US930989A - Convertible system of pressure or vacuum control. - Google Patents

Description

W. J. RICHARDS. CONVERTIBLE SYSTEM OF PRESSURE 0R VACUUM CONTROL.

APPLICATION FILED JAN. 25, 1905.

Patented Aug. 10, 1909.

2 SHEETS-SHEET 1.

W. J. RICHARDS. CONVERTIBLE SYSTEM OF PRESSURE 0R VACUUM CONTROL.

APPLIOATIONIILED JAN. 25, 1905.

Patented Aug. 10, 1909.

2 SHEETS-SHEET 2.

warren J- memos; onmLwAuKEE, wissonsiuiassieuon TO NATIONAL BRAKE & ELECTRIC coMBnN-Y, or MILWAUKEE. WISCONSIN, t CORPORATION 0F WISCONSIN.

souvenir ens srs'rnm or nb. -eso,eee.- I

To all it may concern Be it known that. I, WALTER J. RICHARDS,

" residing in Milwaukee, in the county or Co trol", ofwhich the-following is a description, reference bein'ghad to the accompanying drawings, which area part of this specification.

, This invention relat'es to convertible systems of pressure or vacuum control, and

consists in a system and apparatus by which a pump may be operativ y'connected with either a-com'press'ed air system or a vacuum system,'with automatic means for starting and stopping the. operation of the pump in either case tomaintain' the compression or vacuum within predetermined limits.

This invention is designed for use wherever' a single "pumping mechanism lS 'desired to"-'supply air j inder compression at onetime and to produce a vacuum at another "time, particularly in the case of electric. locomotives which are'adapted to be connected'at onetime with a train equipped with a compressed air brake system and at another time witha train equ pped with a vacuum brake system. In such'cases it is necessary. to provide a compressed air reser-V voir :Eor use with. the former brakesystem a'nd a vacuum reseryou' for use with the latter brake system, and it is a great convenience tote able to charge both of these reservoirs by means-of ,the same pumping ,m'echanism'.

The control of the pumping mechanism for'maintaining the pres'sureof air in-the compressed air reservoir constant or practically so'is accomplished by automatic means sensitive .-.to the pressure in the reservoir, which will start the pumping mechanism in operation when-the pressure reaches apredetermined minimumand will stop such operation of the pumping mechanism when the pressure reaches a predetermined maximum. As it is also desirable to similarly control theoperation of the pumpin mech-' anism when it is in connection with the vacuum reservoir, so. that it will maintain a vacuum therein of a constant or practically constant degree, it is one of the ob-- jects of this-iuventi'onto provide, in combination with avalve mechanism for making Specification of LettersPatent. I Application filed January 25,; 1905. Serial No. 242,616.

rnnssurts on vac, w conrsoL;

Patented Au /1o, 1909,.

, the necessary changes in th pneumatic coll:

nections to enable the pumping mechanism ;-to be operatively connected with one reserresult may befaccomplished. f Another obJect of this invention is to propose which will connect in shunt with each other .two o'rmore field windings of'a series effecting the compression regulation "of the pumping mechanism, and Wh1Cll-W-lll connect =sa1d field windings of the series wound the switch mechanism is in the osition for effecting the suction regulation 0 the pumping mechanism. By this means the pump operating motor is rendered capable of overcoming the greater resistance of back pressure during the compression operation thereof than it is subjected to durlng the suction operation, since the degree of compression ;necessary'for the compressed air reservoir iis considerably greater than the degree of suction necessary for-charging the vacuum reservoir. I 1y i Another object of this invention is, in such a convertible system, to couple together the valve mechanism and the switch mechanism 'is' in position to make the necessary connections between the pumping mechanism and the compressed air reservoir the switch mechanism can only be closed in the position .for making theelectrical connections for'the operation and control of the pump motor for an compression, while the change to the other position of the valve mechanism will so affect the switch mechanism that'it can only be closed to make the necessary connections forcontrolling-and operating-the motor for the-vacuum operation oft-he' pump Another object of the invention is to accomplish the last mentioned object byoperatively connecting the valve mechanism with position of one produces of position vof the other.

With the above and other objects in view the proper change the invention consists in the system and vide a switch" mechanism for the above purpump motor in series with each other when thereofiso that when the valve mechanism- .the switch mechanism, so that the change ofwound pump operatingmotor, when said SW1tCll mechanism is 1n the position formeans for controlling pumps, the and combination of parts as herein set iorth, and

their equivalents.

f is a diagram showing the pneumatic and electrical connections of the several parts constituting the convertible system of pressure or vacuum control of this invention Fig. 2,-is a central sectlonal v ew of the five- .way cock of the valve mechanism; Fig. 3

a side elevationrotzthehand 'switch mechanismthereof; and, Fig. 4 is a side elevation of a modified formofha'nd switch mechanism 'and valve mechanism, showing an erative connection between v them change of. position 'of one produces the proper change of'position of the other.

In these drawings 7 represents the piston of apump which operates in. a cyllnder 8 and is connected to across-head 9 having a Hpitman connection 10-with the'crank 11 of-apump operating motorzxfrThepump cylinder is provided with inlet-valves 12 and outlet valves 13 at each end,'the former being connected together by'a forked suction pipe 14 and the'latter' being connected together by a forked discharge p1pe15. 2:-

A fivesway cock l6. hasrzfivelequi-distant pipe connections arranged .radially therearound, and-its central-valve plug 17 is proconnections.

20 are limited by its engagement with a pair register with 'vide'd with a pair of curved passageways" 18 andv 19 respectively, eachadapted to. connect the openings of two'adjacent pipe connections together. A handle 20-is mounted on a squared end' of the. valve plugfl? by means of which said. Valve plug maybe turned in its casing: to change the position of} the passageways l8 and 19 and-cause them 'to connect the openings of difl'erent pairs-of pipe The movements of said handle of stop shoulders 21 on the casing to-determine the properpositions of the valve plug in which its passageways18 and 19 exactly nectionsbetweenpipe connections 22 and 23, which connects with the atmosphere, either. direct or by way ofa pipe 25. A pipe connection.

26, next to thepipe connection 23,,is connected-by a pipe 27 with a compressed air reservoir,;28, while the fifth pipe connection," 7

29, between pipe connections26 and 22, connects bymeansjofea pipe 30 with a vacuum reservoir 31. p The passageways 18 and 19 of the valve plug 17 are so located, that in :one position of the handle 20, :pas'sageway' 18 connects."

where y the the openings of the pipe- .con-=.

with a pressure gage 41, connecte *pipe collection 29 with pipe connection 22,

establishing a through passage from the vacuumreservoir 31 to the inlet valves 12 of the pump, while passageway 19 connects pipeconnection23 with pipe connection 24, establishing a through passage from the outlet valves 13 of the pump to the atmosphere. ,These are the roper pneumatic connections 'for that COIldltiOll of the system in which the pump is required to maintain a vacuum in the vacuum reservoir, by sucking air from the. vacuum reservoir 31 through the pipes 30 and 14 and discharging it to the atmos phere through pipes 15 and 25. In the other position of the handle 20, passageway 18 connects pipe connection 24 with pipe connection 22, establishing a through assage from the. atmosphere to the inlet valves 12 of the pump, while the passageway 19 connects pipe connection 23 with pipe connection 26, establishing a through passage from the outlet calves 13 of the 'ump to the compressed air reservoir 28. T ese are the proper pneumatic connections for that condition of the system'in which the pump is operation-of the system is shown by dotted lines in Fig. 1, while the position thereof for the compression/operation of the system is shown in Fig. 2,

The vacuum reservoir 31 is provided with a vacuum gage 32. connected thereto by means ofa pipe 33. The gage 32 comprises a Bourdon spring tube 34, which communicates with the pipe 33 and has its closed free end' connected by a link-35 with the outstanding arm of. a pivoted segmental rack 36,

meshin "with aypinion 37 of a age hand 38. The reduction in the degree 0% the vacuum in the vacuum reservoir 3], due to service use, 'causes'the Bourdon tube 34 to straighten and swing the gage hand 38, by means of the segmental rack 36, to the left until it engages The suctlon plpe 14, above ment1oned,con-. nects with one of the pipe connections,22, of, y I the five-way cock and the discharge. pipe 15.- connects with another pipe connect1on,. 23, thereof, there being a pipe connection 24 a minimum contact post 39 and makes an electrical contact therewith for startingthe pump motor in operation by means to be later described. The increase in the degree of vacuum in the vacuum reservoir 31', as the air 15 drawn therefrom by the pump, causes 'the'Bourdon tube 34 to contract and make 38 to the right, until it engages a maximum contact post 40and makes anelectrical contact therewith for stopping the operation of the pump motor by the said means to be later described.

The compressed airreservoir is rovided thereto by means of a pipe 42, which gage is similar in all respects to the vacuum gage 32 of the gage with a maximum contact post 45, for stopping the operation of the pump motor.

An automatic switch is provlded for starting and stopping the pump motor, consisting of a stationary contact 46 and a movable contact 47, the latter being carried by a core 48 surrounded by a pair of oppositely disposed solenoids 49 and 50 respectively. The solenoid 49'is in a position to move the core 48 in the direction to bring the movable contact 47 into engagement with the sta-,

tionary contact 46 for closing the motor circuit, and the solenoid 50 is in a position to move the core 48 in the opposite direction to cause it to withdraw the movable contact 47 from the stationary contact'46 for opening the motor circuit.

One terminal of a source of electrical supply, not shown, usually the trolley wire in the case of an electric locomotive, is indicated by the wire 51, the other terminal thereof being grounded. The motor switch closing solenoid 49 has one end connected to the trolley wire 51 audits other end connected by a wire 52 with the minimum contact post 44 of the pressure gage 41. A wire 53 connects said wire 52 with the minimum contact post 39 of the vacuum gage 32' The meter switch opening solenoid 50has one end connected bymeans of a wire 54 with the maximum contact post 40 of the vacuum ge 32, and by means of a wire 55 leading 4 cm said wire 54, with the maximum contact post 45 of the pressure gage 41. The other end of solenoid 50' connects by means of a wire 56 to a ground connection 57.

A threeoint, double-throw, knife switch is mount on a switch board 58- and is adapted in one position, to make the necessary electrical connections for the system when operating as a vacuum controlling .system, and is adapted in another position,

to make the necessary electrical connectionsfor the system when operating as an air pressure controllingsystem. The movable switch handle member 59 of the doublethrow' switch is shown in Fig. 1 in dotted lines, for convenience of illustration, in" the proper position for operatingthe system as a vacuum controlling system. The three central contacts to which the movable member- 59 has its three switch blades 60, 61

and 62, pivoted are marked 63, 64 and 65 respectively, while the three contacts for the switch at the compression end of the switch board, the left as shown in Fig. 1, are marked 66, 67 and 68 respectively, and those at the, otherend, the vacuum end of the switch board, are marked 69, 70 and 71 respectively.

The stationary contact 46 of the motor switch is connected by means of a wire 72 to the trolley wire 51, while the movable contact 47 thereof, being insulated from the core 48, slides in a contact guide 73 which is connected by means of a wire 74 with contact 65 of the switch board. A wire 7 5 connects said wire 74 with contact 66 of the switch board, while a wire 76 also con nects wire 74 with one of the field windings 77 of the pump motor; The other end of said field winding 7 7 is connected by means of a wire 78 to the contact 69 of the switch board, which contact 69 is connected by means of a wire 79- with contact 64 of the switch board. Awire 80 connects one armature brush 81, of the pump motor with the contact 67 of the switchboard, while the other armature brush 82 of said pump motor is connected by means of a wire 83 with the ground connection 57 before referred to. A wire 84 connects armature brush 81 with one end of another field winding, 85, of the pump motor, the other end of said field winding 85 being-connected by means of a wire 86 to contact 63 of the switch board. The gage hand 43 of the pressure gage 41 connects by means of a flexible conductor 87 with a wire 88 leading to contact 68 of the switch board, while a similar flexible conductor 89 connects the gage hand 38 of the vacuum gage 32 with a wire 90 leading to contact 71 of the switch board. Thecdntact 70 of the switch board is not used to make electrical connections.

The operation of the system, so far as the electrical circuits are concerned, is as follows: The switch handle 59 of the threepoint double-throw switch being thrown to tem, and the vacuum gage 32 indicating a minimum degree of rarefaction of the air in the-:vacuum reservoir 31 by the gage hand 38 contacting with the minimum contact post 3-9, current will flow from the trolley wire 51, through the motor switch closing solenoid 49, the wires 52 and 53, the contact made between the contact post 39 and the gage hand 38, through the wires 89 and 90 to the contact 71 of the switch board, across the switch blade 62 to the contact 65, through wires 74 and 76 to the motor field winding 77, back to the switch board by way of wire 78-to' contact 69, across the switch blade 60 to contact 63, through wire 86 to the other motor field winding 85, to brush 81 by wire 84, through the armature of the motor to circuit through the motor.

brush 82, and by way of wire 83 to the ground connection 57.

Current passing through the motor switch closing solenoid 49, included in the circuit thus established by the closing of the contact between gage hand 38 and contact post 39, causes the core 48 to move to the left and bring the movable contact 47 into engagement-with the stationary contact 46, thereby closing the motor switch to establish a direct Current now passes from trolley wire 51, through wire 72, and the engaged switch contacts 46 and 47, through the contact guide 73 and wires 74 and 76, to the motor field winding 77, by wire 78 to the contact 69 of the switchboard, across the switch blade 60 to contact 63, through wire 86 to the other motor field winding 85, by wire 84 to brush 81 of the motor armature, through the armature to the other brush 82 thereof, and by wire 83 to the ground connection 57.

The connection made by the motor switch contacts 46 and 47 establishes the motor operating circuit, just described, with the two field windings of the pump motor in series with each other and with the armature of said motor, and the motor is thereby caused to operate the pump to pump air from the vacuum reservoir 31 to the atmosphere, until the predetermined maximum degree of vacuum has been attained in the vacuum reservoir 31 and the gage hand 38 of the vacuum gage 32 contacts with the maximum contact post 40 as the result. This contact between the gage hand 38 and the maximum contact post 40 establishes a circuit through the motor-switch-opening solenoid 50 ,by current passing from the trolley wire 51, through wire 72, across the.

engaged motor switch contacts 46 and 47 through the contact guide 73 and wire 74 to contact 65 of the switch board, across the switch blade 62 to contact 71, by way of wires 90 and 89 to the gage hand 38, across the contact made thereby with the maximum contact post 40, through wire 54 .to solenoid 50, and by wire'56' to the ground connection 57.

The motor-switch-opening solenoid 59 being energized, moves the core 48 to slide contact 47 away from the stationary contact 46, and thereby open the motor switch to deprive the motor of its current and stop its operation of the pum This automatic starting and stopping o the pump motor at the predetermined minimum and maximum degrees of vacuum contained in the vacuum reservoir 31 will be repeated to maintain an approximately constant degree of vacuum for vacuum service purposes.

When the handle 59 of the three-point double-throw switch is thrown to the left, or to the compression position, opposite to that in which it is shown in dotted lines in Fig. 1, the vacuum gage hand is no lon er in connection and the pressure gage 41 ecomes operative for controlling the operation of the pump motor instead. Now, when the gage hand 43 indicates a predetermined minimum degree of compression in the compressed air reservoir 28 by con,- tacting with the minimum contact post 44, the motor-switch-closin solenoid 49 is energized, by current passing from the trolley wire 51 through said motor-switch-closing solenoid 49 and the wire 52 to the minimum contact post 44, across thecontact made by the gage hand 43 therewith, through the wires 87 and 88 to the contact 68 of the switch board, across the switch blade 62 to the contact 65, through wires 74 and 7 5 to contact 66, across switch blade 60 to contact 63, through wire 86 to motor field winding 85, by wire 84 to the armature brush 81, through the armature to the other brush 82 thereof, and by way of wire 83 to the ground connection 57. Incidentally there is a branch circuit from the one just traced which connects the field winding 77 of the motor in shunt with the field winding 85,

this branch circuit leadin from wire 74 through wire 76 and the old winding 77, by way of wire 78 to the contact 69, across wire 79 to'contact' 64, through the switch blade 61 to contact 67, and by way of wire 80 to the armature brush 81 where it returns to the circuit formerly described.

The motor-switch-closing solenoid 49, being energized by current passing through this circuit, attracts the core 48 and causes it to move the contact 47 into enga ement with the stationary contact 46, as be ore, to complete a direct motor circuit, which, however, difi'ers somewhat from the motor circuit before established by the closing of this motor starting switch, because of the different position of the double-throw switch. Now the motor circuit passes from the trol ley wire 51, through wire 72 and the engaged contacts 46 and 47, through the contact guide 73 and wire 74 to wire 76, through the motor field winding 77 and wire 78 to contact 69 of the switch board, over wire 79 to, contact 64, across switch blade 61 to contact 67 by wire 80 'to brush 81 of the motor armature, through said armature to the other brush 82 thereof, and by wire 83 to the ground connection 57. The circuit 'just traced includes the field winding 77 in I new board, then across switch blade to con-' until the maximum pressure of said reser-= voir is reached and causes the pressure gage hand 43-to contact with its maximum contact' post ,45 and establish a circuit through the motor switch-opening solenoid 50- to open the motor switch and stop the opera-.

tion of the pump. This contact of the pressuregage causes current to pass from the trolley wire 51, through wire 72 and the engaged. switch contacts '46 and 47, through contact guide 73- and wire. 74 to contact on the switch board, across switch blade 62 to contact 68, through wires 88 and 87 to gage hand 43, across the contact made thereby with the maximum contact post 45, through wires 55 and 54 to solenoid '50, and by wire 56 to the ground connection 57.

-From the foregoing it will be seen that while the pump motor operates as-a series wound motor when connected for either the vacuum control operation of the system or the air pressure control operation of the system, in the former case its two field windings 77- and 85 are in series with each other and in the latter case the said field windings 77- and 85 are in shunt with each other, so that the power of the motor is increased in the latter case for overcoming the greater resistance of the back pressure during the compression operation than it is subj eeted to during the vacuum operation. This change of connection of the field windings has forits object the keeping, of the speed of the motor within reasonable limits when operat: ing-under the light load during the vacuum connection. a

Should the double -,throw switch 59 be thrown to the vacuum position while the five-way cock was in the compression posit:

tion, there would be no control over the operation of the motor, since the pressure gage 41 would not be in-electrical connection, and

therefore the compressed air in reservpir 28 would be allowed to become entirely exsion which the pres re gage. would have permitted, and possi 'ly result in the destruction of some part of the apparatus. The foregoing is also true of the reverse connectlons, when the switch mechanism is closed to the compression position while the five-waycock is set for the vacuum position. Therefore, it is important that some means be adopted to prevent the switch mechanism being closed to make the electrical connections for one operation of the system when the five-way cock is set for another operation thereof.

With the above object in view the switch mechanismis preferably provided with a blocking means in connection with the fiveway cock, adapted to be automatically moved to block the closing of the. switch member 59 in one position or the other, as the five-way cock handle 20'is moved from one position to the other, and thereby prevent the switch being closed to the vacuum position when the five-way cock is in the compression position and vice versa. The blocking means comprises a slide- 91 of insulating material, such as vulcanized fiber,

Whichis slidable longitudinally upon the switch board 58 between the contacts 67 64 and 70 and the contacts 68, 65 and 71, and is guided in its movements by overhanging projections on some-of these contacts. At the ends of thesliding plate 91 .are fixed blocking lugs 92 and 93 respectively through which slides a rod 94 connected by means of a link 95 with the handle20 of the fiveway cock, so'that the movements of the handle 20, as the five-way cock is turned from one position to the other, cause the rod 94 to sllde lengthwise through the blocking lugs. A pair ofset stops 96 are mounted on the rod 94 in positions to engage the inner endskof the blocking lugs 92 and 93 respectively during the movements of the ing the ,movement of the slide plate 91. By

this means the change in position of the slide serves 'as an indicator to inform. the operator when the change in position of the five-way cock is complete and prevents the clos ng of the switch until such change of position of the five-way cock is effected. By this means, when the five-way cock lever 20 1s thrown from.one position to another, the

"slide 91 is automatically moved from one position to the other to bring one or the .rod'94, and cause the slide plate 91 to move other of the blocking lugs 92 and 93 thereof, to a position where it will stand in the path of the cross bar 97 of the switch handle 59 and prevent said handle moving the switch blades into engagement with the switch contacts on that end of the switch board. Thus, when the five-way cock is in position for making the pneumatic connections for the vacuum regulation, the switch handle 59 is prevented by the blocking lug 92 standing in the path of its cross bar 97 as shown in Fig. 1, from being closed to the position for making the electrical connections for the compression operation of the system, and when the five-way cock is in the opposite position, for making the pneumatic connections for the compression regulation, the blocking lug 93 stands in the path of said cross bar 97 of the switch handle 59, so that said switch can not be closed to make the electrical connections for the vacuum operation of the system.

Each of the blocking lugs 92 and93 has its inner end cut away to form a shoulder 98 for engaging and limiting the movement of the cross bar 97 of the switch handle 59 when said switch is being closed. The slide plate 91 has a cut away portion 99 to form shoulders for engaging the opposite sides of contact 64 and limiting the movement of the plate in its slidable mounting. The construction of this blocking means is such, that for converting the system from a pressure controlling system to a vacuum controlling system, or vice versa, the switch 59 must first be opened to allow the motor to come to a stop, if it is then. in-operation. An attempt to change thefive-way valve without first opening the switch would be checked as soon as the loose movement of rod 94 were taken up, since a stop 96 would engage with the blocking lug opposite the switch, and as the slide plate can not move with it, being held by the other blocking lug engaging with the switch, the valve is prevented frommoving farther and has not yet opened the connections for the change of operation of the system. Therefore the operator is first required to open the switch to release the valve and allow the motor to slowdown, then change the valve to move the blocking means from the path of the switch, and finally close the switch to its new position, the old position being blocked.

The modification, shown in Fig. 4 illustrates another method by which the switch mechanism and the valve mechanism are prevented from being set for different operations of the system, and in addition provides for the simultaneous operation of the two mechanisms. In this construction the movable member 59 of the switch has its switch blades projecting on each side of'the handle proper to form an anchor shaped switch member, each of the switch blades 60, 61 and 62 being duplicated as shown by the blades .62, so that the handle 59 is only required to move through a small arc in order to disengage the switch blades from one set of contacts and engage them with the other set of contacts. The five-wa cock is only altered from the five-way coc: of the construction before described by having a crank arm 20 instead of the handle 20, which crank arm 20 is connected to the switch handle by means of the jointed link 95. With this construction, the change of position of the switch mechanism, by throwing the switch handle 59 from one position to another, be-

sides changing the electrical connections from those for one operation of the system to those of the other, also, through the medium of the link 95, changes the position of the five-way cock to change the pneumatic connections from those of one operation of the system to those of the other. Aside from ,this simultaneous operation of the switch ingly, the terms maximum and minimum, as

applied to the vacuum gage, refer tomaximum and minimum degrees of vacuum and not to maximum and minimum pressures.-

The term gage as employed herein with reference to the pressure gage or the vacuumgage is intended to include all devices sensitive' to variations in fluid pressure by which the necessary contacts may be made,

and the claims are tojbe read with this understandin For convenience the swingin parts 0 the three-point double-throw kni e switch, including the :switch blades are referred to as the switch member, and as this member must be in one of its two closed positions in order that the system may be operative, these positions are intended when it is said that the operation of the switch depends upon the operation of the five-way cock or vice versa, and when the switch is said to be changed from one position to another the change from one operative position to the other operative position is meant.

' What I claim as my invention is 1. A convertible system of fluid pressure or vacuum sup'ply, comprising a pump, a suction pipe leading to the inlet valves of the pump, a discharge pipe leading from the outlet valves of the pump, a compressed air reservoir, having a compressed air pipe connected therewith, a vacuum reservoir having a vacuum pipe connected therewithg-"and each other and with the "atmosphere to make the necessary connections between the pump and the-compressed air reservoir for causing the pum to charge the compressed air reservoir'oror makingthe necessary connections between'the vacuum-reservoirand the pump for causingthe pump to charge the vacuum reservoir a '2. A convertible systeinof fluid pressure or vacuum-"supply, comprising a motor operated' pump, a suction pipe connected to the inlet valves of the pumpga discharge pipe connected to the outlet' valves of the pump, a compressed air reservoir, a compressed air pipe connected therewith, -a vacuum -reser-' voir, a vacuum pipe-connected therewith, and a =five=way cock having connection with allof the saidpipes andwiththe atmosphere, adapted in one position toconnect the vacuum pipe with the suc'ti'on pipe'andthe discharge pipe "with the'atmosphere for causing the pump to charge the vacuum rese'rvoir, and adapted in another position to connect the atmosphere with the suction pipe and the discharge pipe with the-compressed ai pipe for causingthe'pump to charge the compressed air'reservoir. v

3. A convertible system of pressure or vacuum control, comprising a motor operated pump, a compressed air-reservoir and a vacuumreservoir, a valve for-'operatively connecting one reservoir or the other with the pump anautomatic switch forclosin and 'openmg the motor operating circuit 0 the pump motor, a pressure gage sensitive topressure in the compressed'a'ir reservoir adapted'to ma'ke electricalconnections to cause the automatic switch to close and open the motor circuit at'the minimum-and maximum pressures respectively within the compressed air reservoir, a vacuum gage sensitive to the degree' of vacuum in the vacuumres'ervoir and adapted to make electrical connections to cause the automatic switch to] close and open the motor circuit at theminimum and maxi mum degrees of vacuum respectively in the vacuum reservoir, and a switch for rendering either the'pressure gage or the vacuum gage inoperative'for the control of'the automatic switch.

4. A convertible system of pressure or vacuum control, comprising 'amoto'r oper-- connection of the vacuum reservoir with the pump, an automatic switch for closing and opening the motor operating; circuit of the pump motor, a pressure gage connectedtothe compressed air reservoir and adapted .to make electrical connections to cause the trical-connections made-by either the pressure gage or the vacuum gage, said switch being so related to the valve mechanism that the valve mechanism when in position for connecting the vacuum reservoir with the pump prevents the switch being operated to cause the connections made by the pressure gage-to become effective and when in posi-- tion for connecting the compressed air reservoir with the pump prevents the switch beingoperated to cause the connections made by the vacuum gage to become efiective.

'5. A convertible system of pressure or 'vacuum control, comprising a motor operated pump, a five-way cock to which the suction and discharge valves of the pump are connected, a compressed air reservoir and a vacuum reservoir connected to thefive-way cock, one of theports of the five-Way cock being connected to the atmosphere, said five- ;wa'y cock being adapted in one'position to connect the vacuum reservoir with the sucition valves of the pump and the discharge valves of the pump to the'atmosphere and in vits other positionto connect the compressed "air reservoir with the discharge valves of the pump and the suction valves of the pump with the atmosphere, an automatic switch for closing and openingthe motor circuit of the pump motor, a pressure gage connected to the compressed air reservoir and adapted to make electrical connections for causing the automatic switch to close andopen the motorcircuit at the minimum and maximum pressures respectively of the compressed air reservoir, a vacuum gage :connected to the vacuum reservoir and adapted to make electrical connections to cause the automatic switch to close and open the motor circuit at'the minimum and maxi- ..mum degrees of vacuum respectively contained in the vacuum reservoir, and a switch for rendering inefi'ective the connections made by either gage.

6. In a convertible system of pressure or .vacuum control, comprising a motor operated pump, acompressed air reservoir and a vacuum reservoir having operative connections with the'pum a valve mechanism adapted to render ine ective the pump connections of the compressed air reservoir in one position and the pump connections of the vacuum reservoir in another position, an automatic switch for closing and opening the motor circuit of the pump motor, a pres sure gageconnected to the compressed air reservoir and adapted to make electrical connections to cause the automatic switch to close and open the motor circuit at the mini mum and maximum pressures respectively of the compressed air reservoir, a vacuum gage connected to the vacuum reservoir and adapted to make electrical connections to cause the automatic switch to close and open the motor circuit at the minimum and maximum degrees of vacuum respectively in the vacuum reservoir, and a switch mechanism adapted to render ineffective the electrical connections made by either the pressure gage or the vacuum gage and also included in the motor circuit.

7. A convertible system of pressure or vacuum control, comprising a motor driven pump, a compressed air reservoir and a vacuum reservoir having operative connections with the pump, a valve mechanism to render inefi'ective the pump connections of the compressed air reservoir in one position and to render inefi'ective the pump- COIlIlcC- tions of the vacuum reservoir in another position, an automatic switch for closing and opening the motor circuit of the pump motor, a pressure gage connected to the compressed air reservoir and adapted to make electrical connections to cause the automatic switch to close and open the motor circuit at the minimum and maximum pressures respectively in the compressed air reservoir, a vacuum gage connected to the vacuum reservoir and adapt-ed to make electrical connections to cause the automatic switch to close and open the motor circuit at the minimum and maximum degrees of vacuum respectively in the vacuum reservoir, and a switch mechanism for closing the electrical connection to onegage in one position and for closing the electrical connection to the other gage in another position, said pump motor having its windings connected with the switch mechanism so that they will be connected in one manner in one position of I the switch mechan sm and will be connected in a different manner in the other position of the switch mechanism. 8. A convertible system of pressure or vacuum control, comprising a motor driven pump, a compressed air reservoir and a vacuum reservolr having operative connections with the pump, a valve mechanism for rendering ineffective the pump connections of the compressed air reservoir in one position and for rendering ineffective the connections of the vacuum reservoir in another position, an automatic switch for closing and opening the motor circuit of the pump motor, a pressure gage connected to the compressed air reservoir and adapted to make electrical connections for causing the automatic switch to close and open the motor circuit at the minimum and maximum pressures respectively of the compressed air reservoir, a vacuum gage connected to the vacuum reservoir and adapted to make electrical connections to cause the automatic switch to close and open the motor circuit at the minimum and maximum degrees of vacuum respectively of the vacuum reservoir, and a switch mechanism adapted to make electrical connection for the pressure gage in one positionand to make electrical connection for the vacuum gage in the other position, said pump motorhaving its field windings connected to the switch mechanism so that they will be connected in series with each other in one position of the switch mechanism and will be connected in shunt with each other in the other position of the switch mechanism.

9. A convertible system of pressure or vacuum control. comprising a motor driven pump a five way cock with which the pump connects, a compressed air reservoir and a vacuum reservoir connected to the five-way cock, said five-way cock adapted in one position to operatively connect the compressed air reservoir with the pump, and in the other position to operatively connect the vacuum reservoir with the pump, an automatic switch adapted to connect and disconnect the motor circuit of the pump motor and having a switch closing solenoid and a switch opening solenoid, a pressure gage connected to the compressed air reservoir adapted to establish a circuit through the switch closing solenoid and through the switch opening solenoid at the minimum and maximumpressures respectively of the compressed air reservoir, a vacuum gage connected to the vacuum reservoir and adapted to establish a circuit through the switch closing solenoid and the switch openin solenoid at the minimum and maximum egrees of vacuum respectively of the vacuum reservoir, a switch mechanism for completing the circuit of the pressure gage in one position and for completing the circuit of the vacuum gage in another position, the field windingsof the pump motor being connected to the switch mechanism so that they will be connected in series with each other in one position of the switch mechanism and in shunt with each other in the other position of the switch mechanism, and means for determining the operative position of the switch mechanism by the operative position of the five-way cock.

'10. A convertible. system of pressure or vacuum control comprising a motor driven pump, a five-way cock with which the pump is connected, a compressed air reservoir and a vacuum reservoir connected to the fiveswitch at the minimum and maximum way cock, said five-way cock being adapted to operatively connect the compressed air reservoir with the pump in one position and to operatively connect the vacuum reservoir with the pump in another position, an automatic switch for closing and opening the motor circuit of the pump motor, a pressure gage connected to the compressed air reservoir adapted to make electrical connections for closing and opening the automatic ressures respectively in the compresse air reservoir, a vacuum gage connected to the vacuum reservoir-and adapted to make electrical connections for causing the automatic switch to close and open the motor circuit at the' minimum and maximum degrees of vacuum respectively in the vacuum reservoir, a switch mechanism adapted to complete the circuit to the pressure gage in one position and to complete the circuit to the vacuum gage in another position, the fieldwindings of the pump motor being connected to the switch mechanism so that in one position of the switch mechanism they are connected in series with each other and in the other position of the switch mechanism they are connected in shunt with each other, a slide mounted on the switch mechanism having-a pair of blocking lugs thereon,-a rod slidable through the blockin lugs, set stops on the rod for permitting oose movement of the rod and for engaging the blocking lugs to cause the slide to move, and a link connect ing the rod with the five-way cock so that in one position of the five-way cock one of the blocking lugs prevents the switch mechanism being closed in one position and in the other position of the five-way cock the other blocking lug prevents the s'witchmechanism being closed in the other position- 1.1. A convertible system of fluid pressure or vacuum control, comprising a motor operated pump, a suction pipe connected to the inlet valves of the pump,'-a discharge pipe connected to the outlet valves of the pump, a compressed air reservoir, a vacuum reservoir, a five-way cock having connection with the atmosphere with the suction and discharge 'pipes and with the compressed air and vacuum reservoirs adapted in one position to connect the vacuum reservoir with the suction pipe and the discharge pipe with the atmosphere for causing the pump to charge the vacuum reservoir and adapted in another position to connect the atmosphere with the suction pipe and the discharge pipe with the compressed air reservoir for causing the pump to discharge said compressed air reservoir, a double throw switch, means for controlling the operation of the pump by variations of conditions in the compressed air reservoir and the vacuum reservoir respectively and having connection with the double throw switch, said double throw switch being adapted to establish the vacuum control connections when closed on one side and to establlsh the compressed air control connections when closed on the other side,

a slide plate, blocking lugs thereon adapted to stand in thepath of the double throw swltch to prevent its closing on one side in one position of the slide plate and adapted to prevent its closing on the other sidein another position of the slide plate, and means for connecting the slide plate with the five-way cock.

12. A convertible system of fluid'pressurc and vacuum control, comprising a motor operated pump, a suction pipe connected to the inlet valves of the pump, a discharge pipe connected to the outlet valves of the pump, a compressed air feservoir, a vacuum reservoir, a five-way cock having connection with the atmosphere with the suction and d scharge pipes and with the compressed air and vacuum reservoirs adapted in one position to connect the vacuum reservoir with the suction pipe and the discharge pipe with the atmosphere for causing the pump to charge the vacuum reservoir and adapted in another position to connect the atmosthe compressed a1r reservoir and the vacuum reservoir respectively and having connection with the double throw switch, said double throw switch adapted to establish the vacuum control connections when closed on one side and to establish the compressed air control connections when closed on the other side, a slide plate, blocking lugs thereon adapt-ed to stand in the path of the double throw switch to prevent its closing on one side in one position of the slide plate and to prevent its closing on the other side in another position of the slide plate, a rod slidable through the blocking lugs, stops thereon to engage the blocking lugs and cause the slide to move, and a connection between the rod and the five-way cock whereby the change in position of the five-way cock changes the position of the blockin lugs, thus requiring a change 111 position 0 the double throw switch before the change in position of the five-way cock may be effected' 13. A double throw switch, comprising a member adapted to swing from one positlon to another, contacts adapted to be engaged by the member in its dlflerent positions, a

blocking device -to prevent the .closing of the switch member in one position or the other thereof, and means for moving the blocking device for removing the bar to the closing of the switch in one position andsubstitute a bar to the closing of the switch 'in. another position.

14. A double throw switch, comprising a switch base, a switch member mounted to swing thereon, contacts on the switch base adapted to be engaged by the switch member in different positions thereof, a blocking mechanism comprising a slide plate slidably mounted on the switch base, blockin lugs carried thereby and adapted to stand 1n the path of the switch member to prevent the closing thereof on one side in one position of the slide plate and to prevent'the closing thereof on the other side in another position of the slide plate, and means for moving the slide plate.

15, A double throw switch, comprising a switch base, a switch member mounted to swing thereon, contacts on the switch base adapted to be engaged by the switch member when closed on either side, a slide plate slidably mounted on the switch base and guided by the contacts, blocking posts on the slide plate to prevent the switch member being closed on one side in one position of the slide plate and to prevent the switch member being closed on the other side in another position of the slide plate, and means for moving the slide plate.

16. A double throw switch, comprising a switch base, a switchmember mounted to swin thereon, contacts adapted to be engage by the switch member when closed on one side or the other, a slide plate slidably senses mounted on the switch base, blockinglugs on the slide plate to prevent the switch member being closed on one side in one position of the slide plate and adapted to preventthe switch member being'closed on the other side in another position of the slide plate, a rod slidably mounted on the slide plate, stopsthereon to engage the blocking lugs and cause the movement on the slide plate, and means for moving the rod.

17. A double throw switch, comprising a switch base, a switch member mounted to swing thereon, contacts adapted to be engaged by the switch member when closed on either side, a slide plate slidably mounted on the switch base, blocking lugs on the slide plate to prevent the closing of the switch member on one side in one position of the slide plate and to prevent the closing of the switch member on the other side in another position of the slide plate, stop shoulders on a the blocking lugs adapted to limit the movement of the switch member when said switch member is closing, a rod slidably mounted through the blocking lugs, adjustable stops on'the rod to engage the blocking lugs and cause the slide plate 'to move, and means for moving the rod.

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

WALTER J. RICHARDS. Witnesses: I

R. S. C. CALDWELL, ANNA F. SCHMIDTBAUER.

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