HANDLING OF EAW MATEEIALS. 



323 



be judiciously employed when the tonnage and the difference in 

 level warrant it. For average tonnage and less, and for vertical 

 differences in level up to about 6 to 7 metres, a special system of 

 automotor car with crane is used such as shown in Fig. 61. It will 

 be seen in that figure that between the bin and the car properly so 

 -called there is geared an electric crane with its commutators, mag- 

 netic brake and different arrangements to render the whole of the 

 necessary manoeuvres automatic once the current is applied to the 

 whole of the car. By this system and by the aid of complementary 

 arrangements of the line, the whole of the car can be arrested in any 

 desired point of its course to pass the 

 current automatically from the upper 

 translating motor to the lower motor of 

 descent, and of lifting, driving the crane 

 a,t will ; automatically to tilt the bin of 

 its contents by the action of the electro- 

 magnet and its lifting crane, after which 

 the empty bin coming to its highest posi- 

 tion acts at the same time on a contact 

 which again causes the current to pass 

 from the elevating and descending crane 

 to the propelling crane, and the whole of 

 ■the car starts in motion again to return 

 to the place where the bins are filled. 

 The latter are filled by themselves at the 

 hopper by a manoeuvre, say exchanged 

 against others filled between times in the 

 course of the journey of the preceding 

 ones. In general, these automotor cars 

 consist of two cheeks of cast-steel firmly 

 held together by cast-iron cross-pieces be- 

 tween which are lodged crucible cast-steel 

 pulleys with deep grooves, the bosses of 

 which turn freely on axes of phosphorous 

 bronze acting as lubricating reservoirs. 

 A wheel gearing with the steel pinion of 



the electric motor is fitted on the outside of one of these pulleys, 

 and on the boss of the other a brake pulley is mounted, the band 

 of which stretched on a powerful spring, on the type of a coach- 

 spring, is automatically liberated when at work by an electro- 

 magnet. There are a very large number of these types of electrical 

 cars, so as to respond to the different problems occurring in in- 

 dustry. For example. Fig. 62 shows a special system of car for 

 spanning very sharp curves. There will also be seen from the 

 figure the difficulties which had to be surmounted in a factory 

 the free space of which at this point is restricted, as shown in 



Fig. 61. — Special Automotor 

 Electric Car with Crane. 



