SAFETY IX WINDING OPERATIONS. 20g 



that the w inchiig-druiu has hecome uncontrolled, ht-ing in-hand 

 neither hy the clutch nor hy the brake. 



Overwinds or runaways due to defective plant amount to 

 about 14 per cent, of the total, that is to say. nine out of the 

 average of 62 may be so classified. The two chief causes of this 

 class of accident are: (i) Troubles with the reversing or control 

 lever ; correct design and regular examination should provide 

 against these. ( 2)F"ailure of the depth indicator to record j^roperlw 

 Chain and sprocket drives have been mostly at fault. They should 

 be watched and the chain not allowed to become too slack. In 

 the one or twti instances where rod and pinion drives have failed, 

 the keys <»f the wheels have been allowed to become slack and 

 drop out. Here again watchful care should be exercised. It is 

 reall}- doubtful in some of the cases just mentioned, and others in 

 which the .locking devices of clutches or brakes have failed, 

 whether the accident should not really have been attributed to the 

 driver's deficiency in the matter of close insj^ection of the j)lant 

 m his charge. 



There have been a few instances of the failin-e of friction 

 clutches due to the iractru'e of some of the parts transnu'tting the 

 l)ressure from the toggle to the eyes of the clutch bands. If the 

 adjustment of the toggle is set incorrectly, so that the toggle lever 

 approaches the vertical, these ])arts and the bands themselves 

 may be stressed to the breaking point. The adjusting bolt at the 

 fixed end of the bands also re(|uires some freedom of motion in 

 its attachment to prevent the occurrence of dangerous repeated 

 bending stresses. Occasional annealing of these parts is also 

 desirable. Engineers who have to deal with this class of clutch 

 are, however, generally aware of the necessity for these precau- 

 tionary measures. In this connection the accident in 191.^ at the 

 " Edgar's " shaft of the Mysore ( lold Mine may be mentioned, 

 in which 42 persons were killed outright. 



Deducting from the total of 62 — 9 ^= 53, a small number of 

 accidents due to miscellaneous causes, such as faulty signalling, 

 physical incapacity, or distraction of attention of driver, etc., 

 etc., it a])pears reasonable to regard 50 overwinds or runaways 

 as being the average number that occur annually due to the 

 faults or omissions of the winding-engine-drivers. 



These may be classified as follows :— 



1. Starting to lower with the reversing lever in the position 



for raising. 



2. Proceeding too far at the conclusion of the wind in either 



direction. 



3. .Allowing a drum to run away through faulty application 



of clutch or brake. 



Dealing with Class i, it has to be noted that this fault has 

 been somewhat checked dtu'ing recent years owing to the intro- 

 duction of Philip's patent safety device. This invention links up the 

 reversing lever, or some part of the gear, with the ])ointer of the 

 depth indicator by means of an electric circuit, which remains 



