MECHANICAL DRIVES 1 INTRODUCTION TO CHAIN DRIVES LEARNING ACTIVITY PACKET BB502-XD05AEN

Transcription

1 MECHANICAL DRIVES 1 LEARNING ACTIVITY PACKET INTRODUCTION TO CHAIN DRIVES BB502-XD05AEN

2 LEARNING ACTIVITY PACKET 5 INTRODUCTION TO CHAIN DRIVES INTRODUCTION This LAP will begin your study of another method of adjacent shaft-to-shaft power transfer, the chain drive. Along with the belt drive, the chain drive is also common in industry because it is more efficient than the v-belt. A chain drive can handle higher power loads than a v-belt, and it does not slip. While there are many types of chain drives, the most widely used type is the roller chain drive. This is the type you will learn about in this LAP. ITEMS NEEDED Amatrol Supplied 950-ME1 Mechanical Drives 1 Learning System Amatrol or School Supplied Assorted Hand Tools FIRST EDITION, LAP 5, REV. B Amatrol, AMNET, CIMSOFT, MCL, MINI-CIM, IST, ITC, VEST, and Technovate are trademarks or registered trademarks of Amatrol, Inc. All other brand and product names are trademarks or registered trademarks of their respective companies. Copyright 2013, 2012 by AMATROL, INC. All rights Reserved. No part of this publication may be reproduced, translated, or transmitted in any form or by any means, electronic, optical, mechanical, or magnetic, including but not limited to photographing, photocopying, recording or any information storage and retrieval system, without written permission of the copyright owner. Amatrol,Inc., 2400 Centennial Blvd., Jeffersonville, IN USA, Ph , FAX

3 TABLE OF CONTENTS SEGMENT 1 CHAIN DRIVE CONCEPTS OBJECTIVE 1 Describe the function of the three basic components of a chain drive OBJECTIVE 2 Describe how to calculate sprocket ratio and explain its importance SKILL 1 Calculate sprocket ratio OBJECTIVE 3 Describe how to calculate shaft speed and torque of a chain drive system SKILL 2 Calculate the shaft speed and torque of a chain drive system SEGMENT 2 CHAIN DRIVE OPERATION OBJECTIVE 4 List four types of chains and give an application of each OBJECTIVE 5 List four types of roller chain drives and give an application of each OBJECTIVE 6 Describe the operation of a single-strand roller chain drive OBJECTIVE 7 Describe how to install, align, and remove a roller chain drive system with adjustable centers SKILL 3 Install and align a roller chain drive system with adjustable centers SEGMENT 3 CHAIN TENSIONING OBJECTIVE 8 Describe how to determine allowable chain sag for a given application SKILL 4 Determine allowable chain sag for a given application OBJECTIVE 9 Describe two methods used to adjust chain sag SEGMENT 4 CHAIN TENSION MEASUREMENT OBJECTIVE 10 Describe how to measure chain sag SKILL 5 Use a rule and a straight edge to measure chain sag SKILL 6 Adjust chain sag to a specifi ed amount using adjustable centers Activity 1 Roller chain drive analysis SEGMENT 5 FIXED CENTER CHAIN INSTALLATION OBJECTIVE 11 Describe the function and operation of a master link OBJECTIVE 12 Describe two methods of installing a lightweight chain which uses a master link SKILL 7 Install and remove a chain with a master link using sprocket teeth OBJECTIVE 13 Describe the operation of a chain puller SKILL 8 Install and remove a chain with a master link using a chain puller 3

4 SEGMENT 1 CHAIN DRIVE CONCEPTS OBJECTIVE 1 DESCRIBE THE FUNCTION OF THE THREE BASIC COMPONENTS OF A CHAIN DRIVE As shown in figure 1, a chain drive consists of three basic components: Chain - The chain is a continuous loop of links, usually having steel rollers, which is wrapped around two toothed wheels called sprockets. The chain transmits speed and torque between the two sprockets. Driver Sprocket - A sprocket is a disk-shaped component with teeth which is mounted to the shaft of the driver or prime mover. When the driver shaft turns, the driver sprocket turns, applying its speed and torque to the chain and causing it to move. Driven Sprocket - The driven sprocket is a sprocket which is mounted to the driven shaft. It turns when the chain moves and in turn causes the driven shaft to rotate. DRIVEN SPROCKET DRIVER SPROCKET CHAIN Figure 1. The Three Basic Components of a Chain Drive 4

5 The relative number of teeth between the driven sprocket and the driver sprocket determine the speed and torque of the driven shaft. The ratio of the teeth of the two sprockets can be selected to either increase or decrease the speed or torque delivered to the driven shaft. OBJECTIVE 2 DESCRIBE HOW TO CALCULATE SPROCKET RATIO AND EXPLAIN ITS IMPORTANCE The speed and torque that are transmitted to the driven shaft of a chain drive can be calculated by using the sprocket ratio, as was done with the pulley ratio of belt drives. The sprocket ratio is the ratio of teeth of the driven and driver sprockets, as the following formula shows: FORMULA: SPROCKET RATIO Sprocket Ratio = No. of Teeth of Driven Sprocket No. of Teeth of Driver Sprocket At first glance, you might think that you could use the sprocket pitch diameters to determine sprocket ratio as you did to determine pulley ratio for a belt drive. This is not the case. In a belt drive, the belt rides along a sheave through the pitch circle at all times, allowing pitch diameters to be used. The chain does not ride along the pitch line because each link is a rigid bar that cannot bend around a circular path. Instead, the links of a chain move around a circle in a series of straight lines, as shown in figure 2. This is called chordal action. Chordal action is very similar to the motion a train makes as its straight cars move around a turn. CHORD DIRECTION OF CHAIN TRAVEL PITCH CIRCLE Figure 2. Chordal Action of a Drive 5

6 SKILL 1 CALCULATE SPROCKET RATIO Procedure Overview In this procedure, you will determine the sprocket ratio of a number of chain drive applications. This is a simple skill but you will use it in the next skill to calculate the speed and torque of chain drive shafts. 1. Calculate the sprocket ratio of the chain drive shown in figure 3. Sprocket Ratio: DRIVER SPROCKET 36 TEETH DRIVEN SPROCKET 18 TEETH Figure 3. Chain Drive Application In this case, the number of teeth of the driver sprocket is 36 and the number of teeth of the driven sprocket is 18. The ratio is therefore 0.5 or 1:2 (SR=18/36= 0.5). 6

7 2. Calculate the sprocket ratio of the chain drive shown in figure 4. Sprocket Ratio: DRIVEN SPROCKET 24 TEETH DRIVER SPROCKET 8 TEETH Figure 4. Chain Drive Application In this case, the number of teeth of the driver sprocket is 8 and the number of teeth of the driven sprocket is 24. The ratio is therefore 3 or 3:1 (SR=24/8=3). 7

8 3. Calculate the sprocket ratio of the chain drive shown in figure 5. Sprocket Ratio: DRIVER SPROCKET 16 TEETH DRIVEN SPROCKET 96 TEETH Figure 5. Chain Drive Application In this case, the number of teeth of the driver sprocket is 16 and the number of teeth of the driven sprocket is 96. The ratio is therefore 6 or 6:1 (SR=96/16= 6). 8

9 OBJECTIVE 3 DESCRIBE HOW TO CALCULATE SHAFT SPEED AND TORQUE OF A CHAIN DRIVE SYSTEM The speed of the driven sprocket is determined by the sprocket ratio. This is because the rate at which the teeth of the driven sprocket engage the chain is the same as the rate at which the driver sprocket teeth disengage the chain. If the sprockets have different numbers of teeth, the driven shaft s rotational speed (RPM) will be different than the driver shaft s rotational speed. The shaft with the sprocket having more teeth will have a slower rotational speed than the shaft with the sprocket having fewer teeth. DRIVEN SPEED 500 RPM DRIVER SPEED 1000 RPM 20 TEETH 40 TEETH Figure 6. Effect of Relative Numbers of Sprocket Teeth on the Speed of the Driven Shaft The relationship between numbers of sprocket teeth and shaft speeds of a chain can be expressed in the following formula: FORMULA: CHAIN DRIVE SPEED Driver Rotational Speed (RPM) Driven Rotational Speed (RPM) = No. of Teeth of Driven Sprocket No. of Teeth of Driver Sprocket As you can see by the formula, the shaft speeds are inversely proportional to the number of teeth. This means that an increase in sprocket size (number of teeth) causes the speed to decrease. Also, notice that the right hand side of the formula is actually the sprocket ratio, so the formula can also be stated as follows: 9

10 FORMULA: CHAIN DRIVE SPEED Driver Rotational Speed (RPM) Driven Rotational Speed (RPM) = Sprocket Ratio In a similar manner to speed, sprocket ratio also affects the torque transmitted to the driven shaft. This is because the number of teeth relates directly to the radius of the sprockets. This means a larger driven sprocket creates more torque on its shaft. DRIVEN TORQUE 1200 in-lbs DRIVER TORQUE 600 in-lbs 20 TEETH 40 TEETH Figure 7. Effect of Sprocket Ratio on Torque of Driven Shaft The calculation of shaft torque is performed using a formula that is similar to the shaft speed formula, except that the torque is directly proportional to the number of teeth. The torque formula is therefore as follows: FORMULA: CHAIN DRIVE TORQUE Driven Rotational Torque Driver Rotational Torque = No. of Teeth of Driven Sprocket No. of Teeth of Driver Sprocket As with the speed formula, the torque formula can be modified to use the sprocket ratio as follows: FORMULA: CHAIN DRIVE TORQUE Driven Rotational Torque Driver Rotational Torque = Sprocket Ratio 10

11 SKILL 2 CALCULATE THE SHAFT SPEED AND TORQUE OF A CHAIN DRIVE SYSTEM Procedure Overview In this procedure, you will use the formulas just described to determine speed and torque of either the driver or the driven shaft. On the job, you will sometimes know the driver data and will need to determine the driven data. In other cases, it will be the reverse. 1. Calculate the driven shaft speed of the chain drive system shown in figure 8. Driven Shaft Speed: (RPM) DRIVER SPEED 600 RPM DRIVER TORQUE 500 in-lbs 70 TEETH DRIVER SPROCKET 35 TEETH DRIVEN SPROCKET Figure 8. Chain Drive Application The driven shaft speed is 1200 RPM 2. Calculate the driven shaft torque of the chain drive shown in figure 8. Driven Shaft Torque: (in-lbs/n-m) The driven shaft torque is 250 in-lbs. 11

12 3. Calculate the driven shaft speed and torque of the chain drive system given the following information. Given: Driver Speed = 1600 RPM Driver Torque = 500 in-lbs Driver Sprocket = 10 teeth Driven sprocket = 20 teeth Driven Shaft Torque: (in-lbs/n-m) Driven Shaft Speed: (RPM) The driven shaft speed is 800 RPM. The driven shaft torque is 1000 in-lbs. 4. Calculate the driven shaft speed and torque of the chain drive system given the following information. Given: Driver Speed = 1200 RPM Driver Torque = 1200 in-lbs Driver Sprocket = 18 teeth Driven sprocket = 18 teeth Driven Shaft Speed: (RPM) Driven Shaft Torque: (in-lbs/n-m) The driven shaft speed is 1200 RPM. The driven shaft torque is 1200 in-lbs. 5. Calculate the driven shaft speed and torque of the chain drive system given the following information. Given: Driver Speed = 3200 RPM Driver Torque = 400 in-lbs Driver Sprocket = 17 teeth Driven sprocket = 68 teeth Driven Shaft Speed: (RPM) Driven Shaft Torque: (in-lbs/n-m) The driven shaft speed is 800 RPM. The driven shaft torque is 1600 in-lbs. 12

13 SEGMENT 1 SELF REVIEW 1. Two and a(n) are the three basic components of a chain drive system. 2. action is caused by straight chain links moving about a circular sprocket. 3. In a chain drive ratio cannot be determined by the pitch diameters of the sprockets. 4. ratio is the ratio of the number of teeth of the sprocket divided by that of the sprocket. 5. The speed and of a driven sprocket can be determined from those same values of the driver sprocket and the ratio. 13

14 SEGMENT 2 CHAIN DRIVE OPERATION OBJECTIVE 4 LIST FOUR TYPES OF CHAINS AND GIVE AN APPLICATION OF EACH Chains are popular for a large number of industrial applications. The four types of chains you will most often encounter are: Roller chain Rollerless chain Silent chain Leaf chain Each of these is described as follows: Roller Chain The roller chain is the most common type of chain used for mechanical drives. It has rollers mounted on pins and bushings, as shown in figure 9. These rollers roll over the teeth of the sprocket to minimize the friction and increase the efficiency of the drive. PINS ROLLER BUSHING Figure 9. The Construction of a Standard Roller Chain 14

15 Roller chains can be found on machinery drives, conveyor systems, robot drives, and timing drives. Rollerless Chain Rollerless chains have nearly the same construction as roller chains except that they have no rollers, as shown in figure 10. PINS BUSHINGS Figure 10. The Construction of a Rollerless Chain Rollerless chains are used in light-weight, low-speed, mechanical drive applications where the friction between the chain and sprocket would cause little wear. They are also used in very dirty applications that would cause roller chain bushings to wear out too quickly if the chain had rollers. Examples include hoisting chains or drives in small cranes. 15

16 Silent Chain The silent chain uses what is called an inverted tooth design which is designed to reduce the noise created by the engagement and release of the sprocket teeth to the chain. CHAIN LOAD PINS FLAT LINKS SPROCKET ROTATION Figure 11. The Engagement and Release of a Silent Chain Silent chains are also more efficient, last longer, and can operated at higher speeds than roller chain. The disadvantage with silent chains is that they are much more expensive. Silent chain is also used in mechanical drive applications such as industrial pumps, fans, and other heavy machinery. 16

17 Leaf Chain Leaf chains are made up of many plates held together by pins, as shown in figure 12. They have no rollers and aren t usually used in chain drive applications. But leaf chains are normally used in forklift or other hoisting applications. Leaf chains with extended pins are also used on chain wrenches, as shown in figure 13. Figure 12. The Construction of a Leaf Chain Figure 13. Leaf chains are used for forklifts and chain wrenches. 17

18 OBJECTIVE 5 LIST FOUR TYPES OF ROLLER CHAIN DRIVES AND GIVE AN APPLICATION OF EACH As you have already learned, the roller chain is the most common type of chain used in industrial chain drive systems. There are four basic types of roller chains: Single strand chain Multiple strand chain Double pitch chain Offset chain Each of these is described as follows: Single Strand Chain This is the type of chain with which you are most familiar. The single strand chain is made up of a single row of rollers with plates on each side, as shown in figure 14. Figure 14. Single Strand Chain Single strand roller chain is used for most general-purpose applications of lowto-medium power transmissions. This type of chain is also found on bicycles. 18

19 Multiple Strand Chain For applications that transmit a great deal of power, multiple strand chains can be used. Multiple strand chains are made up of two or more single strand chains, as shown in figure 15. The chains used in multiple strand chain drives are the same as those used in single strand drives. They are merely joined to create multiple rows. Figure 15. Multiple Strand Chain Multiple strand chain is used in applications with much heavier loads and higher speeds than a single strand chain can handle. 19

20 Double-Pitch Chain Double pitch chain has the same construction as standard roller chain except that the length of its links are twice that of the single-pitch chain, as shown in figure 16. Double pitch chain is normally used when trying to save money and the application has low loads and speeds. They are also used in conveyor drives. DOUBLE PITCH Figure 16. Double-Pitch Roller Chains 20

21 Offset Chain Standard roller chain is made up of two different links that mate with each other. Offset chain, sometimes called cast chain, is made up of a single kind of link, as shown in figure 17. Figure 17. Offset Chain Links Offset chain can come with or without rollers. Because of its offset design, this type of chain doesn t require a connecting link, which is usually weaker than the rest of the chain. For this reason, offset chain is normally made out of high strength steel to be used in heavy-load, low speed applications. 21

22 OBJECTIVE 6 DESCRIBE THE OPERATION OF A SINGLE-STRAND ROLLER CHAIN DRIVE Roller chain is made up of two types of links: pin links and roller links, as shown in figure 18. ROLLER LINK PIN LINK ASSEMBLED LINKS Figure 18. Roller Chain is Made of Pin Links and Roller Links The two types of links are alternately assembled to form a complete link. These links mesh with the driver and driven sprockets so speed and torque can be transmitted between the two. 22

23 The two types of links are described as follows: Pin links are made of two side plates separated by two pins, as shown in figure 19. Roller links are similar to pin links, but are made of two side plates that are separated by bushings, as shown in figure 20. These bushings support the rollers that are mounted to them. PIN LINK PINS SIDE PLATES ROLLER LINK BUSHINGS ROLLERS SIDE PLATES Figure 19. The Construction of a Roller Chain Pin and Roller Link 23

24 The two links form an assembly as shown in figure 20. The jointed link design allows the chain to flex at the junction between links. It also allows the rollers to freely roll, which reduces friction between the chain and the sprocket. EXPLODED LINK ASSEMBLY PIN BUSHING ROLLER LINK ROLLER ROLLER LINK SIDE PLATES ASSEMBLED LINKS Figure 20. Roller Chain Link Assembly 24

25 The single-strand roller chain, as well as other types of chains, transmits power by rotating the driver sprocket so that its teeth engage the roller links and pull the chain around it. This in turn causes the chain to pull on driven sprocket teeth, causing it to rotate, as shown in figure 21. CHAIN PULLS THE DRIVEN SPROCKET DRIVER PULLS THE CHAIN SPEED AND TORQUE ARE TRANSMITTED TO THE DRIVEN SPROCKET Figure 21. Operation of a Roller Chain Drive Unlike the v-belt drive, the chain drive does not depend on friction between the sprocket and chain to drive it. Instead, the chain drives use the engagement or interlocking of the sprocket teeth and chain, which creates a positive drive. This means that chain tension does not have to be as high as v-belt tension, which is one reason why a chain drive is more efficient. The chain tension only needs to be high enough to keep the chain from flying off the sprocket during operation. 25

26 It is worthwhile to note, however, that chain drives still have some losses due to friction between the sprocket and the chain. This is because of the chordal action of the chain links. As the roller link contacts the sprocket, it initially rises up the tooth. Then, as it is wound around the sprocket it slides down the tooth, as shown in figure 22. This action repeats itself as each link contacts the sprocket, creating a certain amount of friction. It is small, however, because the frictional contact is reduced by the a rolling action of the chain s rollers. It is also worthwhile to note that this rising and falling of the links causes a slight speed variation in the chain drive. Even though the driver sprocket s speed is constant, the driven sprocket speed oscillates. The amount of oscillation depends on the number of teeth. If the number of teeth is greater than 25, the oscillation is less than 1% and is usually disregarded. P B A Figure 22. Chordal Action Chain sprockets are normally made of strong, high carbon steel. They can be attached to shafts using an integral hub with a keyseat, or with a bushing. 26

27 OBJECTIVE 7 DESCRIBE HOW TO INSTALL, ALIGN, AND REMOVE A ROLLER CHAIN DRIVE SYSTEM WITH ADJUSTABLE CENTERS Chain drives are easy to install but it is important to do it correctly in order to achieve the maximum life. Regardless of the type of chain you are using, the installation steps are similar. These steps are as follows: Step 1. Mount and Level the Motor and the Driven Component Leveling the shafts is actually part of the alignment of the sprockets, which is step 5 of this process. However, it is easier to place a level on the shaft before the sprockets are attached. As part of this process the motor and driven component should also be checked for a soft foot condition and excessive run-out. The shaft run-out should be no more than inches. Step 2. Inspect the Sprockets for Cleanliness and Wear. Clean or Replace if Necessary If the sprockets have nicks, burrs, gouges, or missing teeth, replace the sprocket. This can cause the chain to fail. At the same time the sprockets should be checked for wear. If the sprocket is excessively worn, replace it. Make sure that the sprocket does not have any dirt or rust on it. Dirt and rust can cause the chain to wear quickly. Use a stiff brush to remove any dirt and rust. 27

28 Step 3. Mount the Sprockets on the Shafts The sprockets should be attached to the shafts using either a fixed bore hub or a bushing. Bushings are commonly used on industrial chain drives. Figure 23. Installation of a Single-Strand Sprocket After you install the sprockets, make sure that they don t wobble by rotating the shafts and observing the motion of the sprockets. If they do, reinstall them or use other sprockets. Step 4. Mount the Chain If the chain drive has movable centers, adjust the driver shaft towards the driven shaft. This will reduce the center distance between the two sprockets so that the chain can be slipped loosely over the sprockets without forcing it. Next place the chain over the sprockets. If the drive system does not have movable centers, the chain can be connected and disconnected using a special link, called a master link. 28

29 Step 5. Align the Sprockets Just as with couplings and belt drives, it is important to align the sprockets. Misaligned sprockets will cause the chain and the bearings to wear quickly. This misalignment can appear in several ways, as shown in figure 24. The goal of aligning sprockets is to avoid twisting or applying excessive forces on the chain. ANGULAR MISALIGNMENT SPROCKET MISALIGNMENT PARALLEL MISALIGNMENT Figure 24. Types of Misalignment 29

30 The sprockets can be aligned by first leveling the two shafts using a spirit level. If this has already been done as part of mounting the motor, you can skip this substep and go to the next one. The next step is to place a straight edge against the faces of the sprockets to align the sprocket teeth and check the parallelism of the shafts, as shown in figure 25. The faces of the sprockets should be made so that they are flush against the straight edge. This means that the shafts are parallel and the sprocket teeth are aligned. STRAIGHT EDGE 4 CORNERS OF SPROCKETS Figure 25. Alignment of Sprockets with Straight Edge If you do not have a straight edge or the distance between sprocket centers is too great, you can use a string, just as described in the previous LAP for v-belt sheaves. Step 6. Apply Tension to the Chain The proper chain tension is very important to the life of the drive. Some slack is necessary for the chain drive to function properly. If the tension is too little, the chain will fly off the sprocket. If the tension is too high, the bearings and the chain will wear very quickly. Tensioning the chain is a 3-step process: Determine the sag needed Apply tension to the chain Measure the sag 30

31 Step 7. Apply Lubrication to the Chain Before the chain can be run, it must be lubricated. In many cases, a new chain will come with suitable lubrication for temporary operation, but in some cases it may not. The easiest way to lubricate a chain is to dip it in an oil bath before installing it. If a bath is not available, simply oil the chain while it is on the sprockets with an oil can. Other types of chain drives may have a continuous means of lubrication. Step 8. Run the Motor Briefly to Test the Drive Briefly run the motor and observe the operation of the drive. It should run smoothly and be fairly quiet. If so, continue running. If not, stop the drive and check for the problems. Step 9. Recheck the Chain Sag After the first 24 hours of operation, the tension in the chain should be rechecked to verify that the chain sag is still adjusted properly. If the chain tension is still as it should be, the drive system can be operated full time. If the chain tension is incorrect, it could indicate that something is wrong with the chain drive system. Chain sag should also be checked at 100 hours and every 500 hours of operation thereafter. Step 10. Chain Removal To remove a chain from a drive system with adjustable centers, simply move the two shafts closer together. This will create enough slack in the chain so that it can easily be lifted off of the sprockets, as shown in figure 26. If the drive does not have adjustable centers, the master link can be disconnected to allow removal of the chain. CENTERS MOVED CLOSER OPERATING CENTER DISTANCE Figure 26. Moving the Sprockets Close Together Makes Chain Removal Simple 31

32 SKILL 3 INSTALL AND ALIGN A ROLLER CHAIN DRIVE SYSTEM WITH ADJUSTABLE CENTERS Procedure Overview In this procedure, you will perform steps 1-5 of the chain drive installation procedure for a system with adjustable centers. You will complete the installation procedure in a later skill in this LAP. 1. Perform the following safety checkout to prepare for working with power transmission equipment. Make sure that you are able to answer yes to each item before proceeding. YES/NO SAFETY CHECKOUT Wearing safety glasses Wearing tight fi tting clothes Ties, watches, rings, and other jewelry are removed Long hair is tied up or put in a cap or under shirt Wearing heavy duty shoes Wearing short sleeves or long sleeves are rolled up Floor is not wet 2. Perform a lockout/tagout on the Motor Control Unit s safety switch. 32

33 3. Place the adjustable mounting base and Constant Speed Motor on the work surface. 4. Perform the following substeps to mount the adjustable mounting base. A. Position the adjustable mounting base over the set of holes in the 950-ME Mechanical Drives System s work surface shown in figure 27. The outlines of the positions of the other components to be mounted are also shown. 1-INCH DIAMETER 5/8-INCH ENDS SHAFT PRONY BRAKE HUB PRONY BRAKE 30 TOOTH SPROCKET 1-INCH BORE BEARINGS CHAIN 15 TOOTH SPROCKET MOTOR ADJUSTABLE BASE Figure 27. Location of Components on 950-ME Work Surface 33

34 B. Locate four bolts with the specification of 3/8-16UNC-2A x 2 Hex Head, along with the compatible flat washers, lock washers, and nuts. C. Fasten the mounting base to the work surface by assembling the bolts, washers, and nuts. D. Tighten the fasteners using a criss-cross sequence. 5. Perform the following substeps to mount and level the motor on the adjustable mounting base. A. Place the motor over the adjustable mounting base s mounting holes. B. Locate four hex bolts with the specification of 5/16-18UNC-2B x 1 inch, along with compatible flat washers and lock washers. C. Fasten the motor to the adjustable mounting base by assembling the bolts, washers and nuts. NOTE Make sure that the lock washer is between the nut and the flat washer. D. Tighten the fasteners to lock the motor in position. This will create a rigid setup. E. Check the shaft for run-out. Record below the amount of run-out. Run-out: (in/mm) The run-out should be less than inches. F. Check for motor shaft end float. End Float (in/mm) It should be less than inches. G. Check the level of the motor shaft. Shim the motor feet as needed. Feeler Gauge Leaf Thickness (in/mm) Effective Level Length (in/mm) Mounting Bolt Distance (in/mm) Shim Ratio Shim Thickness (in/mm) 34

35 6. Perform the following substeps to mount the shaft and pillow block bearings. A. Select four Bearing Standoffs from Shaft Panel 1. B. Make sure that the standoffs, pillow block mounting surface, and mounting area of the work surfaces, shown in figure 27, are free of dirt, rust and burrs. C. Place the four standoffs on the 950-ME work surface. D. Remove two pillow block bearings with 1-inch diameter boxes from Shaft Panel 1. E. Place the pillow block bearings on the standoffs. F. Locate four bolts with the specifications of 3/8-16UNC-2A x 4-1/2 Hex Head, along with the compatible flat washers, lock washers, and nuts. G. Fasten the pillow block bearings and the standoffs to the work surface by assembling the bolts, washers, and nuts. Hand tighten only. H. Select a 8-inch long shaft from Shaft Panel 1 that has a 1-inch diameter with 5/8-inch diameter ends. I. Slide the shaft through the two pillow block bearings. Position it as shown in figure 27. J. Tighten the set screws on each bearing to lock the bearing to the shaft. K. Tighten the pillow block bearing mounting bolts. L. Turn the shaft by hand to make sure it turns freely. If not, loosen the bolts and adjust the positions of the bearings. M. Check the driven shaft for run-out. Run-out: (in/mm) The shaft should have no more than inches run-out. N. Level the driven shaft. Shim the bearing standoffs as needed. Place the shims between the work surface and the standoffs. Feeler Gauge Leaf Thickness (in/mm) Effective Level Length (in/mm) Mounting Bolt Distance (in/mm) Shim Ratio Shim Thickness (in/mm) 7. Install the prony brake on the shaft and work surface in the location shown in figure 27. This brake will be used in later skills to demonstrate how the torque is affected by a sprocket ratio. 8. Locate the 15 and 30 tooth sprockets from Chain Drive Panel 1. 35

36 9. Perform the following substeps to mount the 15-tooth drive sprocket to the motor shaft. These steps are the same steps you used to install the sheaves in a belt drive system. A. Inspect the 15-tooth drive sprocket. B. Locate the set-screw hole which is drilled into the side of the hub of the 15-tooth sprocket. C. Use a hex key wrench to take out the set screw and verify that it is tipped with brass. This will prevent damage to the shaft. D. Clean the motor shaft s key seat and the sprocket s hub key seat with a wire brush to make sure that no dirt or burrs are in the keyseats. E. Select a 3/16 x 1 inch square key from your key stock. F. Slide the key into the keyseat of the motor shaft. Make sure it isn t too tight or too loose. If so, replace the key. G. Remove the key from the shaft keyseat and insert it into the sprocket hub keyseat. It also should slide in without forcing it and have no play. H. Remove the key from the sprocket hub and insert into the shaft keyseat. Line it up flush with the end of the shaft. I. Pick up the sprocket and line it up in front of the shaft so that the hub s key seat is in line with the key on the shaft. Orient the sprocket so that the hub points toward the motor. 36

37 J. Then slide the sprocket hub onto the shaft until the end of the hub is flush with the end of the shaft, as shown in figure 28. The hub should slide on without using tools. If it doesn t, pull it off and check the dimensions. Figure 28. Sprocket Hub Attached to Motor Shaft K. Tighten the setscrew onto the key to lock the sprocket in position. 37

38 10. Repeat Step 9 in a similar manner to mount the 30-tooth driven sprocket onto the driven shaft. The setup should look like figure 29 at this time. Figure 29. Current Setup 38

39 11. Check the sprocket alignment by placing the long straight edge (a 36-inch steel rule) flush against the driven sprocket face. Then check the position of the face of the driver sprocket, as shown in figure 30. The driver sprocket must be adjusted to align with the driven sprocket. If the face of the driver sprocket is also flush against the straight edge, the sprockets are aligned and the shafts are parallel. This means that the sprockets are aligned and you can proceed to step 13. If, however, only one point or no points of the driver sprocket touch the straight edge, the shafts are not parallel. Proceed to step 12 to correct this. Figure 30. Straight Edge Check for Sprocket Alignment 12. Perform the following substeps to align the sprockets. A. Slightly loosen the 4 bolts that fasten the adjustable mounting base to the work surface. B. Move the motor base to a position so that all 4 edges of the sprockets touch the straight edge. C. Tighten the bolts in a criss-cross pattern until the bolts are tight. D. Recheck the alignment with the straight edge after the bolts are tightened. Repeat the alignment steps if necessary. 39

40 13. Perform the following substeps to mount the chain. A. Loosen the jam nuts on the adjustment screw and raise the motor. If more clearance is needed, loosen the fasteners on the motor mount and move the motor mount toward the driven shaft. Position it close enough to be able to put on the chain, as shown in figure 31. MOVE FORWARD IF NEEDED Figure 31. Positioning of Motor Base 40

41 B. Place the chain over the sprockets. C. Lower the motor until the chain does not touch the worksurface, as shown in figure 32. D. Tighten the locknuts against the motor. Figure 32. Motor Base Positioned Until a Small Amount of Sag is Left 14. Rotate the driven shaft by rotating the prony brake drum with your hand. Observe the meshing that occurs between the sprocket and the chain, and how motion is transmitted through out the entire system. You should be able to hear the clicking as the links strike the sprocket teeth. See if you can observe the chordal action. 15. Leave the setup as it is. You will need this same arrangement in the next skill. 41

42 SEGMENT 2 SELF REVIEW 1. chains are similar in construction to a roller chain except they have no. 2. chains create less noise than standard chains because of their tooth-shaped design. 3. Chains that are made up of a series of plates held together by pins are called chains. 4. strand chains are similar to standard chains, but they have two or more widths. 5. The interlocking between chain and sprocket prevent the chain from when a load is applied to the sprocket. 6. Power is from one shaft to another via a. 42

43 SEGMENT 3 CHAIN TENSIONING OBJECTIVE 8 DESCRIBE HOW TO DETERMINE ALLOWABLE CHAIN SAG FOR A GIVEN APPLICATION In order for a chain to function properly its tension must be high enough to enable it to stay on the sprockets. It must also not be too tight or the drive will quickly wear and fail. For this reason, a chain must have some slack in it, which is called sag. Chain tension is determined by how much sag is in the chain, as shown in figure 33. DRIVEN SPROCKET DRIVER SPROCKET SAG Figure 33. Chain Sag 43

44 When a chain is under load, it will have a taut side and a slack side. The taut side is the side of the chain that is being pulled by the driver sprocket. The slack side comes from the effect of the driver sprocket pushing the chain, as shown in figure 34. DRIVEN TAUT SIDE DRIVER SLACK SIDE Figure 34. The Taut Side and Slack Side of a Chain Chain sag is measured by rotating the sprockets so that there is little or no chain sag in the taut side and then measuring the sag in the slack side. Chain sag is measured at the middle of the span between the two sprockets, which is why it often called the mid-span sag. Another term that is often used is the mid-span movement, which is the movement of the sag in both directions, as shown in figure 35. Mid-span movement is always two times the mid-span sag. MID-SPAN MOVEMENT Figure 35. Mid-Span Movement 44

45 The amount of sag a chain drive should have depends on the application for which the drive system is being used. The two applications are: Vertically oriented chain drives Horizontally oriented chain drives A vertically oriented chain drive is defined as a drive where the angle between the line going through the centers of the two sprockets and a horizontal line is greater than 45 degrees, as shown in figure 36. A horizontally-oriented drive is one in which the angle is less than 45 degrees. VERTICAL LINE 90º VERTICAL DRIVES 45º HORIZONTAL DRIVES 0º Figure 36. Vertical and Horizontal Chain Drive The allowable mid-span movement of a vertical chain drive is 2 or 3 percent of the distance between sprocket centers. For example, a vertically oriented chain drive whose distance between centers is 24 inches has an allowable mid-span movement of about 0.6 inch. This corresponds to a mid-span sag of 0.3 inch. The allowable mid-span movement for a horizontal chain drive is 4 to 6 percent of the distance between sprocket centers. For example, a horizontal chain drive whose distance between centers is 24 inches has an allowable mid-span movement of 1 inch. This corresponds to a mid-span sag of 0.5 inch. 45

46 SKILL 4 DETERMINE ALLOWABLE CHAIN SAG FOR A GIVEN APPLICATION Procedure Overview In this procedure, you will determine the allowable chain sag for a given application. This will include both vertical and horizontal chain drives. To begin, you will be lead through the steps. Then, you will do it yourself. 1. Perform the following substeps to determine the allowable mid-span movement and chain sag for the application shown in figure 37. A. Determine whether the drive system is a vertical or horizontal type. Orientation: (Vertical/Horizontal) This application is horizontally oriented. This means that the allowable mid-span movement should be 4-6 percent. B. Locate the distance between centers of the drive system 30 Figure 37. Chain Drive Application Distance between centers: (in/mm) The distance between centers of this application is 30 inches. 46

47 C. Calculate the allowable mid-span movement of the chain drive system. Mid-Span Movement Range: (in/mm) To determine the lower limit of the range, multiply 0.04 (4%) times the distance between centers. To determine the upper limit of the range, multiply 0.06 (6%) times the distance between centers. This is as follows: Minimum Movement = = 1.2 inches Maximum Movement = = 1.8 inches You should find a mid-span movement range to be 1.2 inches to 1.8 inches. D. Divide the mid-span movement by 2 to determine the allowable sag of the system. Chain Sag Range: (in/mm) You should find a chain sag of 0.6 to 0.9 inches. 2. Determine the allowable mid-span movement and chain sag for the application shown in figure 38. Mid-Span Movement Range: (in/mm) Chain Sag Range: (in/mm) Figure 38. Chain Drive Application You should find a mid-span movement range of 0.8 to 1.2 inches and a chain sag range of 0.4 to 0.6 inches. 47

48 3. Determine the allowable mid-span movement and chain sag for the application given the following information. Given: Drive Angle = 60 degrees from horizontal Center Distance = 50 inches Mid-Span Movement Range: (in/mm) Chain Sag Range: (in/mm) You should find a mid-span movement range of 1 to 1.5 inches and a chain sag range of 0.5 to 0.75 inches. 4. Determine the allowable mid-span movement and chain sag for the application given the following information. Given: Drive Type: Vertical Center Distance: 80 inches Mid-Span Movement Range: (in/mm) Chain Sag Range: (in/mm) You should find a mid-span movement range of 1.6 to 2.4 inches and a chain sag range of 0.8 to 1.2 inches. 48

49 OBJECTIVE 9 DESCRIBE TWO METHODS USED TO ADJUST CHAIN SAG During installation and later, after the chain has become worn, the chain sag will need to be adjusted. There are two basic methods used to adjust chain sag: Adjustable Centers Idler You have already learned about adjustable centers. When the sag of a chain needs to be adjusted, the centers of the drive system can be moved either further apart or closer together, as shown in figure 39. Figure 39. Adjusting Chain Sag by Using Adjustable Centers 49

50 Another method that is used to adjust chain sag is a device called a chain idler, as shown in figure 40. A chain idler is a mechanism that has a small sprocket attached to an arm which may or may not be spring loaded. The spring-loaded feature automatically keeps constant tension in the chain drive via the sprocket. If a spring-loaded arm is not used, the idler sprocket must be manually adjusted using a slot on the arm or by some other means. Figure 40. Typical Chain Idler It is important to understand that the adjustment of the chain tension after the drive has been in use for a time is not done because the chain has stretched. Chains do not stretch. They become longer because they wear. Specifically, the bushings inside the roller links wear. As these bushings wear, they become smaller and the length of the chain gets longer. This makes it look as if the chain is stretching. This wear feature is actually a benefit of a chain drive because it allows the chain to be used for a longer time than other types of drives and it makes it easy to determine when to replace the chain by measuring its length. A chain should be replaced when its length becomes 3% longer than the original length. 50

51 SEGMENT 3 SELF REVIEW 1. The two methods commonly used to adjust chain centers are centers and by using a(n) 2. The allowable mid-span movement of a horizontally oriented chain drive is to percent. 3. The allowable mid-span movement of a vertically oriented chain drive is to percent. 4. Dividing the mid-span movement by will give you the chain. 5. If chain tension is too the chain will wobble off of the sprockets during operation. 51

52 8 SEGMENT 4 CHAIN TENSION MEASUREMENT OBJECTIVE 10 DESCRIBE HOW TO MEASURE CHAIN SAG Before the chain drive is put into operation, the chain sag must be adjusted. This requires that you measure the actual chain sag. This is easy to do using a straight edge and a rule. To measure chain sag, one sprocket is rotated while the other is held in place. This causes the sag to be on one side of the drive. A straight edge is then laid across the sprockets on the side with sag. Midway between the sprockets, the end of a rule is placed on the chain. The sag in the chain is then read off of the rule where it crosses the straight edge CHAIN SAG READING Figure 41. Measuring Chain Sag 52

53 SKILL 5 USE A RULE AND A STRAIGHT EDGE TO MEASURE CHAIN SAG Procedure Overview In this procedure, you will perform the next step of the chain drive installation procedure by measuring the chain sag of the chain drive you set up in the previous skill. 1. Perform the following safety checkout to prepare for working with power transmission equipment. Make sure that you are able to answer yes to each item before proceeding. YES/NO SAFETY CHECKOUT Wearing safety glasses Wearing tight fi tting clothes Ties, watches, rings, and other jewelry are removed Long hair is tied up or put in a cap or under shirt Wearing heavy duty shoes Wearing short sleeves or long sleeves are rolled up Floor is not wet 2. Make sure the lockout/tagout is still in place. If not, make it so. 3. Make sure that the chain drive is still set up as it was in Skill 3, as shown in figure 42. If not, repeat Skill 3 to do so. Figure 42. Current Arrangement 53

54 4. Using one hand, turn the driven sprocket in a clockwise direction while holding the other sprocket fixed in your hand. This puts the slack in the upper side of the chain drive and makes the lower side taut. 5. Perform the following substeps to measure the sag in the chain. A. Lay a straight edge across the top of the sprockets, as shown in figure 43. Figure 43. Measuring Chain Sag B. Press a rule into the sagging chain, as shown in figure 43. C. Read the rule where it comes into contact with the underside of the straight edge. Write your result in the blank below. Rule Measurement: (in/mm) This value is the mid-span sag. It can be anything, depending on how you adjusted the chain back in skill Leave the mechanical drives system setup in place and continue directly to the next skill. 54

55 SKILL 6 ADJUST CHAIN SAG TO A SPECIFIED AMOUNT USING ADJUSTABLE CENTERS Procedure Overview In this procedure, you will perform the last steps of the chain drive installation and alignment procedure, which is to adjust the tension to the correct amount. You will then operate the drive. 1. Continuing from the last skill, make sure the lockout/tagout is still in place. Also, make sure the drive setup is still in place. 2. Perform the following substeps to calculate the allowable chain sag. A. Adjust the adjustable mounting base until the chain is taut. B. Using a tape measure, determine the distance between shaft centers. Write the result in the blank below. Center Distance (in/mm) C. Calculate the allowable mid-span movement. Mid-Span Movement Range: (in/mm) D. Calculate the allowable mid-span sag. Mid-Span Sag Range: (in/mm) 3. Use the adjustable mounting base to position the driver sprocket so that the chain sag is set to the midpoint of the range you calculated in the previous step. You may have to recheck the sag several times as you move the mounting. Recheck the sag by repeating Steps 4 and 5 of the previous skill. Lock the adjustable mount in place by tightening the motor locknuts. 4. Lightly coat the chain with teflon lubricant. Congratulations! You have completely installed, adjusted, and aligned a roller chain drive system. 55

56 5. Perform the following substeps to start the motor. A. Make sure that the safety switch power cord is plugged into a wall outlet. B. Make sure the Constant Speed Motor switch is in the OFF or down position. C. Connect the motor s power cord to the Motor Control Unit. D. Install the guard. WARNING Do not operate the mechanical drive system without the guard in place. Also, do not attempt to open or bypass the guard at any time during operation. Performing any of these actions will create a hazardous situation. E. Remove the lockout/tagout. F. Turn on the safety switch. The Main Power Indicator on the Motor Control Unit should turn on. G. Make sure that no one is near the motor. H. Turn on the Constant Speed Motor by moving its power switch to the ON or up position. The motor should accelerate to full speed quickly and run at a constant speed. 6. Allow the motor to run for a few minutes while you observe the operation of the drive. You should notice that it is significantly louder than the v-belt drive. This is one of its disadvantages. 7. Turn off the motor. The motor should coast to a stop. 8. Perform a lockout/tagout. 9. Remove the guard. 10. Recheck the chain tension. Chain Sag: (in/mm) You should find that chain sag will not change after the operation of the motor because a chain will not stretch like a v-belt does. 11. Replace the guard. 12. Leave your setup in place and go directly to the next activity to operate the drive and analyze its operation. 56

57 Activity 1. Roller Chain Drive Analysis Procedure Overview In this activity, you will continue from the previous skill to measure the torque and speed output of the chain drive to prove that the formulas you learned in Segment 1 actually work. 1. Continuing directly from the previous skill, perform the following substeps to start the motor. A. Verify that the guard is installed. B. Remove the lockout/tagout. C. Turn on the safety switch. The Main Power Indicator on the Motor Control Unit should turn on. D. Make sure that no one is near the motor. E. Turn on the Constant Speed Motor. The motor should accelerate to full speed quickly and run at a constant speed. 2. Measure the speeds of the motor shaft and the driven shaft using the tachometer. Record your readings. Driver Shaft Speed (RPM) Driven Shaft Speed (RPM) The unloaded speed of the motor shaft should be close to 1750 RPM. Since the sprocket ratio is 2 (30/15), the speed of the driven shaft speed should be about 875 RPM. This type of drive, where the speed of the driven shaft is lower than the driver shaft, is called a speed-down drive. This is the more commonly used configuration. 3. Now measure the motor s electrical input current for each of the prony brake load settings listed in the following table. Scale Reading (Ounces) Motor Current (Amps) Torque (In-Ounces) 57

58 4. Reduce the load on the motor to zero by turning the load nut counterclockwise until the scale reads zero. 5. Turn off the electric motor. 6. Calculate the torque value for each scale reading in the table of Step 3. Record your calculations in column 3 of the table in Step 3. Use a value of 6.0 inches (15.24cm) for the torque radius of the prony brake to do your calculations. 7. Compare the electrical current readings in the table Step 3 to the electrical current readings you measured in LAP 2, when the motor was directly coupled to the prony brake. You should find that the current required for a given prony brake load is lower than the current measured in LAP 2 because the sprocket ratio is (30/15). The speed decreased and the torque delivered increased. This means that the torque input required to deliver the given torque is less. 8. Perform a lockout/tagout. 9. Remove the guard. 10. Perform the following substeps to partially disassemble the chain drive. A. Loosen the motor s top jam nut and move the motor upward enough to loosen the chain. B. Carefully pull the chain off the sprockets. Make sure that you do not have to use force to remove the chain. C. Use a hex key wrench to loosen the set screw on the hub of the driven sprocket. 58

59 D. Carefully pull the sprocket off the driven shaft, as shown in figure 44. If the sprocket is stuck, use a small punch and tap the key out of the keyseat, or use a gear puller. This will break the sprocket loose to make it easier to remove. Figure 44. Removal of Sprocket E. Remove the motor sprocket using the same steps used to remove the driven sprocket. 59

60 11. Reassemble the drive with the sprockets reversed, so that the large sprocket is on the driver (motor) shaft and the small sprocket is on the driven shaft, as shown in figure Adjust the chain sag to the same amount you did in the last skill. Then, lock the adjustment screw jam nuts. This configuration is called a speed-up drive. This is the least common configuration of the chain drive, because many driven components operate at lower speeds than typical motor speeds and need higher torque. Figure 45. Reversed Sprocket Confi guration 13. Install the guard. 14. Remove the lockout/tagout. 15. Turn on the motor and allow it to accelerate to full speed. 16. Measure the speeds of the motor shaft and the driven shaft using the tachometer. Record your readings. Driver Shaft Speed (RPM) Driven Shaft Speed (RPM) The unloaded speed of the motor should be close to 1750 RPM. Since the sprocket ratio is now 15/30, the speed of the driven shaft speed should be about 3500 RPM. 60

61 17. Now measure the motor s electrical input current for each of the prony brake load settings listed in the following table. Scale Reading (Ounces) Motor Current (Amps) Torque (In-Ounces) 18. Reduce the load on the motor to zero and turn off the electric motor. 19. Perform a lockout/tagout. 20. Remove the guard. 21. Calculate the torque value for each scale reading in the table of Step 17. Record your calculations in column 3 of the table in step Compare the electrical current readings in the table of Step 17 to the electrical current readings you measured in LAP 2, when the motor was directly coupled to the prony brake. You should find that the current required for a given prony brake load is higher than the current measured in LAP 2 because the sprocket ratio is 1:2. The speed at the driven shaft increased and the torque delivered decreased. This means that more input torque is required. 23. Perform Steps in a similar manner to determine a chain drive s output speed and torque when the driver sprocket is a 20-tooth and the driven sprocket is a 30-tooth type. Driver Shaft Speed (RPM) Driven Shaft Speed (RPM) 24. Perform the lockout/tagout. 61

62 SEGMENT 4 SELF REVIEW 1. Chain sag can be measured using a edge and a. 2. On a horizontally oriented drive, it is very important for the sag to be on the strand. 3. Shaft speed is measured using a. 4. Shaft torque can be determined by using a brake and a(n). 5. A chain that has too little sag can the efficiency of the drive system and can cause excess. 62

63 SEGMENT 5 FIXED CENTER CHAIN INSTALLATION OBJECTIVE 11 DESCRIBE THE FUNCTION AND OPERATION OF A MASTER LINK In some mechanical applications, the machine s design does not permit the driver shaft or the driven shaft to be moved in order to remove and install a chain. For these cases, a continuous chain loop must be separated so it can be installed and removed. One way to separate and reconnect a chain is to use a special chain link called a master link. Master links are similar in construction to a standard chain link, but one of its side plates can be removed, as shown in figure 46. With the side plate removed, a master link can be put into a chain or removed from it. This allows the chain to be installed onto sprockets and the master link reinstalled to form a continuous chain. The side plate of a master link can be held onto the two pins by using either a cotter pin, or a locking spring clip. Figure 46. Master Link 63

64 OBJECTIVE 12 DESCRIBE TWO METHODS OF INSTALLING A LIGHTWEIGHT CHAIN WHICH USES A MASTER LINK There are two main methods used to install chains which have a master link: using the sprocket teeth mesh or a chain puller. The simplest of these methods is to use the sprocket teeth mesh. This method is accomplished by engaging one end of the chain with one of the sprockets. The teeth of the sprocket will hold that end in place while the rest of the chain is wrapped around the other sprocket and back to the original end, as shown in figure 47. When the two ends of the chain are next to each other, the master link can then be installed. ENDS OF CHAIN MESHED IN SPROCKET TEETH Figure 47. Using Sprocket Teeth to Install a Chain 64

65 In some cases, the chain is too heavy to lift the chain ends onto adjacent sprocket teeth, or the sprockets have a protective shield over them. In cases like these, a chain puller is used. A chain puller is a tool that is used to hold the two ends of a chain together while the master link is installed, as shown in figure 48. CHAIN PULLER MASTER LINK Figure 48. A Chain Puller Holds the Ends of a Chain Together 65

66 SKILL 7 INSTALL AND REMOVE A CHAIN WITH A MASTER LINK USING SPROCKET TEETH Procedure Overview In this procedure, you will install a roller chain onto two sprockets using a master link. You will use the teeth of the sprocket to help you to hold the chain ends together while the master link is assembled. 1. Make sure the lockout/tagout is still in place. If not, make it so. 2. Remove the guard. 3. Make sure that the drive assembly is still setup as it was in the previous skill, as shown in figure 49. If they are not, repeat Steps 2-13 of Skill 3 to make it so. Figure 49. Current Arrangement 4. Using the straight edge, adjust the motor mount until the distance between the shaft centers is approximately 12-3/4 inches. Then lock the motor in place. NOTE Don t forget to loosen the locking nuts before attempting to move the motor. This distance will simulate a fixed center chain drive setup. 66

67 5. Locate the chain s master link, as shown in figure 50. Figure 50. Locate the Master Link 6. Perform the following substeps to disassemble the master link. A. The locking clip is split at one end. Using your fingernails, you should be able to lift one prong of the locking clip over the grooved pin, as shown in figure 51. If you are unable to do this with your fingernails, needle-nose pliers may be used. If you do use the pliers, please be careful not to damage or lose the locking clip. REMOVABLE SIDE PLATE LIFT HERE LOCKING CLIP Figure 51. Lifting Prongs or the Locking Clip 67

68 B. Once one prong is lifted over the pin, the other prong can easily be lifted in the same manner. C. Slide the locking clip until the split end is on the other pin, as shown in figure 52. SPLIT END Figure 52. Slide the Split End to the Other Pin D. The locking clip can now be removed by lifting the prongs as was done for substeps A and B. E. Once the locking clip is removed, slip the link s side plate off of the pins as well. F. Slide the rest of the master link out from the other side of the chain, as shown in figure 53, and remove the chain. Be careful not to lose any of the pieces. Figure 53. Removing the Master Link 68

69 7. Perform the following substeps to install the chain. A. Place the chain over the sprockets, as shown in figure 54. You should be able to get both ends of the chain into adjacent sprocket teeth, as shown in the figure. The teeth will help hold the chain ends for the next substep. Figure 54. Installing the Chain 69

70 B. Install the master link by running the part with the pins into the ends of the chain, as shown in figure 55. Figure 55. Installing the Master Link C. Slip the removable side plate onto the pins protruding from the other side of the chain as shown in figure 56. D. Then press the split part of the locking clip onto one of the pins until the clip fits into one of the groove of that pin, as shown in figure 56. The locking clip can only be pressed onto a pin at the point of the split. REMOVABLE SIDE PLATE Figure 56. Assembling the Master Link 70

71 E. Position the clip so that the split is on top of the next pin. F. Push the clip forward so that it fits into the groove of this pin, as shown in figure 57. Figure 57. Master Link Installed G. Pull outward on the removable plate to make sure that it is pressing up against the locking clip and not the chain bushings. This allows the panels to freely rotate. NOTE It is important that the clip not rub against the bushings. 8. Rotate the prony brake drum to make sure that the chain moves freely. 9. Rotate the chain drive until the master link is once again positioned on the sprocket where it was assembled. The sprocket will hold the chain in place while you remove the master link. 10. Disassemble the master link as you have before, and remove the chain. 11. Leave the drive assembly set up for the next skill. 71

72 OBJECTIVE 13 DESCRIBE THE OPERATION OF A CHAIN PULLER A chain puller operates by pulling the two ends of the chain together with its jaws. The jaws are opened and closed by the dial on top of the tool. When the jaws are opened far enough, each jaw is inserted into the ends of the chain, as shown in figure 58. Once the jaws are inserted into the ends of the chain, the chain puller is then tightened by turning the dial until the chain ends are close enough to allow the master link to be installed. CHAIN PULLER MASTER LINK Figure 58. A Chain Puller Holds the Ends of a Chain Together 72

73 SKILL 8 INSTALL AND REMOVE A CHAIN WITH A MASTER LINK USING A CHAIN PULLER Procedure Overview In this procedure, you will use the chain puller to hold the ends of the chain together. 1. Make sure the lockout/tagout is still in place. If not, make it so. 2. Continuing from the previous skill, make sure the mechanical drives system is set up as in the previous skill. If it is not, make it so. 3. Perform the following substeps to install the chain using a chain puller. A. Drape the chain over the two sprockets, as shown in figure 59. Figure 59. Chain Draped Over Two Sprockets B. Obtain the chain puller from Chain Drive Panel 1. 73

74 C. Open the jaws of the chain puller as far as they will go by rotating the dial counterclockwise. D. Insert each of the jaws into the ends of the chain, as shown in figure 60. Figure 60. Insert the Jaws into the Ends of the Chain E. Tighten the chain puller by rotating the dial clockwise. This will close the jaws of the chain puller, which will bring the ends of the chain together. F. When the ends of the chain are close enough together, install the master link as you did in the previous skill. 4. After the master link has been installed, slightly open the jaws of the chain puller and remove it from the chain. 5. Make sure that the sprockets are still aligned. 6. Perform the following substeps to make sure that your installation is correct. A. Make sure that the master link is firmly held in place by its locking clip. B. Then, rotate the drive by hand until the master link travels completely around the drive. Carefully observe it as you do as to make sure the master link functions as it should. 7. Disassemble the setup and store components. 8. Remove the lockout/tagout. 74