Current pneumatic piston style motors typically use metal components that require the constant addition of lubrication, typically oil. When the motors and components are not maintained periodically, operators may overcompensate the addition of oil for lubrication, resulting in possible oil contamination of the work area. Regardless, oil style pneumatic motors requiring lubrication may not be suitable for mixing material sensitive to contamination. Furthermore, on occasion, oil enters the air stream, resulting in contamination of the materials being mixed, such as but not limited to paint. Oil contamination of paint causes “fish eyes” and other undesired effects resulting in rejection of the finished product.
Some piston style pneumatic motors use plastic parts impregnated with lubricating properties, overcoming the constant lubrication issue. Some piston style pneumatic motors use a plastic based connecting rod that is attached to the piston via a wrist pin. The wrist pin system is cumbersome during assembly and disassembly. It has also been found that the wrist pin system results in frequent failures of the pneumatic motor, in particular, the failure of connecting rod and piston assembly, over a period of five to six months under normal operating conditions. In studies which replicate a full load on the pneumatic motor, the wrist pin system failed in five weeks. The contact area between the piston and the connecting rod in the wrist pin system, is small which results in frequent wearing down of the connecting rod.
There is a need for a connecting rod and piston system which increases the contact area between the piston and the connecting rod. There is also a need for a connecting rod and piston system without the need of a wrist pin. There is also a need for a connecting rod and piston system for a pneumatic motor without the need for frequent lubrication.