Abstract: A downhole motor universal joint assembly includes a female coupler which receives a male end of a drive shaft. The female coupler has a retainer that prevents separation of the male end and the female coupler. The retainer has a rearward extending skirt with flow passages to prevent solid material from accumulating in an exposed space between the female coupler and the male coupler. Also to prevent solid material from accumulating in this space, a shoulder formed on the male coupler diverts the flow of well fluid towards the outside of the joint. Thrust loads are transmitted between the male coupler and the female coupler by a thrust ball positioned between the male coupler and the female coupler. Torque loads are transmitted between the male coupler and the female coupler by a plurality of balls positioned in annularly spaced concave pockets on the exterior surface of the male coupler.

Abstract: A rotor to rotor coupling providing a connecting rod having longitudinal grooves mating to longitudinal grooves in a rotor end. The mated grooves forming chambers for which pins are received therein. A rotor cap secures the captured pins within the chambers and further strengthens the coupling. An optional thrust bearing assembly is disclosed along with a preferred method of synchronizing the rotors and timing the stators.