摘要 |
A master cylinder device connected with a brake booster device of an input rod pulling type is disclosed. In the brake booster device, the interior of a brake booster is partitioned by a diaphragm with a piston secured thereto, into a constant pressure chamber and a variable pressure chamber. The piston incorporates therein a valve mechanism operated by a brake pedal for making the variable pressure chamber communicate selectively with the atmosphere and the constant pressure chamber. The brake booster device transmits the axial movement of the diaphragm generated based on the pressure difference between the both chambers, from the piston through a reaction mechanism to an output rod. The output rod pulls a piston rod of a master cylinder rearward for making the master cylinder generate a braking pressure. The output rod extends as the piston rod in the master cylinder of the master cylinder device, and a master piston is mounted on the forward end portion of the piston rod so that it is floatable relative to the piston rod, but is restrained from being moved forward relative to the piston rod in the axial direction of the same. Thus, the master piston can be prevented from scraping against the master cylinder.
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