22 to engage the main clutch.