Patent ID: 6474751
Filing Date: 2002-11-05
Classification: B60T,F04C,F15B

Abstract:
A brake apparatus having a master cylinder, wheel cylinder and a rotary pump for supplying brake fluid to the wheel cylinder so as to more increase brake fluid pressure in the wheel cylinder than that in the master cylinder, the rotary pump comprising:first and second rotors made of bearing steel each having teeth portions at least at one of inner and outer peripheries thereof; and a plurality of gaps formed between the teeth portions of the first and second rotors which are in mesh with each other, brake fluid being sucked into and discharged from the gaps according to rotations of the first and second rotors, wherein the first and second rotors have circumferential surfaces of the teeth portions which are respectively processed by at least one of nitriding hardening and carbo-nitriding hardening so that nitrogen is diffused into the first and second rotors to form a layer including CrN.