US2229498A

US2229498A - Compressed air conditioning apparatus

Info

Publication number: US2229498A
Authority: US
Inventors: Clyde C Farmer
Original assignee: Westinghouse Air Brake Co
Current assignee: Westinghouse Air Brake Co
Priority date: 1939-04-27
Filing date: 1939-04-27
Publication date: 1941-01-21
Anticipated expiration: 1958-01-21

Description

Jan. 21, 1941. c. c. FARMER COMPRESSED AIR CONDITIONING APPARATUS Filed April 27, 1939 5 Sheets-Sheet l l ATTORNEY R J a w l gm t T m N P w c N Q m JLJ U 1 Q c m N mm x R R E: 3 3 3: MN N2 3. m i i 5 g mm U x Q Q Q Q 5 x ewm MU mm 3 2. m2 m Nu Nw wwm R. E m m? E m Q w 3 v u g m2 mm Q & a W G mw v .3 3 8 a R i Q 3 L2 m, 2 3 mm mm 3 i E, U Q t @P Jan. 21, 1941. c. a. FARMER CQMPRESSED AIR CONDITIONING APPARATUS 3 Sheets-Sheet 2 Filed April 27, 1939 INVENTOR C LY DE C. F'ARME R *2 AS wS N3 02 We ATTORNEY Jan. 21,1941. Q Q F M 2,229,498

COMPRESSED AIR CONDITIONING APPARATUS Fild April 27, 1939 :ssheets-sheet s i atentec I Jan. 21, 1941 PATENT OFFICE COMPRESSED AIR cgggrrronmo APPARA- Clyde 0. Farmer, Pittsburgh, Pa., assignor to The Westinghouse Air Brake Company, Wilmerding, Pa., a corporation of Pennsylvania Application April 27, 1939, Serial No. 270,286

at; 12 Claims.

This invention relates to compressed air conditioning systems and more particularly to an improved apparatus for dehydrating and purify ing air under pressure for use in air brake systems and the like.

The water vapor content of air which has been drawn from the atmosphere and compressed for use in a railway air brake system is usually relatively high, and must be reduced by precipitation from the air before it is supplied to the pipes leading to the brake controlling valve devices ofthe brake system, in order to prevent 'accumulationl of water in the system in such quantitiesfas'might destroy the lubricant in the various valve mechanisms or result in frozen pipes during cold weather.

One object of my invention is to provide an improved apparatus adapted to be associated with the usual compressor and main reservoir equipment of a locomotive for cooling and dehydrating the compressed air, and including means for preventing the apparatus from becoming clogged or frozen during cold weather.

Another object of my invention is to provide a compressed air dehydrating apparatus adapted to be carried by a vehicle and comprising condenser means, means for injecting a solvent such as alcohol into the condenser to free it from ice orforeign matter, heating means for the condenser, and a control device operative when the condenser becomes clogged to effect initial operation of the injecting means and subsequent operation' of the heating means, until the con- 35 denser is again conditioned to permit free flow of compressed air.

Other objects and advantages of the invention will be apparent in the following description thereof, taken in connection with the accom- 40 panying drawings, in which Fig. 1 is a diagrammatic view of one form of compressed air conditioning apparatus C011! structed in accordance with the invention, the

' essential elements being shown in section;

45 Fig. 2 is a diagrammatic sectional view of a similar apparatus embodying the invention in another form;

Fig. 3 is an enlarged detail, fragmentary view of the cooling conduit shown in Fig. 2;

apparatus of the above class constructed in accordance with still another form of the invention; and

Fig. 5 is a fragmentary sectional view, in enlarged detaiLof the cooling coil shown in Fig. 4.

Fig. 4 is a diagrammatic sectional view of an Apparatus shown in Fig. 1

The apparatus shown in Fig. 1 of the drawings is adapted to be carried on a locomotive, and comprises a steam driven compressor l0, main reservoirs H and I2, a cooling condenser assembly l3, a control device I4, 9. liquid pump l5, and the usual air brake equipment represented by a brake valve device H3.

The compressor I0 is ofthe well known Westinghouse type and is adapted to be operated by steam supplied by way of a steam pipe 20, for supplying air under pressure through a pipe 2| to the main reservoir ll.

Interposed between the main reservoir II and. the reservoir I2 is a conduit 23, which has a coiled section 24 mounted in a chamber 25 that is formed within a body 26 of the condenser assembly I3. The body 26 is provided with an exterior insulating jacket 21, and has formed in the lowermost portion thereof an inlet opening 28 communicating with the atmosphere by way of a duct 29 which is preferably mounted on the locomotive at a point remote from any heat radiating surfaces thereof. An interior wall or lining 26a for the casing 26 having spiral'corrugations or grooves is provided for facilitating circulation of air admitted to the chamber 25 through the duct andopening 23. Mounted in the upper portion of the condenser assembly I 3 30 is a blower or fan 3|, which, when supplied with electric'current as hereinafter explained, is operative to draw the air through the chamber 25 and outwardly by way of a passage 32.

The main reservoir I2 is adapted to collect water condensed from compressed air passing thereto from the coiled section 24 of the conduit,'and is provided with an automatic drain valve device IT for discharging the condensate at intervals. The drain valve device I! may be of any suitable type and as illustrated comprises a. unit similar to that shown and described in the U. S. Patent 2,125,144 issued July 26, 1938, to B. S. Aikman. If. desired, a heat insulating jacket 33 may be secured about the main reservoir I2 for preventing heat radiated from the boiler of the locomotive from warming the air under pressure contained within the reservoir.

The liquid pump 15 comprises a casing 36 having a bore 31 formed therein and communicating by way of a port 38 and valve chamber 39 with the conduit 23, and also connected through a valve chamber 40 and pipe 4| with a reservoir 42 containing a quantity of alcohol or the like. The reservoir may be mounted somewhat higher than the plunger bore 31 to facilitate supply thereto of alcohol. A plunger 44 is'slidably mounted in the bore 3'! and is adapted to be actuated by a piston 45, which is normally held in the uppermost position, as shown, by the force of :a coil spring 46, and which piston is adapted to be forced downwardly upon the supply of fluid under pressure to a chamber 41 formed within the casing.

A ball check valve 48 is disposed in the chamber 40 for preventing back flow of alcohol there-.

from to the reservoir 42. A similar ball check valve 49, disposed in the chamber 39, is normally held in seated position under the force of a spring 50 for preventing back flow of alcohol or air under pressure from the conduit 23 to the bore 31. It will be understood that the alcohol reservoir 42 may be provided with a suitable vent, not shown, for permitting withdrawal of liquid therefrom.

The supply of air under pressure to the piston chamber 41 of pump I5 is controlled through the medium of a magnet valve device 53, which comprises a casing having a valve chamber 54 communicating by way of a pipe 23a with the conduit 23 and containing a valve 55 that is normally urged into seated position under the force of a spring sauna which is adapted to be unseated upon energization of the usual magnet for establishing communication from the valve chamber through a pipe 58 to the piston chamber 41 as hereinafter explained. A valve 51 connected to the valve 55 by means of a fluted stem is provided for normally maintaining communication from the pipe 58 to the atmosphere by way of a vent port 59.

Electric current is supplied to the magnet valve device 53 and to the motor driven blower 3| through separate circuits controlled by a switch mechanism indicated generally at 62, which is operatively associated with the control device I4 hereinafter described The switch device 62 comprises spaced stationary members 63 and 64 having suitable bores within which are disposed the ends of a plunger 65 carrying a suitably insulated contact member 66', which is adapted when the plunger is positioned as shown in the drawings to bridge a pair of contact elements 61, and when the plunger is moved backwardly under the force of the spring 68, to bridge a similar pair of contact elements 69.

With the contact member 66 in engagement with the contact elements 61 as showma circuit is completed forenergizing the motor of the blower device 3|, which circuit includes a gen- .erator or other source of power 12, a conductor 13, the contact elements 51 and 66, a conductor I4, the blower device 3| and a return conductor 15 connected to the generator. When the contact member 66 is shifted to. the other position the above traced circuit is broken and another circuit is established, leading from the generator 12 through the conductor 13,-contact elements 69 and 66, a conductor 11, the magnet of the valve device 53, and a conductor 18 connected to the return wire 15. I

The control device I4 comprises a casing structure having mounted therein a pair of flexible diaphragms M and 82, which are operatively connected by means of an intermediate follower member 83 disposed within a chamber 84 formed between the diaphragms and communicating with the atmosphere. .The diaphragm 8| is subject to the pressure of air in a chamber 85 which communicates with the pipe 230 leading to the conduit 23. The diaphragm 82 is similarly exposed to the pressure of air in a chamber 86 which communicates with a pipe 81 leading from the main reservoir I2 to an auxiliary receiving reservoir 88 and thence to the brake valve device I6 which controls distribution of compressed air to the usual air brake system. A pair of oppositely extending levers 90 and 9| are pivotally mounted onpins 92 and 93, respectively, carried by the casing structure within the chamber 84. The inner ends of the levers 90 and 9! are operatively connected to the follower member 83 by means of a pin 95. The outer end 96 of the lever BI is adapted to engage the adjacent end of the plunger $5 of the switch device 62 whenthe lever and the associated parts ofthe control device are in normal position as shown in the drawings, for thereby maintaining the contact member 66 secured to the plunger in engagement with the contact elements 51.

A coil spring 98 is interposed between the lower wall of the chamber 86 of the control device and a follower member 99 engaging the diaphragm 82 for maintaining both diaphragms, the follower member 83 and the levers 90 and 9| in the I03 normally urged upwardly into engagement with lugs I04 formed on the casing under the force of a coil spring I05. It will be apparent that downward movement of the connected diaphragms 8| and 82 and the associated follower elements will be initially resisted by the coil spring 98, and upon engagement of the stem IBI with the element I03, by the combined fgrces of the spring 98 and of the spring I 05.

The lever 90 of the control device I4 is adapted to operate a steam valve device I08, which comprises a casing having a bore within which is mounted a valve key I09 having an operating arm H0, to which the-outer end of lever 90 is connected by means of a pin III riding in aslot 2 formed in the arm. It will be noted that the terminal portion of the slot I I2 is so aligned with respect to the pivot pin 92 of the lever 90 as to permit an initial movement thereof from the position shown before the pin Ill becomes effective to operate the arm H0 for rotatingv the key I09, this preliminary movement of the elements of the control device I4 being suficient to lift the end 96 of the other lever 9| out of engagement with the switch plunger 55 to permit operation thereof by the spring 68, as hereinafter explained.

In operation, assuming that the several devices s I a i of the apparatus shown in Fig. 1 are initially set L in the position illustrated, steam supplied in the usual manner through the supply pipe 29 effects operation of the compressor III to supply air under pressure through .the pipe 2| to the main reservoir II. From thereservoir H compressed air flows through the conduit 23, and in flowing through the coiled portion 24 thereof is cooled substantially to atmospheric temperature by rea-' son of absorption of heat of compression there-v from into the draft of cooling air, which is circulated through the chamber 25 0f the condenser.

The valve key I09 is adapted to be operated from the normal position illustrated in Fig. 1- to estab-- assembly I3 by operation of the electric blower device 3 I, which is supplied with current through the circuit hereinbefore described. From the cooling coil 24, the compressed air, together with water precipitated therefrom, is carried to the main reservoir I2, from which the precipitate is automaticallydischarged from time to time by operation of the discharge valve device II. The

cool, dry compressed air is then supplied by way of pipe 81 to the auxiliary receiving reservoir 99 and to the usual communications in the brake valve device I6.

It will be understood that during thistime, while the coiled section 24 of the cooling conduit 23 is adapted to permit free flow therethrough of air compressed by the compressor, the pressures of air in both main reservoirs II and I2 and the conduit will be substantially uniform, and that consequently the fluid pressures acting on the diaphragms 8| and 82 in the control device I4 are substantially equalized so that the spring 98 remains effective to hold the diaphragms, to-

gether with the follower member 83 and levers 99 and 9|, in their uppermost position shown in Fig. 1.

During cold weather, however, as moisture is precipitated within the coiled section 24 ofthe cooling conduit 23, a coating of ice may gradually accumulate within the coil, and the resultant clogging thereof may so impede the flow of compressed air as to cause the pressure in the con--' duit 23 and in the upper chamber 95 of the control device to exceed the air pressure in the lower chamber 86 communicating with the outlet end of the cooling conduit.

As the pressure of air in the chamber 85 thus becomes greater than that of air in chamber 88, the associated diaphragms BI and 82 are gradually forced downwardly against the pressure of the spring 98, while the pin 95 carried by the follower member 83 effects rotation of the lever 9| about the pin 93 for causing the end 96 thereof to release the plunger 65 of the switch device 62. The spring 68 thereupon becomes efiective to shift the plunger 65 and the contact member 66 out of engagement with the contact elements 31 and into engagement with the contact elements 69, thus breaking the circuit for the electric blower device 3| and establishing the circuit for energizing the magnet valve device 53.

Upon energization of the magnet valve device 53, the valve elements 51 and 55 are shifted in their lowermost position, against the force of the spring 53, and air' under pressure is then supplied by way of the conduit branch 23a, chamber Y54, and the piston chamber 51 of the liquid pump I5. The piston 45 is thereby operated to move the plunger 44 downwardly in the bore 31, thus forcing therefrom the quantity of alcohol previously drawn into or supplied to the bore by gravity flow fromthe reservoir 42, the alcohol being discharged past the then unseated check valve 49 and chamber 39 into the fluid conduit 23 and thence to the coiled section 24 containing outlet portion of the conduit, so that the diaphragms 9| and'82 and the associated follower members 83 and 99 are shifted further downwardly against the force of the spring 98, and upon engagement of the stem I9I with the elements I93, against the combined forces of the springs 98 and I95. The lever 99 is thereby turned about the pin 92 through an angle sufflcient to efiect cooperation of the pin III thereon with the arm I I9 of the valve device I98, and the valve key I99 is then turned into open position to supply steam from the supply pipe 29 by way of the branch pipe 29a to the chamber 25 within the condenser assembly. Upon circulation of steam about the coiled section 24 of the cooling conduit, the deposit of ice therein is quickly melted so that air under pressure may again be supplied therethroughto the main reservoir I2 in the usual manner.

Upon restoration of air pressure in the chamber 86 of the'control device I4 equal to that in the chamber 85, the diaphragms 82 and 8I are again shifted to their uppermost position by the spring 98, and the levers 99 and 9| are consequentlyoperated to eflect closing movement of the valve key I99 and return of the contact member 66 of the switch device 62 to the'position shown in the drawing, so that the circuit through which current is supplied to the electric blower device 3| is again established. The magnet valve-device 53 is at the same time deenergized, and upon movement of the valves 55 and 51 to their normal position for venting piston chamber 41 of the pump I5, the spring 46 becomes effective to lift the plunger 44 upwardly for again permitting alcohol to flow from the reservoir 42 to the bore 31.

Apparatus shown in Fig. 2

The invention is embodied in somewhat different form in the equipment shown in Fig. 2 of the drawings, which comprises, in association with the compressor I9, main reservoirs II and I 2, and brake valve device IS, a condenser assembly II3, a fluid pressure responsive control device II4, a liquid pump and a steam valve device II6.

The condenser'assembly II3 is similar to the device I3 shown in Fig. 1, and comprises a cylindrical casing structure I29 having interior spirally arranged grooves formed therein and sheathed with an insulating cover I2 I. A cham. ber I22 is formed within the casing I29 and communicates with the atmosphere by way of an inlet passageway I23 and an outlet passageway I24. An electrically operated blower device I25 is mounted in the casing of the condenser assembly II3 adjacent the outlet passageway I24. A cooling coil I28 is mounted within the chamber I22 of the condenser assembly, and communicates by way of an inlet conduit I29 with the main reservoir II and by way of an outlet conduit I39 with the main reservoir I2. In the present embodiment of the invention, the cooling coil I28 is adapted to contain a steam tube I 3I of relatively small diameter, through which tube steam may be supplied to free the cooling coil of ice, as hereinafter explained. As is best shown in Fig. 3 of the drawings, a pipe fitting I33 is interposed between each end of the cooling coil I29 and the adjacent conduit leading to one of the main reservoirs, such as a conduit I39. The pipe fitting comprises a body I32 provided with a neck portion I34 adapted to receive the steam tube I3l and a gasket I39. which is tightly fitted within the neck portion by means of a packing gland I35.

The steam valve device H6 is adapted to control the supply of steam to the tube I3|l and comprises a casing having a valve chamber I38 communication with the tube and containing a valve I39, which is normally held in seated position by the force of a spring I and is adapted to control communication from the steam supply pipe 20 by way of a pipe 20b and through the valve chamber to the tube I3I. The steam valve I39 has a stem MI connected to a piston I42 which is operative, upon an increase on the pressure of fluid supplied to a chamber I43 formed in the casing, to unseat the valve against the force of the spring I00. It will be understood that the pipe 205 may, if preferred, be supplied with steam discharged fromthe operating cylinder portion of the compressor I0.

The liquid pump I I5 comprises a casing having mounted therein a piston I53 adapted to operate a plunger I46 that is slidably mounted in a bore I41 formed in the casing, which bore is adapted to be supplied with alcohol from a supply reservoir I26 communicating therewith by way of a passage I49. The plunger I46 is normally maintained in a retracted position with respect to the bore I41 under the force of a coil spring I5I, and is adapted to be actuated, under the pressure of fluid supplied to a chamber I52 and acting on the piston I53, to move into the bore I61 for expelling alcohol therefrom through a passage I56 and past a ball check valve I55 to a pipe I58, which communicates by way of the conduit I29 with the cooling coil I28. A ball check valve I56 is interposed in the passage I69 for preventing back flow of alcohol from the bore I21 to the reservoir I28.

The control device III comprises a casing structure having mounted therein a pair of flexible diaphragms I60 and NH, which are operatively connected together by a follower member I62 that is disposed Within a central chamber I63 formed between the diaphragms and communicating with the atmosphere by way of an opening I64. The outer face of the diaphragm I60 is subject to the pressure ofair in a chamber I66 communicating by way of a pipe I61 with the inlet conduit I29. The face of the diaphragm IBI opposite that exposed to the chamber I63 is subject to the pressure of air in a chamber I69, which communicates through a pipe I with the outlet conduit I30.

Formed within the casing of the control device I I4 intermediate the diaphragms I60 and I6I is a valve portion I12 having a valve chamber I13, which is connected with the pipe I61 and has mounted therein a relay valve I14 adapted to control communication from the valve chamber to a chamber I15, which in turn is connected by way of a pipe I16 to the piston chamber I43 of the steam valve device I I6. The relay valve I14 is normally held in seated position as shown in the drawing by the force of the spring I18 disposed in the chamber I13, and is provided with a stem I19 extending into the chamber I63 and disposed in operative alignment with a plate I80 carried by the follower member I62. The stem I19 has formed on the outer end thereof a valve portion I8I which is adapted to close communication between the chamber I and the atmospheric chamber I63 when the follower plate I80 is moved into engagement with the stem for unseating the relay valve I14, as hereinafter explained.

The follower plate I60 is also operativel'y aligned with the stem I85 of a plunger I86, which is slidably mounted in a suitable bore in a portion I81 of the casing extending between the associated diaphragms, and which plunger is urged toward the follower plate under the force of a spring I88. Associated with the control device I I5 is a switch I90, which is adapted to control operation of the electric blower device I25 and comprises a spring contact member I9I extending into the chamber I63 within the casing of the control device, and a similar contact member I92 having an insulated end portion engageable with the plunger I86, which is normally adapted to maintain the contact member I92 in engagement with the member I9I, as shown in the drawing. When the switch I90 is thus closed, a circuit is established for supplying current to the blower device I25, comprising a battery I96, a conductor I95, the connected contact members HM and I92, a conductor I96, the motor winding of the blower device I25, a grounded conductor I91 and a grounded battery connection I96.

The control device H6 further comprises a valve portion 209, having formed therein a valve chamber 20I containing a valve 202 which is adapted to control communication from the diaphragm chamber I69 by Way of a. bore 203, the valve chamber 2M, and a pipe 200 to the piston chamber I52 of the liquid pump II5. The valve 202 is normally held in seated position as shown in Fig. 2 under the pressure of a coil spring 206, which is interposed between a cap member 201 secured to the casing and a slidably mounted follower member 208 mounted in a bore in the portion 200 and engaging the valve. The valve 202 has a fluted stem 209 slidably mounted in the bore 203 and extending into operative alignment with the head of a bolt 2I0 carried by the follower member I52 adjacent the diaphragm I6I. With the member 208 in normal position, the piston chamber I53 of pump II5 is connected to the atmosphere by way of the pipe206, a port 2II in the bore containing the member, and a passage 2 I 2 in the cap member 201.

It Will be observed that, when the diaphragms I60 and I6! and follower member I62 are disposed in the normal position as shown in Fig. 2

-of the drawings, the stem I19 is more widely spaced from the plate portion I69 of the follower member than is the stem I85 of the plunger I86, which is thus adapted to be actuated prior to operation of the valve I14 upon movement of the follower member by the diaphragm I60, as hereinafter explained. The fluted stem 209 of the valve 202 is likewise initially positioned so as to be engaged by the bolt 2I0 at substantially the same time as the stem I85 is engaged by the follower plate I80, the valve 202 being thus adapted for operation simultaneously with operation of the switch I90.

Operation of the apparatus under normal conditions will be understood from the explanation hereinbefore presented in connection with Fig. 1 of the drawings, it being apparent that air under pressure supplied by the compressor I0 to the main reservoir II is adapted to flow through the conduit I29 to the cooling coil I26, where the compressed air is cooled due to the draft of atmospheric air drawn through the chamber I22 by operation of the blower device I25, so that moisture carried with the air is condensed therefrom and is collected in the second main reservoir I2, from which the condensate is discharged by the automatic drain valve device I1,

If the cooling coil I 26 becomes clogged with ice. however, the pressure of air in the outlet conduit I30 and main reservoir I2 is gradually reduced below that in the main reservoir II and inlet conduit I29, due to continued supply of compressed air to the fluid pressure brake system, and the pressure of air in the diaphragm chamher I 66 communicating with the conduit I29 is consequently enabled to force the diaphragm I60, follower member I62 and diaphragm I 6| to the right, as viewed in Fig. 2. During initial movement of the follower member the plate portion I80 thereof is brought into engagement with the stem I65 of the plunger I86, which is then moved against the force of the spring I68 to permit movement of the spring contact member I92 away from the contact member ISI for breaking the circuit through which current is normally supplied to the electric blower device I25. Circulation of air from the atmosphere through the chamber I22 of the condenser assembly is thus stopped. At' the same time, the bolt 2I0 is brought into engagement with the stem 209 for unseating the valve 202 and moving the follower member 208 to close port 2 against the force of the spring 206, so that air under pressure is quickly supplied from the main reservoir I2 by way of thepipe I10, chamber I69, past the unseated valve and through chamber 20I and pipe 204 to the piston chamber I52 of theliquid pump I I5. The piston I53 and plunger I46 are thereby actuated to force alcohol from the bore I41 through passage I54, past check valve I55 and through pipe I56 to the inlet conduitl29, from which the alcohol is supplied to the cooling coil If the cooling coil I28 still remains clogged with ice, further increase in the differential between the respective pressures of air from the inlet and outlet conduits I29 and I30 acting on the associated diaphragms I60 and I6I of the control device causes continued movement of the diaphragms and follower member I62 toward the right, as viewed in Fig. 2, until the plate portion I80 is brought into engagement with the stem I19 for unseating the valve I14. Air under pressure is then supplied from the main reservoir II by way of the conduit I29, pipe I61, valve chamber I13, past the unseated valve I14, and through the chamber I15 and pipe I16 to the piston chamber I43 of the steam valve device H6. The piston I42 is thereby operated to move the steam valve I39 away from its seat against the force of the spring I40, and the resultant supply of steam from the pipe 20 to the tube I3I mounted within the cooling coil I26 then effects complete melting of the ice in the coil, and restoration of the desired free flow of compressed air from the inlet conduit I29 through the cooling coil to the outlet tinued supply of air under pressure by operation of the compressor I0 effects build up of substantially uniform pressures in the main reservoirs II and I2 and the associated communications of the system, and the corresponding equalization of the air pressures in the chambers I66 and I69 of the control device II4 permits movement of the diaphragms I60 and I6I and the follower member I62 .to their normal positions as indicated in Fig. 2, while the springs I18 and 206 effect movement of the respective valves I14 and 202 to theirseated positions. The spring I88 is at the same time rendered effective to return the plunger I66 to its normal position, in which the spring contact element I92 is held in engagement with the contact member ISI for closing the circuit through which current is supplied to the blower device I25.

As the valve 202 is moved to its seat by the force of spring 206 acting against the plunger 208, the plunger uncovers the. port 2 through which communication is established from the piston chamber I52 of the pump II5 to the atmospheric exhaust port 2I2, and air under pressure is thereby vented from the piston chamber for permitting return movement, of the piston I53 and plunger I46, by the spring I5I, to the normal position as shown in the drawing. As the plunger I46 is withdrawn from the bore I41, alcohol is again supplied from the reservoir I48 past the check valve I58 and through the passage I49 to the bore, and the pump is thus conditioned for subsequent operation.

Similarly, when the valve I14 is moved to seated position by the spring I18, the valve portion I8I of the stem I19 is unseated, and air under pressure is thereby vented to the atmosphere from the piston chamber I43-of the'piston valve device II6 through the pipe I16 and chamber I15, past the valve portion. I8I, and through the chamber I63 and opening I64, and the spring I is thus rendered effective to return the steam valve I39 to seated position for cutting ofl suppl of steam to the steam tube I3I 1 Apparatus shown in Fig. 4

A somewhat difierent form of the equipment just described is illustrated in Fig. 4 of the drawings, wherein it will be observed that the compressor I0, main reservoirs II and I2, liquid pump II5, steam valve device H6 and control device II 4 are associated with a condenser assembly 2I3, which differs in construction from the condenser assemblies I3 and H3 shown'in Figs. 1 and 2.

The condenser assembly 2I3 comprises a heat insulated casing having an apertured interior baffle wall 2 I 5 which has formed at the lower side thereof a chamber 2I1, and at the upper side'a chamber 21 8 having an atmospheric air inlet passageway 2 I 9 and an outlet passageway 220 formed adjacent the blower device I25. Mounted within the casing of the condenser assembly 2I3 is a cooling coil comprising an upper section 222 disposed within the chamber 2 I 6 and having one end communicating with the inlet conduit I29, and a lower section 223 mounted in the chamber 2I1 and having the upper end thereof connected by means of a pipe fitting 225 with the adjacent end of the section 222 and the lower end thereof conneoted through a pipe fitting 226 with the outlet conduit I30. p

The lower cooling coil section 223 has associated therewith a heat exchange mechanism, comprising an electrically operated refrigerating unit 230 adapted to circulate a cooling fiuid through a tube 23I that is mounted within the section 223. As is best shown in Fig. 5 of the drawings, the pipe fitting 226 comprises a body having a neck portion 233 adapted to receive the tube 23I and a' gasket 235, which is closely fitted thereto by means of a packing gland 234 having screwthreaded engagement with the neck portion. The other end of the cooling tube 23I is similarly held in place by the pipe fitting 225.

The heat exchange or refrigerating unit 230 may be of any suitable type, and is adapted to be operated by current supplied to the circuit con- 1 trolled by the switch I90, the heat exchange unit 23d and the electric blower device I25 being connected in parallel. The circuit for the heat exchange mechanism 230 is also adapted to be controlled by a thermostatically operated switch of conventional type, indicated at 236,, which is responsive to a predetermined minimum atmospheric temperature for cutting the mechanism out of operation, the complete circuit comprising the battery 19d, switch n90, conductor NE, a branch conductor 237, the thermostatic switch 236, a conductor 238, the heat exchange mechanism, a grounded conductor 239 and the grounded battery terminal I98.

In operation, the condenser assembly 213 is adapted to eii'ect cooling of the compressed air supplied by the compressor in two stages. Air under pressure delivered by the compressor l0 flows through the pipe 2!, main reservoir H, which in Fig. 4 is represented as a pair of connected units, and thence through the inlet conduit I29 to the first stage section 222 of the cooling coil, where the compressed air is initially cooled by the draft of atmospheric air drawn through the passageway 2|9, chamber 2H8 and passageway 220 by operation of the electric blower H5 in the usual manner, it being understood that the switch I90 is at this time held in closed position, as hereinbefore explained. As the compressed air flows from the section 222 of the cooling coil to the second stage section 223 thereof, it is further cooled due to absorption of the heat of compression by the cooling fluid circulating through the tube 23! passing through the section 233, assuming that the thermostatic switch 236 is closed as shown in the drawing. The cooled air under pressure, together with the condensate deposited within the cooling

coil sections

222 and 223, then flows through the outlet conduit l3ii to the main reservoir l2, from which air under pressure is supplied to the fluid pressure brake system as already explained.

During cold weather, the temperature responsive switch 236 automatically assumes circuit opening position, and the heat exchange mechanism 230 is thus rendered inoperative to circulate fluid through the tube 23!. If the flow of compressed air through the cooling coil within the condenser assembly becomes restricted due to formation of ice, the control device H4 is adapted to operate in the manner hereinbefore described in connection with Fig. 2 in the drawings, to effect operation of the alcohol pump H5 while openingthe circuit for the electric blower I 25, and to effect subsequent operation of the steam valve device 6. to supply steam through a pipe 240 to the chamber 2 I! of the condenser assembly, and thence through the apertures in the bafile wall 2l5 to'the chamber 2l8, thereby insuring melting of the ice formation within the cooling coils and reestablishment of the supply of compressed air to the main reservoir l 2.

While one embodiment of the invention and several modifications thereof have been described, it is not my intention to limit my invention to that embodiment or otherwise than by the scope of the appended claims.

main reservoir, including in combination, a cool-- ing conduit through which fluid is supplied from the compressor to the main reservoir, blower means operable to force a cooling draft over said condiut at one time, steam supply valve means operable to supply steam for heating said conduit at another time, force-feed mechanism operable to inject a quantity of anti-freeze compound into said conduit, and fluid pressure responsive means subject to the opposing pressures of fluid in the inflow and outflow portions of the conduit for selectively controlling operation of said blower means, steam valve means and forcefeed mechanism.

2. Apparatus for cooling and dehydrating fluid compressed by a compressor for delivery to a main reservoir, including in combination, a cooling conduit through which fluid is supplied from the compressor to the main reservoir, blower means operable to force a cooling draft over said conduit at one time, steam supply valve means operable to supply steam for heating said conduit at another time, force-feed mechanism operable to inject a quantity of anti-freeze compound into said conduit, and'fluid pressure responsive means subject to the opposing pressures of fluid in the inflow and outflow portions of said conduit and operative normally to maintain said blower means in operation, and operative upon a predetermined differential in said fluid pressures to effect operation of said steam valve means and force-feed mechanism.

3. Apparatus for cooling and dehydrating fluid compressed by a compressor for delivery to a main reservoir, including in combination, a cooling conduit through which fluid is supplied from the compressor to the main reservoir, blower means operable to force a cooling draft over said conduit at one time, steam supply valve means operable to supply steam for heating said conduit at another time, force-feed mechanism operable to inject a quantity of anti-freeze compound into said conduit, and fluid pressure responsive means subject to the opposing pressures of fluid in the inflow and outflow portions of said cooling conduit and operative upon a predetermined difierential in said fluid pressures first to stop operation of said blower means while initiating operation of said force-feed mechanism, and then to effect operation of said steam supply valve means.

4. Apparatus for cooling and dehydrating fluid compressed by a compressor for delivery to a main reservoir, including in combination, a cooling conduit through which fluid is supplied from the compressor to the main reservoir, blower means operable to force a cooling draft over said conduit at one time, steam supply valve means operable to supply steam for heating said-conduit at another time, force-feedmechanism operable to inject a quantity of anti-freeze compound into said conduit, and fluid pressure responsive means subject to the opposing pressures of fluid in the inflow and outflow portions of said cooling conduit and operative upon a predetermined initial differential in said fluid pressures to stop operation of said blower means while initiating operation of said force-feed means, and upon continued build up of a greater pressure differential to eifect operation of said steam valve means.

5. Apparatus adapted to be carried on a locomotive for cooling and dehydrating air compressed by a compressor for delivery to a pair of main reservoirs, including in combination, a cooling conduit interposed between said main reservoirs and having a coiled portion, a heat-insulating housing enclosing said coiled portion and having air inlet and outlet openings in opposite ends thereof, electric blower means in one of said main reservoirs, including in combination, a

' mal contact with said coiled portion of the conduit, and a control device comprising a switch normally closing the circuit for said blower means, a valve operable to supply fluid under pressure to said steam supply means, and a movable abutment operative upon a predetermined differential in the respective pressures of air in the inlet and outlet ends of said coiled portion of the conduit first to open said switch and then to effect operation of said valve.

6. Apparatus adapted to be carried on a locomotive for cooling and dehydrating air compressed by a compressor for delivery to a pair of main reservoirs, comprising in combination, a cooling conduit interposed between said main reservoirs and having a coiled portion, a heat insulating housing enclosing said coiled portion, electrically operated cooling means for said coiled portion of the conduit, fluid pressure responsive heating means for said coiled portion of the conduit, and a control device comprising a switch normally closing the circuit for said electrically operated cooling means, a valve operable to supply fluid under pressure to said heating means,

and a movable abutment operative upon a predetermined difi'erential in the respective pressures of air in the inlet and outlet ends of said coiled portion of the conduit first to open said switch and then to operate said valve.

7. Apparatus adapted to be carried on a locomotive for cooling and dehydrating air compressed by a compressor for delivery to a pair of cooling conduit interposed between said main reservoirs and having a coiled portion, a heat insulating housing enclosing said coiled portion, electro-responsive cooling means for said portion of the conduit within the housing, a fluid pressure actuated pump operable to inject alcohol or the like into said conduit, fluid pressure responsive heating means operable to apply heat to said portion of the conduit within the housing, and an automatic control mechanism comprising a normally closed switch controlling the circuit for said cooling means, normally seated valve means controlling supply of fluid under pressure to said pump, normally seated valve means controlling supply of fluid under pressure to said heating means, and common actuating means responsive to restriction in the flow of air through said conduit for efi'ecting operation of said switch and both of said valve means in sequence.

8. Apparatus adapted to be carried on a locomotive for cooling and dehydrating air compressed by a compressor for delivery to a pair of main reservoirs, including in combination, a cooling conduit interposed between and communicating with said main reservoirs, a heat insulating housing enclosing said cooling conduit, electroresponsive cooling means associated with said cooling conduit, a fluid pressure actuated pump operable to inject alcohol or the like into said conduit, fluid pressure responsive heating means operable to apply heat to said conduit within the housing, and an automatic control mechanism comprising a normally closed switch controlling the circuit for said cooling means,

normally seated valve means controlling supply of fluid under pressure to said pump, normally seated valve means controlling supply of fluid under pressure to said heating means, and a movable abutment subject to the opposing pressures of air in the respective main reservoirs for selectively effecting operation of said switch and both of said valve means.

9. Apparatus adapted to be carried on a locomotive for cooling and dehydrating air compressed by a compressor for delivery to a main reservoir, including in combination, a cooling conduit through which compressed air may be supplied by said compressor to a main reservoir, a casing enclosing a portion of said cooling conduit, electro-responsive cooling means associated with said portion of the conduit within said oasing, a fluid pressure actuated pump operable to inject alcohol or the like into said conduit, fluid pressure responsive heating means operable to supply heat to said portion of the conduit within the housing, and an automatic control mechanism comprising a switch for controlling the circuitfor said cooling means, normally seated valve means controlling the supply of fluid under pressure to said pump, normally seated valve means controlling the supply of fluid under pressure to said heating means, and a pair of diaconduit interposed between the compressor and main reservoir, cooling apparatus normally operative. to remove heat of compression from air in said conduit, a supply pump operable to inject alcohol or the like into said conduit, thawing apparatus operable to apply heat to said conduit, and a common control mechanism automatically operative in accordance with variations in the freedom of flow of compressed air through said conduit to effect operation of said cooling apparatus at one time and of said pump and thawing apparatus at other times.

11. A compressed air cooling and dehydrating equipment adapted tobe carried on a locomotive in association with a compressor and main reservoir, comprising, in combination, a cooling conduit interposed between the compressor andmain reservoir, a fluid pressure operated pump adapted to inject alcohol or the like into said conduit, a magnet valve device operable when energized ,to supply fluid under pressure to said pump, fluid pressure responsivethawing apparatus operable to apply heat to said conduit, and a common control mechanism including a switch normally disposed in a first position for closing the circuit for said cooling means and operable to a second position for opening that circuit while closing the circuit for said magnet valve, a normally closed relay valve operable to supply fluid under pressure to said thawing apparatus, and a movable abutment operatively related to said switch and relay valve and operative by a difierential in the air pressures at opposite ends of said cooling conduit initially to effect move-- conducting fluid under pressure from said c'ompressor to said system, blower means for circulat- 7 ing atmospheric air in thermal contact with said first stage conduit, refrigerating means for fur-.

.ther cooling fluid'under pressure fiowing'through said second stage conduit, thermostatically controlled means operable when atmospheric temperature is low to stop operation of said refrigerating means, mechanism operable to inject posits, and control means responsive to restriction in flow of fluid under pressure through said conduits for stopping both said blower means and 5 said refrigerating means while effecting operation of said mechanism.

CLYDE C. FARMER.