Abstract: A plurality of rotating side brake disks and a plurality of non-rotating side brake disks are arranged outside in the radial direction from a motor shaft in a brake case while alternately overlapping with each other. A frictional material is provided on the non-rotating side brake disk, and an oil groove is provided in a frictional engaging surface of this frictional material. It is configured such that, when a braking force is applied by a brake piston to the motor shaft, lubricant oil flowing into the brake case from a lubricant oil inlet port flows from the outer diameter side to the inner diameter side between the rotating side brake disk and the non-rotating side brake disk only through the oil groove. As a result, the lubricant oil having flowed into the brake case efficiently cools the frictional engaging surface.

Abstract: A sliding layer (21) of a sintered copper alloy is formed on a sliding surface (12A) of a valve plate (12). That is, the valve plate (12) is formed of iron-based materials such as cast iron or steel. Then, the sliding surface (12A) which is the front side of the valve plate (12) is covered with the sliding layer (21) formed of a sintered copper alloy containing Cu (copper) and Sn (tin) as principal components and the remaining components as the remainder. The remainder has 2 to 6 wt % CaF2 (calcium fluoride) as an essential component, and an average particle size of said CaF2 is controlled to fall within the range from 40 ?m to 350 ?m. A sliding surface (8A) of a cylinder block (8) which is a opposing part sliding surface is not covered with the copper-alloy sliding layer (21) but is covered with a sliding layer of iron-and-steel based materials.

Abstract: An electric motor is arranged on a reduction device, and a wet braking device which gives braking force to a motor shaft is arranged on an upper end side of the electric motor. The wet braking device has a brake case which accommodates an upper end portion of the motor shaft, an adapter which is detachably disposed to the motor shaft in the brake case, a plurality of rotating side brake disks and a plurality of non-rotating side brake disks arranged on an outer peripheral side of the adapter and a brake piston which gives braking force to the motor shaft by frictionally engaging the rotating side brake disks and the non-rotating side brake disks with each other. At the time of performing a maintenance operation for the wet braking device, the wet braking device alone can be solely removed while keeping the electric motor assembled to the reduction device.

Abstract: A plurality of rotating side brake disks and a plurality of non-rotating side brake disks are arranged outside in the radial direction from a motor shaft in a brake case while alternately overlapping with each other. A frictional material is provided on the non-rotating side brake disk, and an oil groove is provided in a frictional engaging surface of this frictional material. It is configured such that, when a braking force is applied by a brake piston to the motor shaft, lubricant oil flowing into the brake case from a lubricant oil inlet port flows from the outer diameter side to the inner diameter side between the rotating side brake disk and the non-rotating side brake disk only through the oil groove. As a result, the lubricant oil having flowed into the brake case efficiently cools the frictional engaging surface.

Abstract: A plurality of rotating side brake disks and a plurality of non-rotating side brake disks are arranged outside in the radial direction from a motor shaft in a brake case while alternately overlapping with each other. A frictional material is provided only on the non-rotating side brake disk in these rotating side brake disk and the non-rotating side brake disk. As a result, the weight of the rotating side brake disk can be reduced, and drag resistance of the rotating side brake disk rotating also in brake release can be reduced.

Abstract: An electric motor is arranged on a reduction device, and a wet braking device which gives braking force to a motor shaft is arranged on an upper end side of the electric motor. The wet braking device has a brake case which accommodates an upper end portion of the motor shaft, an adapter which is detachably disposed to the motor shaft in the brake case, a plurality of rotating side brake disks and a plurality of non-rotating side brake disks arranged on an outer peripheral side of the adapter and a brake piston which gives braking force to the motor shaft by frictionally engaging the rotating side brake disks and the non-rotating side brake disks with each other. At the time of performing a maintenance operation for the wet braking device, the wet braking device alone can be solely removed while keeping the electric motor assembled to the reduction device.

Abstract: A hydraulic drive system is provided with a front casing 50 and a rear ceasing 51. The front casing 50 is formed of a single member, and accommodates therein rotary members, which include a cylinder block 30A and the like, and a part of an output shaft 36 of a hydraulic motor 30 and rotary members, which include a cylinder block 31A and the like, and a part of an output shaft 32 of a hydraulic motor 31. The rear casing 51 is joined to the front casing 50, and has a ports plate 30C and a ports plate 31C arranged therein. The rear casing 51 has an oilway 52 communicating to a first port 30C1 of the ports plate 30C, an oilway 53 communicating to the oilway 52 and also communicating to a first port 31C1 of the ports plate 31C, an oilway 54 communicating to a second port 30C2 of the ports plate 30C, and an oilway 55 communicating to the oilway 54 and also communicating to a second port 31C2 of the ports plate 31C.

Abstract: A pair of leg portions are provided on a swash plate. A main hydrostatic bearing is provided on one leg portion, in communication with one supply/discharge passage through an oil guide passage, and an auxiliary hydrostatic bearing is provided on the other leg portion, in communication with the oil guide passage. Another main hydrostatic bearing is provided on the other leg portion, in communication with the other supply/discharge passage through an oil guide passage, and another auxiliary hydrostatic bearing is provided on one leg portion, in communication with the oil guide passage. By the main hydrostatic bearings and auxiliary hydrostatic bearings, dissociative forces are generated between the leg portions of the swash plate and a swash plate support member in balance with hydraulic reaction forces which are exerted on the swash plate by pistons.

Abstract: A motion converting section (31) and a translation bar (33) of a feedback mechanism (30) are provided between a lateral side of a swash plate (21) and a control sleeve (26) of a regulator (24). When the swash plate (21) is in a neutral position, the motion converting section (31) is located in an initial position (F—F) at one end of axial direction along an axis line (O—O) passing through a tilting center (C) of tilting motions, and, when the swash plate (21) is driven to tilt in a forward or reverse direction, displaced to the other end of axial direction along the axis line (O—O) to convert a tilting motion of the swash plate (21) into an axial displacement. Through the translation bar (33), the axial displacement is transmitted to the control sleeve (26) of the regulator (24) as an axial displacement.

Abstract: A motion converting section (31) and a translation bar (33) of a feedback mechanism (30) are provided between a lateral side of a swash plate (21) and a control sleeve (26) of a regulator (24). When the swash plate (21) is in a neutral position, the motion converting section (31) is located in an initial position (F-F) at one end of axial direction along an axis line (O-O) passing through a tilting center (C) of tilting motions, and, when the swash plate (21) is driven to tilt in a forward or reverse direction, displaced to the other end of axial direction along the axis line (O-O) to convert a tilting motion of the swash plate (21) into an axial displacement. Through the translation bar (33), the axial displacement is transmitted to the control sleeve (26) of the regulator (24) as an axial displacement.

Abstract: A volume control valve for controlling the volume of a variable displacement type hydraulic rotary machine includes a valve housing provided with a bore in which a spool slides axially to selectively establish and block communication of a pressure oil feed/discharge port with a high pressure port and a tank port. A first pressure receiving portion is formed in the spool to receive a load pressure as a pilot pressure introduced from a pilot port for displacing the spool axially within the bore. A bottomed axial bore is formed in the spool which has a slidable piston therein defining an oil chamber between the piston end and the bottom of the bore to receive a hydraulic reaction force induced within the oil chamber. A second pressure receiving portion is formed by the bottom of the bore to receive an internal pressure of the oil chamber, thereby changing a total pressure receiving area of the spool in conjunction with the first pressure receiving portion.