US1234281A - Pneumatic conveyer. - Google Patents

Description

c.-H. BURTON. PNEUMATIC CONVEYER. APPLICATION FILED MAR-15, i912.

C. H. BURTON. I PNEUMATIC CONVEYEH.

APPLICATION FILED MAII.I6. I9I2. 1l 34,281 I Patented July 24, 1917.

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.` E' AIToIIwfrs Patented July 24,

` Anon/ms BURTON.

PNEUMATIC CONVEYER.

APPLICATION FILED MAH. 16. 1912.

tra i sratrns radianti onirica.

CHARLES H. BURTON, OF WASHINGTON, DISTRICT F COLUMBIA, ASSIGNOR TO UNITED STATES PNEUMATIC COMPANY, OF NEW YORK, N. Y., A CORPORATION OF MAINE.

FNEUMA'IIC CONVEYER.

Specification of Letters Patent.

Patented July 2d, 19t?.

skilled in the art to which it appertains to make and use the same.

This invention relates to pneumatic conveyors, and with regard to certain more speciic features thereof, to pneumatic systems adapted to convey a carrier containing f mail, merchandise or the like from one place to another.

One of the objects of the present invention is to provide a simple and practical apparatus of the above character which will be etlicient in operation. Another object is to provide a self-contained apparatus for the above-mentioned purpose which will be inexpensive to manufacture and install. A. further object is to provide a pneumatic tube system which will be substantially automatic in its operation and. capable of handling a maximum of traffic with a given amount of apparatus. fr further object is to provide an apparatus suoli as aboveanentioned having interchangeable parts which will he silent in its operation and adapted to prevent shocks tending to damage contents of the carrier in starting and stopping. Other objects will part pointed out hereinafter.

The invention accordingly consists in the features of construction, combinations of elements and arrangement of parts which will be exemplified in the construction hereinafter set forth, and the scope of the application of which will be indicated in the following claims.

In the accompanying drawings, wherein is shown one of various possible embodiments of this invention,

Figure l shows a complete system ready for operation;

Cil

Fig. 2 is an enlarged front elevation of one terminal;

Fig. 3 is a plan view of the terminal shown in Fig, 2; l i

Fig. t is a detailed sectional. view of the terminal with the parts in position to receive a carrier;

Fig. 5 is a similar view minal takenfrom the opposite of the same terside with the be in part obvious and in v parts in position to discharge the carrier to a. receiving table;

Fig. 6 is a detailed sectional view of the valves controlling the position of the trapvalves;

Fig.. 7 is a similar view of the valves for changing the terminal from a despatching n to a receiving terminal or vice versa;

Figs. 8 and 9 are detailed views partially in section showing the position of the controlling pistons actuating the trap-valves by the valve mechanisms shown in Figs. 6 and 7 respectively;

Fig. 10 is a transverse sectional view taken through the central part of the terminal shownin Figs. 2 anc 3;

Fig. ll is an enlarged view showing the position of damper-valves of the blower mechanism; and i Fig. l2 is a detailed view of a check-valve.

Figs. 13 and 13a are details.

Similar reference characters refer to sim lar parts throughout the different views of the drawings.

Referring now to these drawings in detail and more particularly to Fig. l which shows the complete apparatus, l denotes the conveyer tube connecting the two terminals A. and B. This tube l may be of any desired size, but, in practice, it is preferably composed of standard sections of eighteen or twenty-four inch cast iron pipe free from internal burs or projections, although it is unnecessary to grind the same to a smooth surface. The system may be of any desired length and is laid under ground a few feet below the surface.

As the device is capable of sending carriers in either direction at will, a single tube is all that is required in connecting any two stations. Inasinuch as the carrier, which is of substantially the style shown in my prior Patent No. 8417284, issued March l2, 1907, does not necessarily lit the tube accurately or in an air-tight manner as usually required in pneumatic systems, the tube may be curved 4where necessary, as, for instance, when rounding street corners, pro viding, of course, that the radius of the curve is not too small. In practice the carrier will easily negotiate any curve having a radius greater than twenty-oney feet.

The present system is preferably operated upon the vacuum or suction principle operating upon the front of the carrier todraw it through the tube7 in contradistinction to the compressed air method of blowing the carrier from one terminal 'to another. A source of motive power is shown in Fig. r1

at each terminal comprising blower mecha-` nism which will hereinafter be referred to more in detail and denoted broadly by the reference characters C and D; the general operation being that in drawing' a carrier from terminal A to terminal B, the blower D is operated, tending to exhaust the air from the tube connecting these two terminals in advance of the carrier. In sending the carrier in the opposite direction, the blower mechanism C is operated instead in a similar manner.

1t is quite clear that the vacuum principle has advantages over the compressed air system inasmuch as there is less air resistance to the carrier in going from one station to the other, and the natural air pressure acting behind the carrier is used, thereby decreasing` the running expenses of the system. In other words, the difference of pressure on the opposite ends of the carrier when operated by compressed air is several times the difference in pressure when actuated on a vacuum principle.

Each terminal comprises, in brief, a pair of rear and front trap- valves 2 and 3 respectively spaced apart suiiiciently to permit the carrier to come to rest therebetween due to the air cushion formed when the front trap-valve 3 is in closed position. These trap-valves and the casings therefor' are of the same size and shape, as shown more` clearly in Figs. e and 5, and are of the cylindrical type provided with a central transverse opening adapted to register with the bore of the tube and being of sutiicient size to close the tube in an air-tight manner, by means of the solid portions et, when in the position of the valve 2, Fig. 5. Each trap-valve is provided at one side and on the outside of the valve casing i Vith a crank arm 5 carrying at its end a stud or pin G. These pins are adapted to be engaged by slotted cam members 7 and S, and given a quarter turn successively to change the valves from one position to another. comprise two upwardly projecting fingers denoted by the numerals 7 and 8, and two shorter upwardly projecting fingers 9 and 10, respectively, providing a slot therebetween for accommodating the crank pin 6 as it swings downwardly and around to turn the trap-valve.

One of these cam members is mounted at each end of a single or continuous piston rod 11 passing through a cylinder 12. They are supported in their sliding movement by means of guide-bars 13 directly connected with the valve casing. It will be noted that as the piston rod 11 reciprocates to the left from the position shown in Fig. 2, it will first rotate the trap-valve 2 to a closed posi- The cam members kvalve 19, which in turn moves head 23 from right to left to close the traption before the pin 6 is drawn out of the slot between the fingers 8 and 10, whereupon the finger 7 will coact with the pin 6 of the trapvalve 3 to swing the same downwardly and around to open position, as shown in Fig. 5.

The movement of the piston rod 11 through the cylinder 12 is controlled by a system of valves E located at the central portion of each terminal. A main supply pipe 11 is connected with any convenient source of compressed air. Leading from the pipe 1st in one direction is a branch pipe 15 which branches into pipes 16 and 17 leading to the opposite ends of the cylinder 12 (see Figs. 6 and 10). Each of the branch pipes 1G and 17 is provided with a three-way valve 18 and 19 respectively provided with actuating arms 2O and 21 connected by a link 22 whereby they operate simultaneously.

It will thus be seen that with the valves in the position shown rin Fig. 6, the air will pass through the valve 1S and the pipe 16 to force a piston-head 23 in the cylinder 12 to the right, as shown in Fig'. 8. When the valves are given a quart-er turn, however, the air is shut olf from the pipe 1G and is permitted to pass through the valve 19 and pipe lto act upon the opposite side of the'piston and move the same to the left. The air behind the piston is permitted to escape through a vent 24 ofthe valve 18 or a vent 25 of the valve'19, according to the direction in which the piston is moving'.

This mechanism is controlled automatically upon the arrival of a carrier at the terminal. As the carrier moves toward the right (Fig. 2) in the main portion of the tube, with the trap- valves 2 and 3 open and closed, respectively, it engages a trigger 26 projecting downwardly into the tube as shown in Fig. 10. This trigger is mounted upon a transverse rock shaft 27 having rigidly secured thereto near its outer end a crank arm 2S which in turn is pivotally connected with the link 22; thus as the trigger is swung upward under the action ofthe carrier, it will move the link 22 to the right, thus closing the valve 18 and opening the the pistonvalve 2 and after a brief interval open the trap-valve 3 as previously described.

This movement of the piston rod 11 from right to left actuates a valve 30 (see Fig. 2) in a pipe 31 connected with a compressed air storage tank 32 to admit air into the trapchamber to force the carrier shown at 33, Fig. 5, out through the trap-valve 3 to a receiving' table 34. As the carrier leaves the tube it engages a depending trigger 35 positioned midway in the tube and forces the same upward from the position shown in Fig. 5 to that shown in Fig. 2. This trigger 35 is mounted on a rock shaft 36 havioo n ing connected at one end thereof a crank 37 to which is pivotally connected a link 38. The opposite end of this link is connected to a crank arm 39 on the valve 19, Fig. 6.

It will thus be seen that as the trigger swings upwardly from the position shown in Fig. 5, it will move the link 3S in the direction of the entrance of the tube, thus rotating the valves into the former or normal po sition shown in Fig. 6, causing the air from the pipe 14 to pass through the valve 18 to move the piston 23 to the right; thus opening the trapvalve 2 which was previously closed, and closing the trap-valve 3, leaving the apparatus in position to receive a second carrier.

As the time 'for discharging a carrier to the receiving table after entering the trapchamber requires but a few seconds, the carriers may be sent one after another at the rate of eight or ten a minute.

When it is desired to send ay carrier in the opposite direction or convert the receiving terminal to a sending terminal, all that is required is to actuate a hand-lever 40 pivotally mounted at the receiving end of the tube. This lever has pivotally connected therewith near its upper end a link 41 which is connected with a crank arm 42 of a threeway valve 43 in a pipe 44 which is one branch of a pipe 45 connected with the same compressed air supply entrance 14 previ ously described. An opposite branch 46 of the pipe 45 is provided with a similar threeway valve 47 having a crank arm 48 pivotally connected by means of a link 49 with the crank arm 42, whereby these valves operate simultaneously to open one and close the other as shown in detail view, Figs. 7 and 9.

The pipes 44 and 46 are connected with the opposite ends of a cylinder 50 having a piston 51 and a piston rod 52. This piston rod is provided at its end with a bifurcated cam member 53 (see Fig. 4) similar to the cam members 7 and 8 previously described, whereby the parts may bc more easily interchanged and replaced, which is adapted to engage a pin 54 on a crank arm 55 on the opposite side of the trap-valve 3 from the crank 5. As this latter crank arm, shown in elevation in Fig. 2 at the opposite side of the trap-valve is free to turn independently of the cam member S, the reversing mechanism may be actuated independently of the trap controlling mechanism; thus when the lever 40 is pulled over to the right the valves 43 and 47 will be actuated to admit air to the cylinder 50 to force the piston 51 to the left, thus giving the trap-valve 3 a quarter turn to open position. The trap-valve 2 being already open will in this manner provide a free passage through the terminal whereby a carrier may be sent from the receiving table 34 into the tube.

viously used when receiving the carriers at B, and start the blower mechanism C to eX- haust the air from the connecting tube or materially reduce the air pressure therein.

The blower mechanism for operating this system comprises an ordinary fan blower 56 connected with the tube 1 by means of a pipe 57. The fan is operated by a motor 58, the speed of which may be regulated by a controller 59, thereby indirectly regulating the speed of the carrier.. The exhaust from the fan is directed through a pipe 6() to a compressed air tank 32, which, as above described, is used for blowing a carrier from the tube after being stopped in the trapchamber. The upper part of the pipe 57 (see Fig. 11) is open to the atmosphere at 61 and is provided with a damper or valve 62 through which the air may be drawn when the blower at the opposite end of the system is in operation; thereby lessening the draft at the open end of the tube near the receiving table and eliminating the chances of articles of merchandise or the like being drawn therethrough into the tube. The valve 62 is connected by means of a cord or chain 63 with a crank arm 64 on a rock shaft 65 supporting a vane 66 in the tube or pipe 57 adjacent the blower. lt is thus seen that When the blower is started the vane 66 will be drawn upwardly into the position shown in Fig. 11 due to the suction of the air which, through the connecting means above mentioned, closes the valve 62, thus insuring the exhaustion of the air from the tube 1 more rapidly.

In order to prevent accidents which might arise by inadvertently leaving both the front and rear trap- valves 2 and 3 open after despatching a carrier, there is provided automatically operated means for restoring the l i trap-valves to normal position; that is, the rear trap-valve 2 open and the front trapvalve 3 closed, so that if a carrier should be immediately returned it would be arrested in the trapphambers above described. This may be conveniently done by positioning in the T-connection 63, between the pipe 57 v leading from the blower and the main body of the tube 1, a trigger 69 positioned in the path of travel of the carrier. This trigger, '1

like the trigger 26, is so connected with a rock shaft 7 O supporting the same that it is permitted to swing free in one direction, yet rotate the rock shaft when moved in the opposite direction by the carrier. The lost motion connection referred to is illustrated in Figs. 13 and 13a as applied to the rock shaft 27 and., the trigger 26. It will be understood that one of the collars illustrated is fastened to the shaft and they collar 26'lll roe Aair against the closed valve 8.

through the tube it will engage the trigger G9 andswing the same upwardly to move a connecting rodfQ to the left; that is, to

carry the parts into the position shown inA Fig. 7, it being remembered, of course,that when sending the carrier, the valve l? was closed and the valve t3 opened, thereby opening the front trap-valve lf a second carrier is to bedespatched immediately af-k terward, it is again necessary to pull the lever e() forwardly in order to open the trap-k valve 3. This mechanism is otherwise entirely automatic in returning `the parts` to normal position. f

Although it is thought from the above description that the operation of the device .may be clearly understood, will, however, be set forth iii brief as follows:

Assuming that a carrier is to be sent from B to A, with the apparatus in the position shown in Fig. l, the blower C is started'to exhaust the air from the tube l which will draw in a carrier through the open trapvalves 2 and 3 ofthe terminal B from the receiving platform 34; the carrier passes 'through the tube toward the terminal fr and through the open trap-valve 2 at terminal A into the trap-chamber where its ino-inenytum is arrested by the compressing of the fr vent T3 is preferably provided at the forward end of the trap-chamber having therein a checlo valve 711, as shown in Fig. l2. Compression of the air by the carrier will close the checkvalve which is normally open to permit the inlet of air when the system is operated in the opposite direction. Otherwisea partial vacuum would be formed, therebydecreasing the cushioning effect of the trap-chainber. As the carrier passes into the trapchainber it engages the trigger 2GL which actuates the valve mechanism E to open the trap-valve 3 and close the trap-valve E2 and also open the valve 30 to permit an inlet of compressed air through the pipe 3l to move the carrier 33 out upon the receiving 'platform 34:. rlhe carrier swings the trigger 35 upwardly which restores the valve mechanism E to its former position, hus opening the valve 2 and closing the valve 3 so that the device is ready for receiving another carrier. lf, however, it is desired to send a carrier in the opposite direction, the blower mechanism C is stopped and the signal is given to the operator at the terminal B to start the blower mechanism D. rilhe lever y among others,

-l-O is then pulled forward to actuate the rvalve shown in Fig. which in turn affects y lt is, of course, to be understood from the previous description that before despatchingl a second carrier rfrom any terminal .it .is necessary to pull the lever a0 forward to open the front trap-valve 3, as this valve is automatically closed after each carrier en y@ages the trigger mechanism iu the T-connection 68 a ftcr leaving the trap-chamber.

is thus seen that this invention provides ay simple and practical device eemprising but asingle connecting tube through which carriers may be sent in either direction, with a minimum yamount of effort on the part of the operator, requiring no material changes in the appa atusl The fact thattlie system conniirises but a single tube and is operated on the vacuum principle of course rgreatly diminishes rthe cost of construction and installation. It is therefore quite clear that the invention accomplishes, all the objects and advantages above set fo'rtl As many changes could be made in the above construction and ymany apparently widely different embodimentsof this inventioncould be made without departing from the scope thereof, it is intended that all matter contained in the above description or shown in the accon'ipanying drawings shall be rinterpreted as illustrative and riet in a limiting sense. f f

lt is also to be understood that the language used in the following claims is intended to cover all of the generiefand speeiiicr features of the invention herein described and all statements of the scope of the invention, which, asa matter of language, might be said to fall therebetween.y

Having described my invention, what I claim as new and desire to secure by Letters Patent is: I f

l., Iny an apparatus of the character described, in combination, a pair of terminals spaced apart, a single tube connecting said terminals, means for 'reducing the air pressure iii the tube for drawing a carrier therethrough, means `associated with each of said terminals for changing the saine from receiving to despatching terminal, at will, and means adapted to be actuated automatically by the carrier passing through a terminal iii either direction for restoring the terminal to receiving position.

2. ln a pneumatic coiiveyer, a pair of ten y mi nals, a tube connecting them, means at each terminal for converting it at will from a receiving 'to a despatching terminal` means at each terminal for exhausting the air from lili the tube and thus acting' upon a carrier at one terminal by the exhausting means at the other; a delivery station, an air cushion chamber tor arresting the motion of the carrier, and vmeans acting after the carrier has been arrested ior moving it from the cushion chamber to the delivery table.

3. In a pneumatic conveyer, terminals spaced apart, a tube connecting them, means for converting a selected terminal from a receiving to a despatching station, means at each terminal acting in alternation to eX- haust the air from the tube and thus acting upon a carrier at one terminal by the eX- hausting means at the other; a delivery station, an air cushion chamber for arresting the carrier, and means for delivering the eX- haust behind the carrier to bring it from the air cushion chamber to the delivery station.

In an apparatus of the character described, in combination, a pair of terminals spaced apart, a single tube connecting said terminals, means associated with each of said terminals for changing the same from a receiving to a despatching terminal t t will, means operative at one end for acting on a carrier on the opposite end of the tube, means for arresting the passage of a carrier through the tube prior to its iinal delivery at the end of the system, and means adapted to direct a current of air to a point behind the carrier after it had been arrested for forcing the carrier out of the terminal.

5. ln a pneumatic conveyer, in combination, a terminal comprising means for reducing the air pressure in advance of a carrier as it passes through the tube, a pair of trap valves spaced apart near the end of said tube and forming a trap chamber therebetween adapted to arrest the movement of the carrier, a delivery station, and means for increasing the air pressure behind the carrier after the same has been arrested to torce the carrier from the tube to the delivery station.

6. In an apparatus of the character described, in combination, a tube through which a carrier is adapted to pass, means adapted to reduce the air pressure in advance of the carrier to draw the carrier through said tube, a trap chamber adapted to arrest the movement of the carrier, a delivery station adjacent said trap chamber, and means adapted to conduct the air exhausted from said tube to said trap chamber to force the carrier out of said trap chamber to said delivery station after its movement is arrested.

7 A terminal for a system of the character described, comprising in combination, a pair of trap valves forming a trap chamber therebetween, a cylinder positioned between said valves, a single piston rod adapted to be actuated by said cylinder for controlling the position of the valves, connections between the piston rod and the valves for actuating the valves, means for admitting compressed air to one side or the other of the piston for opening one of the trap valves and closing the other, said last-mentioned means being` actuated by the passage of a carrier into the trap chamber, and means adapted to open one of said valves whereby said terminal may be converted to a despatching terminal.

8. A terminal for a system of the character described, comprising in combination, a trap chamber formed by a pair of front and rear trap valves, pneumatic means adapted to be actuated by the entrance of a carrier into said trap chamber for actuating the valves to permit the carrier to leave said chamber, means actuated by said first-mentioned means :for admitting air pressure behind said carrier for forcing the same out of the chamber, and means adapted to open one of said valves whereby said terminal may be converted to a despatching terminal.

9. A terminal for a system of the character described, in combination, a trap chamber formed by a pair of front and rear trap valves, pneumatic means adapted to be actuated by the entrance of a carrier into said trap chamber for actuating the valves to permit the carrier to leave said chamber, positively operated means actuated by said first-mentioned means for admitting air pressure behind said carrier for forcing the same out of the chamber, and positively acting automatic means for restoring the valves to receiving position after the carrier leaves the chamber.

10. A terminal for a system of the character described, in combination, a trap chamber formed by front and rearV trap valves, the irst of which is normally closed and second normally open, means adapted to be positively actuated by a carrier entering said chamber for reversing the position of the valves to permit the exit of the carrier, and means actuated by said first-mentioned means for permitting compressed air to enter the chamber behind the carrier in order to force the same out of the chamber.

1l. A terminal for a system of the character described, in combination, a trap chamber formed by front and rear trap valves adapted to cushion and arrest the movement of a carrier on entering the chamber, means adapted to reverse the position of the trap valves, a lever in the path of travel of the'carrier between the trap valves for actuating said means, a source of compressed air connected with the rear of the chamber, and a valve adapted to be opened by said iirst-mentioned means for admitting compressed air to said chamber to blow out the carrier after the trap valve is opened.

12, A terminal for a system of the character described, in combination, a tube, eX- hausting means connected therewith,y a trap chamber formed by front and rear trap valves, a crank arm for each of said valves, a cylinder and piston positioned therebetween, connections between the piston rod and said crank arms, a system of valves adapted to'be opened or closed to move said piston back and forth, means actuated by a carrier on entering said trap chamber .tor closing the rear trap valve and opening the front trap valve, whereby the carrier may be discharged from the tube, ka source of compressed air connected with the rear of said chamber from said exhausting' means, a valve, and means connecting said piston with said valve for admitting air to the chamber after the front trap valve has been opened, whereby the carrier is blown out of 'said chamber.

13. In a receiving` or despatching terminal for an apparatus of the character described, in combination, a tube having a pair of valves spaced apart for opening or closing the passage of a carrier through the tube, automatic means i'cr positioning said valves for receiving` a carrier after each operation of receiving or despatching, and means for positioning said valves whereby the carrier may be despatched.

14. In a receiving or despatching terminal for an apparatus ot' the character described, in combination, a tube having a pair of valves spaced apart for'opening or closing the passage of a carrier through the tube, means for positioning said valves for receiving or despatching a carrier, said means acting automatically to return the parts to normal position after the carrier has been despatched or received.

15. In a receiving` or despatching terminal for an apparatus of the character described, in combination, a tube having` a pair of valves spaced apart for opening or closing the passage of a carrier through the tube, automatic means for positioning said valves for receiving` a carrier, means for positioning said valves whereby the carrier may be despatched, and automaticy means for returning the parts to normal position after the carrier has been despatched, said last-mentioned means comprising ya member projecting in the path of travel of the carrier, and valve mechanism adapted to be actuated thereby for restoring the front trap valve to closed position.

16. In a receiving or despatching terminal for an apparatus of the character de-y scribed, in combination, a tube having a pair of trap valves spaced apart at one end thereotl forming a trap chamber therebetween, the rear valve being normally open and the front valve normally closed to form an air cushion for arriving carriers, manually operated means for opening the front trapvalveV only whereby a carrier may -be despatched in the opposite direction, and

automatic means actuated by the carrierr scribed, in combination, a tube having a pair ot trap valves spaced apart at one end thereof forming a trap chamber therebetween, the rear valve being normally open and the front valve normally closed to form an air cushion for arriving carriers, manually operated means for opening the front trap valve whereby a carrier may be despatched in the opposite direction, and automatic means actuated by the carrier after passing through the rear trap valve for closing the front trap valve whereby the device is in position to receive a carrier, said means including a cylinder and a piston actuated thereby and a connection between the piston and the crank arm oit' the front valve.

18. In a receiving or despatching terminal for an apparatus of the character described, in combination, a tube, front and rear trap valves forming a trap chamber therebetween, the reary valve being normally open and the front valve normally closed, means between said valveswithin said trap chamber adapted to be actuated by a ca rier for closing the rear yvalve and opening the front valve whereby the carrier may be discharged to a receiving table, and means actuated by the carrier on passing out of the tube for restoring the trap valves to normal position.

19. In a receiving` or despatching termi-L nalfor an apparatus of the character described, in combination, a tube, front and rear trap valves forming a trap chamber therebetween, the 'rear valve beingnormally open and the front valve normally closed, means between said valves within said trap chamber adapted to be actuated by a carrier for closing the rear valve and opening the front valve whereby the carrier may be dis-V charged to a receiving table, means actuated by the carrier on passing out of the tube for restoring the trap valves to normal position, and means for actuating the front trap valve independently ot the rear .trap valve whereby the device may be converted into a despatching terminal, at will.

20. In a receiving or despatching termi nalfor an apparatus of the character described, in combination, a tube, front and rearV trap valves forming a trap chamber therebetween, the rear vvalve being normally open and the front valve normally closed, means between said valves within said trap chamber adapted to be actuated by a carrier for closing the `rear valve and opening the front valve whereby the carrier may be discharged to a receiving table, means actuated by the carrier on passing out of the tube for restoring the trap valves to normal position, and means for actuating the front trap valve independently of the rear trap valve whereby the device may be converted into a despatching terminal at will, said last-mentioned means comprising` a cylinder with a piston therein and a loose connection .between said. piston and the crank of said front trap valve :tor permitting independent f action thereof.

21. In a system of the character described, in combination, a single tube having a terminal at each end thereof, blower mechanism at cach terminal adapted to create a partial vacuum in the tube to advance the carrier, a 'trap chamber in each terminal for arresting the carrier, means for releasing the carrier, a delivery station, and a connection between the blower mechanism and trap chamber for directing the exhaust from the blower mechanism to the chamber' at a point behind the carrier for blowing the same out of the tube delivery station when released.

In asystem of the character described, in combination, a tube, a terminal, a station at each end thereof, blower mechanism at each terminal adapted to be operated to draw a carrier therethrough, a trap chamber for arresting the carrier on its arrival at the terminal, valve mechanism adapted to be actuated to permit the discharge of the carrier from the trap chamber, a delivery station and a connection between the exhaust oit the blower and the trap chamber for 'torcing the carrier out of the chamber to the delivery station when released by the actuation oi the valve mechanism.

23. In a system of the character described, in combination, a tube, a terminal, a station at each end thereof, a blower mechanism at each terminal adapted to be operated to draw a carrier therethrough, a trap chamber lor arresting` the carrier on its arrival at the terminal, valve mechanism adapted to be actuated to permit the discharge of the carrier from the trap chamber, a connection between the exhaust of the blower and the trap chamber for forcing the carrier out of the chamber when released by the actuation of the valve mechanism, and a valve in said connection adapted to be opened by the operation of the valves of the trap chamber.

2st. In an apparatus of the character described, in combination, a tube, a terminal, a station at each end thereof, blower mechanism connected with each terminal for reducing the air pressure in the tube, aconnection between the blower and the tube,

and a valve in said connection controllingan opening to the atmosphere adapted to close automatically with the starting of the blower.

25. In an apparatus or' the character described, in combination, a tube having a ter minal at each end thereof, a blower for reducing the air pressure in the tube, a connection between the blower and the tube, a damper in said connection adjacent an opening leading to the atmosphere, and means in said connection adapted to be actuated on starting the blower for closing the opening by said damper whereby the air is drawn out of said tube.

Q6. In an apparatus of the character described, in combination, a terminal for a pneumatic tube operated by vacuum, two trap valves forming an air cushion chamber therebetween, a single piston rod operating the trap valves from a single cylinder, a delivery station, an inlet valve, and means for opening said inlet valve for the purpose ot' admitting compressed air to eject the carrier to the delivery station after it has been received in the air cushion chamber.

27. In an apparatus of the character described, in combination, a tube, means adapted to reduce the air pressure in said tube, two trap valves forming an air cushion chamber therebetween in said tube, and a separa-te inlet valve in said chamber to prevent the exhaustion of air by said pressure reducing means.

28. In an apparatus of the character described, in combination, a tube, and an eX- hauster connected with said tube, two trap valves therein forming an air cushion chamber therebetween, and a separate inlet valve in said chamber to prevent the exhaustion of air, said inlet valve adapted to close automatically by compression of air causedV by the injection of the carrier into the air cushn ion.

29. In a terminal for a system of the character described adapted to receive a carrier and to have a carrier despatched therefrom, in combination, means for placing said terminal in despatching condition, means for placing` said terminal in receiving condition, and means ccperating with said lastmentioned means adapted to automatically place said terminal in receiving condition upon the departure of a despatched carrier from said terminal.

In testimony whereof I affix my signature, in the presence of two witnesses.

CHARLES II. BURTON.

Vitnesses:

FRANK E. ANDERSON, NEENAH LAUB.

Copies of this patent may be obtained for five cents each, by addressing the Commissioner of Patents, Washington, D. c.

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