MECHANICAL DRIVES 1 POWER TRANSMISSION SYSTEMS LEARNING ACTIVITY PACKET BB502-XD03AEN

Transcription

1 MECHANICAL DRIVES 1 LEARNING ACTIVITY PACKET POWER TRANSMISSION SYSTEMS BB502-XD03AEN

2 LEARNING ACTIVITY PACKET 3 POWER TRANSMISSION SYSTEMS INTRODUCTION In the previous LAPs you learned how to attach the motor shaft to a hub using a key fastener. In this LAP you will build on this skill by coupling the motor shaft to an independently mounted driven shaft which requires precise alignment with the motor shaft. Alignment is one the factors that most affects the life of rotating machinery. If it is not done correctly, the components can wear out quickly. Also, as part of this LAP you will learn about two important power transmission components: bearings and couplings. Every transmission machine you will work with has bearings and couplings of some kind. This LAP will serve as an introduction to both. In later LAPs you will learn more about each of them. ITEMS NEEDED Amatrol supplied 950-ME1 Mechanical Drives 1 Learning System Amatrol or School supplied Assorted Hand Tools FIRST EDITION, LAP 3, 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 2014, 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 INTRODUCTION TO SHAFTS OBJECTIVE 1 Describe the function of a shaft and give an application OBJECTIVE 2 List four types of shaft materials and give an application of each OBJECTIVE 3 Describe how shafts are specifi ed SKILL 1 Identify shaft size given a sample SEGMENT 2 INTRODUCTION TO BEARINGS OBJECTIVE 4 Describe the function of a bearing and give an application OBJECTIVE 5 Defi ne three types of bearing loads and give an example of each OBJECTIVE 6 Describe how bearings are positioned to support a load OBJECTIVE 7 Describe the operation of a two categories of bearings and give an application of each OBJECTIVE 8 Describe two methods of mounting a shaft bearing and give an application of each SKILL 2 Install and adjust a pillow block antifriction bearing and shaft SEGMENT 3 INTRODUCTION TO COUPLINGS OBJECTIVE 9 Describe the function of a coupling and give an application OBJECTIVE 10 Describe the function and application of four categories of mechanical couplings OBJECTIVE 11 Describe the operation of a fl exible jaw coupling SKILL 3 Install a fl exible jaw coupling SEGMENT 4 SHAFT ALIGNMENT OBJECTIVE 12 Describe the purpose of shaft alignment and give two types of misalignment OBJECTIVE 13 Describe a general procedure for shaft alignment and give four measurement methods OBJECTIVE 14 Describe the operation of the straight edge and feeler gauge alignment method SKILL 4 Align two shafts using a straight edge and feeler gauge 3

4 SEGMENT 1 INTRODUCTION TO SHAFTS OBJECTIVE 1 DESCRIBE THE FUNCTION OF A SHAFT AND GIVE AN APPLICATION A shaft is a cylindrical piece of material, usually steel, which transmits mechanical power in the form of torque and rotating motion from one location to another. It is a basic component but a very important one. Shafts are often used as part of a machine, such as an electrical motor or gas turbine, to transmit the power to a location outside the machine. Figure 1. Shaft Used in an Electric Motor 4

5 Shafts are also used as extensions to other shafts. An example of this is a drive shaft on a car, which transmits the power from the transmission in the front of the car to the differential gearbox in the rear. DIFFERENTIAL GEARBOX DRIVE SHAFT (ENGINE) Figure 2. Shaft Used as an Extension Still, a third and very common application of a shaft is to provide a means of operating the working components of the machine. For machines which use some type of rotating member to perform the work, a rotating shaft is attached to the member to power it. For example, a drill spindle consists basically of a shaft with a cutter tool attached to it, as shown in figure 3. Another application is in a roller press as used in a printing press or a paper making machine. In these cases, the roller is a part of the shaft. SPINDLE SHAFT Figure 3. Spindle Shaft of a Drill Press 5

6 OBJECTIVE 2 LIST FOUR TYPES OF SHAFT MATERIALS AND GIVE AN APPLICATION OF EACH Most machine shafts are made of some type of steel. The particular type depends on the amount of load the shaft has to carry and the conditions of the environment in which the shaft has to work. If you are replacing a shaft in a machine, make sure that you are using the same material. Do not assume that two materials that look the same are the same. Some examples of common shaft materials are as follows: Cold Rolled Steel (CRS) Hardened Steel Chrome Plated Steel Stainless Steel (SS) Cold Rolled Steel Cold rolled steel is the most common of all shaft materials because it is cheap and easy to machine. It is available in different strengths according to its carbon content. Cold rolled steel is used in most applications. Hardened Steel This is cold rolled steel which has been heat treated to increase its strength in some manner. Hardened steel is used in heavy duty applications such as high speed drive shafts. Chrome Plated Steel This can either be cold rolled steel or hardened steel which has been given a coating or plated with chrome. Chrome is a metal which is resistant to rusting and other corrosive applications. It is often used on rollers in presses. Stainless Steel Stainless steel resists rusting and is very strong. It combines the features of hardened steel and chrome plating. In fact, stainless steel has some chrome in it. A stainless steel shaft would be used where you need resistance to a corrosive environment and either a better surface finish or stronger surface than chrome plating can provide. Applications include machines such as those used in the food processing industry where the equipment must be often washed down with cleaning fluids. These fluids can cause chrome to flake off. In addition to these examples, a shaft can be made from many other types of steel as well as other materials. If you are designing a machine that uses shafts, you must consider the cost of the material, ease of machining, and size as well as the type of duty. 6

7 OBJECTIVE 3 DESCRIBE HOW SHAFTS ARE SPECIFIED Shafts are specified by the type of material, nominal diameter, diameter tolerance, straightness and length. Since a shaft is made from round stock material, nominal (approximate) shaft diameters are usually the same as the common sizes of standard round stock. It is also important to determine the diameter tolerances and straightness needed as well. Standard round stock is often not precise enough, so designers select accuracy stock for most shaft applications. Accuracy stock is precision ground to more exact tolerances than standard round stock, as shown in figure 4. DIAMETER TOLERANCE (in) STRAIGHTNESS (in) NOMINAL DIAMETER STANDARD ACCURACY STANDARD ACCURACY 1/ Unspecified / Unspecifi ed / Unspecifi ed / Unspecifi ed Unspecifi ed / Unspecifi ed / Unspecifi ed Unspecifi ed Figure 4. Standard Stock Sizes NOTE Notice that the accuracy stock s diameter is always less than the nominal diameter. This makes sure that components having a bore the same size will fit on the shaft without interference. Accuracy-type round stock is sold in standard lengths. Since shafts are usually shorter than the standard lengths, they are cut to length. This means the shaft length in a particular machine can be any length. 7

8 SKILL 1 IDENTIFY SHAFT SIZE GIVEN A SAMPLE Procedure Overview In this procedure, you will be given a shaft and asked to measure its diameter and length. The shaft size will determine the bearings, coupling, and other component sizes in a power transmission. Therefore, correctly identifying the shaft size is very important. 1. Place Shaft Panel 1 and Shaft Panel 2 on the work station s overhead rack. 2. Locate the following items from the Storage Unit. 1-inch Micrometer Tape Measure 3. Perform the following substeps to measure the diameter of the shaft. A. Open the micrometer so that it is more than halfway open. B. Place the shaft into the micrometer so that it is positioned for diameter measurement, as shown in figure 5. SHAFT Figure 5. Positioning of Shaft for Measurement 8

9 C. Close the micrometer until the spindle and anvil are very near to the part. D. Rock the micrometer from side to side as shown in figure 6, while turning the thimble clockwise. Continue to do this until you feel that the shaft is perpendicular to the line of measurement. ROCK DIAMETER IS SHORTEST LINE Figure 6. Rocking to Get Shaft Perpendicular 9

10 E. Now, sweep the micrometer as shown in figure 7 to find the high point. This will be the position where the diameter is being measured. SWEEP LONGEST LINE Figure 7. Sweeping to Get Correct Line of Measurement F. Repeat substeps D and E rocking and then sweeping, until you feel confident that the shaft is aligned and you are reading the true diameter. G. Read the micrometer measurement. Shaft Diameter: (in/mm) The diameter of this shaft should be inches. This is a common shaft size and is generally referred to by its fractional equivalent of 5/8 inches. 4. Repeat Step 3 to measure the diameters of the other shafts on Shaft Panel 1 and Shaft Panel 2. NO SHAFT DIAMETER (in/mm) 10

11 5. Perform the following substeps to measure the length of the shafts. The length is not a critical dimension. However, shafts are cut to the length needed for an application. Therefore, this dimension should be checked. A. Pick up the tape measure and a shaft. B. Hook the tape measure to one end of a shaft and stretch the tape measure to the end of the shaft as shown in figure 8. X TAPE MEASURE SHAFT Figure 8. Measuring Shaft with a Tape Measure C. Pull on the tape so that you stretch it tight. D. Position yourself so that you can accurately read the scale, as shown in figure 9. After positioning the hook, you should move to a location that is directly over the measuring point to read the scale. This helps avoid a reading error. SHAFT Figure 9. Operator s Eye Located Directly Over Measuring Point 11

12 E. Now, roll the tape over so that the scale contacts the shaft, as shown in figure 10. This avoids a problem called parallax error. GRADUATED SURFACE SURFACE TO BE MEASURED Figure 10. Eliminating Parallax Error While Reading a Tape Measure F. Read the length to the nearest 1/8 inch. Be careful to look straight down at the measuring point. Shaft Length: (in/mm) 6. Repeat Step 4 to measure the lengths of the remaining shafts on Shaft Panel 1 and Shaft Panel 2. NO SHAFT LENGTH (in/mm) 12

13 SEGMENT 1 SELF REVIEW 1. A(n) is a cylindrical piece of material used to transmit mechanical power in the form of torque. 2. is the most common of all shaft materials because it is cheap and easy to machine. 3. is used to make shafts because it has been heat treated to increase its strength. 4. Shafts are specified by their type of material, diameter, tolerance and. 5. The diameter of a shaft (is/is not) usually the same as the common sizes of standard round stock. 13

14 SEGMENT 2 INTRODUCTION TO BEARINGS OBJECTIVE 4 DESCRIBE THE FUNCTION OF A BEARING AND GIVE AN APPLICATION The function of a bearing is to support and guide a moving machine member with a minimum amount of friction. To understand why bearings are needed, it is important to understand that a machine member often has loads acting on it in several directions. Without bearings to hold the member in place, the loads would cause the member to move out of place and cause the machine to fail. COUPLING PILLOW BLOCK BEARINGS Figure 11. Motor and Shaft System Supported by Bearings 14

15 OBJECTIVE 5 DEFINE THREE TYPES OF BEARING LOADS AND GIVE AN EXAMPLE OF EACH Bearings are designed to counteract three types of loads which are placed on it by the power transmission equipment: a radial load, a thrust load, and a combination of the two. Radial Loads A radial or side load acts in a direction that is perpendicular to the axis of the shaft. For example, in figure 12 the force on the bearings creates a radial load. Bearings which carry a radial load are called radial bearings. RADIAL LOAD SHAFT AXIS BEARING SHAFT Figure 12. Radial Bearing Load 15

16 One source of radial load is the force from the weight of the power transmission component itself. An example is the shaft shown in figure 13. The weight of the shaft creates a force that pulls downward on the radial bearings. SHAFT WEIGHT FORCE RADIAL LOAD RADIAL LOAD Figure 13. Radial Load Created by Weight of Shaft Another type of radial load is caused by the tension or compression of the device the shaft is turning. Examples include the tension caused by a belt drive and the compression caused by a roller press. These forces also create a radial load on the shaft, as shown in figure 14. RADIAL LOAD RADIAL LOAD ROLLER ROLLER BEARING BEARING Figure 14. Examples of Radial Shaft Loads 16

17 Thrust Loads A thrust load acts in a direction parallel to the shaft axis and opposite to the direction of force transmission, as shown in figure 15. These bearings are called thrust bearings. THRUST LOAD THRUST BEARING SHAFT AXIS SHAFT STEP Figure 15. Thrust Bearing Load A thrust load can also be caused by the weight of the drive component. One example is machine element, such as a robot body or an index table, which must rotate parallel to the ground. INDEX TABLE THRUST LOAD Figure 16. Thrust Load Created by the Weight of the Drive Component 17

18 Another example of thrust load is the load created by a screw drive. As the screw drives the load, a thrust load is created on the shaft in the opposite direction, as shown in figure 17. THRUST LOAD Figure 17. Thrust Load Created by Screw Drive Combination Loads As you can imagine, many applications have a combination load with both a radial load and a thrust load. One example is the robot body shown in figure 18. When the body rotates, a radial load is created along with the thrust load from the weight of the machine. In fact, most loads that have a thrust load also have a radial load. WAIST AXIS BEARING RADIAL LOAD FROM ROTATION OF WAIST THRUST LOAD FROM WEIGHT OF ARM Figure 18. Robot Body Having Both a Radial and a Thrust Load 18

19 OBJECTIVE 6 DESCRIBE HOW BEARINGS ARE POSITIONED TO SUPPORT A LOAD No matter what the application, there are some basic concepts that can be applied to understand where bearings are placed in order to support a load. For radial loads, at least two bearings should be used to secure the position of the shaft. The load can either be placed between the two bearings or it can be overhung, as shown in figure 19. An overhung load is often called a cantilever load. LOAD BETWEEN BEARINGS CANTILEVER LOAD LOAD LOAD BEARING BEARING BEARING BEARING Figure 19. Placement of Bearings for Support of Radial Loads In some cases, the bearings are built into the machine rather than mounted externally. An example is an electric motor. All electric motors have two bearings, one on each side of the housing, as shown in figure 20. These bearings are needed to support the motor s rotor and shaft. They are also designed so that they can support an external radial load. This permits a mechanical member to be attached to the shaft without being supported by external bearings. REAR BEARING ROTOR FRONT BEARING SHAFT Figure 20. Electric Motor Having Two Bearings 19

20 In contrast, thrust loads only need one bearing. This bearing can be placed anywhere on the shaft, but it must be oriented so that it can counteract the direction of the thrust load, as shown in figure 21. THRUST LOAD THRUST BEARING SHAFT AXIS SHAFT STEP Figure 21. Placement of Bearing of Thrust Load 20

21 OBJECTIVE 7 DESCRIBE THE OPERATION OF TWO CATEGORIES OF BEARINGS AND GIVE AN APPLICATION OF EACH There are two major categories of bearings used in industry: Plain Bearings Anti-friction Bearings Plain Bearings A plain bearing is a type of bearing in which the surface of the moving machine component slides over the bearing surface, separated only by a lubrication film, as shown in figure 22. SHAFT SOLID BEARING HOUSING LUBRICATION FILM BETWEEN BEARING AND SHAFT Figure 22. Plain Bearing Operation Plain bearings are designed to support either radial loads or axial (thrust) loads. Radial load plain bearings for shafts are commonly called journal bearings. One application is on the crankshaft of a car engine. 21

22 Antifriction Bearings Antifriction bearings, unlike plain bearings, rotate with the moving machine component. This is accomplished by using rollers or balls that rotate within the bearing, as shown in figure 23. These rollers replace the function of the lubrication film of the plain bearing. However, antifriction bearings must use lubrication between the rollers. ANTI-FRICTION BEARING SHAFT HOUSING Figure 23. Antifriction Bearing Operation 22

23 OBJECTIVE 8 DESCRIBE TWO METHODS OF MOUNTING A SHAFT BEARING AND GIVE AN APPLICATION OF EACH All bearings require a housing or mounting of some type in order to hold the bearing in place in the machine. Both plain and anti-friction shaft bearings can be mounted in one of two ways: Pillow Block Bearing Mount Flange Bearing Mount Pillow Block Bearing Mount A pillow block consists of a housing with two mounting feet which are oriented so that the shaft can be mounted to a horizontal or angled surface. A pillow block can be designed as either a single assembly or a split assembly, as shown in figure 24. SINGLE ASSEMBLY SPLIT ASSEMBLY Figure 24. Two Types of Pillow Block Designs Flange Bearing Mount A flange type bearing mount consists of a housing with mounting feet which are oriented so that the shaft can be mounted to a surface which is perpendicular to the shaft. Flanges are designed with either two or four mounting holes, as shown in figure 25. Some flanges are built into the housing of the machine itself, as is the case for an electric motor or pump. FOUR-BOLT SQUARE FLANGE TWO-BOLT FLANGE Figure 25. Flange Designs Both the pillow block and flange bearing mounts are very popular, and are commonly found in industry. 23

24 SKILL 2 INSTALL AND ADJUST A PILLOW BLOCK ANTIFRICTION BEARING AND SHAFT Procedure Overview In this procedure, you will install two pillow block anti-friction bearings and mount a shaft between the two bearings. You will also adjust the pillow blocks to make sure the shaft is correctly aligned. 1. Perform the following safety checkout. 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. 3. Place Shaft Panel 1 on the work station s overhead rack. 4. Remove two pillow block bearings from Shaft Panel 1. Figure 26. Pillow Block Bearing with Lock Collar 24

25 5. Perform the following substeps to mount the shaft within the two bearings. A. Remove a 12-inch long shaft from Shaft Panel 1. The shaft must be straight and round. It must also be free of burrs, nicks, oil, or lubricants in order to properly lock into the bearings. B. Slide the shaft through the back of one of the pillow block bearings, as shown in figure 27. If the shaft will not enter the bearing, make sure the set screws are not locked. The shaft should slide easily through the bearings at this point. If there is significant resistance, check the diameter of the bore hole and the shaft to ensure compatibility. NOTE DO NOT lubricate the shaft or bearing to force the assembly. Try using a different pillow block or 12-inch shaft instead. Figure 27. Slide the Shaft Through the Pillow Block 25

26 C. Slide the shaft through the second pillow block so that the set screws are facing each other as shown in figure 28. Figure 28. Shaft/Bearing Assembly 26

27 6. Perform the following substeps to mount the bearing assembly. A. Remove four bearing standoffs from Shaft Panel 1. These will be used to raise the bearings to the correct height. B. Place the four bearing standoffs on the 950-ME work surface, as shown in figure 29. C. Place the assembly across the standoffs so that the shaft runs parallel to the edge of the surface, also shown in figure 29. Notice that the right block sits above two holes while the left block sits above two horizontal tracks. This configuration shows the right block will be the anchor point when aligning the bearings. 12" SHAFT Figure 29. Mounting the Four Aluminum Standoffs 27

28 7. Perform the following substeps to level the shaft. A. Place the level on the shaft, as shown in figure 30, and observe the position of the bubble. Make sure the level sits on a smooth surface of the shaft. LEVEL SHAFT Figure 30. Perform A Preliminary Level Check B. If the bubble is level or is shifted to the left, proceed to step C. If the bubble is shifted to the right, flip the assembly around and check the level again. It is important that the right bearing sit lower than the left in order to maintain position when aligning the bearings later. This anchor point will hold the shims in place when shifting the assembly around. If necessary, swap standoffs between bearings until the bubble shifts to the left. C. Locate four bolts with the specification 3/8-16UNC-2A x 4-1/2 hex head, along with compatible flat washers, lock washers, and nuts. 28

29 D. Loosely fasten the pillow block assembly to the table by placing the 3/8-16 bolts through the bearing, standoff and mounting surface. Use both flat and lock washers, as shown in figure 31. NOTE Remeber that the lock washer should contacts the nut and the flat washer should contact the mounting surface. PILLOW BLOCK BEARING STANDOFFS HEX BOLT FLAT WASHER 950-ME WORK SURFACE PLATE LOCK WASHER HEX NUT FLAT WASHER Figure 31. Fastener Confi guration E. If the shaft is not perfectly level, insert various feeler gauge leaf sizes under one end of the level until the bubble is centered. Record the thickness. Feeler Gauge Thickness (in/mm) 29

30 F. Measure the distance between the edge of the level and the edge of the feeler gauge (LE), as shown in figure 32. Effective Level Length (in/mm) G. Measure the distance between the bearing mounting bolts (LB), also shown in figure 32. Mounting Bolt Distance (in/mm) FEELER GAGE L E L B Figure 32. Ratio Measurement Distances H. Calculate the shim ratio. R=LB/LE Shim Ratio I. Calculate the shim thickness needed. Shim thickness = feeler gauge leaf thickness x shim ratio Shim Thickness = (in/mm) 30

31 J. Loosen and shim the right anchor bearing, as shown in figure 33. Use the pre-cut shims from the shim package. These shims are slotted in a horse shoe shape to fit around the bolts. Place the shims between the standoff and the mounting surface. This will help prevent the shims from being damaged. Remember to shim each side equally. Use the shim thickness calculated in step I. NOTE Use as few shims as possible. As an example, two inch shims should be replaced by one inch shim. This reduces the amount of moveable surfaces within the assembly. do not shim floating bearing shim anchor bearing Figure 33. Shim the Anchor Bearing on the Right Side NOTE Do not use wrinkled or bent shims. Also, do not push the shims into contact with the bolt. When the bolt is tightened, it will damage the shims. K. Tighten the bolts on the right bearing so the anchor point is secure. 31

32 8. Perform the following substeps to check the bearing alignment and secure final positioning. A. Turn the shaft by hand. The shaft should turn easily. If there is continuous resistance, the shaft is probably bent and needs to be replaced. If resistance is only in certain areas, that will be corrected during bearing alignment. B. Attempt to move the shaft axially through the bearing bores by hand, as shown in figure 34. The shaft should move through both bearings with minor resistance. Figure 34. Move the Shaft Axially Through the Bearing Bores C. If the shaft rotated and moved axially by hand with little resistance, proceed to step 9. If you were unable to move the shaft, loosen and remove the bolts on the left-hand, floating side of the assembly. 32

33 D. Shift the floating side of the assembly to the far left of the horizontal tracks if it is not already, as shown in figure 35. E. Push the shaft back through the anchor pillow block so that the floating block alone touches the shaft, also shown in figure 35. If the shaft will not move, use a rubber mallet and lightly tap the end of the shaft to get it moving. NOTE DO NOT strike or apply pressure to the bearing housing or seals. Always tap the shaft when seating the bearings. It is advisable to use small, light taps instead of heavy strikes in order to perform precise adjustments and avoid damage. Figure 35. Back the Shaft Out of the Anchor Bearing F. Tighten the bolts to the floating bearing again. 33

34 G. Grip the left end of the shaft with a gloved hand and move it towards the anchor housing. Make note of how closely the shaft aligns with the anchor bearing. When the shaft is out of alignment, it will be offset as shown in figure 36. Figure 36. Extremely Unaligned Shaft H. Pull the shaft away from the anchor bearing to leave room to maneuver. Turn the shaft by hand and twist it radially to align it with the bearing horizontally, as shown in figure 37. This may take a lot of force to move. Figure 37. Tap the Shaft for Alignment 34

35 I. To align the shaft vertically, hold one end of the shaft with a gloved hand and tap the surface of the opposite end with a rubber mallet. J. Check the alignment again by slowly pushing the shaft towards the anchor bearing. If the shaft appears to be in perfect alignment, it will look similar to figure 38. If it is not aligned, repeat steps H-J. NOTE Aligning the bearings may require meticulous effort and a lot of trial and error. Try not to use too much force during these steps as you may enter a feedback loop where you overcorrect the alignment, test it, and overcorrect it again. The more the bearings are broken in and maintained, the easier this process will be. Figure 38. Shaft Aligned K. When the shaft is aligned, push it through the anchor bearing. If the shaft enters the bearing and moves axially, proceed to step 10. If there is still a considerable amount of resistance, remove the shaft from the floating bearing and proceed to step 9. It is important that the anchor bearing remains firmly bolted to the table at all times. 35

36 9. Perform the following substeps to check the anchor bearing alignment and secure final positioning. A. Loosen and remove the bolts from the floating bearing. B. Insert the shaft through the back of the anchor bearing and look for misalignment between the bearings, as shown in figure 39. Figure 39. Anchor Bearing Is Not Aligned C. Slip the floating bearing over the end of the shaft and move the standoffs aside, as shown in figure 40. Figure 40. Anchor Bearing Is Secure Against Floating Bearing 36

37 D. Test the vertical alignment of the bearing by sliding a standoff underneath the floating bearing. If the alignment is perfect, the standoff will slide under the bearing and lightly touch it. If the alignment is too low, the standoff will not slide under the bearing or will meet stiff resistance. If the alignment is too high, the standoff and the bearing will not touch, as shown in figure 41. Figure 41. Vertical Alignment Is High 37

38 E. Tap the shaft to correct the alignment. If the bearing is too high, tap the left end of the shaft to lower it. If the bearing is too low, tap the right end of the shaft to raise it, as shown in figure 42. Repeat steps D and E until the feet of the bearing lightly touches the standoff. Figure 42. Tap the Right End to Raise Alignment 38

39 F. To correct the horizontal alignment, position the standoffs so that the boreholes perfectly align with the tracks in the table, as shown in figure 43. Figure 43. Position Floating Bearing Standoffs G. Slowly push the shaft towards the standoffs, and check the alignment between the table, the standoffs, and the holes in the feet of the floating bearing. If the assembly is out of alignment, it will look similar to figure 44. tap to align Figure 44. Horizontal Alignment Incorrect 39

40 H. Tap the right end of the shaft to adjust the alignment as needed. When the adjustment is correct, the bearing, standoffs, and table will be present a full line of sight to the floor that is the width of the standoff bore hole, as shown in figure 45. Figure 45. Bearings Are Horizontally Aligned I. Lightly bolt the floating bearing to the table. J. Test the alignment by turning the shaft and moving it axially through the bearings. If the shaft will not move, repeat step 9. If the alignment is correct, tighten the bolts on the floating bearing and proceed to step

41 10. Position the shaft so that it extends approximately 3 inches from the anchor bearing, as shown in figure 46. APPROXIMATELY 3 INCHES Figure 46. Completed Shaft/Bearing Assembly 11. Make sure the lock collars are set tightly against the bearings and tighten the set screws on each bearing, as shown in figure 47. Figure 47. Attachment of Bearing Lock Collars LOCK COLLAR SET SCREW This will lock each bearing to the shaft and prevent them from slipping. 41

42 12. Check the driven shaft for run-out. In a later procedure, you will attach this shaft to the electric motor using a coupling so it is important the shaft does not have excessive run-out. Run-out: (in/mm) The shaft should have no more than inch run-out. If so, it is bent and should be replaced. 13. Leave your setup in place and continue to the Self Review. 42

43 SEGMENT 2 SELF REVIEW 1. The function of a bearing is to and a moving machine member with a minimum amount of friction. 2. A(n) load acts in a direction that is perpendicular to the direction of force transmission. 3. For radial loads, at least bearing(s) should be used to secure the position of the shaft. 4. A(n) bearing is a type of bearing in which the surface of the moving machine component slides over the bearing surface separated by a film of lubrication. 5. A(n) bearing mount consists of a housing with two mounting feet which are oriented so that the shaft can be mounted to a horizontal or angled surface. 43

44 SEGMENT 3 INTRODUCTION TO COUPLINGS OBJECTIVE 9 DESCRIBE THE FUNCTION OF A COUPLING AND GIVE AN APPLICATION Couplings are used to connect one shaft to another. They are commonly used to connect electric motors and other prime movers to driven devices such as pumps and gear reducers, as shown in figure 48. They can also be used to connect two shafts to create one long shaft. AXIAL SHAFT TRANSMISSION ELECTRIC MOTOR PUMP Figure 48. Electric Motor Coupled to a Hydraulic Pump The coupling provides a secure method of transmitting the torque and speed from one shaft to another. Although they appear to perform a rather simple task, there are many types of couplings, and their correct installation will greatly affect the mechanical efficiency and life of the system. 44

45 OBJECTIVE 10 DESCRIBE THE FUNCTION AND APPLICATION OF FOUR CATEGORIES OF MECHANICAL COUPLINGS The many types of mechanical couplings fall under four general categories: Rigid Couplings Flexible Couplings Universal Joints Clutches Rigid Couplings Rigid couplings are designed to couple two shafts together rigidly, so that the shafts act as a single continuous assembly. One type of rigid coupling is a flange coupling, as shown in figure 49. Figure 49. Flange Couplings 45

46 Rigid couplings allow for no misalignment. They are used mainly to extend the length of a shaft in applications which need very long shaft lengths, as shown in figure 50. Sometimes they are used to connect motors to pumps, but this is not usually recommended because any misalignment will cause the bearings to wear out more quickly. EXTENDED SHAFT SYSTEM BEARING COUPLING BEARING COUPLING Figure 50. Rigid Coupling Application 46

47 Flexible Couplings Flexible couplings are designed to connect two shafts together and allow for some misalignment. Although there are many designs of flexible couplings, in general, they consist of two hubs and some type of flexible component which connects the two hubs together. Figure 51. Two Shafts Coupled by a Flexible Coupling Flexible couplings are used in applications which require two independently supported coaxial shafts to be coupled together. When two shafts are independently supported it is very difficult to align them perfectly. The flexible coupling allows enough misalignment to make the alignment process a practical task. Applications that use flexible couplings include any electric motor or engine which must be coupled to a pump or gear reducer. 47

48 Universal Joint Coupling The universal joint is designed to allow two shafts which are not coaxially aligned to be connected to each other, as shown in figure 52. The universal joint consists of one or two swivel connections that allow it to direct the shaft power to a shaft that is oriented at an angle to the driving shaft. Universal joints are used in drive shafts for automobiles. One example of an industrial application is a paper making machine, which requires a motor to drive a roller that is offset from the motor shaft. Figure 52. Universal Joint Application Clutch Type Couplings The fourth category of couplings is clutches. These couplings are designed to not only connect two shafts together but to also connect and disconnect them while the shafts are turning. Clutches are used to start machines in an unloaded condition, prevent reverse rotation, and act as a safety device if the shaft torque overloads. Figure 53. Clutch Application 48

49 OBJECTIVE 11 DESCRIBE THE OPERATION OF A FLEXIBLE JAW COUPLING The flexible jaw coupling is a type of flexible coupling which uses a rubberlike insert called a spider to connect the two hubs. As shown in figure 54, each hub has jaws that mesh with the spider. When the driver coupling half rotates, its jaws press on the spider, which in turn press on the jaws of the driven coupling half, causing it to turn. This type of coupling belongs to a family of couplings called elastomeric couplings, which refers to couplings that use a rubber-like elements to separate the two coupling halves. Specifically, it is a type of coupling called an Elastomer-in-compression. Figure 54. Flexible Jaw Coupling 49

50 The hubs of a jaw coupling are constructed of either aluminum, cast iron, or steel, depending on the power rating. They can be mounted with either a key fastener or bushing. The spider can be made of either Buna N (Nitrile) rubber, urethane, Hytril, or even metals such as bronze. They are usually designed as a one-piece construction, but can be supplied as pieces, as shown in figure 55. Figure 55. Spider Designs The advantage of this type of coupling is that it allows more misalignment than most flexible couplings because of the elastic properties of the elastomer spider. However, it is usually used for low to medium power/speed applications. This type of coupling is also known as a jaw and spider coupler, elastomeric jaw coupling, and simply a jaw coupling. 50

51 SKILL 3 INSTALL A FLEXIBLE JAW COUPLING Procedure Overview In this procedure, you will install a flexible jaw coupling to connect a motor to the shaft you mounted in the previous segment. 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. 3. Make sure the shaft and bearing assembly is still set up from the previous segment. If not, repeat Skill 2 to do so. 51

52 4. Perform the following substeps to mount and level the Constant Speed Motor. A. Locate the Constant Speed Motor and place it on the work surface. B. Locate the four Constant Speed Motor Risers from Shaft Panel 1. C. Make sure that the motor base, risers, and mounting area of the work surface shown in figure 56 are free of dirt, rust, and burrs. D. Position the Constant Speed Motor over the set of holes on the 950-ME work surface, as shown in figure 56. The outlines of the other components to be mounted are also shown. FLEXIBLE COUPLING MOTOR Figure 56. Location of Components on 950-ME Work Surface 52

53 E. Place one Constant Speed Motor Riser under each of the motor feet. F. Locate four bolts with the specifications 5/16-18UNC-2A x 1-1/2 Hex Head, along with compatible flat washers, lock washers, and nuts. G. Fasten the motor and risers to the work surface by assembling bolts, washers, and nuts. Use a criss-cross pattern to tighten the bolts. H. 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. I. Check for motor shaft end float. End Float (in/mm) It should be less than inches. J. 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) 53

54 5. Perform the following substeps to check the height of the two machines. NOTE It is important that the driven shaft be higher than the motor shaft. This will allow you to correct misalignment by shimming the motor. You will learn more about this in the next segment. It is being done now because it is easiest to do when the couplings are not mounted and a straight edge can be placed across the two shafts. A. Place the 4-inch straight edge across the shaft which appears to be higher, as shown in figure 57. B. Select a combination of feeler gauge leaves which will cause a slight drag on the leaves when they are passed under the straight edge. This is the height difference between the two shafts. Shaft Height Difference (in/mm) If the independent shaft is higher than the motor shaft, proceed to the next step. If it is less, shim the bearing standoffs equally so that it is. Figure 57. Measurement of Shaft Height Difference 54

55 6. Perform the following substeps to mount one of the jaws of the coupling to the motor shaft. A. Loosen the motor mounting bolts and slide the motor back far enough so that the coupling hub to be installed will fit between the shafts. B. Pick up one of the coupling hubs. C. Clean the shaft keyseat and the hub keyseat to make sure that no dirt or burrs are in the keyseats. D. Test the key fit by sliding one of the keys into the keyseat of the hub. The key should fit into the keyseat without forcing it. If it is too tight or too loose, replace it with another key. E. Remove the key from the hub keyseat and insert it into the keyseat of the shaft. It also should slide in without forcing it and have no play. F. Line up the key flush with the end of the shaft, as shown in figure 58. KEY FLUSH WITH END OF SHAFT Figure 58. Key Positioned on Shaft 55

56 G. Pick up the coupling hub in your hand and line it up in front of the shaft so that the hub s keyseat is in line with the key on the shaft. H. Slide the hub onto the shaft and pull it back from the end of the shaft, as shown in figure 59. This position will allow room for the other coupling hub to be put on. The hub should slide on without using tools. If it does not, use precision measuring equipment to measure the dimensions of the shaft and the hub bore. Do not tighten the set screws yet. Figure 59. Hub Slid Onto Shaft 56

57 7. Repeat step 6 to place the other coupling hub on the shaft which is supported by the bearings. 8. Move the two coupling hubs so that each hub is flush with its shaft, as shown in figure 60. Figure 60. Jaws Engaged 9. Tighten the set screws onto the keys of both hubs. 10. Move the motor to a position where the gap between the coupling teeth is large enough to allow insertion of the spider. 11. Then place the spider on the driven shaft coupling hub. Figure 61. Spider Mounted on Coupling Hub 57

58 12. Slide the motor forward so that the two hubs jaws engage. 13. Adjust the gap to 0.5 inches, as shown in figure 62, and tighten down the motor mounting hardware. Now the coupling assembly is complete. The next step is to align it. You will do this in the next skill. Figure 62. Coupling Gap 58

59 SEGMENT 3 SELF REVIEW 1. are used to connect one shaft to another. 2. couplings allow for no misalignment. 3. couplings are designed to allow for some misalignment. 4. couplings are designed to connect two shafts that are not coaxially aligned. 5. The coupling is a flexible coupling that uses a rubberlike insert to connect two hubs. 59

60 SEGMENT 4 SHAFT ALIGNMENT OBJECTIVE 12 DESCRIBE THE PURPOSE OF SHAFT ALIGNMENT AND GIVE TWO TYPES OF MISALIGNMENT The centerlines of two shafts which are connected by a flexible coupling should be brought into line with each other before operating the shafts. This process is called shaft alignment. The goal of shaft alignment is not perfect alignment but just good alignment. This helps reduce vibration and extend the life of the coupling, bearings, and seals. It is well known to be a main cause of early failure of equipment. DRIVER SHAFT CENTERLINE DRIVEN SHAFT CENTERLINE Figure 63. Alignment of Center Lines of Coaxial Shafts The two types of misalignment that are corrected by shaft alignment are angular and parallel misalignment, as shown in figure 64. This can appear anywhere in a 360 degree circle but they are usually measured on the horizontal and vertical planes. ANGULAR MISALIGNMENT PARALLEL MISALIGNMENT (OFFSET) Figure 64. Parallel and Angular Misalignment 60

61 OBJECTIVE 13 DESCRIBE A GENERAL PROCEDURE FOR SHAFT ALIGNMENT AND GIVE FOUR MEASUREMENT METHODS The general procedure for aligning two shafts is to check and correct for angular and parallel misalignment in two planes, vertical and horizontal, as shown in figure 65. Also, the coupling gap is set, which is done when horizontal angular misalignment is corrected. This means that there are five checks and corrections that have to be made: Vertical Angular Vertical Parallel Horizontal Angular and Coupling Gap Horizontal Parallel Notice that the two vertical alignment checks are done first. This is because they require shims to be added to the motor s feet. Doing this last would upset the horizontal alignments. VERTICAL ALIGNMENT HORIZONTAL ALIGNMENT Figure 65. Vertical and Horizontal Alignment To make these five checks of misalignment between the two shafts, measurements are normally taken on the orientation of the two coupling hubs with each other. For this reason, shaft alignment is also called coupling alignment. However, it is important to remember that the real goal is the alignment of the shafts. 61

62 The details of each step are described as follows: Step 1. Vertical Angular Alignment To correct the vertical angular alignment, shims are added to the front or back of the motor, depending on the location of the misalignment. If the gap between the couplings is greater at the top of the coupling, the back of the motor must be raised with shims. If the gap between the coupling hubs is greater at the bottom, the front of the motor must be raised with shims, as shown in figure 66. TOP GAP BOTTOM GAP SHIMS VERTICAL ANGULAR MISALIGNMENT Figure 66. Adjustments for Vertical Angular Misalignment Step 2. Vertical Parallel Alignment Vertical parallel alignment means to make the height of the two shafts the same. To correct for vertical parallel misalignment, the entire motor must be raised or lowered. This is done by adding or removing shims equally on all four motor feet, as shown in figure 67. VERTICAL PARALLEL MISALIGNMENT EQUAL SHIMS Figure 67. Adjustments for Vertical Parallel Alignment 62

63 Step 3. Horizontal Angular Alignment and Coupling Gap The horizontal angular alignment is the same as the vertical angular alignment except that the gap measurements are taken from the sides of the coupling halves. Shims are not used to correct this misalignment. The motor foot mount must be loosened and the motor slightly turned to correct the horizontal angular alignment, as shown in figure 68. OVERHEAD VIEW HORIZONTAL ANGULAR MISALIGNMENT ADJUSTMENT Figure 68. Adjustments for Horizontal Angular Alignment The coupling gap is the distance between the two coupling hubs. This should be set to the coupling manufacturer s specification. This specification is designed to permit the coupling to assemble correctly. Since the measurements for horizontal angular alignment are measuring the coupling gap, it is natural to adjust the gap at the same time. It simply requires that the motor be moved forward or back as well as angled. 63

64 Step 4. Horizontal Parallel Alignment The horizontal parallel alignment is the parallel alignment of the coupling hubs when viewed from overhead. To correct for the horizontal parallel alignment, the motor foot mounts must be loosened and all four feet moved an equal amount, as shown in figure 69. This will often upset the horizontal angular alignment so you should perform step 3 again to check it. In fact, you should repeat steps 3 and 4 until the measurements are within the tolerances before tightening the bolts. OVERHEAD VIEW TOP OF MOTOR TOP OF MOTOR HORIZONTAL PARALLEL MISALIGNMENT MOVE FEET EQUALLY Figure 69. Adjustments for Horizontal Parallel Alignment The actual measurement of the amount of misalignment can be measured by using one of four methods. These are as follows in order of their accuracy from least accurate to most accurate: Straight Edge and Feeler Gauge Method Face and Rim Method using one dial indicator or two dial indicators Reverse Indicator Method using two dial indicators Laser Alignment The straight edge and feeler gauge method is the least accurate method, but it is very quick. It is the method most people use to align a flexible jaw coupling because this type of coupling can accept more misalignment than most other couplings. Other types of couplings require better methods. The straight edge and feeler gauge method is also useful to make a rough alignment before using one of the other methods. More about each of these methods is discussed in later LAPs. 64

65 Pre Alignment Steps Before beginning the 4-step alignment process, there are several points that must be considered. One point is which device is going to be moved and which will remain in place. These are called the Machine to be Moved (M.T.B.M.) and the Stationary Machine. Normally, the driver component is the M.T.B.M. and the driven component is the stationary machine. This is because the driver component is usually easier to move. For example, a pump may not be easy to move if it has rigid plumbing attached to it. The next point is to make sure that the height of the M.T.B.M. is slightly lower than the stationary machine. This is because the movable component will rise as it is shimmed during alignment. To accomplish this, the stationary component can be shimmed when it is mounted, as shown in figure 70. A beginning height difference between the two shafts of to inches is good. INITIAL HEIGHT DIFFERENCE SHIMS Figure 70. Initial Height Different of Components Also, the couplings should be placed on the shafts and the M.T.B.M. then moved into a position where the gap between coupling hubs is approximately the amount recommended by the manufacturer. This is normally done with the coupling hubs mounted flush with the ends of the shafts. One or both coupling hubs will then be secured in place on the shafts, depending on the coupling design and method of alignment used. In some cases, only one hub is secured, usually the stationary machine, and the other is pulled back on the shaft to give room to get at the coupling face for measurement. 65

66 OBJECTIVE 14 DESCRIBE THE OPERATION OF THE STRAIGHT EDGE AND FEELER GAUGE ALIGNMENT METHOD The general 4-step procedure just described is used by the straight edge and feeler gauge method to align two shafts. The specific steps to follow including prealignment are as follows: Step 1. Perform Pre-alignment Steps Before starting the alignment process, you should do the following: Perform a lockout/tagout Clean and make free of burrs the motor and driven machines baseplate, shims, and mounting surface Check both machines for an initial soft foot Mount the motor and driven machine and tighten bolts Check both machines for a final soft foot Check both shafts for run-out and end float Level both shafts Make sure the height of the stationary machine is higher than the machine to be moved (MTBM) Clean the coupling of dirt or grease and mount the coupling hubs on the shafts Adjust the positions of the two machines so that the gap between the couplings halves is approximately the amount recommended by the manufacturer Tighten the mounting bolts of the two machines 66

67 Step 2. Perform Vertical Angular Alignment First, mark the two coupling halves with a chalk or ink mark on a place on the hubs which is free of nicks or burrs This is where all measurements will be taken from during the alignment process. Next, rotate the coupling hubs so that the two chalk marks are both at the 0 degree position, as shown in figure 71. OVERHEAD VIEW TOP OF MOTOR CHALK MARKS AT 0º Figure 71. Check Marks at 0 Degrees 67

68 Use a feeler gage to measure the gap between the two coupling hubs at 0 degrees, as shown in figure 72. Select the feeler gage leaf or leaves that give a slight drag when passed through the gap. Make sure you do not insert the feeler gage leaves too far, less than 1/2-inch. With angular alignment, your measurement will vary depending on how far you stick in the leaves. FEELER GAUGE Figure 72. Measurement of Gap at 0 and 180 Degrees Next, rotate the coupling hubs so that the chalk marks are at the 180 degree position and measure the gap here, as is also shown in figure 72. The difference between the two measurements is the amount of vertical angular misalignment. For example, if the top gap is inches and the bottom gap is inches, the misalignment is inches. To correct this misalignment, either the front two feet or the back two feet must be shimmed. The amount of shims needed can be determined by multiplying the misalignment by the shim ratio. The shim ratio is the ratio of the mounting bolt distance to the hub diameter. In figure 72, for example, the shim ratio is 2 (2=10/5). The amount to shim then (2 x 0.007). If the gap is larger at the top, shim the back two feet. If is larger at the bottom, shim the front two feet. Tighten the motor feet and recheck the gaps. If it is not equal at the top and bottom, or at least within the tolerance, change your shims. NOTE The reason you are rotating the coupling hubs before making each measurement is so that you can take measurements off of the same places on the hubs each time. This avoids errors in measurement caused by imperfections on the outside diameters (rims) of the coupling hubs. In some cases, one or both of the shafts will not rotate by hand. You can still use this procedure but you will not be as accurate. 68

69 Step 3. Perform Vertical Parallel Alignment Before checking the vertical alignment, or offset, first, measure the hub diameters to determine if the hubs are the same size. When hubs have different diameters, the alignment steps are different. If they are the same size, rotate the two marks to the 0 degree position and measure the offset. This is done by placing a straight edge on the hub that is higher and measuring the gap with a feeler gauge, as shown in figure 73. Next, rotate the coupling hubs so that the chalk marks are at the 180 degree position and measure the gap here. If the two measurements are the same, this is the amount of vertical parallel misalignment, or offset. If they are different, calculate the average of the two and use this as the vertical offset. Shim all four motor feet equally with shims having the same thickness as the offset is measured. FEELER GAUGE STRAIGHT EDGE º 180º Figure 73. Measurement of Vertical Parallel Misalignment 69

70 If the diameters of the two hubs are different, shim the MTBM so that the hub gap is the same on both sides, as shown in figure Figure 74. Compensation for Different Hub Diameters Now that the vertical alignments have been done, you can go on to the horizontal alignments. These alignments do not require shimming. Step 4. Perform Horizontal Angular Alignment and Set Coupling Gap First, center the end-play of the driver shaft and the driven shaft if they have any. Then rotate the chalk marks to the 90 degree position (as you look down onto the driver shaft) and use either a steel rule or feeler gage to measure the gap, as shown in figure 75. Loosen the mounting bolts and move the MTBM either in or out to adjust the gap to the manufacturer s specifications. This amount will vary, depending on the type of coupling. TOP OF MOTOR 90º GAP RULE Figure 75. Measurement of Horizontal Angular Misalignment at 90 70

71 Now rotate the marks to the 270 degree position and measure the gap again, as shown in figure 76. Adjust the position of the motor so that the gap is the same (or the difference is within the manufacturer s tolerance) on both sides at both 90 and 270 degrees it is within the manufacturer s gap specification. This sets the horizontal angular alignment. Leave the bolts untightened and go to the final step. RULE TOP OF MOTOR GAP 270º Figure 76. Measurement of Horizontal Angular Misalignment at 270 Step 6. Perform Horizontal Parallel Alignment Use a straight edge and feeler gauge to measure the misalignment when the chalk marks are at the 90 and 270 degree positions, as shown in figure º º STRAIGHT EDGE FEELER GAUGE Figure 77. Measurement of Horizontal Parallel Misalignment 71

72 Carefully bump or move the side of the motor without losing angular alignment until the offset measurements at 90 and 270 degrees are the same or zero. Larger motors have jack bolts which allow you to precisely move the front and the back of the motor equally. TOP OF MOTOR JACK BOLTS Figure 78. Correction of Parallel Misalignment with Jack Bolts Regardless of the method you use to move the motor, you should repeat steps 5 and 6 to recheck the gap and horizontal alignments until the settings are within the manufacturer s specifications. Once done, tighten down the motor s mounting bolts. Then recheck all measurements. If any one of the five measurements, are outside its allowable tolerance, repeat the alignment procedure. 72

73 SKILL 4 ALIGN TWO SHAFTS USING A STRAIGHT EDGE AND FEELER GAUGE Procedure Overview In this procedure, you will continue from the previous skill where you partially completed the installation of the jaw and spider coupling. In this skill, you will align the coupling and complete its installation. 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. 3. Continuing from the previous skill, the flexible jaw coupling hubs should be on the motor shaft and the shaft supported by the pillow block bearings. If you review the steps you followed in the last skill, you will find that you have performed all of the coupling prealignment steps, so your next step is to perform the vertical angular alignment. 73

74 4. Obtain a feeler gauge, a 4-inch straight edge, and a dial caliper. 5. Perform the following substeps to adjust the vertical angular alignment of the two shafts. A. Place a chalk mark on the hub, as shown in figure 79. Choose an area which is free of burrs. B. Rotate the chalk marks to the 0 degree position, as shown in figure 79. ALIGNMENT MARKS AT 0º Figure 79. Chalk Marks at 0 Degrees 74