Abstract: A method for producing centrifugally cast concrete product including charging pumpable concrete into a cylindrical form and rotating the form to cast the concrete by a centrifugal force, in which the concrete contains a high water reducing agent, an air entraining agent and an inorganic fine powder, and 5.5 to 18.5% of air content, thereby considerably reducing the amount of discharged sludge and, in turn, the labor and expenses required for the disposal of sludge, while maintaining the strength of the product as same as or greater than that for conventional products, without the need for complex processes.

Abstract: A reversing mechanism for running a tape or ribbon in one direction or the other between a pair of spools. Each spool has a driven member, and an idler is disposed intermediate the driven members for selective engagement therewith. The idler is driven by a rotatable member which is coupled with a reversible electric motor. A support lever is rotatably mounted on the axis of the rotatable member, and an idle arm is pivotally mounted on one end of the support lever. The idler is rotatably mounted on the idle arm, and is maintained in pressure contact with the rotatable member by a spring extending between the free end of the idle arm and the support lever. As a consequence, the magnitude of torque required to rotate the idler is greater than the magnitude of torque required to rotate the support lever in its free condition.