GB550924A - Improvements in or relating to dash-pots - Google Patents

Abstract

550,924. Dashpots. BROOKHIRST SWITCHGEAR, Ltd., and BARNES, J. H. July 24, 1941, No. 9363. [Class 108 (iii) [Also in Group XXXVII] The action of an electric circuit breaker is restrained by a dashpot in such a way that a port, the size of which can be pre-set, is controlled by a valve in the form of a helical or spiral spring one end of which forms a flap adapted to close the port when a sudden unsustained force is applied to the piston in the operative direction. The opening movement of the circuit breaker moves pistong 11 upwards in its cylinder 10 by polygonal piston rod 12 having a selected one of a number of throttling orifices 14 in the piston in action and controlled by a spring valve 19 which is normally open. This valve consists of a flat curved spring having one end fixed at 20 to the disc 15 and having a flap 21 at its other end co-operating with a hole 16 in the disc. For small sustained overloads the upward movement of the piston is restrained by throttling through the selected orifice 14 in the piston, the valve remaining open ; but for heavy momentary overloads, the valve closes orifice 14 and prevents operation of the cut-out. The disc 15 may be adjusted relatively to the piston to bring any one of the spaced holes 14 in the piston under the flap 21 of the spring valve by raising it to a part 18 of the rod where it can be turned and then lowering it again on to the hexagonal rod, The disc 15 lifts and allows free downward or return movement, additional orifices 23 being provided to assist this action. Upward movement of the valve is limited. Specifications 24392/10, [Class 108 (iii)], 480,805 and 533,040 are referred to.