New Dual-control Brake Valve
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ANEW dual-control hydraulic reaction valve for use in the braking system of articulated outfits has been introduced by Feeny and Johnson, Ltd., 134-136 Ealing Road, Wembley, Middlesex.
Apart from its simplicity, small size and light weight, its most attractive feature, from the practical aspect, is its instantaneous action. Through a fingertip control the valve can be operated to work the semi-trailer brakes only or in conjunction with the brakes on the tractor.
When the brake pedal on the tractor is used, the pressure applied through the hydraulic pipe line lifts the plunger and seals off chamber A from the atmosphere. Further movement will cause the vacuum chamber to open and as this chamber is in communication with chamber A, which in turn leads to the power unit, the semi-trailer brakes are operated by vacuum.
The valve is provided with a readily accessible adjusting nut whereby 'the " cut-in" pressure can be finely set according to requirements. There is a reaction diaphragm on which the vacuum also operates to produce a reaction effect. The complete valve measures 31 in. by 7/16in.