MARIENFELDE-ZOSSEN ELECTRIC-RAILWAY TRIALS. 329 



and regulating the speed of the motors. Below the resistance boxes 

 there are the exciter rollers placed long-itudiually and bearing bronze 

 contact pieces; the corresponding contacts are attached to tv.o steel 

 tubes placed one beside the other and isolated from them. In order 

 to avoid any such disturbances as would attend on an a))rupt increase 

 in collecting the current, the single contacts are inserted not simul- 

 taneously but successively. The exciting rollers are actuated through 

 a longitudinal spindle traversing the whole of the car, rotated from 

 the driver's stand Ijy means of a conical toothed gearing. In order to 

 facilitate the handling of this controlling device, there is a compressed- 

 air apparatus assisting the driver in starting and reducing automaticall}' 

 the exciter to its zero position if the current has to be switched oil'. 

 By means of a special gearing the controlling may be eliected also 

 without the aid of compressed air. 



The trlala. — In connection with the trials made in the course of the 

 fall of 1901, speeds as high as 150 kilometers, and even in one case 160 

 kih)meters, were obtained. As, however, rather material oscillations 

 and shocks were experienced even at speeds of 110 kilometers per hour, 

 no further increase of the speed was thought advisable for the moment, 

 the remainder of the year being given up to veiy valual)le measure- 

 ments and records on the consumption of electric energy. The 

 acceleration obtained after starting was different according to the strain 

 the source of power was put to and the performance of the motors. 

 In order to attain speeds of 100 kilometers, starting distances of 2,000 

 to 3,200 meters, and starting times ranging between 138 and 220 seconds 

 were necessar}^ these figures corresponding- with a mean acceleration 

 as high as 0.13 to 0.20 meters per second. As, however, the motors are 

 capable of supplying for short intervals about 3,000 horsepower, 

 whereas for the above acceleration only TOO to 1,000 horsepower are 

 required, this represents b}^ no means, an upper limit. 



As regards the braking of the (uirs, ))oth cars maybe stopped either 

 ])y means of Westinghouse rapid brakes, hand brakes, or using back 

 current; the Allgemeine P^lekti'izitilts (xesellschaft car is in addition 

 fitted with an electric brake. The Westinghouse and electric brakes 

 may be operated from each motorman's stand sinudtaneously, though 

 the ))raking eciuipments are independent for either of the trucks. In 

 the case of an aii- pressure as high as 6 atmospheres in the braking 

 cylinder, two of which' are placinl on (»acli truck, the pressure on each 

 of the 24 l>raking shoes arranged on both sides of the wheel is about 

 0, »>(»(> kilograms, the l)raking shoes thus receiving a total pi'cssure as 

 as high as 114,000 kilograms — 150 per cent of the weight of the 

 Ciirriage. * * * 



After the trials made in the course of lOdl, a thorough rebuilding 

 of the track, as above stated, was found necessar}-. This occupied 

 part of the year l'J02, the remainder of wiiich w^as taken up in the 



