2T4 SAFETY IN WINDING OPERATIONS. 



braking of high-speed winding-engines,"'* that it appears quite 

 unnecessary to add anything further on the point, except to 

 recall that Mr. Chambers was not in accord with the arrangement 

 as installed on the winding plant which he was describing, whereby 

 the failiu-e of current led to the automatic apjjlication of the 

 inechanical brakes, the eddy-current brake being available for 

 hand application by the driver, lie ])referred the reverse of this 

 proceeding. 



Class 2 {e) deals with a class of accident which is fortunately 

 very rare, and which no properly-trained driver is ever likely to 

 cause. An automatically-operated overspeed device, bringing an 

 eddy-current brake into action, would of course prevent harm 

 resulting. 



With regard to Class 2 (/), a safety ])recaution might easily 

 be applied to prevent the control or reversing lever being moved 

 into the downward position when the opposite clutch is " out.'' 

 This might possibly, under some circumstances, hamper the driver 

 in his handling of the engine when just starting to lower. 



With further reference to Class 3, it remains to be stated 

 that it is a growing practice to interlock the levers on the operating 

 systems of the brake and clutch in a similar manner to that 

 adopted on the railways to link up signals and ])oints. This is 

 effected in many diti'erent ways, there being no standard method, 

 each winding-engine receiving api)ropriate treatment. Where the 

 clutches are operated by steam, it is better for the pin-pose of the 

 lock to utilise the movement of the clutch itself, and not merely 

 that of the slide valve of the clutch engine. Sluggish action of 

 this engine is then provided against, and it becomes impossible 

 to luiclutch a drum unless the corresponding brake is properly 

 applied. 



A runaway drum, es])ecially if of the cast-iron variety, is a 

 very dangerous hap])ening, similar to a flywheel explosion. The 

 whole winding-rope is usualh- lost ; much damage may be caused 

 to shaft, track, and timbering, and, if the drum fractures when 

 the rope has run out to the end, there is great likelihood of tlie 

 engine-room being comi)letely wrecked. 



The Eddy current brake j^rnvides an ideal method of safe- 

 guarding unclutched drums. Mr. Chambers suggested that with 

 steam-winders the existing current for the brakes could be conve- 

 niently obtained from a small direct converted steam-driven 

 generator, situated in the engine-room itself, but it has to be 

 remembered that on several of the older mines, where steam 

 winding prevails, direct-current clectricit\- is imiuediately avail- 

 able. 



The Kddy current 1)rake does not actually stop all motion, 

 but it brings down the speed to a low value, so that counter 

 current or the mechanical brake can be used safely and success- 

 fully to bring the drum or the hoist to rest. 



*Journ. S.A. Assoc, of Engineers. Nov. 1912. 



