Pressure responsive switch actuating mechanism.

摘要

A pressure responsive reed switch operating mechanism (15) comprises a magnet (25) mounted on a rod (19) which is fixed to a dashpot piston and which is spring urged against a movable stop (31). The location of the stop (31) is controlled by a pressure responsive system comprising a fluid pressure servo motor (26), a buckling link (27), a lever (28) and a coil spring (32). The stop (31) is stationary and the magnet (25) displaced from its switch actuating location until a predetermined switching pressure is established whereupon the coil spring (32) yields and the buckling link (27) buckles with a snap action to move the stop (31) rapidly away from the rod (19) which follows slowly whereby the magnet (25) is moved into position to actuate the reed switch (13) a predetermined time interval after establishment of the switching pressure. The buckling link (27) snaps back to return the magnet (25) promptly to its inoperative location when the working fluid pressure falls to a certain pressure below the switching pressure.