Patent GB-233760-A (GB)
Title: Improvements in or relating to friction clutches
IPC: D03D51/00
Filed: 1924-02-09
Abstract: 233,760. Jones, C. E. Feb. 9, 1924. Gearing for stopping and starting machinery. -In gear for driving looms, spinning - machines, &c., and for opening and closing valves, an electromotor is employed as prime mover and both the motor and a centrifugal clutch transmitting the drive to the machine &c. are thrown out of action by the stopping lever or by automatic stop-motion means acting on defective working of the machine or after a given travel of the valve in one or both directions. The armature shaft B of the electromotor A carries a plate I on which are pivoted weighted levers C bearing upon a clutch plate D, which engages a clutch plate E driving the machine &c. through gearing e<3> - &c. when the motor attains a sufficient speed. The levers C may be arranged at the opposite end of the shaft B and actuate the clutch through a rod passing through the shaft. The disengagement of the - clutch is effected by a rod F against which bears a lever G connected by a link g<3> and lever g<4> to the stop-rod J, which may be operated manually or by automatic stop means. The lever g<4> is connected by a pin and slot connection s to a lever s<2> operating the switch S controlling the electric supply to the motor, which is stopped simultaneously with the disengagement of the clutch. The lever G may be actuated by a spring and retained in clutch engagement position by a solenoid, the windings of which are preferably in parallel with those of the motor. The motion of the stop-rod J then breaks the electric circuits to stop the machine. A dash-pot may be used to control the clutch-engaging movement of the lever G, whether its operation is electrical or mechanical, and, in a modified form, Fig. 6<B>, the dash-pot valve k<9> is opened, after part of the stroke of the piston, by engagement of a lever k<10> with a fixed abutment k<13>, so that the clutch is suddenly thrown into operation. A similar effect may be obtained by the electrical device shown in Fig. 14. The switch s<2> for the motor windings a<3> is connected by a spring h<5> to the switch h<4> of the clutch-operating solenoid windings h<3>, a dash-pot h<6> being provided and the parts being so arranged that the switches are moved simultaneously to break the circuits, although the switch h<4> lags when the circuits are closed. This effect is also useful in overcoming the jamming of valves on their seats. In opening and closing valves, it is necessary that the operation should be stopped when the valve is fully closed or opened. For this purpose, the valve may be driven from the clutch by toothed gearing, which also rotates a screwed spindle w<1>, Fig. 16, and causes travel of a nut W adapted to engage lugs w<6>, w<7> on a switch o<2>, which may be single-way if the gearing is to drive the valve only in one direction. The two-way main switch s' so connects the mains to the limit switch o<2> as to provide for forward and reverse excitation of the motor winding a<3>. When the switch o<2> is actuated as the valve is closed or opened it so changes the connections that the current to the windings a<3>, h<3> is broken and the drive stopped and that subsequent throwing over of the main switch s<4> starts the drive in the reverse direction. Where it is necessary to provide also for inching movements of the valve in both directions a more elaborate system of wiring is employed, embodying separate opening, closing, stopping, inching opening, and inching closing push-button switches electrically connected to prevent more than one button being operative at one time. These switches operate in conjunction with limit switches operated by a travelling nut, as in Fig. 16, to control the current in solenoids which operate further switches connecting the mains with the motor and clutch-operating windings. Movement of the valve ceases when the inching buttons are released, but continues, when the opening and closing switches are operated, until the limit switches come into action. The travelling nut which acts as a limit stop device may actuate both the clutch-operating lever G and the motor winding switch by mechanical contact.