SAFETY IX WINDIAC Ol'liKATIONS. _' 1 



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automatically, with success, by such i^ears as the " Whitniore," 

 the " \'isor," and others. 



There are ditiiculties in the \va}- of comijlying with (a), i'his 

 operation must not be too gradual or winding speed is sacrificed. 

 The only successful ai)paratus in use on the Rand for this purpose 

 appears to be that htted to several of the \\'ard-Leonard sets. 

 'J he operating cams in these instances ar;.' readily adjustable 

 to suit various conditions of winding, in tiie case of Ward- 

 Leonard hoists, the speed that the conveyance travels, whether 

 empty or full, downward or upward, is i)ractically fixed for any 

 definite position of the control lever, and in api)roaching i or 

 when at) the neutral, there is consideraljle braking effect, due to 

 the regenerative action of the motors acting as generators. 



The three-phase winding-engine resemljles more the steam- 

 winder, in that the s]:)eed for any position of the contrcr] lever 

 depends on the load as well as on the extent to which resi>tance 

 IS applied in the rotor circuit. The eddy-current brake, howeven 

 if applied to either of them would, inde])endent of the 1; ad or 

 direction of motion, so redtice the speed of the drum tiiat the 

 mechanical brakes, if automatically applied, would effectively 

 prevent an overwind. The E.C. l^rake should, of course, also be 

 automatic in application, both for overspeeding and for o\er- 

 winding. 



The automatic apparatus for either (a) or {b) has, except in 

 the case of winding ])lant used solely for persons, to be set and 

 reset, to provide for the journey to and at, either the collar of the 

 shaft or the tip, and this setting should not be " permissive," but 

 " compulsory " on the part of the engine-driver, or absolutely 

 out of liis hands. There are two or three local inventions installed 

 embodying this principle, or some approach to it. It is therefore 

 very desirable that the working of these appliances be en(iuired 

 into, and that those found to be really reliable should be brought 

 into general use. 



Tt has been oljserved that the induction motor in regard to 

 its suitability for speed control against overwinding is not so w cH 

 fitted as the direct current winder, but attention may be directed 

 to a description of three devices designed to eff'ect this pur])ose 

 contained in an article entitled, " Electric \\Mnding for Mines," by 

 W. I\. Evans, R.Sc. (Eng. ), ptiblished in the Mining MiU/a.cinc, 

 London, September, 1917. It is to be ho])ed that the a])p1icability 

 (if these inventions, under the conditions of winding on the Rand, 

 will l)e seriously considered, and that a suitable apparatus ma\- be 

 installed for trial before long. 



With regard to (7^) and (c) of Class 2, the author can only 

 advertise the necessity for invention in respect of the ])revention 

 of these contingencies, and regret that up to the ])resent nothing 

 satisfactory has to his knowledge been suggested. 



The contingency referred to in (d) of Class 2 has l)een so 

 ably dealt with by Mr. G. K. Chambers, in his paper on " The 



