Abstract: A pull-up/chin-up instrument (1) comprises, as its main components, one support column (2) which is maintained in an erected state by being propped up between a ceiling surface (Sc) and a floor surface (Sf) of a house, and a pull-up/chin-up handle (3) fixed to an upper part of the one support column (2). According to this configuration, there can be provided a pull-up/chin-up instrument, which realizes a reduced installation space and a low product price. The pull-up/chin-up handle (3) is supported by the one support column (2) only. The support column (2) is preferably inclined with a predetermined inclination angle (?) with respect to the direction of gravity. The main part of the support column (2) may include an upper pipe (11) on the side of the ceiling surface (Sc), a lower pipe (12) on the side of the floor surface (Sf) and a middle pipe (13) that is slidably fitted into the upper pipe (11) and lower pipe (12).

Abstract: Provided is a hydraulic shovel capable of moving a boom, an arm, and a bucket at respective adequate speeds even during complex operations thereof, without a significant pressure loss. This hydraulic shovel includes: a first pump (31) connected to a boom actuator (24) and a bucket actuator (28); a second pump (32) connected to an arm actuator (26) and the boom actuator (24); a third pump (33) connect to the arm actuator (26); a boom control valve (54) interposed between the first pump (31) and the boom actuator (24); an arm control valve (56) interposed between the second pump (32) and the arm actuator (26); a bucket control valve (58) interposed between the first pump (31) and the bucket actuator (28); a boom merging valve (55) for speed increase interposed between the second pump (32) and the boom actuator (24); and an arm merging valve (57) for speed increase interposed between the third pump (33) and the arm actuator (26).

Abstract: Provided is a hydraulic shovel capable of moving a boom, an arm, and a bucket at respective adequate speeds even during complex operations thereof, without a significant pressure loss. This hydraulic shovel includes: a first pump (31) connected to a boom actuator (24) and a bucket actuator (28); a second pump (32) connected to an arm actuator (26) and the boom actuator (24); a third pump (33) connect to the arm actuator (26); a boom control valve (54) interposed between the first pump (31) and the boom actuator (24); an arm control valve (56) interposed between the second pump (32) and the arm actuator (26); a bucket control valve (58) interposed between the first pump (31) and the bucket actuator (28); a boom merging valve (55) for speed increase interposed between the second pump (32) and the boom actuator (24); and an arm merging valve (57) for speed increase interposed between the third pump (33) and the arm actuator (26).

Abstract: A construction machine includes a hydraulic actuator circuit including: a first circuit connected to one of travel motors and a boom cylinder; a second circuit connected to the other travel motor and arm cylinder; and a third circuit connected to a slewing motor; control valves for hydraulic actuators; and a merging valve having a first position for unloading hydraulic fluid discharged from a third pump upon no operation except for two travel motors; a second position for merging the hydraulic fluid into the first and second circuits upon a simultaneous operation of the travel motors and an operation of at least one remaining hydraulic actuator except for a boom raising operation; and a third position for merging the hydraulic fluid into the first circuit while blocking it from the second circuit upon the boom raising operation.

Abstract: A circuit for driving a hydraulic cylinder of a construction machine includes: a hydraulic pump; a tank; a control valve; a bottom side line; a rod side line; a quick return circuit having a branch line branched off from the bottom side line and led to the tank and a quick return valve which allows hydraulic fluid to be flowed through the branch line only when the control valve is switched to a contraction driving position; and a recycling circuit which supplies a part of return fluid discharged from a bottom side fluid chamber to a rod side fluid chamber of the hydraulic cylinder. The recycling circuit allows the hydraulic fluid to be flowed only from the bottom side fluid chamber into the rod side fluid chamber of the hydraulic cylinder only when the hydraulic cylinder is switched to the contraction driving position.

Abstract: A construction machine includes a hydraulic actuator circuit including: a first circuit connected to one of travel motors and a boom cylinder; a second circuit connected to the other travel motor and arm cylinder; and a third circuit connected to a slewing motor; control valves for hydraulic actuators; and a merging valve having a first position for unloading hydraulic fluid discharged from a third pump upon no operation except for two travel motors; a second position for merging the hydraulic fluid into the first and second circuits upon a simultaneous operation of the travel motors and an operation of at least one remaining hydraulic actuator except for a boom raising operation; and a third position for merging the hydraulic fluid into the first circuit while blocking it from the second circuit upon the boom raising operation.