A compact utility loader compact utility loader comprising a frame, a first track and a second track positioned on either side of the frame, and a pair of loader arms. The loader arms are configured to couple with an attachment via a hitch plate and a hitch pin. The compact utility loader is configured such that as the loader arms are raised and lowered, the hitch pin follows a path approximately defined by a curve ?(x)=4.641e.sup.0.34x The value x represents a horizontal direction and the function ?(x) represents a vertical direction.

A compact utility loader compact utility loader comprising a frame, a first track and a second track positioned on either side of the frame, and a pair of loader arms. The loader arms are configured to couple with an attachment via a hitch plate and a hitch pin. The compact utility loader is configured such that as the loader arms are raised and lowered, the hitch pin follows a path approximately defined by a curve f(x)=4.641e.sup.0.34x. The value x represents a horizontal direction and the function f(x) represents a vertical direction.

A compact utility loader compact utility loader comprising a frame, a first track and a second track positioned on either side of the frame, and a pair of loader arms. The loader arms are configured to couple with an attachment via a hitch plate and a hitch pin. The compact utility loader is configured such that as the loader arms are raised and lowered, the hitch pin follows a path approximately defined by a curve f(x)=4.641e.sup.0.34x. The value x represents a horizontal direction and the function f(x) represents a vertical direction.

A compact utility loader compact utility loader comprising a frame, a first track and a second track positioned on either side of the frame, and a pair of loader arms. The loader arms are configured to couple with an attachment via a hitch plate and a hitch pin. The compact utility loader is configured such that as the loader arms are raised and lowered, the hitch pin follows a path approximately defined by a curve f(x)=4.641e.sup.0.34x. The value x represents a horizontal direction and the function f(x) represents a vertical direction.

A reinforcement structure that reinforces a boom of a work machine having a top plate, a pair of side plates, and a bottom plate forming an inner space therebetween. The plates are configured to form a curved portion at the middle of the boom along the longitudinal direction. The structure comprises a baffle disposed inside the boom rearward of the curved portion across the inner space. The baffle is a plate laterally bent so as to have a convex shape extending forward in the longitudinal direction. The reinforcement structure helps prevent twisting of the boom while dispersing stress concentrations in rear upper portions of the side plates compare to conventional flat baffle plates.

A front linkage for a construction machine which can uniquely calculate the rotation angle of the work tool relative to the arm and which can prevent the angle detection device from being damaged by contact with the soil during digging. The front linkage has an arm, a first link pivotally connected at one end to the front end side of the arm, and at the other end to one end of a second link, and a work tool which is pivotally connected to the other end of the second link and which is pivotally connected to the arm in a further front end side than the one end portion of the first link. The first link is positioned outward along the outer width of the side wall of the arm. An angle detecting device for detecting the rotation angle of the first link relative to the arm may comprise a magnet disposed on an inner surface of the first link and a magnetic detector disposed on the side wall outer surface of the arm.

The present invention addresses the technical problem of providing an actuator which is provided to prevent leakage through a rod in a hydraulic or pneumatic cylinder-type actuator, and in which an existing sealing member may be used, and in particular, a cable (wire) may be used as a rod for solving the problem regardless of surface roughness thereof. An actuator for solving the above-mentioned problem in accordance with the present invention includes: a cylinder having an inner portion filled with a fluid and a front cover for closing a front end portion thereof; a piston displaced inside the cylinder by the fluid; a sealing member having one end portion fixed to the piston and the other end portion fixed to the front cover; and an operation member inserted in the sealing member and having one end portion fixed to the piston and the other end portion extending out of the front cover. In the present invention, due to the above-mentioned configuration, the sealing of a fluid (f) is already achieved by the sealing member, and thus, the operation member serves a moving function if only slipping relative to the sealing member in the sealing member. Accordingly, a rod or a cable does not need to move while being in close contact with the sealing member. Therefore, as in conventional arts, the present invention has merits in that a remarkable improvement is achieved in terms of wear of the sealing member, and it is not necessary to smoothly and precisely process the rod and to smoothly and hardly coat the cable.

A hydraulic system for a work machine includes a first hydraulic pump driving a swing hydraulic motor; a second hydraulic pumps driving a boom cylinder; a first pump displacement increase valve controlling a volume of the first hydraulic pump; a swing pilot pressure sensor detecting a swing operation amount; a boom raising pilot pressure sensor detecting a boom raising operation amount; and a controller controlling a control signal to the first pump displacement increase valve on the basis of the swing operation amount and the boom raising operation amount. The controller controls the control signal in such a manner that a delivery rate of the first hydraulic pump becomes higher as the swing operation amount is larger and an increasing rate of the delivery rate of the first hydraulic pump becomes lower as the boom raising operation amount is larger during a swing boom raising operation.

The subject matter of this specification can be embodied in, among other things, a multi-axis rotary actuator that includes a first rotary piston actuator configured to controllably actuate a first pivotal joint between a first linkage to a second linkage about a first axis, and a second rotary piston actuator configured to controllably actuate a second pivotal joint connecting the second linkage to a third linkage about a second axis.

The subject matter of this specification can be embodied in, among other things, a fluid actuator including a housing defining a first chamber having a first cavity and a first open end, a first piston assembly including a tubular first piston defining a second chamber having a second cavity and a second open end, disposed in said first housing for reciprocal movement in the first chamber through the first open end, wherein a first seal, the first cavity, and the first piston define a first pressure chamber, and a second piston assembly having an second piston disposed in said first piston assembly for reciprocal movement in the second chamber through the second open end, wherein a second seal, the second cavity, and the second piston define a second pressure chamber, and a first portion of the second piston contacts a first end effector.