Automatic Lubrication System: types, working, advantages & Disadvantages

An Automatic Lubrication System (ALS) often referred to as a centralized lubrication system is a system that delivers a controlled amount of lubricant (either grease or oil) at specific times to multiple locations on a machine while the machine is operating.

This system is more precise and it eliminates the cycle of over-lubrication and under-lubrication that contributes to bearing failure.

Automatic lubrication system generally comprises the following elements.

(a) Controller or timer: It activates the system to distribute lubrication can be linked to a POS system.

(b) Pump with reservoir: It is used to store and deliver the lubricant to the system.

(c) Metering valves / Injectors-. It is a component that measures/dispenses the lubricant to the application points.

(d) Supply lines: It is a pipeline that connects the pump to the metering valves or injectors. The lubricant is pumped through these valves or injectors.

(e) Feed lines:It is a pipeline that connects the metering valves or injectors to the application points.

Reason for automatic Lubrication system:

Whether the equipment is stationary such as in a manufacturing facility or mobile such as trucks, mining, or construction equipment, applying lubricant is often most effective when it is dispensed in small, measured amounts over short and frequent time intervals.

However, time and human resource constraints or sometimes, the physical location or type of machine often make this approach to lubrication impossible.

As a result, production cycles, machine availability, and manpower availability dictate the intervals at which machinery is lubricated which are not optimal for the point requiring lubrication.

Automatic lubrication systems are installed on machinery to address this problem.

Benefits of automatic lubrication system:

  • All critical components are lubricated regardless of location or ease of access
  • Lubrication occurs while the machinery is in operation causing the lubricant to be equally distributed within the bearing and increasing the machine’s availability.
  • proper lubrication of critical components ensures the safe operation of the machinery.
  • Less wear on components means extended component* life, few breakdowns, reduced downtime, reduced replacement costs and reduced maintenance costs.
  • Measured lubrication amount delivery facilitates no wasted lubricant.
  • There is no climbing around machinery or inaccessible areas (gases, exhaust, confined spaces, etc.) and hence, the safety is improved.
  • It lowers the energy consumption due to less friction.
  • It increases the overall productivity resulting from an increase in machine availability and reduction in downtime due to breakdown or general maintenance.

These are the most commonly used types of automatic lubrication systems;

(a) Single line parallel
(b) Dual-line parallel
(c) Single line progressive
(d) Mist lubrication
(e) Multi-port direct lubricators.

Single line parallel

A single line parallel system can service a single machine, different zones on a single machine or even several separate machines and it is ideal when the volume of a lubricant varies for each point.

Automatic Lubrication system
Single Line Parallel

In this type of system, a central pump station automatically delivers lubricant
through a single supply line to multiple branches of injectors. Each injector serves a single lubrication point, it operates independently and it may be individually adjusted to deliver the desired amount of lubricant.

The operation begins when the controller or timer will send a signal to the pump starting the lube cycle. The pump begins pumping lubricant to build up pressure in the supply line connecting the pump to injectors.

Once the required pressure is reached, the lube injectors dispense a predetermined amount of lubricant to the lubrication points via feed lines. Once the entire system reaches the required pressure, a pressure switch will send a signal to the controller indicating that grease has cycled through to all distribution points. The pump shuts off.

The pressure is vented out of the system and grease in the line is redirected back to the pump reservoir until the normal system pressure level is restored.

Advantages 

  • It is easy to design.
  • It is an easy and cost-effective installation.
  • It has individually adjustable injectors.
  • It has proven dependable design.

Disadvantages : 

  • It may not be suitable for combinations of heavy lubricants, cold temperatures, long supply line runs between pumps and injectors.

Dual-line parallel system:

A dual-line parallel system is similar to the single line parallel system. It uses hydraulic pressure to cycle adjustable valves to dispense measured shots of lubricant. It has 2 main supply lines which are alternatively used as pressure/vent lines. The advantage of a two-line system is that it can handle hundreds of lubrication points from several thousand feet using significantly smaller tubing or pipe. single pump station over
The operation begins when the controller/timer sends a signal to the pump to start the lubrication cycle. The pump begins pumping lubricant to build up pressure in the first (the pressure) supply line while simultaneously venting the second (vent) return line. Once the
required pressure is reached, a predetermined amount of lubricant is dispensed by the metering devices to half of the lubrication points via feed lines.

Once the pressure switch monitoring main supply line pressure indicating a preset pressure in the line has been reached, the system is hydraulically closed. The controller shuts off the pump and signals a changeover valve to redirect lubricant to the second main supply line. The next time the controller activates the system, the second mainline now becomes the pressure line while the first line becomes the vent line. The second line is pressurized and the entire process is repeated lubricating the remaining lube points.

Advantages:

  • It easily handles very viscous (heavy) greases.
  • It can accommodate long supply line runs between pump and metering devices.

Disadvantages:

  • It may not be the most cost-effective for smaller systems.
  • It requires two supply lines (another cost).

Single line progressive system:

A single line progressive system uses lubricant flow to cycle individual metering valves and valve assemblies. The valves consist of dispensing pistons moving back and forth in a specific bore.

Each piston depends on flow from the previous piston to shift and displace lubricant. If one piston does not shift, none of the following pistons will shift. Valve output is not adjustable.

The operation begins when the controller will send a signal to the pump to start the lube event. The pump then feeds lubricant into the supply line which connects to the primary metering valve for either a preprogrammed amount of time or number of times as monitored through a designated piston cycle switch.

Lubricant is fed to the multiple lubrication points one after another via secondary progressive metering valves sized for each series of lubrication points and directly to each point via the feed lines.

Advantages:

  • It accommodates a wide range of system control/monitoring options
  • It can identify blockage by monitoring a single point.

Disadvantages:

  • One blockage can disable the entire system
  • Large systems may require complex piping/tubing runs.

(d) Mist lubrication:

Another simple system, mist lubrication facilitates low oil consumption and cool running bearings. Mist is generated with heat and/or air currents and it is carried through the pipe to the lubrication point with low-pressure air.

Then, it is sized to the appropriate droplet before it is dispensed to the bearing. Closed-loop systems are environmentally friendly because they return the mist to the generator.

Advantages:

  • It cools and lubricates bearings
  • Low pressure keeps pipe material cost down
  • Positive pressure helps keep contaminants out of bearings.

Disadvantages:

  • Environmental/health concerns of “stray mist,” is especially with open-loop systems
  • It handles oil only
  • It is highly sensitive to flow, viscosity and pressure variables
  • It has an extra pipe cost for closed-loop systems.

(e) Multi-port direct lubricators:

When the controller in the pump or external Controller activates the drive motor, a set of cams will turn and activate individual injectors dr pump elements to dispense a fixed amount of lubricant to each lubrication point.

Systems are easy to design, direct pump to lube point without added accessories and easy to troubleshoot.

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