Lubrication systems
Single-line, dual-line, progressive and oil circulation: which system for which machine
Five families of central lubrication, each built for a different number of points, line length, pressure and lubricant quantity.
The families
| System | How it works | Where it fits |
|---|---|---|
| Progressive | One pump feeds a block of metering pistons that move in sequence, each serving one outlet. Compact and simple | Small and medium machines, groups of nearby points. One blocked outlet stops the whole sequence, so it needs monitoring |
| Single-line | A pump pushes lubricant through one main line to metering devices (injectors) that dose each point. The line is relieved between cycles | Large machines with many points, big lubricant quantities and high pressure, such as large mobile equipment |
| Dual-line | Two main lines are pressurised alternately, so metering devices dose each point from either side. Very high-volume pumps | Heavy equipment, long lines, many points, high pressure: crushers, mills, big gearboxes, conveyors |
| Oil circulation | A reservoir, pump, filter, cooler and heater supply oil continuously and return it to the tank | Mill and kiln gearboxes and bearings, large drives running 24 hours a day |
| Open gear spray | Spray nozzles apply grease to the teeth of an open gear in short bursts, usually air-assisted | Girth gears on kilns, mills, dryers and presses |
Choosing in four questions
- How many points, and how far apart? Few and close: progressive. Many and spread out: single-line or dual-line.
- How much lubricant per cycle, and at what pressure? Large quantity at high pressure favours single-line or dual-line.
- Grease or oil? Oil at flow rates of litres per minute is a circulation system, not a grease line.
- Is the point an open gear? Then it is a spray system, not a metering line.
Common to all
A central system is only as good as its monitoring. Fit a low-level alarm on the reservoir and a pressure or cycle monitor, so that a blocked line or an empty tank is a message and not a failed bearing.
Takeaway. Match the system to the point count, line length and quantity. Then monitor it, because the failure mode of automation is a silent stop.
Put it to work in the tool