September 28, 1883.] 



SCIEXCE. 



421 



The American brake couipanj- of St. Louis, 

 Mo., exhibited full-sized working-models of a 

 brake of tiiis class. 



Between tlie floor-sills, and at the inner end 

 of the drawbar, is hung a bell-crank lover, B. 

 which carries in one of its jawed ends the pnsh- 

 bar.d, and, in the other, doiible-pull rods carry- 

 ing a spiral spring transmitting the strain to 

 bell-crank levers, D,D. snspcndcd from the sills 

 by hangers, C,C. The bell-cranks D,D. are 

 connected to the brake - beams ; and conse- 

 quently compression on the draw-head acting 

 on the lever ^-1 causes the brake-shoes to be 

 pressed on the wheels, the amount of pressure 

 being regulated by its transmission through the 

 spiral spring. But, since a brake simply made 

 ■as above described would not admit of a train 

 being backed, a device is attached which re- 

 moves the objection, and. fur- 

 tlier, onh' allows the brake to 

 be applied when the car is 

 moving at a speed alwve six 

 miles per hour. 



The push-bar A can only 

 come in possible contact with 

 the draw-head by the centrifu- 

 gal force of governor-balls at- 

 tached to the axle. These 

 balls, E,E. are attached by 

 means of links to a movable 

 disk, F, encircling the axle. 

 One end of a lever, O, boars 

 against the disk, and the other 

 end is connected bj- means of 

 rods, etc., to the push-piece A. 

 AVhen the car is running at 

 speed, the governor-balls draw 

 the disk towaids tliem, leaving 

 the lever G free to follow it. 

 and permitting the push-bar A to drop behind 

 the draw-l)ar, when the brake is ready for ac- 

 tion, going on din^ctly the draw-gear is put in 

 compression. AVhen the speed falls below six 

 miles an hour, the centrifugal force of the 

 governor-weights becomes so feeble, that a 

 spring (not shown in the illustration) restores 

 the disk to its former i)Osition. lifting the push- 

 piece A clear of the draw-head. 



The brakes can be released at any time by 

 the engineer putting on steam, and giving a 

 pull to his train ; and the train can be backed 

 from a state of rest without the brakes going 

 on, the push-piece A lying on the draw-head, 

 but being unable to fall behind it. 



The engineer can apj)ly the brake, when 

 l)usliing the train, by momentarily applying 

 th(! lirake on the engine or tender, thereby 

 ])utting the draw-gear in tension, and letting 



the lever A fall behind the draw-head. When 

 steam is again put on, the consequent com- 

 pression applies the br.ake. 



This brake has been in use for some time on 

 the St. Louis and San Francisco and man3- 

 other railroads, and appears to give very satis- 

 factory results ; the wear being very small, 

 wliile the fn-st cost is low enougli to allow of 

 its extensive application to freight-cars. 



The brake exhibited bj' the Tallman auto- 

 matic car-brake company of New York also 

 acts by the compression of the draw-heads, 

 which force together two friction-wheels, one 

 of which is keyed on the axle, and the other is 

 geared to a drum winding u|) the brake-chain. 

 A ratchet-wheel, which can be shifted by hand, 

 prevents the brake from acting when the train 

 is backed. 



.SUTOMATIC BRAKE. 



The AValdumer electric I)rake company of 

 Chicago exhibited a working-model of a verj- 

 jiromising form of continuous brake, which is 

 just emerging from the experimental stage. 

 The weak point of all continuous brakes has 

 been the conveyance of the 0|)erating force 

 — compressed air, vacuum, hydraulic power, 

 etc. — along the length of a train, the pipes 

 and couplings being generally expensive, and 

 formed partly of perishal)le substances, while 

 chains are unsatisfactory from .every point 

 of view. JIany brakes that work well and 

 promptly on a short train become slow and 

 irregular in their action, when applied to a 

 train of thirty- or more vehicles. The instan- 

 taneous action of electricity, and the simplicity 

 of the moans used for its transmission, make 

 it i>rol)able tiiat an electric brake would be 

 especially suited for long freight-trains. The 



