US1619707A

US1619707A - Power-control device for pneumatic-dispatich systems

Info

Publication number: US1619707A
Application number: US92182A
Authority: US
Inventors: James T Cowley
Original assignee: Lamson Co
Current assignee: Lamson Co
Priority date: 1926-03-04
Filing date: 1926-03-04
Publication date: 1927-03-01
Anticipated expiration: 1944-03-01

Description

' 1 1,619,707 March 1 1927' J. T. COWLEY POWER CONTROL DEVICE FOR PNEUMATIC DISPATCH SYSTEMS Filed March 1926 3 Sheets-Sheet l I var/676$!) 1' (7211x0196 Z 6 0 Zey M W 23 E a alga.

March 1 i927. 1,619,707

' J. T. COWLEY POWER CONTROL DEVICE FOR PNEUMATIC D SPATCH SYSTEMS I I Fil ed March 4, 1926 3 Sheets-Sheet 2 4 4 43 ?77 a (\b lqzaz 6 March 1 1927. 1,619,707

J. T. COWLEY POWER CONTROL DEVICE FOR PNEUMATIC DISPATCH SYSTEMS Filed March 4, 1926 5 Sheets-Sheet 5 vvewvbrf Jfarzes Z C aw Zsy wags.

Patented Mar. 1, 1927.

U E. I)? STATES JAMES T. COWLEY, OF SYRACUSE, NEW YORK, ASSIGEIOR T9 LAMSON COMPANY, OF SYRACUSE, NEW YORK, A CORPORATION OF MASSACHUSETTS.

POWER-GONTROL DEVICE FUR; PNEUMATIC-DISPATCH SYSTEMS.

Application filed March 4, 1926. Serial No. 92,182.

This invention pertains to pneumaticdispatch systems of the so-called minimum flow vacuum type and relates more-particularly to automatic power controlling appa- 5 ratus for use in such a system.

Power control apparatus of this general character is disclosed in the patent to Libby No. 968 576, dated August 30, 1910. The patented apparatus provides automatic pressure actuated means for initiating a carrier impelling-air flow through the transmission tube whenever a carrier is entered therein as well as means for cutting off such: flow after the lapse of a predetermined period of time. While I regard the patented device as generally correct in principle and highly eflied tive in practice I believe it preferable to have the cessation of carrier impelling air flow depend directly upon the discharge oi the carrier from the delivery end of the tube rather-than upon the operation of a timing device, and the principal object or": this in vention is to provide an improved power control apparatus comprising means actuable automatically upon insertion of a carrier within the dispatch terminal-to initiate flow of the air propellingcurrentand also operating automatically whenthelast carrier emerges from the delivery terminal to 30 cut off the air current without appreciable delay.

In the accompanyingdrawings-ll have disclosed one preferred embodiment of the invention by way of example;

Fig. 1 being a fragmentary elevation illustratingpart of the central station desk of a pneumatic dispatch system having the improved power control apparatus applied thereto;

Fig. 2 is a vertical section to largerscale than Fig. 1 and taken on the line 2 2 of Fig. 5, showing the interior construction of the improved controlapparatus, the several partsibeingin a position which they assume when the line is empty;

Fig.3 is a View. similar 'to Fig. 2 but showing the control valve open to permit carrier impelling airflow to pass through thetransmissionutube Fig. t is a view similar to Fig. 2 but showing the parts in the positionpwhich they occupy at the instant; aiter the last carrier has been delivered.ttromthe transmission tube;

Fig. 5 is-a horizontal section substantially on the line 55 of Fig. t;

and is attached thereto in any desired 1n Fig. 6 is a fragmentary side elevation looking toward the left-hand side of tlie apparatus illustrated in Fig. .2;

Fig. 7 is a plan view 01 a cut-,oti device auxiliary to the control valve;

Fig. 8 is a fragmentary section to large scale substantially on the :line 8 8 ot Fig. 3; and i Fig. '9 is a fragmentary section substantially on the line 9 9 otFig. 2.

Referring to the drawings, thenumeral 1 indicates a. fragmentary portion .o ftlie central station desk of a. pneun'iatic dispatch system comprising. transmission tubes, such forexample as the tube Qwhich leads from the central station desk. Each tube 2 is furnished with a delivery terminal 3 and' is provided with a continuation 4 connectingit to an.individuallpower control deviceindicat ed generally by the numeral 5. This power control. device is connected in turnbymeans of a suction tube 7 to a vacuum drum or header9 in which a-low pressure is,. contin u ally maintainedhy means of a suitable puin'p. exhauster or equivalent apparatus, not shown.

Air openended dispatch terminal G-is provided at the central station. for each of the transmission tubes 2; such dispatch terminal forming the entrance :tothat run of the tube which. leads to the corresponding remote sending station. The above arrangement in general is old and well known in this art and further details of such. general arrangement are. therefore unnecessary, the present invention being confined to improvements in the power control apparatusper se.

Referring more particularly to Figs. 2 to 9 inclusive, the power control device proper comprisesthe hollow casing Spr-ovided at its 7 upper end with a cover 8 and at itslower end with a bottom member 8 i The cover member 8 is furnished with an opening, preferably defined by an a 11nui.a1qtlange 4;, adapted to receive the. lower end otthe tube extension d. The cover 8 as here, shown is separate from the body portion of the 'casi ner, although if preferred the. covermem 11' may heintegral with the. body offthecasing. v

The bottom I member 8 is, attached to the body of the casing by means of bolts 11 and the margin of flexible diaphragm 12is clamped.betweenthe; body of the casing and the edge otthe. cover memben 8. The space 13 between the diaphragm 12 and the bottom member 8 communicates with the outer at mosphere by means of a small port 14 which is always open. The space 13 may also communicate with the outer atmosphere by means of a relatively large opening 15 provided with a flap-valve 16 which is normally held closed by means of a light spring 17 The space within the casing is divided into an inlet chamber 18 and an outlet chamber 19 by means of a septum or partition 20. The space 18 communicates freely at all times with the transmission tube while the outlet chamber 19 freely communicates with the suction tube 7 leading to the drum 9, the body portion 8 of the casing being furnished with a socket 22 for the reception of the end of the tube 7.

The partition or septum 20 is preferably of U-shape and its upper wall 20" is furnished with a valve aperture 21 which is preferably, though not necessarily coaxial with the tube extension 4. A controlling valve governs the passage of air through the valve aperture 21. The controlling valve structure preferably comprises a dish-like head or valve proper 23 adapted to fit snugly within the aperture 21 and a body portion 24 which carries a second head or disk 25 at its lower end. This lower head 25 has a free sliding fit in a cylindrical chamber 25 provided in the lower wall 20 of the septum 20. The chamber 25 is closed on all sides but communicates by means of a passage r 26 extending through the body 24 of the valve with the space above the valve member 23. The pressure upon the upper and lower faces of the valve structure in thus always balanced so that the valve may move very easily under all conditions.

The valve body 24 is secured to the upper end of a valve stem 27 sliding in a guide opening in a boss 28 on the lower wall 20 of the septum 20. The stem 27 also passes through a guide opening in a boss 31 upon the bottom member 8 of the casing.

The valve stem is connected by a pin 29 to a clamping member 30 secured to the'eentral part of the diaphragm 12. The lower portion of the stem 27 is screw threaded as shown at 32 and receives an adjustable stop 33 adapted to engage the boss 31 as the valve stem moves upwardly, and thus to limit such upward movement. A spring 34 surrounds the outwardly projecting part of the valve stem, bearing at one end against the under surface of the member 8 of the case and at its other end against an abutment member 35 which may be adjusted to vary the tension of the spring by means of a nut 36 engaging the threaded portion of the stem.

When the valve 23 is closed a minimum flow of air through the transmission tube toward the suction drum is provided for by means of passage 37 extending from the chamber 18 to the chamber 19 and which is controlled by a rotary valve plug 38. By adjustment of this plug the amount of air flowing through the passage 37 may be regulat-ed. While this mode of roviding for the minimum flow is preferrech since it permits adjustment of the flow from a point outside of the casing, I contemplate that this minimum flo v may be provided for in any of the ways usual to apparatus of this type, as for example by holding the controlling valve slightly spaced from its seat when closed.

A lever arm 39 is mounted in the upper part in the inlet chamber 19 and supports an auxiliary valve or cut-off device, 40, here shown as a shallow inverted circular cuplike cover having a depending annular flange rim 41. The flat upper surface of the member 40 is of substantial area and is prefer ably disposed directly in the path of the air entering the inlet chamber 18 from the tube extension 4. To hold the auxiliary valve or cut-off device in its normal inoperative position as indicated in Fig. 2, I provide a spring 42 secured at one end to the lever arm 39 and at the other to a rod 43 passing up through an opening in the cover 8, the upper end of the rod being screw threaded for engagement by an adjusting nut 43 by means of which the tension of the. spring 42 may be varied. A bracket 44 projects from the inner surface of the cover 8 and acts as a stop to limit upward movement of the cut-off device 40.

The cup-like auxiliary valve or cut-off device 40 is of an internal diameter somewhat greater than the valve member 23 and the flange 41 is of such a depth that when the cut-off device is positioned as shown in Fig. 4, the valve 23 being fully open, the.

cut-off device completely houses the valve 23 while the lower edge of its rim 41 rests against the septum 20 and thus forms complete closure for the valve aperture 21. lVhen in this position the flange 41 of the cut-off device also constitutes a closure for the entrance end of the minimum flow passage 37.

Referring more especiallyto Figs. 7 and 8, the lever arm 39 is preferably provided at its end with spaced

ears

45 and 46 having aligned journal openings for the reception of the aligned

pintle members

47 and 48 respectively projecting inwardly from the wall of the casing 8.

Preferably the side wall of the casing 8 is furnished with an aperture 47 leading to the outer atmosphere and this aperture is normally closed by a flap-valve 48. A pivoted arm 49 is arranged within the inlet chamber 18 with its free end disposed in position to engage the inner surface of the valve member 48. The upper end of this arm 19 is provided with a journal opening for the reception of a pivot member 51 (Fig. 8) whose opposite ends are received within the inner portions of the journal openings in the

ears

45 and 46 respectively of the lever 39. The arm 19 is thus pivotally suppor ed between the ears 45 and i6 and is adapted to be actuated by a finger 52 projecting downwardly from the arm 39.

The operation of the device is substantial- 1y as follows, it being assumed that when the transmission tube is empty the controller parts occupy the positions shown in Fig. 2 and that a suitable vacuum or sub-atmospheric pressure is maintained in the suction tube 7 by an exhauster or other suitable device. Under these conditions a small or minimum flow of air is entering the open terminal 6 and after passing through the tubes 2 and 1, traverses the upper part of the inlet chamber 18 of the casin and passes on through the passage 37 to the suction tube 7. The spring 34 is so adjusted that the slight decrease in pressure in. the chamber 18 occasioned by this minimum fiow is not sufficient to raise the diaphragm 12.

hen a carrier is inserted in the transmission tube either at the terminal 6 or at the outlying sub-statiointhe minimum flow is cut-off or. substantially diminished, thus resulting in a decrease in pressure in the inlet chamber 18. As the diaphragm 12 is always exposed to'the pressure in the chamber 18, such pressure being substantially that of the transmission tube, and as the opposite side of the diaphragm is exposed through the smallopening 141, to atmospheric pressure, the diaphragm now risesin opposition to the spring 34 and opens the control valve 23. The valveorifice 1 1 is made quite smallso that. thevrise of the diaphragm will be gradual, thus avoiding the production of heavy oscillations in the air current which is established by the opening of the valve 23.

As soon, as the valve 23 is opened, a full carrier impelling air flow is set up in the transmission tube, the air current passing through the latter into the chamber 18 and thence through the valve orifice 21 into the chamber 19 and tube 7. Thespring 4:2 is so adjusted that althoughthe broad upper surface of the member 40 issubjected to this carrier impelling air flow, it is maintained inv the position shown in Fig. 2, until the last carrier emerges from the transmission tube.

hen the last carrier is delivered from the transmission tube a sudden rush of air ensues, the velocity. of the air duringsuch sudden rush exceeding the velocity of the carrier impelling air current. The impact of this sudden rush of air uponthe broad upper surface of the member 40 overcomes the tension ofspring 42 and the latter yields, permitting the member 40 to swing down into the position shown in Fig. 1. The pivotal axis of the lever 39 is so disposed that the cup-like cut-off member lO swings freely down over the opened valve 23 without contact with the latter until as above stated it occupies the position shown in Fig. 4 where the lower edge of its flange 11 engages the upper wall of the septum 20 in substantially concentric relation to the edge of the opening 21.

While the cut-off member initially re sponds to the sudden rush of air, thus moving toward the position of Fig. l, it is as sisted in completing its movement by the increasingly different pressures upon its upper and lower surfaces as it approaches the cut tingoif position, since as soon as its lower edge passes the valve member 23 it begins to restrict the air passage beneath the edge of the valve 23 and thus to cut off the how to some extent, so that during the final part of itsmovement it is positively sucked down to its seat. Thus even though the rush of air may be but momentary. the cut-off device is caused to assume the cuttiiW-ofl position with certainty.

As the cut-off device reaches the position of Fig. l, its liange 11 closes the entrance to the minimum flow passage 37 so that the inlet chamber 18 is completely cut oil from the suction tube. The air pressure upon theupper and lower surfaces of the valve structure is now instantaneously balanced through the passage 27 and since the pressure-in the chamber 18 rises substantially to that of the atmosphere as soon as the cut-off member-is seated, the spring 34 is now free to return the valve 23 to its closed position. This movement may take place rapidly, since the flap valve 16 opens outwardlyvery easily to permit the air trapped in the chamber 18 to escape.

In order to make sure that the air pres sure in chamber 18 is restoredsubstantially to that of the atmosphere in'nnediately upon closure of the cutoff; member, the valve 418 is provided, and as the lever 89 swings down into the position of Fig. 4: the finger 52 en gages the lever 4-9 and opens the valve 48, thus permitting atmospheric air to enter the chamber 18 freely Without passing through the length of the transmission tube, and compensating any suction leakage past the controlling valve or through the minimum flow passage. 7

With the parts arranged as herein disclosed, the diaphragm 12 being substantially concentric with the tube extension A, there is quite a pronounced hammer effect from the moving column of air directly upon closi ure of the cut-off member 40. This hammer blow of the air column acts upon the upper surface of the diaphragm 12 andassists the spring 34- in closing the valve :23. l/Vhile this hammer effect is useful in quick-ening' the closure of the control valve, it is not necessary to the operation of the device and if desired the diaphragm 12 may be arranged in some position such that it does not receive the direct impact of the hammer blow of the air column.

From the above description it will be noted that while the valve 23 with its actuating diaphragm 12 determines the establishment of carrier impelling air flow through the transmission tube, the cut-oft device 40,

acting independently of the valve 23, deter mines the termination of such carrier impelling flow.

While certain specific structural features have herein been described as desirable in embodying the present invention in an operative device, I contemplate that various changes in the shape, proportion and arrangment of parts may be made without departing from the spirit of the invention. Moreover, while the apparatus has been shown as embodied in a suction system, it is contemplated that certain of its broader features might well be applicable to a pressure minimum flow system, and further that under certain circumstances, certain of its operative parts might be dispensed with or united in a single member having their combined function.

I claim:

1. Power control apparatus for a pneumatic dispatch system of the minimum flow type having a transmission tube, said apparatus comprising a pair of independent controlling devices for cutting off carrier impelling air flow through the transmission tube, one of said devices normally being so disposed as to cut off carrier impelling air flow, but opening in response to the introduction of a single carrier into the transmission tube, and the other of said devices normally being open but closing in response to delivery of the lastcarrier from the tube.

2. Power control apparatus for a pneumatic dispatch system of the minimum flow type having a transmission tube, said apparatus comprising a pair of independent controlling devices for cutting oii carrier im pelling air flow through the transmission tube, one of said devices normally being closed, and a pneumatic responsive to pressure change resulting from reduction in the minimum flow through the transmission tube and by such response opening said normally closed device to permit a carrier impelling flow through the tube, the other of said controlling devices normally being open but closing to. cut off carrier impelling air flow through the tube upon delivery or" the last carrier from the latter.

3. Power control apparatus for a pneumatic dispatch system of the minimum flow type having a transmission tube, said apparatus comprising a pair of independent controlling devices for cutting oil carrier impelling air flow through the transmission tube, one of said devices normally being closed, and a pneumatic connected to the normally closed controlling device, the pneumatic being exposed to transmission tube pressure and responding to reduction in such pressure due to reduction of the minimum flow by introduction of a carrier into the transmission tube and by such response opening said normally closed controlling device to permit a carrier impelling air flow through the transmission tube, the second of said controlling devices normally being open and being at all times exposed to transmission tube pressure, said device responding to the rush of air incident to delivery of a carrier from the tube to close and there by out off carrier impelling air flow.

l. Power control apparatus for a pneumatic dispatch system of the minimum flow type having a transmission tube, said apparatus comprising a pair of independent controlling devices for cutting oil' carrier impelling air flow through the transmission tube, one of said devices normally being closed, and the other of said devices normally being open, both of said devices being exposed at all times to transmission tube pressure, the normally closed device opening when a carrier is introduced into the transmission tube and the normally open device closing when a carrier is delivered from the tube.

5. Power control apparatus for a pneumatic dispatch system of the minimum flow type having a transmission tube, said apparatus comprising a pair of independent valve devices for cutting oil? carrier impelling air flow through the transmission tube, one of said devices normally being positioned to cut off carrier impelling air flow and the other normally being open, and means for opening the normally closed device when a carrier is inserted in the trans mission tube, the normally open device being always exposed to transmission tube pressure and moving to closed position in direct response to the sudden rush of air when a carrier leaves the tube.

6. Power control apparatus for a pneumatic dispatch system of the minimum flow type having a transmission tube, said apparatus comprising a pair of independent valve devices for cutting oiicarrier impelling air flow through the transmission tube, one of said devices normally being closed and the other normally being open, and a pneumatic for opening the normally closed device when a carrier is inserted in the transmission tube, the normally open device having a broad surface always exposed to the air current flowing through the transmission tube and responding to air flowing through the transmission tube at a velocity in excess or that of carrier impelling flow and bysuch response causing said device't'o close.

7. Power control apparatus for a pneumatic dispatch system of the ininimun'i flow type having a t'ansmission tube, said apparatus comprising a pair of independent controlling devices for cutting oii carrier impelling air flow through the transmission tube, one or" said devices normally being closed and the other open, and a pneumatic for opening the normally closed controlling device when a carrier is inserted in the transmission tube, the normally open device comprising a pivotally supported element exposing a surface ofsubstantial area to the carrier impelling air current, and yielding means normally holding said device open in opposition to the pressure of the air current against said surface but permitting the device to close when the velocity of the air current exceeds the normal velocity of carrier impelling flow.

8. Power control apparatus for a pneuinatic despatch system of the minimum flow type having a transmission tube, said apparatus comprising a pair of independent controlling devices for cuttingolt carrier inipelling air flow through the transmission tube, one of said devices normally being closed and the other open, means for automatically opening the normally closed device to establish carrier impelling air flowwhen a carrier is inserted in the tube, the normally open device comprising a pivotally supported member having a broad surface disposed transversely of the air current, a! spring for yieldably holding said surface in normal position in opposition to the pressure of carrier impelling air flow, and means toradjusting the spring so that the device may move in response to a velocity ot air flow exceeding that of normal carrier impelling and thereby close to cut off the flow.

9. Power control apparatus for a pneumatic dispatch system having a transmission tube means for creating carrier impelling air flow through the tube, a controlling valve governing carrier impelling flow of air through the transmission tube, a minimum flow of air through the tube normally being permitted when saidvalve is closed, and a pneumatic responsive to a change in pressure due to introduction of a carrier into the transmission tube and by such response opening the controlling valve, one side of the pneuniatic being at all times exposed to transmis sion tube pressure, said apparatus comprising means disposed at the inlet side ofthe controlling valve for cuttingoif the carrier iinpelling air flow when the carrier is delivered lflOlll the transmission tube.

.10. Power control apparatus of the min.-

imum flow type for a pneumaticdispatch ffStQlH having a transmission tube, means for latter and by its response cutting off car rier imp-elling air flow through the tube, said cut-off means being disposed at the inlet side of the valve and beingmovable to closed position' without changing the position of the controlling valve.

11. Power eontrol apparatus for a pneumatic dispatch systei'n having a transmission tube, means for creating carrier iinpelling air flow through the tube, a controlling valvegoverning carrier impelling flow of air through the transinission tube, a minimum flow of air through the tube normally being permitted when the valve is closechand a pneumatic responsive to a change in'pr'essure due to introduction of a carrier into the transmission tube and by such response open ing the controlling valve, said I apparatus co nprlsing a pivote d cut-oil device at the inlet side of tl' e; valve, said cut-oit devi'ce sponding to the rush ot air incident to delivery of a carrier from the tube to cut-off said flow independently of any action of the main valve. I w I 12. Power control apparatus for apn'eumaticdispatch system ot the minimum flow type having a transmission tube, and means for creating carrier impelling air flQW there through, said apparatusbeing provided with chambers communicating respectively with the transmission tube and flow creating means, a septum separating said, chambers, the septum having a valve aperture therethrough, said aperture being open during the flight or a carrier throughthe tube and means directly responsive to the sudden rush of air incident to delivery of the carrier from the tube for closing said valve aperture.

13, Power control apparatus for pneumatic dispatch system having atrans nission tube, means for creating carrier impell ng air flow therethrough, a casing provided to pressure change resulting from introduction of a carrier into the tube and by such response opening the controlling valve, said apparatus comprising a cup-like cover adapted to close the valve aperture independently of the controlling valy e, said cover moving to aperture-closing position when the carrier is delivered from the transmission tube.

14. Power control apparatus for a pneumatic dispatch system of the minimum flow type having a transmission tube, and means for creating carrier impelling air flow therethrough, said apparatus being provided with chambers communicating respectively with the transmission tube and flow creating means, a valve aperture providing communication between said chambers, a pivoted cover adapted to close the valve aperture, and yielding means normally holding the cover in inoperative position during the flight of a carrier through the tube, the cover closing the valve aperture in response to the rush of air following delivery of the carrier fl'OlTl the tube.

15. Power control apparatus for a pneumatic dispatch system having a transmission tube, means for creating carrier impelling air flow therethrough, means providing chambers communicating respectively with the transmission tube and flow creating means, a septum separating said chambers, the septum lltlVlllP' a valve aperture therethrough, a controlling valve for closing said aperture to terminate carrier impelling air flow through said tube, a minimum flow of air through the tube normally being permitted when the controlling valve is in closed position, and a pneumatic responsive to pressure change resulting from introduction of a carrier into the tube and by such response opening the controlling valve, said apparatus comprising a cover adapted to close the valve aperture independently of the controlling valve, said cover normally standing in the path of the air current flowing toward the aperture and moving to aperture closing position in response to the rush of air incidentto delivery of the carrier from the tube.

A 16. Power control apparatus for a pneumatic dispatch system or" the minimum flow type having a tl'tUlSlHlf-7Sl011 tube and means for creating carrier impelling air flow therethrough, said apparatus being provided with chambers communicating respectively with the transmission tube and flow creating means, a valve aperture connecting said chambers, a pivoted cover for the valve aperture normally standing in open inoperative position and presenting an inclined face to the air current flowing toward the aperture, and yieldable means normally holding the cover in said inoperative position, the cover swinging in response to the sudden rush of air which occurs when the carrier leaves the tube and thereby cutting off carricr propelling air flow through the tube.

17. Power control apparatus for a pneumatic dispatch system having a transmission tube and means for creating carrier impelling air flow therethrough, said apparatus being provided with chambers communicating respectively with the transmission tube and flow creating means, there being a valve aperture providing communication between said chambers, a controlling valve for closing said aperture to terminate carrier impelling air flow through said tube, the apparatus having a minimum flow passage leading from the inlet chamber, a pneumatic responsive to pressure change resulting from introduction of a carrier into the tube and by such response opening the controlling valve, and a cover normally occupying an inoperative position spaced from the valve aperture, said cover moving in response to the sudden rush of air through the tube incident to delivery of a carrier from the latter to an operative position in which it closes the valve aperture in the septum independently of the controlling valve, theeover having a flange which closes the minimum flow passage when the cover is in said operative position.

18. Power control apparatus for a pneumatic dispatch system having a transmission tube and means for creating carrier impelling air flow therethrough, said apparatus being provided with chambers communicating respectively with the transmission tube and flow creating means, a septum separating said chambers, the septum having a valve aperture therethrough, a controlling valve for closing said aperture to terminate carrier impelling air flow through said tube, the apparatus having a passage leading from the inlet chamber at a point. adjacent to the septum to provide for a minimum flow of air through the tube when the controlling valve is in closed position, a pneumatic responsive to pressure change resulting from introduction of a carrier into the tube and by such response opening the controlling valve, and a cover of inverted cup-like Shape having a depending circular rim, the lower edge of the rim being normally spaced from the septum, said cover moving in response to the rush of the air when a carrier leaves the tube until the edge of the rim is concentric with the valve aperture and engages the septum thereby cutting elit the flow of air thro h the valve aperture, the rim at the same time forming a closure for the entrance to the minimum flow passage.

19. Power control apparatus for a pneu matie dispatch system having a transmission tube and means for creating carrier impelling air fiow therethrough, said apparatus being provided with chambers communicat,

ingrespectively with the transmission tube= and fiow creating means, a septum separat ing said chambers, the septum havinga valve aperture therethrough, a controlling, valve for closing said aperture to terminate carintroduction of a carrier intothe tube and by such response opening the controlling valve,- .a substantially, circular: movable cover normally spaced from the septum, and means movably supportingthecover to permit it to move inrespouse to the sudden rush of: air through the tube when; the carrier leaves the latter into a position where its edge is coaxial with and bears against the septum at the margin of the ap turein the latter thereby cutting oil? carrier impelling airflow.

20. Power control apparatus for; a pneumatic dispatch system having a transmission tube and means for creating. carrier impeliling air flow therethrough, said apparatus being provided with chambers communic-atingrespectively with the transmission tube and flow creating means, the chambers communicatingby means of a valve aperture, a COn': trolling valve for closing said aperture to terminate carrier impelling 'air flow through said tube, Zl-lllllllllllllll'l flow of air'throughthe tube normally being permitted when thecontrolling valve is inclosed position, a pneumatic responsive to pressure change rcsultiugfrom introduction of a carrier into the tube. and by such response opening the controlling valve, the controlling valve in,

opening. moving oppositely to the air current, and a cupped cover normaly spaced from the valve aperture soias-to permit free air flow through the latter, said cover moving in responseto the rush of air. in the tube incident to delivery of a carrier therefrom until it houses the opcni valve and cuts oft" the air flow through the aperture.

21. Power control apparatus for a pneu matic dispatch system having a transmission tube, means for creating carrier impelling air flow th-erethrough, a casing provided with chambers communicating respectively with the transmission tube and flow creating means, aseptum separating said chambers, the septum having a valve aperture therethrough, a controlling valve for closing said. aperture to terminate carrier impell-ing air flow through said tube, a minimum flow oi? air through the tube normally being permitted when the controlling valve is in closed posit-ion, and a pneumatic responsive to pressure change resulting from introduction 0t a carrier into the tube and by such response opening the controlling valve, said apparatus comprisinga movable cover disposed in that chamber of the apparatus which;communicates with the transmission tube, and aspring, normally holding the cover in inoperative position, the. spring yieldingto permit the cover tomove to a position where it coverszthe aperture in the septum when a carrier is delivered ironrthe tube.

22. Power control apparatus for a pneumatic dispatch system having'a trans 'ision tube, an exhauster, a casing provided with an inlet and an outlet chamber, comn'uinicating respectively with the tube and cXhauster, a controlling valve for govern: ing carrier in'ipclling air flow from the inlet to the outlet chamber, a minii'uumtlow of. air throughtl'ie transmission tube normally being pern'iittedwhen the controlling valve. closed, anda pneumatic constantly exposed on one side to thepressure in the inlet than her, saidv pneumatic being connected to the valve and automatically opening the latter when a carrier, is inserted in the transmis sion: tube, said apparatus comprising means independent of the controlling valve for cut ting off communication between the inlet and outlet chambers and for substantially terminating the minimum flow when the carrier is delivered from the transmission tube.

23. Power control apparatus for a pneumatic dispatch system having a transmission tube, an exhaust-er, a casing provided with an inlet and an outlet chamber communicating respectively with the tube and exhauster, a controlling; valve for governing carrier impclling, air flow from the inlet to the outlet chamber, a minimum flow of air through the transmission tube normally beingpermitted when the controlling valve is closed, and a pneumatic constantly exposed on one side to the pressure in the inlet chamber, said pneumatic being connected'to the valve and automatically opening the latter when a carrier is inserted in the transmission tube, said apparatus comprising an air o erat cut-oil device independent of the controlling valve for cutting off communication between the inlet and outlet chambers. a spring normally holding the cut-off device in inoperative position, and means for adjusting the tension of the spring, the cut-pit device mov. ing from inoperative to operative position in response to the rush of air following delivery of the carrier from the tube, said cut-off device when in operative position also substantially cutting off the minimum flow.

24;. Power control apparatus for a pneumatic dispatch system having a transmission tube, an eXhauster, a casing provided with an inlet and an outlet chamber coinmunicating respectively with the tube and exhauster, a controlling valve for governing carrier impelling air flow from the inlet to the outlet. chamber, a minimum flow of air through the transmission tube normally. be-

ing permitted when the valve is closed, and a pneumatic constantly exposed on one side to the pressure in the inlet chamber, said pneumatic being connected to the valve and automatically opening the latter when-a carrier is inserted in the transmission tube, said apparatus comprising a movable cut-oil device yieldably supported directly in the path of air through the inlet chamber, the cut-oil device being moved by air having a velocity exceeding that of normal carrier inipelling air flow and'by such movement cutting off communication between the inlet and outlet chambers and simultaneously cutting off the minimum flow.

25. Power control apparatus for a pneumatic dispatch system having a transmission tube, an exhauster, a casing provided with an inlet and an outlet chamber communicating respectively with the tube and exhauster, a controlling valve for governing carrier impelling air flow from the inlet to the outlet chamber, a minimum flow of air through the transmission tube normally being permitted when the controlling valve is in closed position, and a pneumatic constantly exposed on one side to the pressuim in the inlet chamber, said pneun'iatic being connected to the valve and automatically opening the latter when a carrier is inserted in the transmission tube,

said apparatus comprising an air operated cut-otl device within the inlet chamber, said device being independent of the controlling valve, said cut-oil device moving in response to delivery of the carrier from the tube and thereby cutting off communication between the inlet and outlet chambers, and means actuable by the cut-0d device for opening communication between the inlet chamber and the outer atmosphere.

26. Powencontr'ol apparatus for a pneumatic dispatch system having a transmission tube, an exhauster, a casing provided with an inlet and an outlet chamber communicating respectively with the tube and exhauster, a controlling valve for governing carrier impelling air flow from the inlet to the outlet chamber, a minimum flow of air through the transmission tube normally being permitted, when the controlling valve is in closed position, and a pneumatic constantly exposed on one side to the pressure in the inlet chamber, said pneumatic being connected to the valve and automatically opening the latter when a carrier is inserted 'in the transmission tube, said apparatus comprising a two armed lever pivotally supported within the inletchamber, a cut-off member mounted upon one arm or the lever, said cut-oil member when in operative position cutting oil" cominunication between the inlet and outlet chambers, a spring connected to the lever normally holding the cutoil device in inoperative position, and a normally closed valve controlling a passage connecting the inlet chamber directly with the outer atmosphere, said valve being disposed in the path of movement of the other arm of the lever to be opened thereby when the cutoil device moves to operation.

27. Power control apparatus for a pneumatic dispatch system having a transmission tube, an exhauster, a casing provided with an inlet and an outlet chamber communicating respectively with the tube and eXhauster, a controlling valve for governing carrier impelling air flow from the inlet to the outlet chamber, a minimum flow of air through the transmission tube normally being permitted when the controlling valve is in closed position, and a pneumatic constantly exposed on one side to the pressure in the inlet chamber, said pneumatic being connected to the valve and automatically opening the latter when a carrier is inserted in the transmission tube, said apparatus comprising means independent of the controlling valve for simultaneously cutting-oil carrier impelling air flow through the tube and for opening direct communication between the inlet chamber and the outer atmosphere.

28. Power control apparatus for a pneumatic dispatch system having a transmission tube, an exhauster, a casing provided with an inlet and an outlet chamber communicating respectively with the tube and exhauster, a controlling valve for governing carrier impelling air flow from the inlet to the outlet chamber, a minimum flow of air through the transmission tube normally being permitted when the controlling valve is in closed position, and a pneumatic constantly exposed on one side to the pressure in the inlet chamber, said pneumatic being connected to the valve and automatically opening the latter when a carrier is inserted in the transmission tube, said apparatus comprising means independ ent of the controlling valve for cutting-oft carrier impelling air flow through the tube and for suddenly equalizing the pressure at opposite sides of the pneumatic.

29. Power control apparatus for a pneumatic dispatch system having a transmission tube, an exhauster, a casing provided with an inlet and an outlet chamber communicating respectively with the tube and eXhauster, a controlling valve for governing carrier impelling air flow from the inlet to the outlet chamber, a minimum flow of air from the inlet chamber to the outlet chamber normally being permitted when the cont-rolling "alve is in closed position, and a pneumatic constantly exposed on one side to the pressure in the inlet chamber, said pneumatic being connected to the valve and automatically opening the latter when a carrier is inserted in the transmission tube, said apparatus comprising an air operated device independent of the controlling valve for substantially completely cutting off communication between the inlet and outlet chambers.

when the controlling valve is closed, and a pneumatic constantly exposed on one side to the pressure in-the'inlet chamber, said pneumatic being connected to the valve and automatically opening the latter when a vcarrier is inserted in the transi-nission tube,sa id apparatus co1nprising means movable inde pendently of the controlling valve for cut ting ofl' communication between the inlet and outlet chambers, and for simultaneous 1y closing the minimum flow passage, said last named means normally being inoperative'bu t moving to operative position inrospouse to the sudden rush of through the system following the deliver-yet the carrier from the tube. V

31. Power control apparatus for a pneumatic dispatch system having-a transmission tube, an exhauster, a casingprovided with an inlet and an outlet chamber com municating respetci'vely with the tube and exhauster, a controlling valve for governing carrier impelling air ilow from the inlet to the outlet chamber, there being a passage leading "from the inlet chamber to the outlet chamber to provide for a minimum flow of air when the controlling valve is in closed position, and a pneumatic constantly exposed on one side to the pressure in the inlet chamber, said pneumatic being connected to the valve and automtically opening the latter when a carrier is inserted in the transmission tube, said apparatus comprising means, independent of the controlling valve, located in the inlet chamber and responding to the rush of air following delivery of the carrier from the tube, to close the minimum flow passage and to cut oil communication between the inlet and outlet chambers.

32. Power control apparatus for a pneumatic dispatch system having a transmission tube, an exhauster, a casing provided with an inlet and an outlet chamber communicating respectively with the tube and exhauster, a controlling valve for governing carrier impelling air flow from the inlet to the outlet chamber, a minimum flow of air through the transmission tube normally being permitted when the controlling valve is closed, and a pnemnatic constantly exposed on oneside to the pressure in the in let chamber, said pneumatic being connected to the valve and automatically opening the latter whena carrier is inserted in the transmission tube, said apparatus comprising a hinged cover within the "inlet 'chamber, a

sarinF nornirall i holdin said. cover in in operative position, and adjustable means 'outside ot the casing tor so tensioning the spring that "the cover moves to operative position in response i to the rush of air through the system following delivery of the carrier from the tube andt'hereby cuts oil communication between the inlet and outlet chambers.

. 35 Power control apparatus for a pneu matic dispatch system havmg a transmission tube, an exliauster, a casingprovided municatling respectively with the tubeand with an inlet and an outlet chamber com,

I exhauster, acontrolling valve for govern 7 .mg "carrier impelling arr flow from the inlet to the outlet chamber, a minimum flow of air through the transmission tube normally being permitted when the controlling valve is closed, and a pneumatlc constantly exposed on one side to the pressure in the in let chamber, said pneumatic being connected to the valve and automatically opening the latter when a carrier is inserted in the transmission tube, the controlling valve moving into the; inlet chamber when it opens, said apparatus comprising a cup-like cover within the inlet chamber, and means holding the cover in inoperative position during flight of the carrier, but permitting it tomove in response to the. rush of air following delivcry of the carrier from the tube until it houses the open valve and cuts off communh cation between the inlet and outlet chamber.

34:. Power control apparatus for apneumatic dispatch system of the vacuum minimum flow type having a transmission tube, an exhauster, a casing divided by a septum into an inlet and an outlet chamber communicating respectively with the transmission tube and the exhauster, the septum having an aperture, a controlling valve for closing the aperture, means tending to maintain the valve in closed position, a minimum .flow of air through the transmission tube normally being permitted when the controlling valve is closedand a pneumatic for opening the valve, one side of the pneumatic being always exposed to transmission tube pressure, the pneumatic responding to diminution in pressure in the tube due to the reduction of the minimum flow by insertion of a carrier in the tube and by its response opening the controlling valve, said apparatus comprising means independent of the controlling valve for cutting oil both carrier impelling flow and minimum flow through the tube when the carrier is discharged from the latter.

35. Power control apparatus for a pneumatic dispatch system of the vacuum mini mum tlow type having a transmission tube, an exhauster, a casing divided by a septum into an inlet and an outlet chamber comn In municating respectively :with the transmis sion tube and the exhauster, the septum having an aperture, and a controlling valve for closing theraperture, means tending to maintain the valve in closed position, a minimum flow otair through the transmission tube normally being permitted when the controlling valve isclosed, said apparatus,

comprising a pneumatic for opening the valve, one side of the pneumatic being always exposed to transmission tube pressure, the casing having a space at the opposite side of the diaphragm which may communicate with the atmosphere through a port of large capacity, the pneumatic responding to diminution in. pressure in the tube due tothe reduction of the minimum flow by insertion of a; carrier in the tube and by its response openingthe controlling matic dispatch system of the vacuum minimum flow type having a transmission tube, an exhauster, a casing divided by a septum into an inlet and an outlet chamber communicating respectivelywith the transmission tube and the exhauster, the septum having an aperture, a controlling valve for closing the aperture, means tending to maintain the valve in closed position, a minimum How of air through the transmission tube normally being permitted when the controlling valve is in closed position, a pneumatic for opening the valve, one side of the pneumatic being always exposed to transmission tube pressure, the pneumatic responding to diminutionin pressure in the tube due to the reduction of the minimum flow by insertion of a carrier in the tube and by its response opening the controlling valve, said apparatus comprising means independent of the controlling valve for suddenly cutting oil carrier impelling air flow when the carrier leaves the transmission tube, the pneumatic being so disposed as to experience'substantially the full hammer effect of the suddenly arrested column of air in the system, thereby facilitating closure of the controlling valve.

37. Power control apparatus for a pneumatic dispatch system of the vacuum minimum flow type having a transmission tube, an exhauster, a casing divided by a septum into an inlet and an outlet chamber communicating respectively with the transmission tube and the exhauster, the septum having an aperture, a controlling valve for closing the aperture, and meanstending to maintain the valve in closed position, a minimum flow of air through the transmission tube normally being permitted when the controlling valve is in closedposition, said apparatus comprising a pneumatic for opening the valve, one-side of the pneumatic being always exposed to transmission tube pressure,

the pneumatic responding to diminution in pressure in the tube due to the reduction ot' the minimum flow by insertion of a carrier in, the tube and by its response opening the controlling valve, the pneumatic constitut-' ing that wall of the inlet chamber which lies .directly opposite to the point at whichthe air enters the latter,'and a cut-off device disposed in the air current entering the inlet,

chamber and adapted to respond to air velocity above a predetermined amountto suddenly cut'ofl' carrier impelling air flow.

38. Power control apparatus for a pneumatic dispatch System of the vacuum minimum flow type having a transmission tube,

an exhauster, a casing divided by a septunr into an inlet and an outlet chamber communicating respectively with the transmission tube and the exhauster, the septum having an aperture, a controlling valve for closing the aperture, means tending to maintain thev for varying the minimum flow, said appa-w ratus comprising a cut-off device disposed in the air current entering the inlet chamber and adapted to respond to air velocity exceeding a predetermined amount and by its response suddenly cutting oii both the car rier impelling andminimum air.

39. Power control apparatus for a pneumatic dispatch system of the vacuum minimum flow type having a transmission tube and an exhauster, a casing divided by a septum into an inlet and an outlet chamber communicating respectively with the trans lli) mission tube and the exhauster, the septum v having an aperture, a controlling valve for closing the aperture, means tending to maintain the valve in closed position, a minimum fiow of air through the transmission tube normally being permitted when the controlling valve is in closed position, a pneumatic for opening the valve, one side of the pneumatic being always exposed to transmission tubepressure, the pneumatic responding to diminution in pressure in the tube due to the reduction of the minimum flow by insertion of a carrier in the tube and by its response opening the controlling valve, and means operative to cut oil carrier impelling naraaov:

ling valve ;is in open position.

v54:0. Powerwcontrol apparatus toraupneumatic dispatch-system of'the vacuum minie mum flow itype having aitransmission :tube, aniexhausteiga casing dividedby a septum into an inlet and ansoutlet.chambencommunicatingrespectively with the transmission tube and the exhauster, the septum having an aperture, a controlling valve for closing the aperture, means tending to maintain the valve in closed position, a minimum flow of air through the transmission tube normally being permit-ted when the controlling valve is closed, a pneumatic for opening the valve, one side of the pneumatic being always exposed to transmission to pressure, the pneumatic responding to diminution in pressure in the tube due to the reduction of the minimum flow by insertion of a carrier in the tube and by its response opening the controlling valve, and means for adjustably limiting the opening movement of the controlling valve, said apparatus comprising a movable cut-oi device disposed in the current of air on its way to the controlling valve, said device moving in response to a velocity of air flow exceeding that necessary to propel the carrier through the tube and by such response cutting off the air flow while the controlling valve is still in open position.

41. Power control apparatus for a pneumatic dispatch, system of the vacuum minimum flow type having a transmission tube, an exhauster', a casing divided by a septum into an inlet and an outlet chamber communicating respectively with the transmission tube and the eXhauster, the septum having an aperture, a controlling valve for closing the aperture, means tending to maintain the valve in closed position, a minimum flow of air through the transmission tube normally being permitted when the controlling valve is closed, and a pneumatic for opening the valve, one side 01 the pneumatic being always exposed to transmission tube pressure, the pneumatic responding to diminution in pressure in the tube due to the reduction of the minimum flow by insertion of a carrier in the tube and by its response opening the controlling valve, said apparatus comprising an air actuated check device independent of the controlling valve for cutting off air flow through the tube when the velocity of flow exceeds a predetermined amount.

42. Power control apparatus of the vacuum minimum flow type having a transmission tube, a suction tube, a casing divided into an inlet and an outlet chamber communicating erspectively with the transmission tube and the suction tube, a controlling valve governing a passage leading from the inlet to the outlet chamber, means tending to maintain the valve in closed position, a

minimum flo;w=ot air through .the :transmission rtube normally being vpermitted when.

the ,controllingvalve is in closed position, and a pneumatic tor-opening theicontrolhug valve athereby substantially equalizing :the

pressure .lll athe inlet 1 chamber with :that Llll the outlet chanibenithe pneumatic. respond- I .ing to diminution *in pressure :in :the :tube due to reduction of the minimum flow by insertion of a carrier in the tube and by such response opening the controlling valve, thereby exposing the pneumatic to the pressure of the outlet chamber, said apparatus comprising air actuated means responsive to increase in velocityin the air current beyond a predetermined amount for suddenly cutting off the pneumatic from the outlet chamber pressure.

, 43. Power control apparatus of the vacuum minimum flow type having a transmission tube and a suction tube, a casing divided into an inlet and an outlet chamber communicating respectively with the transmission tube and the suction tube, a controlling valve governing a passage leading from the inlet to the outlet chamber, means tending to maintain the valve in closed position, there being a passage leading from the inlet chamber toprovide tor a minimum flow of air through the transmission tube when said valve is in closed position, a pneumatic for opening the controlling valve, the pneu-. matic responding to diminution in pressure in the tube due to reduction or" the minimum flow by insertion of a carrier in the tube and by such response opening the controlling valve, thereby exposing the pneumatic to a pressure substantially equalling that of the outlet chamber, and an air actuated cut-off device in the inlet chamber, said device normally being inoperative but moving in response to the rush of air following delivery of the carriertrom the tube to an operative position in which it closed the passage from the inlet to the outlet chamber, said device having an element which closes the minimum flow passage when the device occupies said operative position.

4A. Power control apparatus of the vacuum minimum flow type having a transmission tube and a suction tube, a casing divided into an inlet and an outlet chamber communicating respectively with the transmission tube and the suction tube, a controlling valve governing a passage leading from the inlet to the outlet chamber, means tending to maintain the valve in closed position, a minimum flow of air through the transmission tube normally being permitted when the controlling valve is closed, a pneu matio for opening the controlling valve, the pneumatic responding to diminution in pressure in the tube due to reduction of the minimum flow by insertion of a carrier in the tube and by such response opening the controlling valve, thereby exposing the pneumatic to the pressure of the outlet chamber, means for maintaining a substantially balanced pressure upon opposite sides of the 5 controlling valve, and a normally inoperative cut-ofi' device located in the inlet chamber, said device comprising a part exposing a broad surface-transversely t0 the air current flowing through said chamber and mov 111g in response to fill velocity exceedlng that oi carrier propelling air flow to a position such that it closes said passage from the inlet chamber to the outlet chamber.

Signed by me at Syracuse New York this second day of March, 1926.

' JAMES T. COWLEY.