Hydraulic clutch and work-vehicle travel power transmission apparatus including the hydraulic clutch

A hydraulic clutch comprising:

• a clutch body;
• a tubular clutch hub located inside a tubular clutch plate support section included in the clutch body;
• a plurality of first clutch plates to be locked to the clutch plate support section and arranged in a direction extending along a rotation axis of the clutch body;
• a plurality of second clutch plates to be locked to the clutch hub and arranged in the direction extending along the rotation axis;
• oil supply holes extending through the clutch hub to supply lubricating oil from an interior of the clutch hub toward the first clutch plates and the second clutch plates;
• and
• an injection port to allow injection of the lubricating oil into the interior of the clutch hub;
• wherein the injection port is located in the interior of the clutch hub at a location between the clutch hub and the rotation axis;
• and
• the clutch hub includes an inner circumferential portion including:
• an opposing portion opposing the injection port;
• and
• a first portion closer to a first end portion of the clutch hub than the opposing portion in the direction extending along the rotation axis, the first portion including an inclined inner circumferential surface structured such that a radius of the clutch hub decreases toward the first end portion;
• the clutch body includes, in the interior thereof:
• a clutch piston to press and release the first clutch plates and the second clutch plates;
• a return spring to return the clutch piston to a release position;
• and
• a stopper to receive and support the return spring;
• the stopper includes an inserted portion inserted into the interior of the clutch hub;
• the injection port is located in the interior of the clutch hub at a location opposing a portion between opposite end portions of the clutch hub in the direction extending along the rotation axis;
• the inner circumferential portion of the clutch hub further includes a second portion closer to a second end portion of the clutch hub than the opposing portion in the direction extending along the rotation axis, the second portion including an inclined inner circumferential surface structured such that the radius of the clutch hub decreases toward the second end portion;
• the inserted portion is provided at a position opposing the second portion;
• and
• the second portion has an inclination angle that is less steep than an inclination angle of the first portion.