Maintaining Lubrication systems (Fitting and Turning Level 3)

1)      Understanding the system

2)      Safety procedures

3)      Planning Maintenance

4)      Prepare the site for maintenance

5)      Inspect and assess the system

6)      Fix the faults

7)      Check that system operates correctly

8)      Record information on work completed

Understanding the system.

The principles of lubrication systems (How does it work?)

A lubrication system applies oil or grease to parts of a machine to reduce friction between the parts and to keep them moving smoothly. It keeps the machine in good working condition and reduces wear and tear on the moving parts. Parts that needs lubrication are bushing slides, bearings and gears.

Lubrication systems can be:

                Manual – Works with a spot lubrication gun and needs a person to operate it or

                Automatic – This system is built into a machine and work as part of the machine based on the requirements of the machine. Although the work without an operator they still need to be maintained.

A lubrication system consists of the following main parts.

a.       A reservoir or container to store the lubricant.

b.      A pump, to force the lubricant through pipes to the parts that need to lubricated. 

c.       A filter to ensure that the lubricant is kept clean.

In addition to reducing friction, lubrication has the following functions.

v  They prevent corrosion

v  They cover dirt and/or dust particles to prevent the moving parts from seizing

v  They reduce the operating temperature by reducing friction

v  They provide insulation in electrical systems such as oil cooled transformers

v  They transmit power in hydraulic systems. (hydraulic fluid, brake and clutch fluid)

The characteristics of a lubricant:

v  It will stay viscous (fluid) and will not become solid

v  It is not acidic

v  It is not abrasive

v  It keeps it film thickness

v  It is very slippery.

There are four main types of lubrication systems:

·         The gravity feed oil lubrication system

·         The grease lubrication system

·         The oil splash lubrication system

·         The forced oil and grease lubrication system.

The gravity feed oil lubrication system:

This system uses the force of gravity to feed the oil into the system. This method is usually used in parts requiring a small amount of oil. Two types of lubricators using this system are:

The siphon-wick lubricator: This lubricator consist of a container filled with oil. A pipe is positioned in the middle of the container ending above the level of the oil. A wick is placed in the oil and fed down the pipe. The wick soaks up the oil in the container and gravity makes it flow down the wick in the pipe delivering it as drops at the end of the wick. The amount of oil delivered depends on the thickness of the wick.

Sight-feed lubricator: This lubricator is a container mounted on a metal base with a hole in the center. The container has a metal cap fitted with a tapered needle valve that extends to the hole at the bottom. A lever connected to the needle lifts the needle when oil flow is needed and lowers the needle when no oil is required.

The grease lubrication system:

This system is only used for plain bearings that carries small loads at low speeds. There are three types of lubricators that use this lubrication system:

The Stauffer grease cup: This lubricator consist of a closed container filled with grease and screwed down onto a base with a tapered hole in it. The grease is forced through this hole onto the surface of the bearing.

The telltale grease cup: This lubricator has a fluted upper container filled with grease. The bottom part of the container narrows to a very thin pipe. The top part has a spring-loaded piston that is smaller than the cup. This prevents the piston from forcing all the grease from the cup. The piston forces the grease through the narrow opening at the bottom of the cup onto the surface of the bearing.

The hand grease gun: The hand grease gun has a cylinder filled with grease. A spring loaded piston connected to a handle provide mechanical advantage to assist in forcing the grease through a bendable pipe into a grease nipple. The grease nipple is positioned on the bearing surface where the grease is then delivered. Modern grease pumps works with rechargeable batteries.

The splash lubrication system:

this system is designed into the machine when it is manufactured. It consist of a reservoir or sump, filled with oil or lubricant through which one or more of the moving parts will operate. As these parts move through the lubricant, pick up the lubricant and splashes it onto the rest of the parts. There are two types of splash systems in operation:

The scoop system used in machines that run at high revolutions. The scoop picks up the oil and splashes it onto the parts.

The ring oiler system used in machines that run at low revolutions has an oil ring that dips into the oil and scoops it up to lubricate the applicable parts.

The forced lubrication system:

This system uses a pump to deliver the lubricant (mostly oil) under pressure onto the part(s) that need it. The oil is drawn from the sump through a filter and discharged through pipes and channels to be delivered onto the parts that need lubrication. This system forms part of the machine and is fully automatic. It starts when the machine starts and stop when the machine stops.

The correct sequence of activities to follow:

Step 1.           Study and understand the instructions and information on the job card, previous reports and engineering drawings to determine the service history of the lubrication system.

Step 2.           Study the records and manufacturers manual to determine the correct lubricants to be used.

Step 3.           Find out which filtration parts you need to use.

Step 4.           Identify the tools and equipment you will need to complete the maintenance.

Step 5.           Check the worksite and make sure it is safe to work in.

Step 6.           Isolate the equipment and make sure that the system is safe to work on.

Step 7.           Inspect the lubrication system while in operation.

Step 8.           Diagnose the system faults.

Step 9.           Identify the parts to be serviced and the parts to be replaced.

Step 10.       Remove the parts and service or replace them.

Step 11.       Fit the serviced and replaced parts.

Step 12.       Select the testing tools and equipment.

Step 13.       Run a full operational test to check that the system is working properly and without leaks.

Step 14.       Write a report on your work.

The implications of not following this sequence of activities:

Ø  You will contaminate the workshop floor with oil if you do not drain the oil from the system first.

Ø  You will damage the lubrication system and the machine if you use the wrong lubricant.

Ø  You will waste time if you realise halfway through the job that you don’t have the right tools, equipment or spares to continue.

Ø  You will damage parts, have breakdowns or cause leaks if you fit the parts in the wrong order.

Ø  You will get an electrical shock if you haven’t isolated the equipment before you start working on it. 

Safety procedures.

Safety in the workshop is very important. Failing to comply to safety measures can lead to injury or even death to yourself or someone else.

Safety rules to follow while working on lubrication systems:

o   Check that the machine you are working on is disconnected from the power supply or you will get an electrical shock.

o   Use a lock-out device to make sure the machine can’t be switched on while you are working on it.

o   If you get oil or grease into an open wound, get medical treatment immediately or the wound may become infected.

o   Drums containing oil and grease are very heavy. Get someone to help you move it in the workshop. If you drop a drum it can crack or burst, spilling oil or grease all over the floor. People may slip on the oil or grease and hurt themselves.

o   Never add lubricants in a machine that is still running.

o   Never reach over, under, through or around moving parts of machinery.

o   Don’t remove any protective guards from moving parts of the machine, like open gears or couplings, until the machine is isolated and disconnected. Make sure you replace the guards as soon as you have finished the job.

o   Wear rubber gloves while working with grease and solvents to prevent yor skin from becoming irritated.

o   Never smoke around any petroleum products, and handle them with care as they can catch fire.

o   Dispose of any leftover solvents and waste rags soaked with this liquid in the special hazardous waste material containers provided in the workshop.

o   Dispose of the lubricants that you removed from during maintenance in the special hazardous waste material containers in the worksite, as they are harmful to people, animals and the environment.

Planning Maintenance.

Obtain the following documents to investigate the service history and obtain details about lubricants.

o   The job card

o   The maintenance schedule

o   The manufacturer’s manuals for the machine

o   The reports on all work done to the machine

o   The engineering drawings

The job card: You will get the job card from your supervisor. The job card will tell you if it’s a scheduled maintenance job or if there is a problem on the machine that needs repairing. It will also include information like the name and number of the machine. 

The maintenance schedule: this is a schedule that describes all the inspections, tests, service details and repair or replacement work that needs to be done on the specific machine or specific parts of the machine. This will help you to plan the work. You need to complete all the tasks on the schedule and your supervisor will sign the schedule after the work is complete.

 The manufacturer’s manual: This will give you specific information on the type of lubrication to use, as well as any important maintenance you need to know about the lubrication system. It will also contain technical specifications about settings, tolerances and performance requirements you need to know.

The reports on all work done to the machine: This is a complete history of all work done on the machine. This will tell you how often the system has been serviced and when the filters have been replaced. Other problems related to the lubrication system like;

§  Bearings overheating

§  Leaking seals

§  Couplings changing color

can all indicate problems with the lubrication system. It will also tell you about all the lubricants used in the past and problems experienced with specific lubricants.

The engineering drawings: These detailed drawings show all the parts, their sizes, as well as how they fit together. It will also indicate all the lubrication points on the machine. Find the position of the lubrication system and you will see which parts you must remove to get to the lubrication system.

Additional information on the nameplate (also called a data plate) of a machine: The following information are required for nameplates and will help you choose the correct lubricant. Lubricants are designed to work under specific conditions like pressure, load and temperatures and you need to confirm the details on the nameplate with the information of the manufacturer’s manual, as the manufacturer will specify the lubricant to use on the machine.

Ø  The manufacturers name, model and serial number

Ø  The rated voltage and full load amperage

Ø  The rated electrical frequency

Ø  The phase

Ø  The rated full load speed

Ø  The rated temperature rise or insulation class and ambient temperature

Ø  The duty rating

Ø  The rated horsepower

Ø  The design code letter.

Different types of lubricants:

We will look at oil, grease and a material called self-lubricating thermoplastics.

Oil – The four categories of oil are

Animal oil: - examples- lard, sperm oil and tallow. Animal oils are much better than mineral oils with regard to the pressure they can stand but unfortunately they are expensive and turn to sludge easily.

Vegetable oil: - examples- castor oil, palm oil, olive oil and linseed oil.

Mineral oil: - found under the earth’s service in the form of crude petroleum. It keeps its properties well in air and if it is pure, it do not get sticky or dry up. This properties makes mineral oil an ideal, all-purpose lubricant to use in all systems.

Synthetic oil: - made using a chemical process to change carbon dioxide, carbon monoxide and methane into oil. Synthetic oil is always a better option than conventional oil in the following situations: 

·         In high temperatures, conventional oil becomes thin and tents to leak, while synthetic oil remains at the right grade of viscosity.

·         In low temperatures, conventional oil becomes thick while synthetic oil remains at the right grade of viscosity.

·         For engines and machines that run at high revolutions, synthetic oil causes them to run more quietly at all speeds than conventional oil does.

·         In outdoor conditions, synthetic oil is the better choice because of its stability over a wide temperature range.

A thin, light lubricant like oil is chiefly used in in machines that operate at high speeds and with light loads.

Grease – A common lubricant used on slow-moving machinery parts such as bearings, bushes and hinges. It consist of a combination of a lubricating agent, and additives like graphite and a thickener (made of substance like copper or non-metallic substance like graphite, lithium or Teflon.)

Conventional greases use a petroleum-based product like mineral oil as base.

Synthetic greases use a synthetic lubricant made of plant oils. This ingredients mean that synthetic greases can cope with much wider temperature extremes than conventional greases. Synthetic greases is a better choice than conventional greases in the following applications:

·         In high temperatures, conventional grease soften and leaks, while synthetic grease remains more stable.

·         In low temperatures, conventional grease becomes thick while synthetic grease remains more pliable.

·         For high speeds, synthetic grease is quieter at high speeds than conventional grease.

·         In outdoor conditions, synthetic grease is the better choice because of its stability over a wide temperature range.

Self-lubricating thermoplastics – This is a type of plastic material that has a lubricant already build into it. This has been developed to overcome the problem of oil and grease building up dirt and grit over time which is what a lubricant actually try to prevent. Parts made from thermoplastic are not affected by this problem because they don’t need oil or grease lubricant, they are able to resist friction and, therefore, wear extremely well.

Self-lubricating thermoplastics components are starting to replace metal and ceramics parts because they have the following advantages:

·         The parts can be assembled easily

·         The parts are easy to manufacture

·         The parts are flexible with regard to design

·         The parts are very reliable because they do not deteriorate quickly

·         The parts can operate at very high performance levels at high or low speeds, and with high and low fixed loads.

However, thermoplastic material has the following disadvantages:

·         They are expensive

·         Thermoplastics bushes or bearings cannot carry heavy axial loads.

Identify the filtration components to be used:

The lubrication system will have a filter to prevent dirt from getting into the pumped oil. This filter will be accessible from the outside of the machine for easy replacement and will come with a seal to prevent leakage of lubricant, and damp from entering the system. You will need to identify the component so you can order a replacement part before you remove the used filter. The manufacturers manual will provide you with the information to order the correct part.

Identify the correct tools and equipment for the job:

Once you identified the machine you can draw up a list of tool and equipment that you are going to use. Don’t forget to include the safety equipment you may need. Some of the common tools and equipment you may need for maintenance on a lubrication system may include:

·         A complete set of ring and flat spanners

·         An oil filter wrench

·         A complete set of screwdrivers

·         A complete set of Allan keys

·         Cleaning materials like waste rags

·         A container into which you can drain the used oil.

Prepare the site for maintenance.

Make sure the worksite is safe to work in, taking into account the type of machine you are going to work on. (Heavy, electrical, hydraulic, etc.)

Identify the type of lubricating system.

If the machine has a filter and a sump, then it uses an oil lubrication system. (high speed machine)

If the machine has a grease nipple, then it uses a grease lubrication system. (slow speed machine)

Prepare the work site so that it is safe:

Make sure the work site is clean and there is no water or oil on the floor. Check that all the necessary safety signs are visible and the personal protective gear needed for the job is checked and ready for use.

Select the correct tools and equipment and make sure you know how to operate them safely.

Use the right lubricants and fluids or solvents for each part making sure you wear protective gloves.

Isolate the system:

·         Switch off the machine and install a lock-out device

·         Put up a safety sign to show that you are working on the machine.

·         Isolate the machine you work on mechanically according to the machine type.

Inspect and assess the system.

·         Hold a screwdriver against the machine near the bearings and listen for any strange noises or vibrations

·         Hold a thermometer against the machine to see if the temperature runs to high

·         Check to see if the coupling have changed colour or if the seals are leaking

·         Check through the sight glass if the lubricant changed colour and if so take some oil samples

·          Test the oil to see if it contains any water. Do so by pouring some in a glass container and wait for a while. The water will sink to the bottom.

·         Put a couple of drops of oil on blotting paper. If a star pattern or rings appear, the oil is contaminated or dirty

·         Check for thickness changes and service deposits on the oil

·         Check the filters to see if they are blocked

System faults and possible causes:

Symptom	Possible causes
The machine produces strange noises or vibrations.	Damage parts, for example the bearings or couplings, or loose parts
The temperature of the machine is to high.	Incorrect lubricants
	Lubricants that have broken down chemically
	Dirty lubricants
	Abnormal friction or wear
The coupling change colour to blue or the seals leak.	Problems with the lubrication, causing a coupling to overheat
The colour of the oil has become darker	Oil has overheated
	Dirt and impurities in the oil
	Wrong lubricant has been used
Ongoing foam forms at the top of the oil.	Oil is dirty or contaminated
The oil separates.	The oil is contaminated with water
The oil shows the star burst or rigs during the blotting paper test.	Oil is dirty or contaminated. (clean oil forms a uniform oil colour on the paper)
The viscosity or thickness changes in the oil, and service deposits.	May indicate an oil pressure problem
Filters are blocked.	May indicate the presence of soft contaminants like sludge and organic material

Fix the faults.

Identify parts to be serviced or replaced:

Based on the results of your research you are now ready to draw up a list of parts that need to be replaced and serviced. For instance: you need to replace the seals, the filter and the oil. If the couplings changed colour you need to replace them as well and depending on the condition of the bearings you need to either replace or service them.

Remove, service and replace serviceable and new parts:

You should drain the oil at operating temperature because it will flow more quickly. Replace any seals that are worn or damaged. Look for loose clamps, worn or cracked pipes and leaking seals and replace any damaged parts. Remove the old oil filter. Make sure that you do not burn your hands with too hot oil. Replace the old filter with a new one. Put some oil on the filter seal before you replace it to make sure of a good fit. Fit the drain plug with a new washer and replace the plug. Once the plug is in place you can fill up the reservoir with the right grade and quantity oil through the filler hole.

If the lubrication system has an oil pressure sensor, check the oil pressure when you restart the engine. If the oil pressure is too low, make sure that you used the correct grade and amount of oil. If the type and amount of oil is correct, check the lubrication system or the oil pump system for possible leaks.

Check that system operates correctly.

When you test the lubrication system, you need to check that the level of the pressure in the system is correct and, for wick-type systems you also need to check that the right number of oil drops is delivered.

Check the pressure level in a lubrication system:

Step 1.      Check the manufacturer’s manual to find out the correct pressure at which the lubricating system must operate.

Step 2.      Connect the pressure gauge to the pipes in the lubrication system that you are about to test.

Step 3.      Start the engine and let it run until it reach the right operating temperature, as stated in the manufacturer’s manual.

Step 4.      Take a reading on the pressure gauge that you have connected.

Step 5.      Check the fluctuations in pressure because any fluctuations greater than specified in the manufacturer’s manual mean that the lubrication system is faulty.

Record information on work completed.

After the maintenance work on the lubrication system is finished you must write a report on the work you have carried out. You need to include the following information in your report:

·         The date you serviced the lubrication system

·         The procedure that you followed

·         The type of lubrication system you worked on

·         The different parts that you replaced

·         Your opinion about why these parts failed, for example operator’s negligence

·         The type and amount of fluids and lubricants that you used

·         Any defects relating to the specific machine

·         The results of all the tests you carried out.

Store the information in a safe place.