Machine Design Belts
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This document provides an overview of belt drives for power transmission. It defines a belt as a flexible loop used to link rotating shafts. Belts transmit power efficiently and can accommodate shafts that are not axially aligned. The document outlines the advantages of belts, such as being cheap, vibration-free, and tolerant of misalignment. It also notes some disadvantages like varying angular velocity. Different types of belts are described, including flat belts, V-belts, timing belts, and others. Key factors in belt selection and design are also summarized.
Machine Design Belts
- 1. MACHINE DESIGN PRESENTATION ON BELTS MADE BY:- MAYANK BHATIA 14MEU045 NAGESHWAR SINGH 14MEU048 NITIN SONI 14MEU057 NAVEEN CHAUHAN 14MEU050
- 2. WHAT IS A BELT…?? A belt is a loop of flexible material used to link two or more rotating shafts mechanically, most often parallel. Belts may be used as a source of motion, to transmit power efficiently, or to track relative movement. Belts are looped over pulleys and may have a twist between the pulleys, and the shafts need not be parallel. The main function of a belt is power transmission.
- 3. POWER TRANSMISSION Belts are the cheapest utility for power transmission between shafts that may not be axially aligned. Power transmission is achieved by specially designed belts and pulleys. The demands on a belt drive transmission system are large and this has led to many variations on the theme. They run smoothly and with little noise, and cushion motor and bearings against load changes, albeit with less strength than gears or chains. However, improvements in belt engineering allow use of belts in systems that only formerly allowed chains or gears.
- 4. ADVANTAGES AND DISAVANTAGES ADVANTAGES:- Cheap Works on non axial shafts Noise and vibration free No lubrication needed High efficiency High tolerance to misalignment Different speeds can be obtained DISADVANTAGES:- Angular velocity keeps on changing The work in a particular temperature range They wear off easily
- 5. FACTORS TO BE CONSIDERED WHILE DESIGNING BELTS Shafts should be properly in line Pulleys should neither be too close nor too far Tight side of the belt should be at the bottom Maximum distance should not exceed 10m Minimum distance should not be less than 3.5 times the dia of larger pulley
- 6. SELECTION OF BELT DRIVES The factors to be considered while selecting belt drives are:- Speed of the driving and driven shafts Power to be transmitted Centre distance between the shafts Space available Service conditions
- 7. TYPES OF BELTS DRIVES Light drives - They are used to transmit small power at belt speeds upto 10mps. Medium drives - They are used to transmit medium power at belt speeds between 10mps to 22mps. Heavy drives - They are used to transmit large power at belt speeds above 22mps.
- 8. TYPES OF BELTS Flat belts Round belts V-belts Multi-groove belt Timing belt
- 9. FLAT BELTS Flat belts are widely used in line shafting to transmit power in factories. They are also used in countless farming, mining, and logging applications, such as bucksaws, sawmills, threshers, silo blowers, conveyors for filling corn cribs or haylofts, balers, water pumps and electrical generators. The flat belt is a simple system of power transmission that was well suited for its daily usage. It can deliver high power at high speeds (500 hp at 10,000 ft/min or 373 kW at 51 m/s), in cases of wide belts and large pulleys.
- 10. V-BELT V belts solved the slippage and alignment problem. It is now the basic belt for power transmission. They provide the best combination of traction, speed of movement, load of the bearings, and long service life. They are generally endless, and their general cross-section shape is Roughly trapezoidal . The belt also tends to wedge into the groove as the load increases—the greater the load, the greater the wedging action—improving torque transmission and making the V-belt an effective solution, needing less width and tension than flat belts. V-belts trump flat belts with their small center distances and high reduction ratios. The preferred center distance is larger than the largest pulley diameter, but less than three times the sum of both pulleys. Optimal speed range is 1,000–7,000 ft/min (300–2,130 m/min). V-belts need larger pulleys for their thicker cross- section than flat belts.
- 11. TIMING BELTS Timing belts are a positive transfer belt and can track relative movement. These belts have teeth that fit into a matching toothed pulley. When correctly tensioned, they have no slippage, run at constant speed, and are often used to transfer direct motion for indexing or timing purposes. They are often used in lieu of chains or gears, so there is less noise and a lubrication bath is not necessary. Camshafts of automobiles, miniature timing systems, and stepper motors often utilize these belts. Timing belts need the least tension of all belts, and are among the most efficient. They can bear up to 200 hp (150 kW) at speeds of 16,000 ft/min (4,900 m/min).
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