Courseware Sample F0

Transcription

1 Career & Technical Education Mechanical Training System Courseware Sample F0 AB

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4 CAREER & TECHNICAL EDUCATION MECHANICAL TRAININ SYSTEM COURSEWARE SAMPLE by the Staff of Lab-Volt (Quebec) Ltd Copyright 2005 Lab-Volt Ltd All rights reserved. No part of this publication may be reproduced, in any form or by any means, without the prior written permission of Lab-Volt Quebec Ltd. Printed in Canada April 2005

5 Table of Contents Courseware Outline Belt Drives 1... V Sample Exercise Extracted from Belt Drives 1 Job Sheet 4 Belt Tensioning...3 Other Sample Extracted from Belt Drives 1 Post-Test...9 III

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7 Courseware Outline BELT DRIVES 1 Job Sheet 1 Job Sheet 2 Job Sheet 3 Job Sheet 4 Job Sheet 5 Job Sheet 6 Introduction to Belt Drives Sheave and Belt Installation Sheave Alignment Belt Tensioning Speed, Torque, and Pulley Ratios Sheave and Belt Maintenance Appendices A Components of the Belt Drives 1 System B Unit Conversion Table C Post-Test We Value Your Opinion V

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9 Sample Exercise Extracted from Belt Drives 1

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11 4 BELT TENSIONIN OBJECTIVES In this job, you will adjust the tension of a two-sheave belt drive. You will use a belt tension tester to measure the tension of the belt. EQUIPMENT REQUIRED C Universal Base Assembly, model C Motor Package, model C Couplings - Shafts Panel, model C Pillow Block Bearings Panel, model C Belt Drives, model C Test/Measurement Package, model C Tool Box Component Package, model SAFETY PROCEDURES Before proceeding with this job, complete the following check list. You are wearing safety glasses. You are wearing safety shoes. You are not wearing anything that might get caught such as a tie, jewelry, or loose clothes. If your hair is long, tie it out of the way. The working area is clean and free of oil. The floor is not wet. Your sleeves are rolled up. PROCEDURE Lockout/Tagout Procedure 1. Set the disconnecting switch to OFF. BELT DRIVES 1 3

12 BELT TENSIONIN 2. Write your name on a tag, and install it in the lockout device. 3. Lock the disconnecting switch with the lockout device. 4. Lock the lockout device with your padlock. 5. Ask the instructor and each teammate to install their own padlocks in the lockout device. Note: The universal base should be set up from Job Sheet 3. Repeat Job Sheet 3 if necessary. Belt Span Measurement 6. Using a straightedge, measure the belt span as shown in Figure 4-2. Belt span: Figure 4-2. Measurement of belt span. Belt Tension Tester Setup 7. Position the large O-ring of the belt tension tester at the measured belt span. 8. Position the small O-ring at zero on the deflection force scale. 4 BELT DRIVES 1

13 BELT TENSIONIN Belt Tensioning 9. Tension the belt slightly by turning the tension adjustment screw in the clockwise direction on the motor mounting base. Move away the base if more tension is needed. Realign the sheaves as described in Job Sheet 3 if you do so. Note: It is preferable to increase the tension of the belt gradually until the recommended tension is obtained, instead of removing tension after over tensioning. Positioning the Tension Tester 10. Place the tension tester squarely on the belt at mid-span as shown in Figure 4-3. Lay a straightedge across the sheaves. Figure 4-3. Belt deflection force measurement. 11. Apply a force on the plunger perpendicular to the straightedge until the bottom of the large O-ring is even with the bottom of the straightedge. Reading and Adjusting Tension 12. Remove the tension tester and read the force applied from the bottom of the small O-ring on the deflection force scale. 13. Compare the force applied to the recommended values shown in Table 4-1. Add tension as required. BELT DRIVES 1 5

14 BELT TENSIONIN V-BELT CROSS-SECTION SMALL SHEAVE PITCH DIAMETER RANE in. RECOMMENDED DEFLECTION FORCE lbf MINIMUM MAXIMUM A (4L) Table 4-1. Recommended deflection force. 14. Ask the instructor to check your work. Name: Date: Instructor's approval: 6 BELT DRIVES 1

15 Other Sample Extracted from Belt Drives 1

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17 Post-Test 1. Which of these belts are well suited for timing mechanisms? a. Flat Belt b. V-Belt c. Synchronous belt d. Multiple V-Belt e. All types can be used. 2. What makes the pitch diameter of a sheave change? a. The belt used b. The distance between the shaft centers c. The speed of the driving shaft d. The belt tension e. The speed ratio between the driving and driven sheaves 3. What is the drive misalignment called that results when the sheaves are at a different angle with the vertical plane? a. Parallel misalignment b. Horizontal angular misalignment c. Vertical angular misalignment d. Planar misalignment e. Vertical parallel misalignment 4. Which tool is used to check for sheave parallel alignment? a. Straightedge b. Combination square c. Tape rule d. Feeler gauge e. No tool is needed, the eye is precise enough. 5. Which parameters are represented by the two scales on a belt tension tester? a. Deflection distance and belt span b. Deflection force and belt type c. Deflection force and belt width d. Deflection distance and small sheave diameter e. Deflection force and belt span 6. If the driving sheave of a belt drive has an outside diameter of 6 in. and the driven sheave has an outside diameter of 3 in., the driven sheave rotates a. two times faster than the driving sheave. b. half as fast as the driving sheave. c. slower than the driving sheave. d. at the same speed as the driving sheave. e. Impossible to tell from the given data. BELT DRIVES 1 9

18 Post Test (cont'd) 7. What is a photo-reflective tachometer used for? a. Measures the torque on a sheave b. Measures the speed of a sheave c. Takes a picture of a sheave as it rotates d. Measures the wear on a belt e. Examines the surface of a sheave 8. Which type of belt is used with sprockets? a. F.H.P. V-belt b. Timing belt c. Flat belts used on conveyors d. Multiple V-belts e. None 9. Power is transferred between an electric motor and a pump with a belt drive. Calculate the required driven sheave pitch diameter and belt length if the motor and pump shafts are 20-in. apart and the pump shaft must rotate at 1800 r/min. The driving sheave is installed directly on the motor shaft and has a pitch diameter of 5 in. The plate on the motor indicates a nominal speed of 1000 r/min. a. Driven sheave pitch diameter is 2.8 in. and belt length is 52.2 in. b. Driven sheave pitch diameter is 9 in. and belt length is 52.2 in. c. Driven sheave pitch diameter is 9 in. and belt length is 62 in. d. Driven sheave pitch diameter is 2.8 in. and belt length is 62 in. e. Impossible to tell from the given data. 10. What should be used to clean belts? a. A solvent b. Water and soap c. A glycerine/spirit mixture d. Sandpaper e. They should never be cleaned. 10 BELT DRIVES 1

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