Patent ID: 7562472
Filing Date: 2009-07-21
Classification: E02F,F15B

Abstract:
1. A work machine comprising: a lower structure adapted to be driven by a travel motor; an upper structure that is rotatable on the lower structure by a swing motor generator, and a work equipment mounted on the upper structure and comprising a boom, a stick, and a bucket that are sequentially connected and adapted to be pivoted by a boom cylinder, a stick cylinder and a bucket cylinder respectively; the work machine further including: a hybrid type drive system comprising: a travel/stick/bucket control circuit that serves to control hydraulic fluid fed from the main pump of the hybrid type drive system to the travel motor, the stick cylinder, and the bucket cylinder; a boom control circuit that includes a boom pump, which is provided separately from the main pump of the hybrid type drive system, the boom control circuit serving to control hydraulic fluid fed from the boom pump to the boom cylinder; and a swing control circuit that serves to: wherein the boom control circuit further includes: