Wet brake device

A wet brake device comprising:

• a brake case in which a rotational shaft is rotatably fitted to extend in a vertical direction in the brake case;
• a plurality of rotating side brake disks arranged outside in a radial direction of said rotational shaft in said brake case and rotating together with said rotational shaft;
• a plurality of non-rotating side brake disks arranged in a non-rotating state in said brake case while alternately overlapping with each of said rotating side brake disks and opposing said rotating side brake disks in the vertical direction;
• a brake piston which applies a braking force to said rotational shaft by pressing said rotating side brake disks and said non-rotating side brake disks to frictionally engage with each other;
• a lubricant oil inlet port provided in said brake case and into which lubricant oil flows toward outer diameter sides of said rotating side brake disks and said non-rotating side brake disks;
• and
• a lubricant oil outlet port provided in said brake case and said lubricant oil, which is discharged from inner diameter sides of said rotating side brake disks and said non-rotating side brake disks, flows out from said lubricant oil outlet port in said brake case,
• wherein one or more of said non-rotating side brake disks respectively includes:
• a frictional material disposed on said non-rotating side brake disk to frictionally engage with said rotating side brake disk,
• one or more oil grooves, through which said lubricant oil flows from the outer diameter sides to the inner diameter sides of said rotating side brake disk and said non-rotating side brake disk, which are disposed on said frictional material, and
• a hole having a diameter larger than a shaft diameter of said rotational shaft provided in a central portion of said non-rotating side brake disk, and
• said frictional material is provided on an outer portion of said non-rotating side brake disk in a radial direction thereof,
• wherein one or more of said rotating side brake disks respectively includes:
• an engaging hole which is provided in a central portion of said rotating side brake disk to engage with said rotational shaft,
• one or more through holes through which said lubricant oil flows provided in a frictional material non-contact surface of said rotating side brake disk, where said frictional material non-contact surface is provided between said engaging hole and a portion of said rotating side brake disk which frictionally engages with said frictional material,
• wherein said lubricant oil, flowing into said brake case from said lubricant oil inlet port when a braking force is applied by said brake piston to said rotational shaft, only flows from the outer diameter sides to the inner diameter sides between said rotating side brake disks and said non-rotating side brake disks through said one or more oil grooves,
• wherein said lubricant oil flowing into said brake case from said lubricant oil inlet port is a part of return oil of operating oil circulating from an operating oil tank in a return line after having driven a hydraulic actuator and is in a pressurized state,
• wherein a lubricant oil line which makes said return line communicate with said lubricant oil inlet port has a first end connected to said return line on an upstream side of a cooler provided on said return line, and a second end of said lubricant oil line is connected to said lubricant oil inlet port, and
• wherein said lubricant oil continuously flows from the outer diameter sides to the inner diameter sides between said rotating side brake disks and said non-rotating side brake disks in the pressurized state.