Most commonly used lubricators used in machineries and industries are as follows: 1. Screw Cap Lubricator 2. Tell-Tale Lubricator 3. Glass Bottle Lubricator 4. Wick Feed Lubricator 5. Ring Oil Lubricator 6. Splash Lubricator 7. Full Pressure Lubrication.
Lubricator is a device for applying a specific amount of lubricant to the engine shaft and machine components such as bearings, gears, and other engine parts such as trunk piston, gudgeon pin, connecting rod, etc. For simple machine parts, simple types of lubricators are used such as oil can, grease plug, grease gun, etc.
1. Screw Cap Lubricator (Grease Lubricator):
Figure 8.4 shows the screw cap lubricator. It has a lubricator body to hold grease. A knurled cap is screwed over the top portion of the lubrication body.
The lower part of the body has a threaded nipple to be fitted with the bearing or machine parts to be lubricated. The operation of the lubricator is very simple. The grease is kept in the body. It can be operated manually by turning the knurled cap. The amount of grease is pushed in through the capillary to the engine parts to be lubricated. Such lubricators have been found in flour mills, agriculture equipments.
2. Tell-Tale Lubricator:
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Figure 8.5 depicts a tell-tale lubricator. It is the improved version of the screw cap lubricator. The grease is kept in a container. It forces the grease by spring pressure exerted through a plunger attached with the knob. The flow of grease is accelerated with the help of a knob which moves the plunger downward pushing the grease through grub screw. The knob attached with the piston acts as a tell-tale which is visible from a distance and indicates the level of grease. One rotation of the knob supplies the grease to the surface to be lubricated.
3. Glass Bottle Lubricator (Needle Lubricator):
Glass bottle lubricator is a bottle made of glass which holds the lubricating oil. The glass bottle is fitted with a tapered wooden cork which is also equipped with a loosely fitted steel needle. The bottle is fitted as shown in Fig. 8.6. The wooden fixture fitted with bottle is also fitted with bearing cap.
When the shaft rotates, the needle is well accelerated and due to vibration and jerks developed, the oil flows into the bearing by gravity.
4. Wick Feed Lubricator:
Figure 8.7 show the assembled drawing of wick feed lubricator. The working of this lubricator is based on the siphon principle. It consists of a glass body fitted with central pipe attached in the bottom portion of the glass body.
The lower portion of the body has the provision to fix the threaded nipple to the machine components and the machinery to be lubricated. The threaded nipple will have an oil hole through which the oil drops down. A cotton wick hangs about 40 mm below the oil level. The cotton wick gets soaked in the oil.
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The oil is dripped off by gravity and vibration caused by the motion of the machine components. The flow rate depends on the type and twist of the rope. A wire hook is provided to take out the wick when machine is in idle conditions. Wick feed lubricators are used for the lubrication of slides, guides, spindles, and plain bearings.
5. Ring Oil Lubricator:
Ring oil lubricator is shown in Fig. 8.8. It consists of an oil trough to keep sufficient oil in it. The trough acts as storage of oil and is placed below the shaft to be lubricated.
A metallic ring hangs over the shaft and the bottom portion of the ring hangs in oil. When the journal rotates, the ring also rotates and it carries oil from the oil bath and spreads the oil. The oil is placed on top of the bearing. The oil is further distributed to the bearing through the oil grooves. The excess oil spread drops down in the oil trough.
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The system is found suitable for slow-speed horizontal shaft. For high-speed engine shaft, the ring slips due to excess centrifugal force developed due to high rotation. In place of ring, steel chains can also be used. The sheet chains carry more lubricating oil.
6. Splash Lubricator:
The method is well known and generally used for the lubrication of internal combustion engine components. The closed crank case holds the lubricating oil up to such level that the crank pin dips into the oil. In each revolution of crank, the pin dips in the oil and splashes on the surface of cylinder liner, piston, gudgeon pin, piston rings, and crank shaft bearing. The excess splashed oil returns back to the crank case. Figure 8.9 shows that splash lubrication system has been used for the lubrication of single cylinder internal combustion engine.
A scoop is connected in the lower part of the big end of the connecting rod. When engine runs and the lower part of the big end comes down nearer to the oil level, a scoop attached with the big end dips in oil and splashes the oil from oil trough engine parts to be lubricated. It is the simplest and cheapest method of lubrication.
7. Full Pressure Lubrication:
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Full pressure lubrication system, shown schematically in Fig. 8.10, is used for the lubrication of engine parts. Multi-cylinder IC engines have many moving parts and are required to be lubricated for its proper functioning. The engine lubrication system circulates oil from the crank case at the bottom and may be called wet sump lubrication. In this case, oil is forced through different parts under pressure by a pump.
Oil enters the connecting rod bearing and crank shaft through drill passages. The system is capable of supplying oil to crank shaft bearing, cam shaft, valves, rocker arms, piston, piston rings, etc. Full pressure lubrication system is best suited for large multi-cylinder engines. After lubrication, excess oil returns back to the oil sump and the process is repeated.