To provide a cylinder control device and a working machine capable of solving the deterioration of efficiency caused by a pressure loss in a control valve and the deceleration of an attachment operation speed.
The control valve 33, the head side 15h and the rod side 15r of an attachment cylinder 15 are made to communicated with each other by main passages 51 and 52. The control valve 33 and a tank 30 are made to communicate with each other via a return passage 54. A return bypass passage 56 communicable with the tank 30 is branched from the main passage 51 on the head side 15h, and a return bypass passage 57 communicable with the tank 30 is branched from the main passage 52 at the rod side 15r. Electromagnetic variable relief valves 58 and 59 are arranged in these return bypass passages 56 and 57, respectively. When controlling one of the main passages 51 and 52 to the return side, a controller 49 has a function of controlling one of the electromagnetic variable relief valves 58 and 59 connected to the return side main passages 51 and 52 in a low-load communicating state.
SHIMABARA SEI
NAKANISHI MANABU
SHIBATA MASAFUMI
| JP2008133842A | 2008-06-12 | |||
| JP2002339904A | 2002-11-27 |
Satoshi Kabazawa
Tetsuya Yamada
Naozumi Ono
Sachiko Okunuki