192 



CONTINUOUS EAILWAY BTIAICKS. 



vacmim reservoir, and tlie brakes are applied by tlio cx> 

 ternal atmosj)heric pressure on the lower side of the brakq 

 piston. 



As to the merits of the " Hardy," it complies with Board 

 of Trade requirements. The use of a vacuum reservoir of 

 large dimensions, an absolute necessity, is a drawhach, as 

 is also the use of a diaphragm valve with double seat. 



It will be seen that the movement of the valve depends 

 on the pressure on the diaphragm ; and the direction in 

 which it moves the brake determines whether the brake is 

 going " on " or " off." 



The " Hardy " brake is heavy, and all the parts are large, 



The " Westing irousE" Pressure Brake. 



In the " Westinghouae " automatic pressure brake, the 

 use of a separate reservoir attains its best results, as 

 the use of "differential" pressures does in the case of the 

 automatic vacuum brake. The results obtained by the 

 " Westinghouse " brake have not been equalled in any other 

 system. The following is a brief description of the -brake. 



An air-compressing pump, worked with steam from the 

 engine, forces air into the main reservoir on the engine. 

 Prom the main reservoir a pipe leads by way of the driver's 

 brake valve to the continuous train-pipe, which, by means 

 of branch pipes, communicates through the " triple " valve 

 with the auxiliary reservoirs under the carriages. 



Each reservoir communicates with its brake cylinder also 

 by way of the " triple " valve. 



Supposing, now, tlio main reservoir to be stored, and tlio 

 air-pump to be working slowly, and the brakes to be " off," 

 the train-pipe and auxiliary reservoirs being all charged. 

 The pressure in the main reservoir is about 15 lbs. higher 



