The importance of lubricants in machinery just cannot be ignored, infact one can understand the lubrication system in machinery as important as the blood supply system in our body. The lubricants being used in machines, if tested thoroughly could give an invaluable insight into the health and status of the machinery.
Over years as the world has become more industrialised, investment in the R&D of new lubricants has grown exponentially along with it. No doubt, our Motorcycles too need lubricants so that various parts sub-systems can function properly.
Various oils that are used in motorcycles are mentioned below.
In an engine of motorcycle there are many moving parts like piston, camshafts, valves etc. To reduce the wear and tear of the moving parts, engine oils are used. Engine oils are derived from petroleum-based and non-petroleum-synthesized chemical compounds.
Engine oil comprises of oil which is generally enhanced with additives. Engine oil must have the following characteristics.
Corrosion resistant – Metal parts coated with oil prevent parts from being exposed to oxygen, which prevents oxidation at high operating temperatures and thereby preventing corrosion. Additives that prevent corrosion may also be added to the engine oil.
High thermal capacity – Engine oil experiences very high temperatures during operation and is expected to dissipate heat to some extent. Therefore, it must have sufficiently high thermal capacity.
Lubrication– Engine oils are supposed to form a separating film on adjacent moving surfaces to prevent direct contact and thereby decreasing heat created due to friction. Viscosity is a key parameter that determines the ability of separating film in providing lubrication. Engine oils that have higher viscosity tend to thin less at higher temperatures. Therefore, engine oil should be according to engine type in which it is used. In case of diesel engine, the oil would be of comparatively higher viscosity as compared to oil used in petrol engine.
Cleaning capacity – Engine oil must keep the engine clean and should minimize oil sludge from build-up. Many engine oils have detergents added in them that keep the engine clean.
There are several grades of engine oil available for various applications. The Society of Automotive Engineers (SAE) has uses a numerical code system for grading oils according to their viscosity characteristics.
Brake oil / Clutch oil
Brake fluid is a type of hydraulic fluid used in hydraulic brake and hydraulic clutch applications in motorcycles. It is used to transform force into pressure and to amplify braking force. It works because liquids are incompressible. A brake fluid must have certain characteristics for it to function efficiently.
Brake fluid is subjected to very high temperatures in the wheel cylinders of drum brakes and disk brake calipers. It must have a high boiling point to avoid vaporization. Vaporization is a problem because vapor is highly compressible compared to liquid and therefore prevents the hydraulic transfer of force.
Viscosity - For reliable and consistent brake system operation, brake fluid must maintain a constant viscosity under wide range of temperatures.
Compressibility - Brake fluids must have low level of compressibility which should not vary much with temperatures.
Corrosion – A brake fluid must not corrode the metals used inside components such as calipers, wheel cylinders, master cylinders and ABS control valves. A fluid must also protect the components from corrosion. Certain additives (corrosion inhibitors) are also added to the base fluid to accomplish this.
A coolant is a fluid which flows through or around a part and prevents its overheating by transferring the heat produced by the device to other devices that use or dissipate it. An ideal coolant must have the following properties.
High thermal capacity- Thermal capacity is a measure of the ratio of the heat added to an object to the resulting temperature change. A coolant with high thermal capacity will have comparatively lesser rise in temperature in comparison to a coolant with low thermal capacity when they are subjected to an equal amount of heat.
Low viscosity- Viscosity is the resistance to flow. Since coolant is required to flow around parts that are to be kept cool, it is desirable that the coolant is of low viscosity.
Chemically inert – A coolant must be chemically inert and should not cause damage to the parts that come in contact with it.