Its solid drive shaft makes the 70500 the ideal choice for handling liquids with a tendency to set up -- and eventually build up -- in a hollow-shaft model. That includes thermosetting adhesives, concrete, grout, plaster and other materials which have the potential to harden inside the shaft. When these materials are allowed to build up and harden, they inhibit free movement of the connecting rod, resulting in connecting rod breakage. In designing the 70500, Roper Pump Company engineers moved the pin joint connection from the middle of the drive shaft out to the end. This modification moved the connecting rod within the suction housing where material can be easily flushed.