Stage Rigging Handbook, Third Edition

Contents

vii Contents Preface to the Third Edition xvii Preface to the Second Edition xix Preface to the First Edition xxi Symbols and Abbreviations xxiii PART 1. LOAdS And REACTIOnS 1 1.01. The 4 Ks 1 1.02. Knowing the Rigging System 2 A. Load and Force 2 B. Static Equilibrium 2 1.03. Supporting a Load 3 A. The Engineer and the Rigger 3 B. Seat-of-the-Pants Experience 4 C. Free-Body Diagram (FBD) 4 D. Summation of Forces 5 E. Moment of Force 7 F. Examples 9 G. Continuous Beams 12 1.04. Summation of Forces 13 A. Resultant Force 13 B. The Law of Sines 14 C. Table of Multipliers for Resultant Forces 15 D. Vectors 16 1.05. Bridle Analysis 17 A. Bridle-Length Calculation 18 B. Vertical and Horizontal Forces 19 C. Bridle Tension 21 D. Vector Analysis 22 viii E. Hanging Points of Different Heights 23 F. Ratio of Horizontal to Vertical Distance 26 G. Allowable Loads 28 H. The Effect of Bridles on Hanging Points 28 1.06. Strength of Materials 29 A. Types of Applied Forces 30 B. Stress, Strain, and Hooke’s Law 31 C. Yield Point and Elasticity 32 D. Breaking Point 33 E. Allowable Deflection 34 F. Torsion 35 G. Unpredictable Forces 35 H. Design Factor of Components 38 I. Determining the Design Factor 38 PART 2. BLOCK-And-TACKLE RIGGInG 42 2.01. Introduction 42 2.02. Anatomy of a Block-and-Tackle System 43 A. Wooden Blocks 44 B. Metal Blocks 44 C. Other Types of Blocks 45 2.03. Load distribution on a Block 45 A. Static Load 45 B. Dynamic Load 47 2.04. Mechanical Advantage 49 A. Apparent Mechanical Advantage 49 B. Actual Mechanical Advantage 49 C. Calculating Lead-Line Pull 52 D. Mechanical Advantage of Common Systems 55 E. Calculating the Total Load on the System 57 F. Rope and Sheave Wear 57 G. Mechanical Advantage of Complex Systems 58 2.05. Lacing and Reeving of Blocks 59 ix 2.06. Inspecting a Block-and-Tackle System 61 2.07. Using a Block-and-Tackle System 62 A. User’s Checklist 62 B. Attaching 62 C. Operating 63 D. Storing 63 PART 3. HEMP RIGGInG 65 3.01. Introduction 65 3.02. The Hemp Systems 65 A. Single-Line System 65 B. Multiple-Line System 66 C. Sandbag and Arbor Attachment as Counterweight 68 3.03. The Rope 69 A. Considerations of Rigging Rope 69 B. Types of Natural-Fiber Rope 70 C. Synthetic-Fiber Rope 71 D. Tensile Strength or Breaking Strength 73 E. Strength and Allowable Working Load of Rope 73 F. Effects of Knotting 75 G. Care of Rope 75 H. Indications of Wear 79 I. Testing a Rope 80 J. Bo’sun’s Chair 81 K. Selecting the Right Rope for the Job 81 3.04. Blocks 82 A. Hemp-Rigging Blocks 82 B. Loads 85 C. Head Blocks 86 D. Loft Blocks 88 E. Spot Blocks 88 F. Mule Blocks 88 G. Idler Pulleys 88 x H. Sag Bars 88 I. Snatch Blocks 88 3.05. Pin Rail 92 A. Fixed-Pin Rail 92 B. Loose-Pin Rail 92 C. Single-Pin Rail 92 D. Double-Pin Rail 92 E. Pins 92 F. Tying Off 94 3.06. Sandbags and Arbors 97 A. Attaching Sandbags and Arbors with a Sunday 99 B. Attaching Sandbags and Arbors with a Trim Clamp 100 3.07. Jack Line 101 3.08. Spot-Line Rigging 101 A. Positioning Loft Blocks 101 B. Positioning Head Blocks 102 C. Fleet Angle 102 D. Aligning Blocks 103 E. Running Rope 104 F. Attaching Weight to Rope 104 3.09. Operation of Hemp Rigging 104 A. Safety Inspection of All Components 104 B. Untying a Line Set 106 C. Attaching Loads 106 D. Removing Loads 107 E. Trim Marks 107 F. Lashing with Small Tie Line 108 G. Retrimming 109 H. Coiling and Dressing 109 I. Showtime Operation 110 3.10. Operation Summary 110 3.11. Historical Summary 110 xi PART 4. COUnTERwEIGHT RIGGInG 112 4.01. Introduction 112 4.02. Single-Purchase Counterweight System 113 4.03. double-Purchase Counterweight System 114 4.04. Miscellaneous Hardware 115 4.05. wire Rope 116 A. Properties of Wire Rope for Stage Rigging 116 B. Construction of Wire Rope 119 C. Grades...