Lubrication and Oils

Lubrication and Oils

• Open gears require high viscosity oil.
• Flaking of bearing surfaces can result from installation misalignment.
• For machinery difficult to reach, a solid lubricant is useful.
• Anti-friction bearing is could be a type of thrust bearing.
• When exposed to air, oil will oxidize.
• When replacing an antifriction ball bearing, apply force only to the press fit race.
• Molybdenum disulphide is commonly used as a solid lubricant.
• The type of grease for heavily loaded, slow-speed machinery is specialty grease.
• Lubrication is the separation of two surfaces with an interposing liquid.
• Adding too much grease to a bearing can cause it to overheat.
• Air compressor oil should have low carbon residue.
• Aluminum based greases cannot be used in high speed applications due to high internal friction.
• Boundary lubrication occurs when the lubricant supply is intermittent.
• Oil grooves in a sleeve bearing distribute oil along the length of the shaft.
• False brinelling is an anti-friction bearing failure from stationary bearings subject to vibration.
• The pour point is the lowest temperature at which oil will flow.
• Grease is the preferred bearing lubricant when speeds are moderate and the bearing must be sealed against atmospheric contaminants.
• Mineral oils are made from petroleum.
• The most common and cheapest greases are unsuitable for temperatures above 70°C.
• Lubrication does not fulfill corrosion enhancement.
• Fixed oils are a class of liquid lubricant not often used on its own.
• Shock absorption is very important at the intermeshing of gear teeth.
• The rolling elements of an anti-friction bearing travel in between two races.
• The best way to clean a bearing is by first removing it from the machine.
• Fixed oils are also known as fatty oils.

Pumps and Compressors

• A circulating pump is usually connected with some type of heat exchanger system.
• Single stage reciprocating air compressors consist of one or more cylinders of the same size.
• Priming a water pump means filling the pump casing and suction line with water.
• A wearing ring reduces the clearances of the rotating impeller and the stationary casing.
• Strainers are found on the suction side of the pump.
• Cooling water for an air compressor is turned on before starting the compressor.
• When repacking a pump gland with a stuffing box bore of 8.6 cm and a pump shaft diameter of 6.7 cm, use a 0.95 cm packing.
• An air compressor with two compression strokes per crankshaft revolution is a single cylinder double acting compressor.
• The determining factor as to which type of compressor to use is the maximum operating pressure required.
• When replacing pump packing, the ring joint should be staggered 90 degrees.
• A belt driven lubricator is very popular on a sliding vane unit.
• To protect the driver, a start-stop air compressor should be equipped with pre-start automatic unloading.
• Priming a centrifugal pump involves filling the pump casing with liquid and removing the air.
• Gear compressors are a type of positive displacement air compressor.
• Most pump failures/damage occurs during initial start-up.
• A stuffing box decreases leakage out of the casing when the pressure is above atmospheric and is filled with packing.
• An aftercooler with a shut-off valve between it and the receiver should also have a safety valve.
• A feedwater pump produces water pressure above boiler pressure to add water to the boiler.
• The safety head on a refrigeration compressor protects against liquid in the cylinder.
• Bauxite ,silica-gel, and activated alumina are used as an adsorbent.
• Centrifugal pumps convert rotating mechanical energy into kinetic energy then into potential energy in the form of pressure.
• Emergency backup compressors are usually driven by an Internal Combustion engine.
• When a pump is operating, you should check the discharge pressure during inspection.
• Rotary pumps should be started with the discharge valve open because they are a positive displacement pumps.
• The liquid to a lantern ring keeps the air out of the pump.