Lubrication Concepts and Bearings and Couplings Community College
Lubrication Concepts and Bearings and Couplings Community College of Vermont
§ Click on the link below to watch an introductory video on the concepts for this week’s lesson. You’ll get more in-depth information throughout the lesson. § Lubrication Basics
§ Total Productive Maintenance (TPM) is a holistic approach to equipment maintenance that strives to achieve perfect production with no breakdowns, no small stops or slow running, and no defects, along with valuing a safe working environment with no accidents. Lean Production—TPM emphasizes both predictive and preventative maintenance. § Predictive Maintenance helps to determine the condition of in-service equipment in order to predict when maintenance should be performed. It lowers costs, as maintenance is performed only when warranted. Predictive maintenance allows for convenient scheduling, which allows for shorter and fewer stops. § Preventative Maintenance is the care and servicing of equipment through inspection, detection, and correction of failures before they occur, or before they develop into major issues.
Preventative Maintenance (PM) § Driven by time, meter, or event based triggering § Tasks are pre-determined based on factors including experience, age, manufacturer’s recommendations, etc. § Relevant parts are removed, replaced, or rebuilt on or before the expected failure point. § For example, getting the oil changed in your car every 10, 000 miles. Predictive Maintenance (Pd. M) § Determined by the condition of the equipment rather than an expected life span. § Predicts failure in a machine before it happens by monitoring the machine during normal operations. § For example, monitoring the oil in your car at regular intervals, and replacing it when it degrades beyond a certain point.
As you saw in the kick-off video this week, lubricants have several functions: § Friction is reduced due to the lubricant creating a slippery film between the two surfaces. This lowers the chance of seizing due to high heat, and reduces wear on components due to the grinding of surfaces on one another. § In addition to lowering the heat cause by friction, lubricants can also carry heat away from the system by absorbing it and carrying it to another part of the machine. § Lubricants act as a shock absorber between parts. This keeps machines quieter, and helps them to run longer. § Lubricants prevent corrosion by keeping oxygen and other elements away from the surface of the metal. § Lubricants keep contaminants low both by keeping gaps filled, and by flushing contaminants away.
Liquid Example: Oil used in hydraulics Semisolid Example: Greases in bearings and joints Solid Example: Dry film used in roller presses Gas Example: Coolant for moving parts
Vegetable and Animal Oil Extracted from plant and animal tissues Not often used for industrial machinery Break down easily Can be mixed with mineral oil Mineral Oil Refined from crude oil Most common type of oil used in industrial machinery Aren’t very complex, and don’t break down easily Used to lubricate bearings, chains, and gears Synthetic Oil Artificial, man-made oil Used in extreme conditions that natural oils can’t withstand Space equipment and auto racing use synthetic oils, along with lubricating industrial machinery Oils are the most commonly used lubricant.
§ Viscosity is defined as a resistance to flow. Viscosity that is too high can lead to not enough flow, while viscosity that is too low can lead to leaking and low protection. § Viscosity is measured in units called Saybolt Universal Seconds (SSU or SUS) in the United States, and in centistokes using metric measurement. § Oils are heated to a specified temperature, and then measuring the time it takes for the oil to flow into a container. § A viscometer is a hand-held device used to measure viscosity. § Watch the following short video for an example: Viscosity Measurement using a Viscometer
§ Greases are made by adding a thickener to a liquid lubricant. The thickeners are most often metallic soaps. Head Cap Pump Handle § When specifying a grease, three qualities are used: Type of Soap, Hardness, and Dropping Point. Grease Hose § Greases are often applied using a grease gun. Grease Coupler Barrel Plunger Rod
Aluminum General purpose grease Example: Food grade FLG-1 White Grease Lithium Most often used Moderate Loads High Temperatures Calcium Low temperatures Mild bearing loads Sodium Special Applications Handheld Tools Greases are used in applications where oils cannot be used. Some examples include applications where oil cannot be retained, where frequent re-lubrication would be necessary, or high speed applications where bubbles and foaming would occur.
§ A mechanical power transmission system is used to transmit force and motion from one device to another using components such as pulleys, gears, and bearings. § The system has a driver (also called the prime mover, or the drive motor), the device that sends the power, and the driven device, that receives the power.
§ As was discussed in the safety unit, OSHA establishes the rules around health and safety in the workplace. Due to the moving parts in mechanical equipment, it is important to follow these rules. They include: § Dress Rules: § Eye protection § No loose fitting clothing that can get caught, including no jewelry, ties, or other accessories § Long hair must be pulled back or tucked away § Proper footwear must be worn § Make sure the power is off and lockout tagout procedures are followed when working with machinery. Don’t enter the area until the machine is fully stopped. § Keep tools clean and organized, and don’t work on wet floors. § Make sure all guards are in place. § Get help lifting heavy parts. § Make sure no one else is in the area when starting a machine, and announce that you are starting a machine so others can clear the area.
§ A bearing is a machine element that constrains relative motion to only the desired motion, and reduces friction between moving parts. § Placement of bearings depends on the application. For instance, for a radial load, use at least two bearings to secure the position of the shaft. § Bearings can be mounted externally or can be built into the machine. For instance, electronic motors have a bearing on each side of the housing. § See this website: How Bearings Work
Plain Bearings Anti-Friction Bearings § The surface of the moving machine § Rotate with the moving machine component slides over the bearing surface, with a lubrication film between them. § Can support either radial loads or axial loads. § Example: Crankshaft of a car engine. component, with the use of rollers or balls within the bearing. § Number of balls contained in the bearing increases the radial load capacity. § Lubrication is present between the rollers. § Example: In-line skates
Conrad Ball Bearing Single row bearing Deep raceways Mainly supports radial loads Angular Contact Bearings Ball bearings with inner and outer races Can support a combination of radial and heavier axial loads Tapered Roller Bearings Cylindrical rollers that are tapered at one end Can support a thrust load and a radial load, in one direction only For both directions, bearings are mounted opposite each other Linear Roller Bearings Set of rollers between two moving surfaces Supports and guides the load Rollers follow an oval path Very little maintenance needed, long life There are many types of antifriction bearings. This slide explores four that are commonly used.
Pillow Block Bearing Housing with two mounting feet Can be mounted horizontal or angled Can be single or split Machined Housings Designed and manufactured for a particular installation Bearing must be installed into the housing Flange Bearing Mount Housing with mounting feet to mount perpendicular to the shaft Flanges have two or four mounting holes Criss-cross tightening should be used Built-in Housing Bearing housings are built in to support bearings Bearing is mounted into the housing and pressed into the shaft by the assembler Example: Engines and Transmissions Both plain and anti-friction bearings need to be mounted. Here are four ways to mount or house them. Pillow Block Flange Bearing Machined Built-in Housing
§ Adjusting a Pillow Block Anti-Friction Bearing
Rigid Coupling Couple two shafts together into a single assembly Example: Flange Coupling Universal Joints Allows two shafts that are not coaxially aligned to be connected Has one or two swivel joints Example: Papermaking machine Flexible Coupling Connect two shafts together and allow for some misalignment Example: Electric motor connected to a pump Clutches Allows turning shafts to connect and disconnect from each other Can act as a safety device Couplings connect one shaft to another, such as an electric motor to a pump. Couplings can also connect two shafts to create a longer shaft.
§ The flexible jaw coupling uses an insert called a “spider” to connect the two hubs. § Check out how it works here: Jaw Coupling
§ Why is shaft alignment important? Proper shaft alignment reduces vibration and extends the life of couplings, bearings, and seals. § Watch this short video for Shaft Alignment Basics and check out the rest of the videos in this series: Shaft Alignment Concepts Video Library
§ A gear is a wheel with teeth that engage with the teeth of another gear. In this way, a gear can drive another gear. § Gear drives have a few main components: § Driver gear attaches to the shaft. § Driven gear is turned by the driver gear. § Idler gear (when present) is used to change the direction of the rotation, or to transfer power further from the driver.
Pitch Ratio Formula Gear Ratio Formula § § Understanding Gears shows examples
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