Abstract: An oil spraying pump having a piston which is stationary with respect to a movable cylinder having a discharge opening therein. A normally sealed bore-hole extends through the piston from the cylinder interior to atmosphere. Means are provided to supply oil to the cylinder interior whereby when the bore-hole is sealed, relative movement between the cylinder and the piston causes oil to be sprayed from the discharge opening. The pump further includes a follower joined to the bore-hole seal. The follower is periodically displaced to move the seal out of sealing relationship with the bore-hole thereby venting the cylinder interior to atmosphere and preventing oil from being sprayed from the discharge opening.