Patent GB-728501-A (GB)
Title: Improvements in or relating to power transmission
Inventor: TROFIMOV LEV ALEXANDER
IPC: F16D35/00
Filed: 1950-08-15
Abstract: 728,501. Operating clutches; mechanical relays. FAIRCHILD ENGINE & AIRPLANE CORPORATION. Aug. 15, 1950, No. 20222/50. Class 80 (2). [Also in Group XXIX] A disc clutch, e.g. 7 or 8, transmits torque with variable slip through shear resistance of oil films permanently separating the discs, the films being maintained under pressure continuously by the action of relative rotation on one or more straight or curved generally radial slots or grooves 105, Figs. 9 and 11, closed at their outer ends, open at the inner periphery of the discs to a low-pressure external liquid supply, and having inclined wedging surfaces 106 in their faces whereby the liquid is forced under pressure into the film space by relative rotation, and operator-controlled axial force applying means to move the discs closer together in opposition to the disc-separating liquid pressure, to control the thickness of the liquid film and hence the torque transmitted, decreased film thickness resulting in increased torque. Two such clutches are shown used in a reverse gear or mechanical relay and the application to marine, automotive, winch, hoist and steering-gear drives is referred to. The two clutches 7, 8 are on an input shaft 2, driven by an induction motor 1, and selectively drive a parallel output shaft 11 through a forward gear-pair 9, 15 and a reverse gear or chain drive 10, 17, 16 respectively. Oil is supplied continuously at low pressure by an input driven pump 34, through the hollow input shaft 2 to the inner peripheries of the clutches 7, 8 and into the radial slots 105, to form the drive-transmitting oil films. The reverse drive clutch 8 may have a lesser number of discs (e.g. only one) where the reverse load is light. The thickness of the oil films in one clutch is reduced, whilst that in the other is simultaneously increased, by axial movement of a central control-spool 53, actuated through ball thrust-bearings and a forked lever 56, by a nut 67, screwed along a shaft 69 by a hand wheel 83. With the controlspool 53 in a central position, each clutch 7, 8 is equally effective and no drive is transmitted, whilst moving the spool in either direction produces variable drive in the corresponding direction. To obviate reverse torque of the idle clutch 7 or 8, its oil supply may be cut off by triple valve-plates 61, 62, integral with the control-spool 53 and slidable in grooves in the shaft to cover the radial oil-supply ports 51, 52 of the clutches, whereby the idle clutch is cut out before the operative clutch reaches the solid drive condition. Pressure oil reaches the shaft supply duct from the pump 34 through a radiator 43, pump pressure being limited to 71b./ sq. in. by a relief-valve 48 and supply pressure to 31b./sq. in. by a relief-valve 50. Several manual and powered methods of operating the control-nut 67 are described. In the first of these, a shaft 69 is held stationary by meshing a toothed wheel 72, splined thereon, with fixed detent teeth 77, so that turning the control-nut 68 by a hand wheel 83 screws the nut along a thread on the now fixed shaft 69, thus traversing the clutch-control spool 53 in the appropriate direction. The device is converted into a mechanical relay by sliding the toothed wheel 72 out of mesh with the detent teeth 77 and into mesh with a toothed wheel 99 fast on the output shaft 11, so that when the hand wheel 83 is now turned to screw the control-nut 67 along the shaft 69, the consequent rotation imparted to the output shaft 11 through the clutch 7 or 8 causes the shaft 69 to screw the control-nut 67 backwards, to disengage the operative clutch 7 or 8, thus producing a follow-up effect whereby the movement of the output shaft 11 exactly corresponds in speed and direction with that of the hand wheel 83 and ceases when the hand wheel stops. An alternative method of use is provided by arranging that the friction in the thread of the control-nut 67 exceeds that in the bearings of the shaft 69, so that once rotation of the output shaft 11 has been started by turning the hand wheel 83, the latter can then be released, whereupon the nut 67 and shaft 69 turn together and rotation of the output shaft 11 can only be stopped by gripping and stopping the hand wheel 83. Power-operated remote control is provided by a motor 85 driving a shaft 93 on which is splined a pinion 94 which can be meshed with a toothed wheel 84 fast to the hand wheel 83. The follow-up control then causes the speed and direction of the output shaft 11, as driven by the main motor 1 through a clutch 7 or 8, to correspond at all times with those of the control motor 85, which latter is controlled by a reversing switch 92 and speedvarying resistor 89.