Railcar axle box and method of producing the same

A railcar axle box comprising an axle box main body accommodating a bearing supporting an axle,

• the axle box main body including
• an inner surface defining an accommodating space accommodating the bearing,
• a first side surface provided at an outer side of the inner surface and at one car width direction side of a center of the accommodating space, and
• a second side surface provided at the outer side of the inner surface and at the other car width direction side of the center,
• a shortest distance between the first side surface and the center and a shortest distance between the second side surface and the center being equal to each other in a car width direction,
• wherein the axle box main body includes:
• a spring seat provided at an upper portion of the axle box main body;
• a first horizontal surface for chucking, the first horizontal surface being located at one car width direction side of the spring seat;
• and
• a second horizontal surface for chucking, the second horizontal surface being located at the other car width direction side of the spring seat.