Answer Questions 15.1 through 15.23

EXERCISES AND STUDY QUESTIONS 15.1 Explain the term point of operation. 15.2 Name several types of mechanical hazards on machines in general. Which is the most important from a safety standpoint? 15.3 Identify several examples of in-running nip points. 15.4 Name two ways of safeguarding a machine that require no physical guard or device at all. What is the difference between these two methods of safeguarding? 15.5 What is a lockout? How does it differ from an interlock? 15.6 What are the disadvantages of nylon mesh guards for fans? 15.7 The stopping time of the ram on a certain part-revolution press has been measured to be 0.333 second. At what minimum safety distance should a presence-sensing device be placed? 15.8 A popular mechanical power press has a full-revolution clutch and 14 engagement points on the flywheel, which rotates at 90rpm. At what minimum distance from the point of operation on this press should a two-hand trip device be placed? 15.9 Name some reasons why a machine might have bolt holes in its feet. 15.10 Name several types of safeguarding devices for the point of operation. 15.11 What is the difference between an interlocked-barrier guard and a gate? 15.12 What is the difference between two-hand controls and two-hand trips? 15.13 What is the difference between type A and B gates? 15.14 What is the advantage of Allen-head screws over wing nuts for machine guards? 15.15 A guard has a maximum opening size of 3/4 inch. The guard openings are 6 inches from the danger zone. Does the opening size meet requirements? 15.16 What is an awareness barrier? What is a jig guard? 15.17 Explain the terms full revolution and part revolution as applied to press clutches. Which is safer? 15.18 What is muting of safeguarding devices, and when is it permitted? 15.19 What is the principal reason that galvanized wire mesh is a better material for constructing machine guards than is ordinary screen mesh? (Hint: The answer is not rust prevention.) 15.20 What is the biggest disadvantage of pullbacks? 15.21 What is the difference between pullbacks and restraints? 15.22 A part-revolution clutch press has a brake stop time of 0.37 second. At what minimum distance should two-hand controls be placed? 15.23 Where should a presence-sensing device be placed on the press of Exercise 15.22