GB742508A - Improvements in and relating to hydrostatic couplings - Google Patents

Abstract

742,508. Clutches. LOHMANN & STOLTERFOHT, AKT.-GES. July 21, 1953 [July 21, 1952]. No. 20284/53. Class 80(2) A hydrostatic coupling, comprising planet gears 3 carried by the driving shaft 1 and engaging internal teeth on an annulus 4 so as to form gear pumps, is in series with a friction clutch comprising flexible tubes 7 carried by an annulus 5 secured to the driven shaft 2a and cooperating with the external surface of annulus 4. The clutch is automatically disengaged at a predetermined degree of slipping of the coupling. Oil is supplied continuously to the gear pumps 3 by a pump 23 through a filter 24, pipe 16 and passages 11 in shaft 1, discharge from the pumps 3 being through passages 12 in shaft 1 and a common relief valve 13 in shaft 1. A valve 14, also arranged in shaft 1, automatically changes over the connections of passages 11, 12 on reversal of shaft 1. Valve 13 is loaded by pressure oil continuously supplied by a pump 27 through filter 28, pipe 18 and conduit 15. Tubes 7 are supplied with pressure oil by pump 27, or a separate pump, through pipe 20 and passages 8, 9, 10 under the control of a manually-operated rotary valve 29 and an automatically-operated piston valve 36, 37, 38, the piston 38 being of larger diameter than the pistons 36, 37. A pipe 35 leads to the end of piston 36. In the disengaged position of valve 29, pipes 30, 35 are closed and pipe 33 is open to a drain pipe 34, so that the pressure in tubes 7 is relieved through pipes 20, 32, 33, 34 and the clutch is disengaged. In the intermediate position of valve 29, pipes 30, 35 are opened. so that the piston valve is moved to the right against a spring 39, allowing pressure oil to flow to engage the friction clutch through pipes 31, 20, pipe 32 being now closed by piston 36. In the final, engaged position of valve 29, pipe 35 is connected to drain pipe 34, but the piston valve remains in its rightward position due to the larger area of piston 38. If the hydrostatic coupling slips, pressure in pipe 16 falls and spring 39 functions to move the piston valve to the left, so causing the friction clutch to be disengaged. Alternatively, the friction clutch may be controlled by an electric switch operated by the pressure in pipe 16.