Dripfeed application of gear oils may be considered semi-automatic in that it is adjustable to a certain degree. The feed for the oil in this case may be by gravity or even by circulation if the stream in the latter instance can be throttled down sufficiently. In the first case a container can be filled by hand or even a small drum can be connected with piping ending in a valve or cock to permit adjustment of the feed. Here, as the amount of oil in the container becomes less, the feed will decrease. Where such a feed is partly mechanical, the oil will come either from a storage tank to which a pump has delivered it or directly from a circulating line. In either case the amount of used can be calibrated.
While dripfeed can be applied to enclosed gearing it is more often used on open gearing. Here it is applicable to softer types of gear oils including cut back types. This is more desirable method of lubricating open gears than the methods previously mentioned. Also, in case cut back gear oil is used, any vapor from the same will escape slowly and hence will be less of a hazard than if the mixture were sprayed on. Further, there are fewer tendencies to over lubricate by a drip method than with other methods of hand application. Therefore, there is a consequent reduction in waste and poor housekeeping.
