Feed circuit for railway braking systems

A feed circuit for feeding a railway train braking system and usable in conjunction with a compressed air system or with a vacuum system, the feed circuit including an air compressor (1) and being characterized in that it further includes a static vacuum pump (14) powered by the compressed air delivered by the compressor.

The present invention relates to a feed circuit for feeding a railway train 
braking system, including an air compressor and providing either 
compressed air or else a vacuum. 
BACKGROUND OF THE INVENTION 
Although locomotives are always fitted with compressed air braking systems, 
a portion of the rolling stock available on some railway networks is still 
fitted with vacuum brakes while the remainder has compressed air brakes. 
The locomotives in use on these networks must therefore be capable of 
providing braking for trains fitted with vacuum brakes or for trains 
fitted with compressed air brakes. Since the flow rate of available vacuum 
pumps is limited, it is sometimes necessary to provide a locomotive with 
two vacuum pumps in addition to a compressor. This means that a locomotive 
needs three piston apparatuses to be installed thereon, which can give 
rise to problems of mass, of bulk, and of cost. These three apparatuses 
together with associated means are bulky, and they become difficult to 
drive using pulleys and belts within the restricted space available. 
The object of the present invention is to provide a feed circuit for 
railway braking systems which can be used equally well with trains made up 
of rolling stock braked by compressed air or with trains made up of 
rolling stock braked by vacuum, with said feed circuit being more compact 
and lighter than prior circuits, and additionally reducing vibration and 
reducing maintenance operations. 
SUMMARY OF THE INVENTION 
The present invention provides a feed circuit for feeding a railway train 
braking system and usable in conjunction with a compressed air system or 
with a vacuum system, the feed circuit comprising an air compressor and a 
vacuum pump which is a static pump and which is powered by compressed air 
delivered by the compressor.

MORE DETAILED DESCRIPTION 
A high capacity compressor 1 is connected by a hose 2 to a cooler 3 and 
then via a duct 4 fitted with a safety valve 4A to an air dryer 5. The air 
dryer feeds a compressed air supply tank 7 via a retaining nonreturn valve 
6. 
This makes it possible to reduce the frequency of compressor operation. The 
tank 7 feeds the main compressed air duct 9 via a connection pipe 8, with 
said main duct feeding the locomotive brakes with compressed air and also, 
optionally serving to feed the braking circuit of the train. 
Regulator means 10 connected to the compressed air duct serve to start up 
the compressor whenever the pressure in the duct falls below a minimum 
value. 
In addition, the compressed air duct feeds a static vacuum pump 14 via a 
pipe 11, a valve 12, and an expander 13. the static vacuum pump does not 
include any moving parts and as a result it produces much less noise and 
vibration than does a piston pump. In addition it is compact. The vacuum 
pump is connected via an interrupting non-return valve 15, and a filter 16 
to the general vacuum duct 17 suitable for connection to the vacuum-braked 
rolling stock of some trains.