Abstract: A hydraulic hose guiding device allowing hydraulic hoses to be connected to an operational pattern switching valve in a construction machine with better operational efficiency is provided. The hydraulic hoses to be connected to the operational pattern switching valve are lead through a clearance between an operator's cab disposed on an upper revolving superstructure and a cooler chamber of a hydraulic power unit. A guide member that holds the plurality of hydraulic hoses neatly in place by preventing their displacement toward the cooler chamber is disposed between the operator's cab and the cooler chamber.

Abstract: Locking elements 3d and 3j are provided at an inner member 3 connected to a kelly bar 1, and a locking element bearing plate 6f is provided at an outer member 6. The outer member 6 includes a cylindrical bucket 7 and a grab bucket 8 housed inside the cylindrical bucket 7. When an excavating tool 2 is in its most contracted state, the inner member 3 is rotated forward to lock the locking elements 3d and 3j at the locking element bearing plate 6f, thereby disallowing relative vertical movement of the inner member 3 and the outer member 6. As the excavating tool is rotated by applying a force to the kelly bar 1 along the lifting direction in this state, an excavating operation can be executed while applying a load smaller than the load of the excavating tool 2.

Abstract: A working machine such as a hydraulic excavator is provided with a working apparatus including a boom pivotally mounted on the body of the working apparatus and a boom-cylinder hydraulic system for the working apparatus. The hydraulic system includes an actuator for moving the boom up and down and a directional selecting valve. The directional selecting valve is arranged to effect selective switching of the feed of a pressurized working fluid to and the discharge of the working fluid from with respect to the rod-side and the bottom-side hydraulic chamber. The hydraulic system further includes a device for relieving the pressure of the bottom-side hydraulic chamber of the actuator. This relieving device is connected to the bottom-side hydraulic chamber of the actuator via a hydraulic circuit. When the pressure in the bottom-side hydraulic chamber changes from rise to fall, the pressure is released to a low-pressure side of the hydraulic circuit, thereby suppressing oscillation of the boom.