An automatic lubrication system is a system built to deliver controlled amounts of lubrication to different parts of a machine during its operation. We are going to be looking at the differences between single line and dual-line lubrication systems. 

Single line lubrication system 

This system can serve a single machine, different parts of a machine or multiple machines. This system uses a central pump station that will automatically deliver lubricant through one supply line to a series of injectors. These injectors are lubrication points and can be adjusted to produce the desired amount of lubrication. 

The central pump station begins by pumping lubrication to create pressure in the supply line. When the desired pressure is reached the injectors dispense the predetermined amount of lubricant to the parts that need to be lubricated in the machine. After this process, the pump shuts down and the pressure is vented out of the system allowing the remaining grease in the single line to be redirected to the reservoir. This is to restore the normal pressure levels in the system. The whole system is controlled by a timer or controller that signals the pump. 

Dual-line lubrication system 

A dual-line lubrication system is very similar to a single line lubrication system. It can handle hundreds of injectors using a single pump station over several feet using smaller tubing or pipe. 

Similarly to the single line lubrication, the pump is signalled by a timer or controller to start the lubrication cycle. The pump starts by building pressure in the first line of supply while simultaneously venting out the second supply line. When the first line reaches the desired pressure, the lubrication is dispensed by the metering devices to only half of the lubrication points. 

The difference comes here as a dual-line lubrication system uses a switch monitor to monitor the pre-set pressure and whether it has been reached to close the system. The system off, the monitor will indicate a changeover in the valve so that the lubrication is directed to the second supply line. This means when the controller reactivates the second line will become the line with pressure and the first line will be the line being vented.