Work machine swiveling frame and assembly method for work machine swiveling frame

A slewing frame that is supported on a lower body of a work machine so as to be turnable about a turning center axis that extends in a vertical direction, the slewing frame comprising:

• a front frame that forms a front side portion of the slewing frame, and is turnably supported by the lower body;
• and
• a rear frame that forms a rear side portion of the slewing frame, and is detachably connected to the front frame,
• wherein the front frame has a pair of left and right front connecting portions each of which includes a positioning pin that extends in a left-right direction, the pair of left and right front connecting portions being disposed on a rear end portion of the front frame spaced apart from each other in the left-right direction,
• in the pair of left and right front connecting portions, a front side pin hole that allows a connecting pin that connects the front frame and the rear frame to each other to pass therethrough is formed in the left-right direction below the positioning pin respectively, a distance between the front side pin hole and the positioning pin being set to a predetermined reference distance as viewed in the left-right direction,
• the rear frame has a pair of left and right rear connecting portions that are disposed spaced apart from each other in the left-right direction on a front end portion of the rear frame such that the pair of left and right rear connecting portions face the pair of left and right front connecting portions in the left-right direction,
• the pair of left and right rear connecting portions each include an inner peripheral surface that defines an opening portion that allows the positioning pin to pass through the opening portion in a vertical direction, and a pin fitting portion that communicates with the opening portion above the opening portion and is configured to fit on an outer peripheral surface of the positioning pin such that rear frame is rotatable about the positioning pin,
• a rear side pin hole that allows insertion of the connecting pin is formed along the left-right direction in a portion of each of the pair of left and right rear connecting portions below the pin fitting portion, a distance between the pin fitting portion and the rear side pin hole is set to the reference distance as viewed in the left-right direction,
• the pair of left and right front connecting portions of the front frame each have a rotation preventing portion capable of preventing rotation of the rear frame in a downward direction about the positioning pin, and
• the pair of left and right rear connecting portions of the rear frame each have a contact portion that is disposed on a plane that is orthogonal to the left-right direction and passes the rotation preventing portion, the contact portion being configured to be brought into contact with the rotation preventing portion such that further rotation of the rear frame is prevented at a position where the front side pin hole and the rear side pin hole are aligned with each other in the left-right direction along with the rotation of the rear frame, wherein
• the positioning pin is disposed behind the front side pin hole such that a straight line passing through a center of the positioning pin and extending in the vertical direction does not intersect the front side pin hole, and the pin fitting portion is disposed behind the rear side pin hole such that a straight line passing through a center of the pin fitting portion and extending in the vertical direction does not intersect the rear side pin hole, as viewed in the left-right direction,
• each of the pair of left and right rear connecting portions further has an inclined surface that is disposed below the pin fitting portion and above the rear side pin hole, and is brought into contact and guide the positioning pin, the inclined surface being frontwardly and upwardly inclined toward a rear side so as to be connected with the inner peripheral surface that defines the pin fitting portion in a posture of the rear frame where the pin fitting portion opens downward, and
• in the rear frame, the contact portion is disposed behind and below the rear side pin hole, the inclined surface is disposed above the rear side pin hole, and the rear side pin hole is formed between the contact portion and the inclined surface.