| 摘要 |
PURPOSE:To supply quickly the master cylinder pressure to a wheel cylinder when a pump is in trouble, by providing a piston that can close a by-pass by a negative pressure, and supplying a negative pressure when a controlling hydraulic pressure is supplied to apply braking. CONSTITUTION:An adjustor 5 comprises a pressure governing section 12 and a pressure generating section 13, and a high pressure is generated in a pipe 24 by moving a spool 47 of the generating section 13 to the left. An electromagnetic valve 58 selectively connects a negative pressure piping 57 or an atmosphere communicating pipe 58 to negative pressure chambers 39, 49 and is actuated by a brake switch 11 and a pressure switch 25. By receiving a negative pressure, the piston 40 is moved to the right to open the by-pass 29 as well as to open a valve 37 to permit the pressure governing section 12 to operate. When the pump 16 becomes in trouble, and a hydraulic pressure is not generated, since the electromagnetic valve 58 would not work, the by-pass would remain open, and therefore the rising of the wheel cylinder pressure would not be delayed. |
