Automatic Lubricator

Some vehicles that require lubrication come equipped with automatic lubricators. This is a small device housing two meters. The left meter shows the vehicle's oil storage level. The right meter shows oil level in the drivetrain bearings that this device lubricates.

When the vehicle is in motion, oil in the bearings will be spent. However, the automatic lubricator automatically replenishes it from the onboard storage.

If the vehicle has been parked and the bearings have run dry, however, the lubricator must be manually primed by turning a crank on it, until the bearings are full, before the vehicle can be set in motion again.