Title:
HYDRAULIC CIRCUIT OF AUGER LIFTING AND LOWERING EQUIPMENT
Document Type and Number:
Japanese Patent JP2009001982
Kind Code:
A
Abstract:
To provide a hydraulic circuit of auger lifting and lowering equipment with an auger free-descent mechanism capable of avoiding the breakage of a hydraulic motor in a free-fall state and preventing the free fall of an auger rotary-drive unit.
The auger rotary-drive unit is provided in a vertically movable manner in a leader. The hydraulic circuit of the auger lifting and lowering equipment makes the auger rotary-drive unit lifted and lowered by the hydraulic motor 18 which is operated by a hydraulic fluid supplied from a hydraulic pump 23 via a control valve 25 and a load holding valve 26. A cross relief valve 27 which makes relief pressure switchable is provided between the hydraulic motor and the load holding valve.
Inventors:
MURATE TOKUO
YAMASHITA KIMIKAZU
TANAKA KATSUTO
YAMASHITA KIMIKAZU
TANAKA KATSUTO
Application Number:
JP2007161517A
Publication Date:
January 08, 2009
Filing Date:
June 19, 2007
Export Citation:
Assignee:
NIPPON SHARYO SEIZO KK
International Classes:
E21B7/00; E02D7/22; E21B44/00
Attorney, Agent or Firm:
Kazuhiko Kido
Yoshihiko Kido
Yoshihiko Kido
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