Improvements in control valves for air braking systems

摘要

1,034,828. Air brakes; valves. GIRLING Ltd. July 3, 1964 [July 17, 1963], No. 25355/63. Headings F2F and F2V. A vehicle braking system includes a control valve having a pressure-sensitive control member of which the effective area is variable with the load on the vehicle to regulate automatically the pressure of fluid supplied to the brake cylinders, the member controlling the area being normally held out of engagement with the means responsive to vehicle loading variations and urged into engagement with that means only at brake application. Air from the driver's valve enters port 14 and passes through channel 20 to act between the variable area diaphragm 27 and the control member 28 to overcome spring 38 and bring rod 29 into engagement with the said load responsive means. At the same time piston 26 is moved upwards to open valve 21, 22 and allow air to reach the brake supply port 24. Air from this port also passes through passage 32 to act above the diaphragm 31 until the piston is maintained balanced between the downward force on diaphragm 31 and that on the inner side of the variable area diaphragm 27. The shape of the lower face of piston 26 determines the convoluted shape of the diaphragm and thus its effective area. Increase or decrease in vehicle load moves rod 29 up or down, respectively, to increase or decrease the said effective area, the piston 26 consequentially rising or falling to open valve 21, 22 or valve 34, 35 to respectively increase or decrease the pressure in the brake cylinder. In a second embodiment (Fig. 3, not shown) the part 33 is extended upwards to abut the valve seat 21 and there perform the function of valve 34, 35. In a third embodiment (Fig. 4, not shown) a port connected to the driver's valve is directly connected to the chamber below diaphragm 27 and the valve controls the connection between a reservoir and the brake cylinder.