Patent classifications
F15B2211/321
Spool valve and hydraulic apparatus including the same
A spool valve is provided. A valve housing has a pilot fluid passage, and a first portion and a second portion lengthwisely spaced apart from each other. A spool is movably inserted in the valve housing, and includes a plug able to enter the pilot fluid passage between the first portion and the second portion to change a flow area of the pilot fluid passage following movement of the spool. A hydraulic machine provides that when pilot fluid is supplied to the pilot fluid passage through the first portion, at least a portion of the supplied pilot fluid is provided to the holding valve through the second portion. The holding valve allows a flow of working fluid from the first chamber to the spool valve, and the spool moves to a third position to forward working fluid to the second chamber.
Hydraulic drive with rapid stroke and load stroke
A hydraulic drive including a first differential cylinder that includes a first and a second pressure chamber and a first piston that separates the first from the second pressure chamber and having two pumps delivering in opposite direction. The hydraulic drive further includes a second differential cylinder that includes a first and a second pressure chamber and a second piston that separates the first pressure chamber from the second pressure chamber, and a directional control valve that has a first and a second switching position. The pumps in the first switching position are respectively hydraulically connected via pressure chambers of the first differential cylinder that are different from each other and whereby the pumps in the second switching position are respectively connected via pressure chambers of the second differential cylinder that are different from each other.