applied to the first stage is not as efficient as with system pressure however it is acceptable and allows brake application capability and anti skid protection to be retained check valve 34 and or fluid flow restrictor 36 prevents the brake metered hydraulic flow from being lost to the failed system if failure is caused by a leak similarly if slide 23 should jam in the dotted position shutting off system pressure when it is needed check valve 31 again allows sufficient flow for anti control valve function restrictor 37 in the input passage from port 16 to check valve 31 restricts flow to prevent excessive loss of brake metering pressure and flow and braking in the event of a failure which vented the volume between lands 24 and 25 to return port or to ambient in such a failure restrictor 36 would serve to limit losses from the hydraulic system if there should be a failure inside valve 13 such as a failed seal or a cracked valve casing which allowed pressure flow from the hydraulic system supply pressure to be coupled to port 16 and the brake metered pressure line 14 either restrictor 36 or 37 would limit the flow rate to a level which line 14 can accommodate as it returns the flow to system return through the pilot 39 s metering valve 11 of fig1 without reaching pressure levels which could cause the brakes to be inadvertently applied it is evident from the preceding that harmful quiescent flow which tends to erode the first stage valve in the anti skid control valve is limited to.