US1248658A - Single-tube pneumatic-despatch system. - Google Patents

Description

C. P. HIDDEN.

' SINGLE TUBE PNEUMATIC DESPATCH SYSTEM.

APPLICATION FILED SEPT.'24. I914.

Patented D90. 4, 191?.

ZUz'ZkS; %M r (X may 'UNTTFEU eraarne ran urea CHARLES P. HIDDEN, OF BROOKLINE, MASSACHUSETTS, ASSIGNOR TO THE LAIVISON COMPANY, OF BOSTON, MASSACHUSETTS, A CORPORATION OF NEW JERSEY.

SINGLE-TUBE PNEUlVZATIC-DESPATCH SYSTEM.

Specification of Letters Patent.

Patented Dec. t, 1917..

To all whom it may concern:

Be it known that 1, CHARLES P. HIDDEN, a citizen of the United States, residing at Brookline, in the county of Norfolk and State of Massachusetts, have invented certain new and useful Improvements in Single Tube Pneumatic Despatch Systems, of which the following is a specification.

This invention relates to pneumatic despatch apparatus and more particularly to that type of apparatus of this description which is generally characterized as a single tube system. I

The invention has for one of its objects the provision of means whereby in a single tube system, a carrier which cannot be despatched from a station toward which the carrier propelling current of air is moving,

'is automatically despatched upon the cessation of said air current; such despatch of a carrier automatlcally establishlng a current of air through the tube in a reverse dlrectlon to that in which the air current has previously flowed.

A further object has been to economize the expenditure of power in systems of this description to a minimum, and to further permit of the successive despatch of a plurality of carriers from one station toward. another while at the same time permitting of the automatic despatch of carriers from another station, in the manner above described.

These and. other objects of my invention will be hereinafter referred to and the novel elements and combinations of means whereby said objects may be attained will be more particularly pointed out in the claims appended hereto.

In the drawing 1 have exemplified a preferred construction but as I am aware of various changes, substitutions and modifications which may be made herein without departing from the spirit of my invention, I desire to be limited only by the scope of said claims.

Referring to the drawing, in which like reference characters designate like parts throughout the several views,

Figure 3 is a somewhat diagrammaticropresentation of a single tube pneumatic despatch system which embodies 1 y invention.

Fig. 2 is a vertical section taken on line IT[II of Fig. 3, and showing the construction of one of the elements of the preferred system.

Fig. 3 is a transverse section taken on 'llne IHHT of Fig. 2.

Fig. at is a vertical detail section of certain elements disposed at the despatching stations.

Fig. 5 is a similar section taken through one of the delivery terminals.

Fig. 6 is a detail section taken on line VIVI of Fig. 4-.

Fig. 7 is a vertical detail section taken through the axis of one of the delivery terminals and through the axis of the conduit adjacent thereto; and Fig. 8 is a fragmentary detail of a storage terminal.

The single normally dead tube connecting stations A and B has been designated 1 and connects at station A with a Y-shaped casing 2 which constitutes the despatching terminal at this station and correspondingly with a similar casing 2 located at station B. One of the arms of each of these casings is in turn connected by sections of normally dead tube 1 with a. delivery terminal; this terminal at station A being designated 3 and at station 13', 3. In the foregoing, the expression normally dead the tubing. is intended to be construed in the sense in which this expression is used in the art, namely, that the tube is one in which the air therein, when no carrier propelling current of air is flowing, is at substantially atmospheric pressure.

Each of these terminals 3, 3 is preferably provided with a triple contact device shown in section in Fig. 5, and which device is substantially identical to the construction shown and claimed in my copending application Serial Number 836,650, entitled Carrier despatch power control system, filed May 6, 1914 the so, already claimed, construction, per 80, not being claimed herein.

Briefly, however, this device comprises a pair of contacts 4 and which are controlled by a trip 6, as described in my said application, a second and similar set of contacts 7 and 8, controlled by a trip 9, and preferably upon the opposite side of the terminal, a third set of contacts 10 and 11, controlled by a somewhat. longer trip or cam finger 12.

applied to The trip or cam fingers 6 and 9 are spaced apart substantially the distance between the centers of the felt heads of a carrier 13; this latter being shown in dotted lines in Fig. 5. When the carrier is so engaged with these trips the body or shell thereof is also in engagement with the finger 12, and at such time, and only at such time, will the three sets of contacts all be closed. These sets of contacts are in series as shown in Fig. 5; a wire 14 connecting contact 5 with contact 10, and a second wire 15 connecting contact 11 with contact 8.

The sets of contacts may respectively be housed in casings 16 and 17, attached in any suitable manner to the body of the terminals 33.

Referring now to Fig. 4, there is therein shown a section of terminal 2 or 2 pivotally mounted in which, at 18, is a spring pressed stop 19, which is normally held in the position in which it is shown in Fig. 4, in the path of a carrier which is to bedespatched through the terminal.

Ordinarily the weight of the carrier will overcome the light spring which holds the stop 19 in the position shown, so that the latter will be swung aside to permit the carrier to pass, and at such time the shaft 18 and arm 20 also mounted thereon, will be rotated counter-clockwise as viewed in Fig. 4; the hooked extremity 20 of the arm 20 clearing a corresponding projection or hook 21 disposed at the free end of an arm 21 which is pivotally mounted at 22 within the casing 23 which extends laterally from the upwardly extending arm or branch of the terminal 2.

The arm 21 preferably forms a part of a bell-crank-like element the other arm of which, designated 24, carries an armature 25 which isadapted to co-act with a small electromagnet 26, mounted in the upper portion of the casing 23.

Whenever this magnet is energized the arm 21 will of course be rotated counter clockwise against the action of its spring 24 and its hook 21 will move into the path of the projection 20, to thereby prevent rotation of the stop 19 by a carrier. The mode of energizing this magnet will be hereinafter referred to.

At the upper end of the terminal arm upon which is mounted the casing 23, is a closure or door 27 which is provided with a spring 27 of suliicient strength to retain the closure in place against the pressure which may be exerted thereagainst by the carrier propelling current of air, when a carrier or carriers are being transmitted from station A to station B by compressed air.

At the lower extremity of the terminal 3 is a closure 28 somewhat similar to closure 27, but the spring 28 which normally holds this closure in its closed position, is relatively weak, so as not to oppose the emergence of carriers from the terminal.

Closure 28 has rearwardly projecting therefrom, as best shown in Fig. 7, a lug 29 which is adapted for engagement with the preferably conical extremity of a locking pin 30. This pin is guidedly mounted in a casing 31 within which is a diaphragm 32, to which the inner extremity of the pin is connected. As shown in Fig. 7, the right hand side of this diaphragm is in communication with the conduit through which air is transmitted to or withdrawn from the transit tube 1. lVhen compressed air is being supplied to the transit tube, diaphragm 32 will be driven to the left and its pin 30 will somewhat wedgingly engage the lug 29 whereby to firmly lock the closure 28 against inadvertent movement toward its open position due to the pressure of air thereagainst within the terminal Since the compressed air has first to pass through the conduit 33 before it can enter the terminal 3, it is obvious that this locking act-ion will occur before sullicient air can accumulate in terminal 3 to force open its closure.

When, however, air is being exhausted through the conduit 33 from the transit tube, the diaphragm 32 will be pressed to the right, withdrawing the locking pin from its engagement with lug 29, suction aided slightly by the spring 28 serving at such time to maintain the closure 28 in its operative position. There is hence provided a novel lock for terminal closures which is particularly adapted to co-act with a system such as that herein described.

Within the casing 34, shown in Figs. 1. 2 and 3, are mounted two light wheels 35-36, one of which, designated 35. carries upon its inner face and upon its periphery a contact shell or cup 35 and upon its outer side a ratchet wheel 37. The inner side of the wheel 36 carries a light spring contact 36 the free end of which is adapted for engagement with shell 35 but which normally is out of engagen'ient therewith owing to the provision of a recess 38 in the side of the shell 35 which permits the spring 36 to bear directly against the inner side of the wheel 35. lVhecls 35 and 36 are preferably made of fiber or some other light insulating material and the contact elements carried thereby should also preferably be as light in weight as possible.

lVheels 35 and 36 are mounted upon a shaft 39 which extends between brackets 40, and above said wheels is a pin or shaft 41 upon which is mounted an escapement 42 adapted for engagement with the ratchet 37. The shaft 41 also carries a second escapement 43 which is adapted to actuate a ratchet wheel 44 which is mounted upon the outer side of the wheel 36. Light springs 45 normally hold the escapements in the position in which one of them is shown in Fig. 2, and each escapement has connected there to, by a pin and slot connection, a lever 46 of which there are two, one for each escapement, and each of these levers carries an armature 47 which is adapted to co-act with the corresponding one of a pair of electromagnets respectivelydesignated 48 and 48. The periphery and inner Wall of the Wheel 36 is provided with a contact shell similar to that designated 35 and resilient wiping contacts 49 and 50 respectively engage the conductive shells or cups carried by the wheels 35 and 36.

Referring again to Fig. 1, it will be noted that the conduit 33 preferably leads into a drum 51 which is connected to a blower 52 Cl11"611 by a reversible motor 53. In the present case in order to effect a reversal of the direction of rotation of this motor I prefer to reverse the direction of the armature current while leaving undisturbed the direction of the current through the field coils. 1

The switche for effecting the reversal of the armature current have been diagrammatically represented and comprise actuating solenoids 54 and 55 and switches 56 and 57 mounted upon a depending stem of the core of solenoid 54, and switches 58 and 59 correspondingly attached to the core of the solenoid 55. The switch 56 is adapted for engagement with contacts 60 and 61; switch 57 for engagement with contacts 62 and 63; switch 58 for engagement with contacts 64 and 65; and switch 59 for engagement with contacts 66 and 67.

The remaining electrical connections will now be considered while discussing the mode of operation of .the system.

Assuming that the lead 68 be positive and that a carrier is to be despatched from station A to station B, the closure 27 will be opened and the carrier will be dropped into the terminal 2, whereupon the stop 19 in said terminal will be swung aside and a contact arm 69 mounted upon one end of the shaft 18 will be turned into engagement with a contact segment 70. Thereupon current will flow from lead 68 through a wire 71, wire 72, contacts 69 and 70, wire 73, to

the magnet 48, in casing 34, energizing this magnet, and passing thence through a return wire 74 common to both magnets 48 and 48, to the negative lead 75.

The energization of magnet 48 attracts its armature 47 and thereby rocks the escapement 42 clockwise, advances the wheel 35 one step, which brings the spring contact 36 into engagement with the contact shell 35. Thi completes a controlling circuit for the solenoid 54, as follows:

Current flows from positive lead 7 6 35, spring 36 and the contact shell of wheel 36, to spring contact 50. Thence through wire 79 to solenoid 54 and out via wire 30 V to the negative lead 81.

Energization of magnet 26 at station B locks the stop 19 and thereby prevents the despatch of a carrier from station E until the line is clear, at which time magnet 26 will no longer be energized as hereafter de scribed.

The solenoid 54, also energized at such time, draw switches 56 and 57 into engagement with their contacts and completes the following circuit: 7

Current flows from the positive main through Wire 82 to the usual connection of the motor which leads to the field thereof; thence out via wire 83, contact 62, switch 57, contact 63 and wire 84, to the armature; thence out by way of wire 85 to contact 66 and across from this contact, over the permanent connection shown, to contact 61; thence through switch 56 to contact 60, whence the current flow through wire 86 to the negative main 81.

This causes the motor to drive the blower in a direction to compress air into the drum 51 whence the air flows up through conduit 33 to the transit tube and propels the carrier, which has in the meantime dropped into this tube, toward station E, and out through the terminal 3 at this latter sta tion.

Assuming that but a single carrier has been despatched from station A in this manner, then as this carrier passes the triple contacts in casings 16 and 17 at station B, it will complete the following circuit:

From lead 68 through wire 87, contacts 4 and 5, wire 14, contacts 10 and 11, wire 15, contacts 7 and 8, and wire 88 to magnet 48, which it energizes; and thence through common return wire 74 to wire 75 and out.

This energization of magnet 48 in casing 34, causes a single actuation of wheel 36, which snaps the contact 36 out of engage ment with the shell 35 interrupting the circuit through wire 7 9, above described, and thereby denergizing solenoid 54.

Switches 56 and 57 then drop out of engagement with their contacts and the motor ceases to run.

Should a series of carriers be despatched from station A. to station B, so closetegether that two or more are traversing tube 1 at the same instant, then for each carrier despatched, the magnet 48 will be separately energized to cause an advance of wheel 35 one step per carrier despatchcd. Correspondingly as these carriers emerge from terminal 3, to fall, for example, into a basket 3" or the like, each will successively cause wheel 36 to rotate step by step, as said carriers pass the triple contacts in casings 16 and 17 Since there is but one aperture in the shell 35, it is obvious that it will only be after the last carrier has emerged that the circuit through wire 79 will be interrupted;

hence there will be no interference with the operation of the motor tending to cause a slowing down of the same, so long as a single carrier is in course of transit.

If, now, while this series of carriers is being despatched from station A to station B. the operator at station B desires to send a carrier to station A, he raises the closure 27 and inserts said carrier, as shown in Fig. 1. Since, however, the magnet 26 at station B remains energized as long as does the solenoid 54, and since this magnet controls the stop 19 of holder, the carrier so inserted for despatch at station B will not be able to drop down into the transit tube, but will remain latched up until this tube is clear.

The instant that the solenoid 5% becomes de'e'nergized by the emer ence of the last carrier traveling toward station 13, stop 19 will be released and the carrier to be despatched from station B will fall by gravity into the transit tube. As it moves past stop 19, however, the rotative movement of this part causes a contact 69 at station B to engage a contact which completes a'circuit as follows:

Current flows from wires 68 and 87 through a wire 89, contacts 69 and 70, and wire 90, to the magnet i8 within a casing 34:, which causes a. movement of the wheel 35 in said casing whereby to effect the completion of a circuit through wires 76 and 91, similar to the way in which the circuit through wires 78 and 7 9 was completed, as per the foregoing.

It will be understood, of course, that the mechanism within casing 34: is identical to that in casing 34.

When current is thus permitted to flow from wire 7 6 to wire 91, solenoid 55 becomes energized and the current flows thence through wire 92 to the magnet 26 within the casing 23 at station A, energizing this magnet. This prevents the despatch of carriers from station A to station E in the same way that carriers were previously prevented from being despatched from station B to station A.

The current emerging from magnet 26 at station A, traverses wire 86 to the negative lead 81.

The energization of solenoid 55 completes the following circuit:

Current flows from lead 76 through wire 82, the motor field, wire 83, contact 6'7, switch 59, contact 66, wire 85, the motor armature, wire 84, contact 63, across to contact 64, through bridge 58 to contact 65, and thence out via wire 86 to lead 81.

Thus the current in this latter instance has traversed the field in the same direction as in the previous case, but, it will be observed, the current through the armature is in this latter case reversed, so that the motor is oppositely driven and the blower now exhausts air from conduit 88 and the transit tube instead of propelling air thereinto.

As soon as a moderate vacuum has been formed in conduit 3, diaphragm 32 will move to the right, to release the closure 28, and the carri r which was despatched at station B is propelled by atmospheric pres sure therebehind toward station A until it passes the contacts in casings l6 and 17 of terminal 3, and thereafter emerges past closure 28 at said terminal. The passage of a carrier past these last mentioned contacts closes the following circuit:

Current flows from wire 68, through wire 71, the triple contacts in casings 1(3 and ii, wire 93, to the magnet -l-.S of casing 31-, which it energizes, and thence out via wire 7 4: to the negative lead 75.

It is obvious of course in this case also that as many successive carriers may be despatched from station 13 to station A, as may be desired, and that the instant that the last carrier emerges through terminal I"; "he motor will shut down, or that some equivas lent saving of energy may be ell'ected. Also it is evident that a carrier may repose in the terminal 2, preparatory for despatch to station 13, until the line is again clear, after which this carrier will descend into the tube and the motor will again be reversed, to again stop upon the emergence of this carrier.

Should it be desired to make ln'oVision for the automatic despatch of a plurality of carriers from a station, such a construction as is shown in Fig. 8 may be used in lieu of the vertical limb of the terminal 2, for example.

Herein, this branch or limb of the ter' minal is made of suilicient length to accommodate the number of carriers which it may be desired to accommodate or store therein; and while the device is provided with the carrier holder or support 19, previously referred to in connection with the description of parts contained in casing 23, the contacts 69 and 70 controlled by this element replace the contacts 10 and 11 of the construction shown in Fig. 5.

The casing 16 with its associated contacts and parts 456789 is disposed opposite the casing 23 and the arrangement in other respects is very similar to that shown in said Fig. 5; a wire 94 connecting contact (39 with contact 5, wire 95 connecting con- 1,sae,ets

tact 4 with contact 7, and contact 8 being connected with contact segment by means of a wire 96.

In this arrangement, so long as the stop 19 is latched, which, as in the preceding case, will be so long as the motor controlled solenoid 55 is energized, two or more carriers may be sustained thereby in the receptacle or terminal branch; and all these carriers will be simultaneously released as soon as the tube is clear for their transmission to station B. The provision of the triple contacts is again of value in that every one of the carriers as it passes the point where its heads simultaneously engage cam fingers 6 and 9, will unfailingly energize the magnet 48 in casing 34:.

The stop 19 in this case, further performs the same function as the finger 12 in the preceding instance, since if by any chance a carrier should repose against this stop when the latter is latched, and at the instant that said carrier was released, a second carrier should be inserted past the closure 27, for despatch, and the rear head of the first carrier should happen to be spaced from the forward head of the following carrier sufii= ciently to cause both of the fingers 6 and 9 to be simultaneously pressed as these carriers descend into the transit tube, nevertheless, in such contingency the stop 19 would have swung upwardly between these carriers ELSLllllClGllt distance to interrupt the circuit between contacts 69 and 70", so that no incorrect recording of the despatch of carriers within casing 34 is possible.

Having thus described my invention, what I claim is 1. A single tube pneumatic despatch system comprising a transit tube for despatching carriers in either direction therethrough, a station at each end of said tube, a pump for creating a carrier propelling current of air through said tube, a motor for driving said pump, means to control said motor and pump from either of said stations whereby to cause said current of air to flow in one direction or the other, in accordance with the station toward which a carrier is to be despatched, and for limiting the duration of said carrier propelling current substantially to the time required to despatch one or'more carriers, as the case maybe, from one of said stations to the other, and means to automatically despatch acarrier in the opposite direction through said tube from the station toward which said one or more carriers are being sent, aftersaid one or more carriers have been transmitted.

2., A single tube pneumatic despatch system comprising a transit tube for despatching carriers in either direction therethrough, astation at each end of said tube, a pump for creating a carrier propelling currentjof air through said tube, a reversible motor for driving said pump, and means to hold a carrier to be despatched from one of said stations toward the other until a carrier approaching said one of said stations from said other has been transmittedand to automatically despatch said held carrier and reverse said motor to transmit the same after said approaching carrier has substantially arrived at its destination c 3. A single tube pneumatic despatch system comprising a transit tube for despatching carriers in either direction therethrough, a station A at one end of said tube, a station 13 at the other end of said tube, apuInp for creating a carrier propelling current of air through said tube, a reversible motor for driving said pump, a switch for control ling the direction of rotation of said motor, a holder at station A for a carrier to be despatched from said station to station B, saidholder being adapted to retain said carrier so long as said switch isset to drive said motor and pump for the transmission of a carrier from station E to station A, and means to cause the despatch of said carrier in said holder and reverselv set said switch after the carrier approaching station A has arrived thereat.

t. A single tube pneumatic despatch system comprising a transit tube for despatching carriers in either direction therethrough, a station A at one end of said tube, a station Bat the other end of said tube, a pump for creating a carrier propelling current of air through said tube, a reversible motor, for driving said pump, a switch for controlling the direction of rotation ofsaid motor, a holder at station A for a carrier to be despatched from said station to station B, said holder being adapted to retain said carrier so long as said switch is set to drive said motor and pump for the transmission of a carrier from station B to station A, means to automatically cause the despatch of said carrier in said holder after said carrier approaching station A has arrived thereat, and means, controlled by the automatic despatchof said carrier, to set said switch to rever-sely actuate said motor.

5. A single tube pneumatic despatch sy tem comprising a transit tube for despatching carriers in either direction therethrough, a station A at one end of said tube, a station 13 at the other end of said tube, a pump for creating a carrier propelling current of air through said tube, a reversible motor for driving said pump, a switch for controlling the direction of rotation of said motor, a holder at station A for a carrier to be despatched from said station to station B, said holder being adapted to retain said carrier so long as said switch is set to drive said motor and pump for the transmission of a ict carrier from'station B to station A, means to automatically cause the despatch of said carrier from said holder by gravity after saidcarrier approaching station A has arrived thereat, and means controlled by the automatic despatch of said carrier, to set said switch to reversely actuate said motor. 6. A single tube pneumatic despatch sys tem comprising a transit tube for despatching carriers in either direction therethrough, a station at each end'of said tube, means for producing a carrier propelling current of air in either direction through said tube, means tonormally maintain said air current producing means operative to furnish said current of air in one direction through said tube so long asthere remains in said tube any one of a series of carriers, despatched from one of said stations to the other at intervals so close asto prevent the emergence of oneof said carriers before the succeeding one is in the tube, and means to automaticallylcause the despatch of a carrier from said other station after said series of carriers has been transmitted.

v7. A single tube pneumatic despatch sys tem comprising a transmit tube having a station at each end thereof, mechanism for producing a carrier propelling current of air through said tube in either direction, means at one station for controlling said mechanism to cause it to produce an air current in one direction to propel a carrier from one of said stations to the other, means to automatically despatch a second and Waiting carrier at said other station, and carrier controlled means at said other station for automatically effecting a reverse actuation of said mechanism to produce an oppositely flowing current of air through said tube to cause the transmission of said second carrier from said other station back to said one after said first mentioned carrier has been transmitted and said mechanism has ceased to produce said air current, and co-acting means for automatically limiting the operation of said mechanism whereby to produce said cessation of said. air current.

"8, A singletube pneumatic despatch system comprising a transit tube having at one end thereof a station A and at its other end a station B, means, including mechanism for producing a carrier propelling current of air in either direction through said tube, for despatching a plurality of carriers, which are in course of transit'through said tube at the same time from station A to station B,

and co-acting means for automatically despatching a carrier from station B to station A and reversing the direction of said air current substantially as soon as the last of said plurality of carriers has arrived at station B.

9. A single tube pneumatic despatch system comprising a transit tube having at one end thereof a station A and at its other end a station B, means, including mechanism for producing a carrier propelling current of air in either direction through said tube, for

despatching a carrier from station A to station B, co-acting means for automatically despatching a carrier from station B to station A and reversing the direction of said air current substantially as soon as the first mentioned carrier has arrived at station B, and auxiliary means for rendering inoperative said mechanism substantially as soon as said automatically despatched carrier arrives at station A.

10. A single tube pneumatic despatch system comprising a transit tube having at one end thereof a station A and at its other end a station B, means, including mechanism for producing a carrier propelling current of air in either direction through said tube, for despatching a plurality of carriers, which are in course of transit through said tube at the same time, from station A to station B, and co-acting means for automatically despatching a plurality of carriers from station B to station A and reversing the direction ol said air current substantially as soon as the last of said first mentioned plurality of carriers has arrived at'station B.

11. A pneumatic despatch tube system comprising a transit tube having a plurality of stations, mechanism for producing a carrier propelling current of air through said tube, an electric circuit for controlling said mechanism, means controlled by said electric circuit for automatically despatching a carrier from one of said stations toward another of the same, and automatic means for controlling said electric circuit by the arrival of a second carrier at a determined point in said tube.

12. A single tube pneumatic despatch system comprisinga transit tube having stations therealong, mechanism for producing a carrier propelling current of air through said tube in either direction, and means for controlling said mechanism, including electric circuits and a stop for preventing the despatch of a carrier from one of said stations when said mechanism is producing an air current opposite to that which is to propel said carrier, said stop having provisions along, the interior of said tube being normally at all times in substantially free communication with the outer air, mechanism for producing a current of air through said tube adapted to simultaneously propel a plurality of carriers therethrough, co-acting means to thereafter disestablish said current of air only when said tube is free from said carriers, and means to automatically despatoh a carrier. through said tube from one of said stations.

14. A pneumatic despatch system comprising a normally dead transit tube having stations therealong, mechanism for producin g a current of air through said tube adapted to simultaneously propel a plurality of carriers therethrough, coacting means to thereafter disestablish said current of air only when said tube is free from said carriers, and means to automatically despatch said plurality of carriers sequentially from one of said stations.

15. A pneumatic despatch tube system comprising a terminal having a plurality of sets of contacts adapted to be simultaneously rendered operative by a passing carrier, means, controlled by such actuation of said contacts, for producing a carrier propelling current of air through said system, an element adapted for engagement with said carrier, for rendering one of said sets of contacts operative, and means for causing said element to act as a stop for said carrier.

16. A pneumatic despatch tube system comprising a part through which carriers travel havin therein a contact makin device adapted to be actuated by passing carriers, means controlled by said device for determining the directions of travel of a carrier through a part of said system, and means for automatically preventing actuation of said device by a carrier until the path of travel which said carrier is to take is clear.

17. A single tube pneumatic despatch system comprising a transit tube having a station at each end thereof, one at least of said (topics of this patent may be obtained for stations having a despatching terminal the opening in which is separate from the car rier delivery opening at said station, mechanism for producing a carrier propelling current of air in either direction through said tube, means for automatically despatching a carrier from said despatching terminal by compressed air supplied by said mechanism, and means for automatically sealing said carrier delivery opening against the emergence of said compressed air therefrom,

18. A single tube pneumatic despatch system comprising a transit tube, means for propelling carriers by compressed air in one direction through said tube and for 0ppositely propelling carriers therethrough by atmospheric pressure, a closure past which move carriers propelled through said tube by atmospheric pressure, a conduit eXtending between said propelling means and tube, a chamber in communication with said conduit, a member in said chamber displaceable by fluid pressure and having means for locking said closure when said member is subjected to said compressed air, the current of the latter passing through said conduit normally displacing said member to automatically lock said closure before the latter is subjected to the pressure of said air.

19. A pneumatic despatch system comprising a normally dead transit tube having stations therealong, mechanism for producing a current of air through said tube adapted to simultaneously propel a plurality of car riers therethrough, co-acting means to thereafter disestablish said current of air only when each and every one of said plurality of carriers has been efiectively transmitted, and means to automatically despatch a carrier through said tube from one of said stations.

In testimony whereof I have affixed my signature, in the presence of two witnesses. CHARLES P. HIDDEN. WVitnesses:

CHARLES O. LAURIN, M. K. PORTER.

five cents each, by addressing the Commissioner of Patents, Warshinon, D. G. p

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