Abstract: A brake master cylinder includes a shiftable seal that provides an apparatus for maximizing compensation fluid flow during minimal fluid draw conditions such as occur through automatic traction control brake intervention type operation. The shiftable seal moves forward to compress a low load spring during fluid draw from the master cylinder's high pressure chamber to open a compensation flow path between the seal and the piston.

Abstract: A ring seal for sealing a piston of a master cylinder is provided. The ring seal is fitted within a generally rectangular groove of the piston, the groove having front and rear walls joined by a floor. The ring seal prevents fluid communication from a first chamber to a second chamber during high pressure differentials and allows fluid communication from the second chamber to the first chamber under very low pressure differentials.

Abstract: The present invention provides an apparatus and method of utilization thereof of a vehicle brake master cylinder proportioning valve. The valve includes a valve body having a main bore fluidly connected with the master cylinder, primary and secondary circuits. A first housing fluidly seals the main bore into first and second chambers. A second housing fluidly separates the main bore second chamber from the secondary circuit. A valve piston spring biased away from the first chamber is mounted within a bore of the housing. The valve also has fluid communication between the second circuit and second chamber when the fluid pressure within the second circuit exceeds the fluid pressure within the second chamber. At an increase in master cylinder pressure past a first predetermined pressure the valve piston moves towards the first chamber, reaching a pressure balanced position metering pressurized fluid flow from the master cylinder to the second circuit.