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further chemically manipulated after distillation to produce semi-synthetics, mineral-based oils with enhanced operational benefits and a more stable structure.

Task 2 Ring method Oil rings typically operate best in an as-designed speed range with closely maintained depth of immersion, ring concentricity, shaft system horizontality and surface roughness of contacting parts. For long life and low frictional losses, different bearings are sometimes best lubricated with different viscosity lubricants. In the ring method of lubricating machinery, when using a mineral oil it would need a oil change every six to 12 months. With a clean, premium-grade synthetic lubricant, you would typically extend oil change intervals to at least 24 months. This process works by the shaft rotating and the ring will rotate at the same time, the ring will collect oil from the sump then the oil will run down the shaft keeping the shaft lubricated when the machine is in working order.

Packing lubrication for a bearing Some bearings use a thick grease for lubrication, which is pushed into the gaps between the bearing surfaces, also known as packing. The grease is held in place by a plastic or rubber gasket that covers the inside and outside edges of the bearing race to keep the grease from escaping.

Splash method

Splash feed is a term applied to a variety of intermittently lubricated bushings or journal bearings. The bearings are splattered with oil from the action of various moving parts regularly dipped in the lube oil. Splash feeding is practical when the housing can be positively oil-tight and when the rotation is not fast enough to churn up the oil.

Drip feed Drip feed systems, also referred to as gravity feed systems, consist of a loosely covered cup or manifold of oil placed above the bearing that meters out oil at a set interval. The supply to the bearing is controlled by a needle or conical valve, and can be adjusted as necessary. A drip feed reservoir can be connected to only one bearing, called a single point system, or connected by pipes or ducts to several bearings, which is referred to as a multiple point system. A drip feed system can also be pressurized to supply oil to a bearing system under pressure. The reservoir is partially or completely transparent, and is refilled by

hand when it reaches a certain level.

Task 3

Hydrodynamic seals Rotary shaft seals are used throughout many industries in a variety of different application conditions. These conditions can vary from high speed shaft rotation with light oil mist, to a low speed shaft in muddy environments. Rotary shaft seals can be required to seal lube oil in high speed crankshaft applications or for petrol and diesel engines, these engines may be found in submarines, oil tankers, windmills, steel mills, paper mills, refineries, automobiles and plant machinery. Rotary shaft seals work by squeezing and maintaining the lubricant in a thin layer between the lip and the shaft. Sealing is aided by the hydrodynamic action caused by the rotating shaft which creates a slight pump action. The amount of frictional heat that is generated in an application is dependent on a combination of many operating parameters: shaft surface, internal pressure, operating speed, lubricant type, lubricant levels, lip geometries and lip materials are just a few conditions that should be considered, and it is important to note that these conditions are interactive.

Hydrostatic Bearing Hydrostatic bearings use an external pump to supply pressurized fluid to the bearing, a flow to each side of the bearing creates a high pressure is forced and injected between opposing surfaces. Hydrostatic bearing have a very high load capacity and stiffness, they require the expense of a clean pressure supply system. This type of bearing can with stand high load capacity as they have a large surface area. Accuracy limited only by the drive system, Lateral is limited by the rails and isolation from the pressure source.

Stiffness  

Easily made many times greater than other components in the machine. Dynamic stiffness is very high due to squeeze film damping.

Vibration and shock resistance  

Excellent for liquid bearings. Modest-to-poor for gas bearings.

Friction  

Zero static friction. Dynamic friction depends on gap and fluid viscosity.

Thermal performance   

Finite dynamic friction coefficient generates heat. Fluid flowing at pressure released to atmospheric pressure shears and generates heat equal to pump power. A cooler is often needed to control fluid temperature. Expanding gas creates cooling (Joule Thompson cooling)

Environmental sensitivity 

Very intolerant of dirt and where the fluid has to flow past a tiny, it can clog. Gear pump flow-dividers and self-compensating bearings are self cleaning

Support equipment     

Pumps Screw-type pumps are most quiet. Piston pumps are noisiest. Accumulators and pressure relief valves are needed to keep pressure pulsations from increasing error motions. Pumps which generate heat....