| 摘要 |
<p>PURPOSE:To amplify oil pressure to a given level with the aid of a pressure amplifier by securing oil pressure at a desired level through reduction valve and by eliminating higher oil pressure in case where oil pressure suppliable by a variable hydraulic source. CONSTITUTION:When the first and the second electromagnetic valves 11 and 16 are synchronously shifted to b position, all channels to an oil tank 14 are shut off and oil pressure is held in series channels from a hydraulic source 1 to a negative brake 9. Then, a given level of oil pressure P transmitted to the oil chamber 27 of the pressure amplifier 6 via the reduction vlave 2 is supplied to the second oil chamber 29 by way of an oil path 22 within a stepped piston 21 and by way of the check valve, and then, increases oil pressure on the side of the second oil chamber 29 in proportion to the ratio between the area Al of a large-diameter end and the area A2 of a small-diameter end of the stepped piston 21 when the check valve is closed.</p> |
