Fabric reinforced tubular rubber bladders and method of making same

A reinforced rubber half of a two-piece annular air brake comprising:

• a semi-circular flattened tubular body formed of a first outer body ply of unreinforced rubber, second and third fabric reinforced rubber intermediate body plies, and a fourth unreinforced rubber inner body ply, said flattened tubular body having two flat sides and rounded side edges and being curved in a plane transverse to the flat sides;
• a first pair of end patches of fabric reinforced rubber folded substantially in half, one over each end of the flattened tubular body between the second and third body plies, with each half of each first end patch folded flat against the flat sides of the second body ply and with each side of each first patch pinched together at, and trimmed along, the rounded side edges of the second body ply;
• a second pair of end patches of fabric reinforced rubber folded substantially in half, one over each end of said flattened tubular body between the third and fourth body plies, with each half of each second end patch folded flat over the flat sides of the fourth body ply and with each side of each second end patch pinched at, and trimmed along, the rounded side edges of the fourth body ply, and;
• a third pair of end patches of unreinforced rubber folded substantially in half, one over each end of the flattened tubular body between the third and fourth body plies and under the second pair of end patches, with each half of each patch folded flat against the flat sides of the fourth body ply, and with a center flap on each side of each third end patch in alignment with the associated end of the flattened tubular body folded down along the adjacent rounded side edge of the tubular body and with a side flap formed on each side of each third end patch folded circumferentially around the tubular body and over the adjacent center flap.

A method of making a reinforced rubber bladder comprising steps of:

• forming from a plurality of rubber plies, at least some of which are fabric reinforced, a flattened tubular, open ended, multilayer body member, having two flat sides and rounded side edges;
• folding a fabric reinforced rubber end patch substantially in half over at least one open end of the flattened tubular body, with each half of said patch folded flat against one of said flat sides and extending laterally beyond each rounded side edge;
• pinching the two halves of said patch together where they extend laterally beyond each rounded side edge;
• trimming off the pinched portions of the end patch along said rounded side edges.

A method of making a fabric reinforced half of an annular air brake comprising the steps of:

• laying up in order, one on top of the other on an arcuate mold half, a first planar body ply, a second planar body ply, a first pair of end patches, a third planar body ply, a second pair of end patches, a third pair of end patches and a fourth planar body ply, each pair of said patches extending longitudinally outward beyond the ends of said body plies,
• folding the sides of said fourth ply over each other and securing them together to form an open ended flattened tubular body,
• folding the third pair of end patches longitudinally over the open end of the tubular body formed by the folded fourth ply to close the same and sealing the sides of said folded patches around the tubular body,
• separately folding the second pair of end patches longitudinally over said third pair and sealing the sides of said second pair of folded patches,
• folding the sides of the third body ply over the tubular body and over the folded portions of the second and third pairs of end patches to add a second layer to the tubular body,
• folding the first pair of end patches inward longitudinally over the folded third ply, and sealing the sides of said first pair of folded patches,
• folding separately in succession, the sides of the second body ply and the sides of the first body ply to add layers to the tubular body,
• folding a sheet of rubber over each end of the tubular body to cover therewith the first end patches, and
• curing the tubular body with the covered ends.

A method of sealing the end of a flattened tubular body having two flat sides joined by two rounded side edges constructed from at least one rubber body ply, said method comprising the steps of:

• folding a rubber end patch substantially in half over the end of the flattened tubular body with each half of the patch flat against one of said flat sides, and with the patch extending laterally beyond the rounded edges of the flattened tubular body;
• making two cuts inward from each side edge of the patch to the adjacent rounded side edge in alignment with the ends of said flat sides, to form at each side a center flap and two side flaps;
• removing from each side of the patch one of the said flaps;
• folding each center flap such that it extends longitudinally along the adjacent rounded side edge of the flattened tubular body;
• folding each remaining side flap circumferentially around the flattened tubular body over the adjacent folded center flap;
• and
• curing the resultant construction to bond the patch to the flattened tubular body and to seal the seams formed by the folds.