Abstract: Paint sprayer apparatus includes a paint sprayer frame having a sprayer apparatus mounted thereon, and two or more prime movers either of which may be interchangeably mounted on the frame for use in driving the sprayer pump. Each prime mover is provided with a pair of shoulder bolts in diagonally opposite corners of the respective prime mover bases that are adapted to be dropped into one or more pairs of correspondingly spaced slots in the paint sprayer frame. Fastener knobs threaded onto the outer ends of the shoulder bolts may be tightened or loosened and removed by hand to permit removal and replacement of one prime mover with another, and also loosened to permit proper adjustment of the belt tension. A belt tensioning stud may also be provided on the respective prime movers for receipt in an upwardly opening belt tensioning slot in the paint sprayer frame.

Abstract: Outlet valve assembly for a paint sprayer and the like includes a spring stop engageable by the outlet valve during opening of the outlet valve to dampen the outlet valve movement during opening of the outlet valve. There is a slight initial clearance between the spring stop and outlet valve when the outlet valve is in the closed position. During each cycle of operation of the paint sprayer, the impact of the outlet valve striking the spring stop compresses the spring stop somewhat, whereby the distance between the spring stop and outlet valve when the outlet valve is in the closed position is less than when a rigid stop is used to obtain the desired amount of outlet valve travel during opening of the outlet valve. At the end of the delivery stroke of the pump, the force of the spring stop acting on the outlet valve pushes the outlet valve to the closed position.

Abstract: Inlet valve assembly for a paint prayer and the like includes an adjustable inlet valve stop movable toward and away from an inlet valve seat to reduce or increase the amount of free movement of the inlet valve for obtaining optimum volumetric efficiency by reducing the back flow through the inlet valve. The adjustable stop includes a rebound spring and a holder therefor which is threadedly mounted, whereby rotation of the holder in opposite directions varies the initial clearance space between the spring and inlet valve when the inlet valve is closed. The holder has a non-circular opening in the center to enable the user to insert a turning wrench or the like therein to turn the holder to the desired adjusted position. Access to the adjustable stop for turning the holder may be obtained by inserting the tool through an outlet valve opening in the sprayer pump upon removal of an outlet valve assembly therefrom. A conical lock spring may be used to frictionally lock the holder in the desired adjusted position.

Abstract: A plug and filter assembly for a paint sprayer is characterized by a hand turnable knob that is rotatably coupled to a sealing plug to reduce the torque needed to install or remove the assembly from a paint head by axially advancing the plug into or out of an O-ring seal without having to turn the plug in the O-ring. The rotatable coupling is effected by a fastener having a head and a cylindrical shank portion which is received in an oversized central axial bore in the knob. The cylindrical shank portion has a diameter greater than that of a threaded end portion of the fastener secured in the plug and thus defines a shoulder which engages an axial end face of the plug positively to fix the axial spacing between the fastener head and plug to a distance greater than the axial length of a portion of the knob axially trapped between the fastener head and plug for free nonbinding rotation of the knob.