In machinery which requires lubrication and greasing for proper and continuous operation, it is necessary to perform a resupply of lubricant at periodic intervals so as to insure that the moving structural elements have a lifetime which is limited only by mechanical fatigue. In order to reduce the maintenance required for relubrication, it is known to provide ball and roller bearings with as large a reservoir of lubricant as possible. However, it has been found that only a relatively small amount of the grease from these reservoirs actually reaches the rolling tracks for the ball and roller bearings so that the desired effect is attained only to a very limited degree. Very often the grease which remains in the grease reservoir begins to harden and develops crust-like layers which contain particles that had been abraded from the bearing material and other substances which further prevent any movement of the grease in the direction of the bearing and to those points where it is most needed. Accordingly, it is possible that the moving parts of the bearing which are in rolling or gliding contact with stationary parts will receive no lubrication at all, which leads to rapid deterioration. A still further consideration is that the supply with grease is subject to temperature dependencies and that grease which is very cold is virtually incapable of migrating from the grease reservoir chambers to the races of the ball or roller bearing.