Liquid pressure braking systems for vehicles

Claim 1

An antilock means for a liquid pressure braking system comprising a servo device with movable diaphragm means therein dividing it into a first chamber and a second chamber, valve means in said servo device normally held in an open position to connect a brake cylinder to a source of fluid pressure until a tendency to skid is sensed, first conduit means normally connecting said first chamber to a source of low fluid pressure to maintain said first chamber at a minimum volume, second conduit means normally connecting said second chamber to a source of high-pressure fluid to maintain said second chamber at a maximum volume, a valve plunger in said servo device in contact with said movable diaphragm means to keep said valve means open when said second chamber is connected to said high-pressure fluid source, other valve means connecting said first conduit means and said first chamber to a source of high-pressure fluid and connecting said second conduit means and second chamber to a source of low fluid pressure source, said other valve means normally being disposed to maintain a fluid pressure differential across said movable diaphragm means in a direction to hold said valve means open by said plunger, and a skid-sensing device operatively connected to said other valve means to reverse the normal connections of said first and second chambers with said high and low fluid pressure sources respectively and to connect said first chamber with the high source of fluid pressure and to connect said second chamber with said low fluid pressure source to close said valve means and cut off communication of said brake cylinder with its source of fluid pressure until said wheel stops its skid, and means are provided whereby the pressure in at least one of said chambers of said servo device resulting from the action of the sensing device varies with the pressure exerted in the braking system by the liquid pressure source thereof.