When pipelines 5 and 6 are connected to the atmosphere, the components of the valve are in the positions shown in Fig. a. Fluid delivered by the pump is directed through grooves of valve spools 1 and 1' to the power cylinder of the friction clutch, engaging the clutch and through regulating valve 2 to the hydraulic accumulator. The power cylinders of the accelerator and brake are connected to the housing. When a vacuum is set up in pipeline 6, piston 8 moves downward, lever 4 is turned by spool 1 which is lifted by spring 9 (see Fig. b). At this, the pump delivers fluid under pressure to the accumulator which maintains the pressure in the system. Fluid from the hydraulic accumulator is delivered through regulating valve 2 and valves 1 and 1' to the power cylinder of the brake. At the same time, fluid is admitted into the chamber above regulating valve 2, shifting the spool downward. Fluid delivered from the accumulator is throttled through an orifice of regulating valve 2. This gradually reduces the pressure in the system, ensuring smooth braking. The power cylinders of the accelerator an friction clutch are connected to the housing. When a vacuum is set up in pipeline 5, piston 7 moves downward, lever 4' is turned by spool 1' which is lifted by spring 10 (see Fig. c). At this, the pump delivers fluid under pressure through a groove of valve spool 1' to the power cylinder of the accelerator. The power cylinders of the friction clutch and the brake are now connected to the housing. Ball relief valve 3 protects the system against overloads.
$3958$LHP,Va$