A coatings application apparatus pumps liquid paint through a flexible conduit within a rotary variable displacement peristaltic pump to a conventional applicator head. Through constant speed rotating lobes peristaltic action squeezes coating liquid within the conduit through the paint applicator control handle and applicator.The control handle permits changes in the paint flow rate. Upon constriction of the conduit within the control handle, flow rate is reduced, back pressure develops with resulting tube distortion. Distortion levered forces act upon a pre-set loaded pump spring. Variation in pump displacement results. The liquid flow rate within the supply conduit is inversely proportional to the back pressure so developed. If fluid flow is completely arrested by full supply tube constriction, back pressure becomes a maximum and pump displacement becomes zero. The pump continues to operate, however, at constant R.P.M., requiring no high starting torque.The pump unit employes two reverter train speed reduction systems in tandem. A conventional planetary or epicyclic gear system provides a first reduction in R.P.M. The pump rotor element itself, as a secondary reduction unit, allows economy in selection of a high speed, low power, motor drive for the peristaltic pump.