GB707408A - Improvements relating to magnetic transmissions - Google Patents

Abstract

707,408. Magnetic couplings. TRIST & CO., Ltd., R. May 16, 1952, [May 18, 1951], No. 11695/51. Class 35 A magnetic coupling device to control boiler water level comprises a driving magnet 14 pivotally mounted on one side of a non-magnetic wall 28 and two driven magnets 36, 38 pivotally mounted on the other side of the wall 28, both driven magnets 36, 38 being successively repelled by the magnet 14. The driven magnets 36, 38 carry two-way mercury switches 52, 52' respectively. The feed water is cut off when the water level is as shown in Fig. 1 and, as the water falls from this level, the pole 34 of the magnet 38 snaps downwards (Fig. 5) so changing over the switch 52<SP>1</SP>. This switch controls a feed pump. If the water level continues to fall, the pole 30 of the driving magnet 14 reaches the position shown in Fig. 6 and the pole 32 of the upper driven magnet 36 snaps downwards and so the switch 52 changes over. This switch controls a low water alarm. As the water rises again the reverse operation occurs. The invention describes various modifications concerning the location, size and relative movements of the driving and driven magnets. For instance, if the driven magnets are to snap over in quick succession they have to be staggered and the driving magnet 68, Fig. 8 (not shown), have to be made of greater width than the two driven magnets. Again, as shown in Fig. 10 (not shown), the arcs of travel of the various poles need not be in parallel planes. The driven magnets may, if required, be arranged to travel together in one direction of the movement of the driving magnet. The magnets need not be bar magnets; they can have horseshoe shape. If a large number of switches are to be controlled by a single member such as a float, there may be provided three or more driven magnets each mounted similarly with a driven pole moving through a different arc.