Abstract: The apparatus is of the type having a tensioning roller, a motor drive for rotating the roller in the direction of the band to tension the hooping band, and a locking device which may be raised or lowered by a thrust drive guided in a casing to press against the portions of the band to lock them together.The improvement comprises a control member associated with the motor drive of the tensioning roller. The position of the control member is determined on the one hand by a reaction force proportional to the tangential force exerted on the tensioning roller, and on the other hand by an opposing force acting on the control member. When the band tension exceeds a particular value, the motor drive of the roller is switched off by the control member and the thrust drive of the locking device is switched on.

Abstract: The primary thrust drive for a punch and die set which presses together two superimposed portions of the band to be locked utilizes the mechanical advantage afforded by a symmetrical angle lever pair. The arms of the levers are turned about a pair of pinions by a pneumatic piston drive. At the end of the other arms is a pressure roller which rides on a pressure surface of a pressure plate to convert the rotation movement of the angle levers to an outward linear movement on the pressure plate towards the pinions. The pressure plate carries the die. The pressure surface upon which each of the rollers acts is made to have a cylindrical curvature away from the roller. This has the effect of making more linear the characteristic increase of the mechanical advantage of the toggle arrangement as a function of the outward travel of the pressure plate and thereby making the adjustment of the die travel less critical.