| 摘要 |
PURPOSE:To prevent the erroneous operation without varying the urging force of a spring by making a partial piston onto which the front and rear wheels brake hydraulic pressure act, into a stepped piston having the larger piston area on the front wheel side than the piston area on the rear wheel side. CONSTITUTION:A valve plunger 30 is operated by the change of the interval between a car body and an accelerator, and the rear wheel brake hydraulic pressure introduced through a flow passage 26 is controlled and supplied into a rear wheel brake operation part through an opened port 23, and a rear wheel side brake is controlled according to the load. A partial piston 70 is arranged under the valve plunger 30, and the rear wheel hydraulic pressure is introduced through the flow passage 26, and the front wheel hydraulic pressure is introduced into an opened port 24. The piston pressure receiving area A3 on the front wheel side is made larger than the piston pressure receiving area A4 on the rear wheel side, and the erroneous operation which deflects the spot point on the sharp brake application in the medium loading state can be prevented without varying the urging force of a spring 71.
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