Coupling assembly and friction shoe therefor

In a friction coupling assembly, the combination of an inflatable fluid extensible annular tube;

• a plurality of friction shoes;
• means for removably attaching said shoes to a circumferential surface of said tube so that said shoes move radially with the tube as the tube is inflated and deflated;
• said tube having a plurality of circumferentially spaced transversely extending grooves;
• each of said friction shoes comprising a backing plate, a pad made of friction material secured to one side of said backing plate, and a driving bar also made of said friction material extending transversely of said plate, said friction material extending through at least one hole in said backing plate and secured to the side of said backing plate opposite from said pad whereby the driving bar of each friction shoe is positioned in a groove of said tube, said bars and grooves having cross sectional shapes which precisely fit each other, said backing plate, pad and driving bar being integrally joined together into a unitary structure by the friction material forming said pad and bar to improve the torque transfer between the shoes and said tube.