2jO safety in winding operations. 



open normally, but becomes closed if the reserving lever is not 

 in the correct i)osition when the cage or skip enters the " danger 

 zone." When the circuit is closed, an electric hooter or loud- 

 sounding bell comes into operation close to the driver. 



The chief reason that Philip's safety device, although litted, has not 

 prevented accidents in many cases, is that, as most of the licensed winding 

 plants are used for ordinary rock hoisting as well as the conveyance of 

 persons, the contact whicli closes the circuit has to he set for the tip. 

 that is, unless there is a two-way switch in the circuit to be operated by 

 the driver when the conditions of hoisting alter. If there is no such 

 switch, and the driver does start to lower with lever in the wrong direc- 

 tion, a certain amount of speed is acquired before the warning is given, 

 and an accident is not averted. This also may occur if the device is set 

 too "coarse," as it may be in some cases where a "fine" adjustment leads 

 to a frequent blowing of the hooter, which irritates the driver. Incident- 

 ally it may be remarked that optical warning signals, such as a red li.ght, 

 have been found to be of little effect for the circumstance under consi- 

 deration. The htting of the two-way switch is not itself sufficient for 

 the change-over may be forgotten. It is really necessary to interlock this 

 switch with another one in the bell circuit, so that reply, " three bells." 

 signifying that persons may enter the cage, cannot be given by the driver 

 unless he has set the Philip's device for the bank. Exact adjustment is 

 not ahvaj's possible, owing to slack motion on the reversing and indicating 

 gears, and, unless the warning is given directly the lever is out of the 

 neutral, it is too late to be of service. Failures also have occurred through 

 rope grease being thrown on to the contact plates, cither at the Iiack of the 

 indicator dial or on the driver's platform. 



Class 2 must be sub-divided for full consideration. Sixteen 

 years' experience guides the author to the following classifica- 

 tion : — 



(</) Driver, in raising or lowering, neglects to apply the means of 

 control early enough when nearing the end of the trip. This 

 may be due to " driver new to the engine," forgetfulness, 

 mental aberration, preoccupation, or some sudden physical dis- 

 ability. The results are usually very serious. The loss of life 

 may be very great, as in the case of the Brakpan Mines 

 disaster in 1915; or when persons have not brippened to be 

 travelling, great damage to plant may ciccur. tlie top of the 

 headgear being taken clean off. as in the " Rmulcixiort United" 

 accident in 1913. 



(b) After changing winding from a higher ti) a lower level, the 

 engine-driver may forget the fact, and. watching only the 

 " down " indicator, occasion an overwind at great speed on 

 the other side. A variant of this class is provided by the case 

 of the driver forgetting to unclutch. and fancying tliat he has 

 done so, as was the case ;it Xo. 8 Ivandfontein, in 1017. wlien 

 the headgear was decapitated. 



(<" ) After changing the conversance from skip to cage, tiie driver 

 forgets the fact, or the driver fails to remember tliat the skip 

 has Ijeen loaded with persons on an occasional trip. 



<(/) Lowering unbalanced, with electric winder on counter current, 

 tjoo great speed developed, or too sudden application of 

 reverse current, tripping of switch of stator current, and failure 

 of single brake to control the runaway drum. 



(e) Lowering with steam winder on compression, with reversing 



lever against the motion, too nuich compression created, cage 



stopping too soon or descending too slowly, when the driver 



puts reversing lever over to the other position without safe- 



4 guarding the motion with the brake- 



