In scroll compressors, the orbiting scroll must orbit without rotating and, in addition, is subjected to axial forces from the gas being compressed. A number of approaches have been developed for preventing rotation such as the Oldham coupling, balls moving in slots and rollers. The anti-rotation devices add structure to the scroll compressors.
Scroll compressors typically have an Oldham coupling between the orbiting scroll and the crankcase. This has two effects, it increases the height/length of the assembly and reduces the available thrust surface. In scroll compressors it is desirable to have a press fit motor so that the standard diameter of a motor defines the maximum diameter of the crankcase/pump assembly. To minimize cost it is necessary to use the smallest motor suitable for the job, but then it becomes necessary to provide the necessary thrust surface within the size constraints dictated by the motor. The present invention permits the use of a smaller motor while maintaining thrust surface requirements.