GB734533A - Improvements relating to torque converters combined with gearings - Google Patents

Abstract

734,533. Variable speed gearing. STANDARD MOTOR CO., Ltd. Nov. 24, 1953 [Dec. 22, 1952], No. 32397/52. Class 80 (2). [Also in Group XXXIV] In variable speed gearing wherein a three-element hydraulic torque-converter (not shown) is combined with toothed epicyclic gearing which gives a low forward drive and a reverse drive, the two drives are engaged by respective brakes 27, 28, and a direct drive between the torque - converter shaft 17 and the output shaft 14 is engaged by a cone clutch 31 when the brakes are released, the clutch being actuated by an annular hydraulic plunger 39 whose cylinder 37 is part of the non-slidable element 30 of the clutch. Hydraulic pressure is generated by a pump (not shown) connected to the outer element of the torque converter. The epicyclic gearing comprises a driving sun 18 on shaft 17, a driven carrier 20 on shaft 14, intermeshing planetary pairs 22, 23, a free sun 25 and a free annulus 24, one or other of the two latter members being held by the brakes 27, 28 to provide a reaction for the forward and reverse drives respectively. The slidable clutch element 31 is splined on the shaft 17 and is lightly spring- loaded to the off position. A keyway in the plunger 39 is engaged by a peg 41 on a flange of the back plate of cylinder 37. Hydraulic pressure is supplied through a port 44 to the cylinder 37 to clutch sun 25 to shaft 17, i.e. to sun 18, and so provide a direct drive. To entrain the epicyclic gearing, the cylinder 37 is exhausted through port 44 and the clutch is freed by means of a low hydraulic pressure continuously applied through port 47 to the element 31, the area of element 31 being greater than that of the annular plunger 39. As soon as the element 31 has been released the low pressure acts on the plunger 39 to hold it inoperative, a bleed hole 48 being provided. The fluid providing the said low pressure comprises lubricant which is continuously supplied along bore 46 to the bearings of the gearing. Preferably, the brakes are hydraulically operated, and a tandem hydraulic mechanism is shown for applying the reverse brake band 28, Fig. 3, through a strut 50, the mechanism comprising a first plunger 51 reacting on a stationary abutment 52, and a second plunger 53 reacting on an end wall 54. Fluid is supplied to the back of the plunger 51 along a passage 56, and is fed to the back of plunger 53 through a bore 57 in the latter. The brake band 27 is applied by a single hydraulic mechanism. A compound control valve such as that disclosed in Specification 734,534 may be used to engage the clutch and brakes as required, this particular valve supplying fluid at a higher pressure for the brakes than for the clutch.