By injecting or pumping oil
drop-by drop into an air stream the air will carry the lubricant to the points of application, such as gears. A similar mixture
can be obtained by the aspiratory action of compressed air. With such systems,
provision can be made to start the oil flow with the start of the machine and
stop it when the gears stop. The delivery is positive and there is little
chance for contamination because the gear box is under some pressure which
prevents entry of dust. Also,rate of oil feed can be regulated.
On the negative side, it is necessary to provide compressed air and a
considerable flow of air escapes through the vent of the gear case. While this
air will have some cooling value, it may carry some oil mist. The oil is used
on a once through basis and provision has to be made to drain the sump of the
gear case at times.
