| 摘要 |
1,151,180. Hydraulic brakes; brake indicators. WEATHERHEAD CO. 18 July, 1967, No. 33049/67. Headings F2E and F2F. [Also in Division H1] A switch for use in a dual fluid system comprises a housing having a bore 24 therein, a first fluid inlet 27 at one end of the bore and a second fluid inlet 28 at the other end of the bore, piston means making electrical contact with the housing and slidably mounted in the bore between the fluid inlets the piston means comprising first and second axially spaced sealing portions 58, 60 and a portion 62 of reduced diameter therebetween, switch means mounted on or in the housing and being electrically insulated therefrom having a stud 75 projecting into the bore 24 intermediate the sealing portions 58, 60 and operable by the piston means to provide an electric signal when the piston means moves in either direction in the bore from a central position and spring means 65, 66 to bias the piston means to said central position, whereby a pressure differential between the first and second inlets is operable to shift the piston means to produce the electric signal. As described the piston member is in two parts, comprising a first piston 57 having a recess in the back of its head, into which fits an elongated shank 62 formed on a second piston 61. The switch member 75 is connected to an external terminal 79 and supported from a screwed bushing member 70 by means of insulating sleeves 72, 78. The springs 65, 66 are held in position by means of loose fitting plugs 31, 44, respectively, received in enlarged end portions of the bore 24, the plugs having conical outer end portions and being retained in position by inverted flare type fittings for connection to the hydraulic lines. The arrangement is intended for use in a dual hydraulic brake system for a vehicle having a single master cylinder with two pistons, the two fluid outputs of which are connected to the fluid inlets 27, 28, respectively, the housing being provided with outlets 38, 39 and 48, respectively, for connection to a pair of front brakes and a rear brake line, respectively: terminal 79 is connected to a warning lamp which, upon operation of the brake pedal, provides an indication if either fluid system is defective (Fig. 1, not shown). |
