326 MARIENFELDE-ZOSSEN ELECTK1C-RA.ILWAY TRIALS, 



beginning 3.8 meters; this has been increased up to 5 meters in con- 

 nection with the recent successful trials. The distance between the 

 centers of each two trucks is 13.3 and 14.3 meters, respectively, and 

 the diameter of the wheel tread 1.25 meters. Two springs are placed 

 against the axle boxes, namely, one plate spring, 1..5 meters in length, 

 abov^e each axle })ox, these plate springs ])eing in turn maintained at 

 their ends by spiral springs, the tension of which is regulated by 

 means of screws. As the trucks, in connection with the earlier exper- 

 iments, followed au}^ deviation in the direction of the track, the dis- 

 tance of the wheels, as above said, was increased to 5 meters, and the 

 bearing springs placed so as to be visible and connected with one 

 another by compensating levers. The center bolts, which formerly 

 were rigidly fixed to the lower frame, were in the course of the recent 

 reconstruction provided with lateral pegs fitted with springs, so as to 

 pre\'ent any transmission of the oscillations of the body to the frame. 



The connections of the cars.-^Uhe, connections of the cars are shown 

 in plate iii. In the AUgemeine Elektrizitats Gesellschaft car, the 

 currcnit is led b}^ means of armored cables from the two groups of col- 

 lectors to the main switch in tlie machine room and thence by separate 

 conductors to the transformers. The main cut-out switch is operated 

 only after the run is completed, or as an emergency switch in case of 

 disturbances occurring during the run. From the transformers the 

 low-tension conductors lead through the main controller to the motors. 

 The main controller is also placed in the machine room of the car, 

 being easily actuated from each driver's stand through a steering wheel 

 connected by toothed gearing to an axle traversing the whole length 

 of the car. This controller directs the working current to the motors 

 and through the resistances, and permits forward and reverse running, 

 besides providing for the braking of the car by means of reverse cur- 

 rent. There is in addition a small controller in the driver's stand, 

 conveying low-tensLon current from the transformer to the motor for 

 operating the air compressor in connection with the compressed-air 

 brake. 



The connections in the Siemens & Halske car are somewhat different, 

 the high-tension current being first conveyed to one of the two main 

 switches for forward and backward running, which may be controlled 

 from the driver's stand, and thence to the two large transformers, 

 whence the working current is again conveyed through individual 

 switches toward the motors and the resistances. From the main con- 

 ductors on the roof of the car, part of the current is in addition branched 

 off toward the small transformer placed above the motorman's stand, 

 and conveyed to the electric motor operating the two air pumps. Two 

 special cranks are provided in the motorman's stand for actuating the 

 reversing switch and the motor switch, respectively, the working re- 

 sistances being controlled by the driver through a special controlling 



