Importance

Loading Importance Indicators...

Abstract

A ball for ball game comprises a rubber hollow spherical bladder, a valve holder fixed to the tube for charging air into the tube, a valve member attached to the valve holder; a fabric layer covering the bladder surface and a leather layer. The fabric layer is composed of a plurality of equilateral quadrilateral pieces sewn together to form a sphere. The equilateral quadrilateral pieces each include two sheets of approximately trapezodial fabric pieces that are sewed together symmetrically at a central seam line. The equilateral quadrilaterla pieces are sewed together such that central seam lines of adjacent equilateral quadrilateral pieces fall at right angles to ech other. The fabric layer gives sphericity, dimensional stability and durability to the ball. The leather layer is adhered to the fabric layer directly or through a rubber based thin intermediate layer. On a circumferential line in the fabric layer which includes one seam line, at least one other seam line exists at a prescribed interval to equally divide the un-sewn portions. All segments on the spherical surface of the fabric layer, which are divided by a plurality of circumferential lines including all of the seam lines, have the same shape.

Loading the Abstract Image...

First Claim