US1498714A - Switch mechanism for electric motors - Google Patents

Description

June 24, 1924. 1,493,71

B. $.AIKMAN SWI TCH MECHANISM FOR ELECTRIC MOTORS Original File May 21. 1,917 5 sheets- Sheet 1 June 24, 1924.

B. S. AIKMAN SWITCH MECHANISM FOR ELECTRIC MOTORS 5 Sheets-Sheet 3 Original Filed May 2 917 ma d 498,734 s. AlKMAN 4 SWITCH MECHANISM FOR ELECTRIC MOTORS Original Filed y 1917 5 Sheets-Sheet 3 inflame Eurim S.

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B. S MKMAN SWITCH MECHANISM FOR ELECTRIC MOTORS Original F1163 y 21. 1917 5 Sheets-Sheet 4.

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June 24 19240 SWITCH MECHANISM FOR ELECTRIC MOTORS 5 Sheets-Sheet 5 Originai Fil M y 21. 1917 16 v; 1 I I l5 Q? x V j I m Hf w 7 W N w 99 za flying/rim Biz/22372 Patented June 24, 1924.

UNITED STATES PATENT. OFFICE.

BIiItToN s. AIRMAN, or IL AUKEE, WISCONSIN, ASSIGNOR o NATIONAL BRAKE a ELECTRIC CCMP NY, or MILWAUKEE, wIsCoNsIN, A CORPORATION or wIs- CONSIN.

SWITCH MECHANISM FOR ELECTRIC MOTORS.

Original application filed May 21, 1917, Serial No. 169,997. Divided and this application filed November 5, 1919. Serial No. 335,815. 9

I '0 all whom it may concern:

Be it. known that I, 'BURTON S. AIRMAN, a citizen of the United States, residing at Milwaukee, in the county of Milwaukee and State of Viisconsin, have invented a certain new and useful Improvement in Switch Mechanism for Electric Motors (Case of which the following is a full, clear. concise, and exact description, reference being had to the accompanying drawings, forming a part of this specification.

This invention relates to switch mechanism for electric motors.

In my copending application Serial No. 169.997 filed May 21, 1917, I have described a starting and control system for-motor driven compressors which automatically effects the starting and stopping of the motor and' the loading and unloading of the compressor and which is particularly characterized by provision for safe-guarding the electrical apparatus as well as the compressor itself against, damage which might occur as a result of continued operation under improper working conditions.

The present application is a division of the application above referred to and has to do with the motor switch mechanism forming a part of the control system above outlined. Although the embodiment of the invention disclosed in this application is primarily designed for use in a system of this character, it will be understood that fea- "tures of the invention hereinafter claimed are capable of a wider and more general use.

'One object of the present invention is to provide a switch mechanism especially adapted for use with a control system of the character referred to.

Another object is to provide an improved means for controlling the'starting resistance for a motor.

Another object is to rovide an improved blow-out for the switc Another object is generally to improve the construction and operation of switches of this character.

The accompanying drawings which form a part of the present specification illustrate one embodiment of the present invent-ion.

lows:

Figure 1 is a front elevation of a switch board attached to a compressor and support-- The figures of the drawings are as fol- Figure 2 is a rear elevation of the switch board.

Figure 3 is a side elevation, partly in section, of the switch board. This view is taken from the left in Figure 1.

Figure 4: is a side elevation taken in the. direction opposite to that of Figure 3.

Figure 5 is a bottom plan view.

Figure 6 is a. diagram of the circuit connections for the motor.

The embodiment of the invention hereinafter described is designed primarily for use with a polyphase induction motor of .the wound rotor type. As diagramatically illustrated in Figure 6 the Circuit from the main lines 10, 11 and 12 through the primary leads 13 of the motor is completed through the main switch 14 whose terminals are connected with the main lines and the primary leads through the leads 15, 16, 17 and 18. The motor secondary circuit includes the secondary leads 19, the starting resistances 20, 21 and 22 and a cut-out switch 23 connected in parallel with the resistances for short circuiting the resistances when the motor has come up to its rated s eed.

Switches let and 23, as well 'as their operating mechanisms, are preferably removably mounted upon a switch board 9 of any approved type (see Figures 1 to 4). The main switch 14 includes two relatively fixed contactsM and 25 and two relatively movable contacts 26 and 27 carried by a cross-head 28 actuated by a plunger 29. The relatively fixed contacts 24 and 25 are electrically connected with suitable terminals 30, and 31 mounted noon the rear of the switch board and suitably insulated therefrom. These terminals are connected with the feed wires 15 and 16 joined by separable connectors 32 of any preferred type to the line wires 10 and 11. The relativelyfixed contacts 24,

and 25 comprises. pivot arm 33 swinging about a shaft 34- and pressed down by a spring 35. Upon vthe outer end of the arm is mounted an arc receivingcontact 36 for making the initial and final contact with the corresponding member of the relatively movable terminals. The conducting or actual switching contact 37 is mounted in or 31, respectively.

Th one main line wire 12 is connected directly'to the motor through the lead 39 it being unnecessary to lead this line wire through the switch- The other two primary leads 40 and 41 are connected through suitable-connectors 32 to the wires 17 and,

18, respectively, which are joined to suitable terminals 43 and 42 upon a pair of lugs 44 and 45 forming a part of theswitch operate ing cylinder 46, the terminals being suitably insulatingbarriers 53, 54, 55 and 56 which insulated from the frame of the machine.

The switch operating cylinder 46 is provided with a spriiig containing housing 47 and a pair of stationary wiping contacts 48 and 49 which lie along-the side of this housing with plates of insulation 50 and 51 interposed. The plunger 29 hereinabove referred to is actuated by a piston 52 reciproeable in the cylinder 46. The movable contacts 26 and 27 carried by the cross-head 28 are constructed in substantially the same manner as the contacts 24 and 25 except that the same are not yieldably mounted.

The cross-head 28 carries a plurality of form a pair of arc chambers 57 and 58, for the contact pairs 2426 and 25'-27 respec tively. These barriers are spaced apart by suitable insulating collars through which clamping bolts are passed. The ' 1novable contacts 26 and 27 are connected by means of movable wipers 59 and 60 to the stationary wipers 48 and 49. It can now be seen that when the contacts 26 and 27 are brought against the contacts 24'and 25, the line wires 10, 11 and 12 will be connected directly to the primary leads 13 of the motor. I

The mechanism for actuating the piston 52 of the main switch operating cylinder 46 I will now be described.

The cylinder head 61 of the cylinder 46 is I provided with a'boss 62'which has formed therein a-plurality of valve ports and passages, later to be described. The boss is covered by a recessed cap-member 63 comprisin a cylinderhaving a cylinder lining 64 wit in which slides the cylindrical portion 65 of a valve member 66 having at its upper end an enlarged shoulder or flange 67 ber 66 is normally covered by the cylinder lining 64 when the valve member is in its lowermost position. When the valve member is raised however against the action of the spring 71 (see Figure 1) the port 72 effects communication between the chamber 73 within the cap member 63 and a passageway 74 leading to the main switch operating cylinder 46. Chamber 73 is connected by the pipe 75 to any source of fluid pressure. The spring-housing 47 of the cylinder 46 contains a spring 76 interposed between the upper end of the housing and a flange 7 7 of' a hollow sleeve 78. A spring 79 of less strength than the spring 76 is positioned within the sleeve 78 and interposed between an internal flange 80 thereof and the top of the piston 52. These springs act to yieldably retain the piston 52 in its lowermost position as illustrated in Figure 3.

Passageway 7O hereinabove referred to communicates with a passageway 81 formed in the switchboard 9 and leading to a pair of arc blow-out nozzles 82 and 83.- These nozzles are supported upon the switch-board adjacent the fixed switch contacts 24 and 25 and are designed to blow fiat streams of air through the compartments 57 and 58'to extinguish the arcs which might be formed at the time the main switch is opened.

The operation ofopening and closing the main switch will nowbe described. lVhen it is desired to close the main switch fluid is admitted under pressure through the pipe 75 to the chamber 73 causing the valve member 66 to be raised to the uppermost position of Figure 1 and thus close off the end of member 69. The fluid under pressure then passes through port 72 and enters the main cylinder 46 by way of the passage 74. This causes the piston 52 to move upwardly against'the action of the springs 76 and 79 until the movable contacts 26and 27 are forced against the fixed contacts 24 and 25, when the main switch is closed. When the pressure in the chamber 73 has been destroyed the valve 66 is forced to return to its lowermost position of Figure 3, thus cutting 05 communication between passageway 74 and chamber 73 and opening communication between passageway 74 and the interior of very rapidly at first and then spring 79 acts -to move it more gradually during the latter ited amount of air under high pressure and the valve member 66 is provided with a bleed opening 84 therethrough. This opening permits 'a leakage of air from the pipe 75 and chamber 73 to the interior of the member 69 when the valve member 66 is in its uppermost position. The main portion of the air from the air reservoir passes from the pipe 75 into the chamber 73 and finally into the cylinder 46 to effect the closing of the main switch in the manner just described. The switch is thus held closed until the pressure in the reservoir, and hence pipe 75, has been depleted due to the escape of the air-through the bleed opening 8 1. At that timethe valve member 66 returns to its lowermost position and the piston 52 returns to its lowermost position and reopens the switch, unless some means is provided for preventing such return. Means for this purpose will be later described in connection with the description of the construction and operation of the cut-out switch 23.

The cut-out switch is preferably removably mounted on the switchboard near the main switch and includes a pair of relatively fixed contacts 85 and 86 and a pair of relatively movable contacts 87 and 88 constructed in substantially the same manner as the corresponding contacts of the main switch. The fixed contacts 85 and 86 are connected with suitable elongated terminals 89 and 90, respectively, mounted upon and suitably insulated from the rear side of the switch board 9. One end of terminal 89, is connected to a secondary lead from the motor through a feed wire 91 and separable connection 32. The corresponding end of the terminal 90 is similarly connected to another secondary lead through a feed wire 92. The other ends of the terminals are re: spcctively connected to the upper ends of the two compressible resistances 21 and 20 by means of flexible conductors 93and 94. The third secondary lead from the motor is connected to a feed wire 95 which leads .up

in front of the' switch-board and is connected to a terminal 96, as shown in dotted lines in Figure 2. A metallic conductor 97 (Figures 1 and 2) joins this terminal with a terminal 98 extending through the switchboard 9 to the rear thereof which terminal is electrically connected to the upper end of the third compressible resistance 22 through always in contact with he stationary wiper" plates 102 and 103. The stationary wiper plates 102 and 103 are electrically connected to the terminals 104 and 105 mounted upon the secondary switch operating cylinder 106. Suitable .insulating strips 107 and 108 sepa-' rate the stationary wiper plates 102 and 103 from the cylinder. Both tel .ninals 104 and 105 are electrically connected to the feed. wire 95 through a suitable conductor 109 (see Figures 2'and 4). Thus it will be seen that when the cut-out switch is closed by forcing the movable contacts 87 and 88 against the stationary contacts 85 and 86, respectively, current may pass from the motor through either of the feed wires 90 or 92 across the corresponding switch contacts and through feed wire 95 back to the motor, or vice versa, without passing through theresistance.

The movable switch contacts 87 and 88 are carried by a cross-head 110 supported upon a vertically movable plunger 111 secured to aipiston 112 reciprocable in the cylinder 106. A compression spring 113 acts to yieldably retain the piston 112 in the lowermost position of Figure 4:. The piston 112, is raised however by the admission of fluid under pressure to the cylinder 106 through the passage 106. This passage may be connected with any source of fluid pressure through a pipe 114. When the pressure in the cylinder has been reduced the piston, 112 is returned to its lower, position by the action of the spring 113 and the cutout switch is reopened. Mechanism is provided r'or compressing or expanding the resistances 20, 21 and 22 to vary their effective resistance as the cut-out switch mechanism moves toward and from closed position. The mechanism will now be described.

A lever 115 is pivotally mounted intermediate its ends as at 116 to the top of the switch-board 9. The forward end thereof projects over the cut-out switch mechanism while the other end engages an insulated above the resistance members 21 and 22.

()ne end of the lever bears against-an in '124 fixed to the switch-board.

Suflicient tension is maintained through:

this system of levers-to retain the several resistances in-position by a spring means whlch will now be described. This means includes a telescopic connection between the forward end of lever 115 and an insulating stud-or collar 125 secured to and carried by the cut-out switch cross-head 110. The telescopic connection includes a sleeve 126 and a cylindrical member 127 surrounded by a strong compression spring 128. Spring 128;

bears at one end against the stud or collar 125 and at the other end against a flange 129 formed on the cylindrical member 127. The cylindrical member is counterbored to receive a smallspring 130 which places the system of levers just described under the desired initial tension. The tension of the spring 130 may be adjusted by a set screw 131' to control the value of the starting resistance. I

During the upward travel of the crosshead 110 the tension of the spring 128 is gradually materially increased causing a corresponding increase of tension through the system of levers above described. This increased tension effects an equal compres sion in all of the resistances 20, 21 and 22 thus causing a decrease in their effective resistance to permit a greater flow of current through the motor secondary circuit as the motor speeds up. This. decrease in resistance continues until the cut-out switch is closed and the resistances short circuited.

Mechanism is provided for preventing the opening of the main switch until the cut-out switch has been opened and the full resistance thrown into the motor secondary circuit. In stopping, the speed of the motor is thus gradually reduced and the danger of severe arcing at the main switch contacts whenthis switch opens is avoided. This mechanism includes a latch in the form of a bellcrank lever having a substantially horizontal trip arm 131 and anupright latch arm 132. This lever is pivotally mounted upon the spring housing 47 of the main switch operating cylinder by means of a horizontal pin 133. A spring 134 bearing against the arm 131 tends to move the lever to the latching position shown in Figure 1. The cross-head 28 carries a downwardly and rearwardly projecting rigidarm 135 having a shoulder In 136 for engagement with the upper end 13 of the latch arm 132 of the lever. As the cross-head 28. reaches its extreme upper position in which the main switch'is closed the spring 134 throws the end 137 of the latch arm 132 beneath the lug 136 to retain the switch in closed condition.

The cross-head 110 of the cut-out switch carries a projection 138 which engages the trip arm 131 of the bellcrank lever to trip the lever at the time the cross-head reaches its lowermost position (Figure 4). This re- I the trip arm 131 permitting the latch arm 132 to lock the -main switch closed. Fur-. ther .upward movement of the cross-head gradually reduces the resistances and finally short circuits the resistances by closing the cut-out switch -as above described. In order to stop the motor it is necessary to reduce the fluid pressure in the cylinder 106.

This is accomplished by the use of an exhaust valve 139 yieldably held to its seat by a spring 140 to close the valve port 141. Spring 140 bears against a piston 143,slidable in a cylindrical portion of a chamber 144 and connected to'the ,valve 139 by a valve stem 145. A small chamber 146 is formed beneath the piston 143 and is 0011* nected with a'suitable source of fluid pressure through a pipe 147.

When it is desired to stop the motor, fluid under pressure is admitted to the chamber 146 through pipe 147 to raise the piston 143 and consequently lift the valve off its seat to open the valve port 141. This permits escape of the fluid from the cylinder 106 and the consequent lowering of the piston 112 to open the cut-out switch. Continued A downward movement of the cross-head 110 reduces the pressure upon the resistances 20, 21 and 22 so that their effective resistance is increased. Finally the projection 138'on the cross head strikes the trip arm 131 of the latch mechanism, thus releasing the main, switch and permitting the same to open.

The fluid escaping fromthe switch operating cylinder 106 through the valve port 141 into the chamber 144 may pass out through an exhaustpipe 148. When a hibrieating oil is employed as the pressure medium, as in the application above referred to, a passageway 149'may be provided connecting the chamber 144 with the upper end of the cylinder 106 so that as the oil escapes under pressure from the lower end supply passage, a fluid exhaust passage, an

of the cylinder some of it may be forced up into the upperportion of the cylinder above the piston 112 to provide the necessary lubrication for these parts.

Means may beprovided for manually closing the main switch in addition to the fluid operated means hereinabove described. Amechanism for this purpose is illustrated in Figures 1 and 3 and includes a lever 150 pivoted at one end to the front face of the switch-board 9 as at 151. This lever is preferably provided with an anti-friction roller 152 engageable with the end 153 of the rigid arm 135, hereinabove mentioned, secured to the cross-head 28 of the main switch. lVhen it is desired to close the main switch the handle 154 of the lever 150 is raised thus forcing the roller 152 against the rigid arm 135 and lifting the cross-head 28 to the switch closing position.

Although the invention has been described in connection with a polyphase induction motor it is clear that it may be employed for controlling motors of various other types.

Various changes may be made in the embodiment of the invention hereinabove described without departing from or sacrificing any of the advantages of the invention as defined in the following claims.

I claim 1. In combination a main switch, means for yieldably retaining said switch in one position, means for moving said switch to a second position against the action of said yieldable means, a second switch, and a latch controlled by said'second switch for holding said main switch in the second position.

*2. In a switch mechanism the combination of a switch having fixed and movable contacts, a single acting cylinder, a piston in said cylinder and connected with said movable contact, means for admitting compressed" air to said cylinder, means for depleting thepressure of the live air admitted to said cylinder, means for moving said piston to expel the air from said cylinder and to open said switch, and means for utilizing the air thus expelled to blow out the are formed during theopening of said switch.

3. In aswitch mechanism the combination of a switch havin fixed and movable contacts, a single acting cylinder, a piston in said cylinder connected with said movable contact, means for admitting air under pressue to said cylinder to move the piston outwardly to close said switch and to trap the air in said cylinder, a blow-out nozzle connected with said cylinder, and means for moving said piston inwardly in said cylinder to open said switch and to force the air from said cylinder through said blow-out nozzle.

cylinder, a piston in said cylinder, a fluid arc blow-out nozzle connected with said exhaust passage and a valve for effecting communication either between said cylinder and said supply passage to close said switch or between said cylinder and said exhaust passage to blow out the are when said switch opens.

5. In combination a mounting board, stationary switch contacts mounted on' said mounting board, a movable switch contact, an operating cylinder for said movable con tact, a piston movable in the cylinder, a spring for moving the piston to open the switch, jet means for directing a flow of fluid between the stationary contact and the movable contact, a valve and passageways for connecting the cylinder with said jet means when the piston is moved by said spring.

6. In combination a stationary switch contact, a movable switch contact, an arcing chamber surrounding said contacts, a single acting cylinder having an operating piston moved by airwpressure for closing said contacts, spring means for opening the contact and expelling the air from the cylinder and means for projecting a jet of air expelled from the cylinder through said arcing chamber when the switch is opened.

7. In combination a switch, an operating cylinder for said switch, a pneumatic blowout for the switch, a valve mechanism having passages leading to the blowout, to the cylinder and to a source of fluid under pressure, said valve being operated by admission of fluid under pressure to admit fluid under pressure to the cylinder for operating the switch and means to operate the valve to connect the cylinder with the pneumatic 5 blow-out when the switch is opened.

8. In combination a switch, an operating cylinder for closing said switch, a pneumatic blow-out for the switch, a valve mechanism having passageways leading to the cylinder, to the pneumatic blowout and to a source of fluid under pressure, said valve being operated by introduction of fluid under pressure to admit said fluid to the piston to close the switch, said valve having leakage means to permit the fluid under pressure to escape and means for moving the ,valve to connect the cylinder with the pneumatic' blowout when the switch is open.

for operating the switch, valve mechanism for said cylinder, said valve mechanism comprising a pair of ports and a movable valve element adapted to obstruct one of said ports at a time, a passage communi' eating with the cylinder, a passage communicating with the blowout nozzle and one of said ports, a passage communicating with one of said ports andadapted for connec- 13o tion with a' source of fluid under pressure, said valve mechanism being actuated by the fluidpressure to admit fluid under pressure to the cylinder, aspring for moving said movable va'lve elements to connect the cylin'der with the blowout nozzle and means.

for opening the switch.

10. lin combination a main switch, a blow.- out nozzle for said main switch, an operating cylinder for closin said main switch, means for admitting n I to said cylinder to close the switch, a meanda chanical detent for holding said switch in closed osition, a'. spring for moving the piston in said cylinder'and to open the. switch, a resistance controlling means for connecting the cylinder with the blowout nozzle.

11. In combination a switch, a blowout nozzle for the switch, a cylinder for closing the switch, a mechanical detent for holding said. switch in closed position, a spring for opening said switch, a valve and a conduit for connectin said nozzle with thecylinder to blow out t e are when the switch lowed to open. Y 1

12. The'co'mbination of a switch, means forclosing said'switch including a piston and a single acting cylinder, "a pneumatic blow-out connected with said cylinder so that air is forced through said blow-out by the return movement of said piston, and;

initial movement of said piston and a slower. .final movement of said piston -14. The combination of a switch, a"cylin-- der, a piston in-said cylinder for actuating,

said switch, means for admitting a limited amount of'fluid under .pressure to said cyle *inder to close said switch, and means permitting a leakage of .said' fluid to efiect a reopening of said switch. after a predetermined time interval.

15. The combination of a switch, a cylinder'," -1a piston in said cylinder for actuating saidfsw'itch, means for admitting a limited amount of fluid under pressure to' said cylinder to close said switch, a latch for holding said switch closed, and leakage means for depleting the fluid pressure after apredetermined'time, interval.

16. The combination of a switch, a piston and cylinder for actuating said switch, a

id under pressure switch adapted to release said detent and valve is -al-' passage for admitting fluid under pressure to said cylinder,fan exhaust passage for said cylinder, a valve actuated by the fluid under pressure for efiecting communication be tween said cylinder and said fluid inlet passage, and movable to eiicct communication between said cylinder and said exhaust passage, anda bleed opening through'said valve communicating with said fluid inlet passage and said exhaust passage.

17. The combinationof a switch having fixed and movable contacts, a piston and cylinder for actuating saidanovable' contact, means for connecting saidfiied contact'with a source ofelectric current, a terminal sup ported by said cylinder, and an extensible conductor between said terminal andsaid movable contact including a stationary wiper plate connected with'said terminal and ,a movable wiper plate engaging said stationary plate and connected with said movable contact.

18. In combination a switch, said switch. comprising a relatively stationary and a relatively movable contact, an operating cylinder for said switch, a piston rod for said cylinder, said piston rod being connected to the movable contact, said cylinder having a spring housing, said piston rod passing through said housing, a spring in said housing, normally holding said contacts separated, a piston in said cylinder connected to .said rod,.-a stationary wiper plate mounted on the side of. said springihousing, and a movable wiper contact carried by said piston rod and connected. to said movable contact.

'- 19. In combination a mounting board, stationary and movable contacts mounted on said board, an operating cylindenmounted on said board, a piston rod supporting the movable contact barrier chambers surrounding' the. movable and stationary contacts,

X said barrier chambers being mounted on said piston ma'stai aary .wiper contactssupported rby"'the cylinder, and movable wiper contacts" supportedby" the piston rod.

20. The combination of a switch, a cylinder, a piston in said cylinder for actuating said'switch, a port for admitting fluid pres sure to said cylinder to close said switch, an exhaust port of greater capacity than said first'named port,-andvalve mechanism for controlling said ports to effect a closing of said switch or a quickopening of said switch. 21. The combination of a switch, a cylinder, a switch actuating piston in said cylinddi and means for-admitting fiuid'to or from said cylinder to actuate said piston, said means being constructed-to' permit the flow of fluid-faster in one direction thanithe other so as to efiect a relatively slow closing of the switch and a rapid opening of the switch. '4

22. The combination of a switch, a cylinder, a switch actuating piston in said cylinder, a fluid inlet port, a fluid outlet port,

switch and for opening said second named port to open said switch with a quick action.

24;. The combination'o'f a switch, means for closing. said switch and for holding said switch closed for a predetermined period, means operable to hold said switch closed for an indefinite period, and means for effecting the opening of said switch wit-ha quick action when released.

25. The'combination of a switch, fluid means for closing said switch and for bold ing said switch closed for a predetermined period, and means for opening said switch with a quickaction after said switch has been released.

26. The combination of a switch and fluid means for closing said switch and for hold ing said switch closed fora predetermined period, said means including a valve mecha nism for effecting a quick opening of said switch after said switch hasbeen released. 27. In combination, a mam switch, means for closing the main switch and holding it closed for a predetermined time only, a starting resistance cut-out switch in series with the main switch and means controlled by said latter switch for holding'the main switch closed until the latter switch is opened.

28. In combination, a pivoted contact member having an arcing horn and a main contact portion, a cooperating movable. switch member having a main contact portion and'an arcing horn, means for moving said members into engagement with each other to bring the arcing horns into engageinent first and thereafter to bring the main contact portions into engagement, and an arcing chute surrounding saidcontact members and movable with the second contact member.

29. 'In combination, a relatively stationary switch member, a relatively movable switch member, a spring tending to separate said members, and pneumatic means operated by said spring for projecting a blast of fluid upon the'contact members as they are separated, said movable member having mo tion for creating said pneumatic pressure before the contacts are separated.

30. In combination, a pair of contact members, one of said members being movable with respect to the other, a spring for moving said movable contact member, and pneumatic means operated by said spring for directing a blast of air upon the contacts when they separate, said movable memher having motion prior to. separation of the'swit'chmembers for creating said pneumatic pressure.

31. In combination, a pair of switch members, a single actin cylinder having a pismoving the movable member into engage-- ment with the stationary member, a spring for moving said piston and movable switch member to open the switch, means for admitting a predetermined quantity of air under pressure to said cylinder and for thereafter exhausting the same, said means directing the air compressed by the return movement of the piston upon the switch members when the switch is opened by said spring.

33. In combination, a switch, a cylinder having a piston for operating said switch, an auxiliary reservoir, means for connecting the auxiliary reservoir to said switch cylinder, and means for bleeding away the pressure of said auxiliary reservoir and switch cylinder;

34:. In combination, a switch, a cylinder having a piston for operating said switch, an auxiliarygeservoir, means for connecting the auxfliary reservoir to said switch cylinder,-and means for bleeding away the pressure of said auxiliary reservoir and switch cylinder, a mechanical detent for holding the switch closed.

35. In combination, 'a switch, a cylinder having a piston for operating said switch, an auxiliary reservoir, means for connecting the auxiliary reservoir to said switch cylinder, and means for bleeding away the pressure of said auxiliary reservoir and switch cylinder, a mechanical detent for holding the switch closed, and a cutout switch controlling said mechanical detent.

ton driven outwar 'ly by fluid pressure for 36. In a switch, a stationary contact mem-' one spring with the top of the other spring and a housing for enclosing said springs,

said first spring at its upper end engaging the housing, said piston being adapted to engage the lower end of the lbarrel whereby the first spring applies its pressure directly to .the piston and thereafter the second spring applies pressure to the piston for giving the piston arapid start but relatively slow travel towards the end of its motion. 37. In a switch, a stationary contact member, a relatively movable contact member, a piston, a cylinder, means comprising a source of fluid pressure for moving the p1ston to close the switch, and means for moving the piston to open the switch, said means comprising a pair of concentric springs, a barrel member connecting the lower end of one spring with the top of the other spring and a housing for enclosing said springs, said first spring at its upper end engaging the housing, said piston being adapted to engage the lower end of the barreliwhere by the first spring applies its pressure directlyto the piston and thereafter the second spring applies pressure to the piston for giving the piston a rapid start but relatively slow travel towards the end of its motion, and a blow-out nozzle connected to the cylinder for directing a blast of air upon the switch contact. 1

38. In combination, a cylinder, a piston,

a air of switch members including a movab e member connected to said piston, a pair of s rings of different strength for moving t e piston inwardly to separate the contact, the stronger spring first applying its pressure directly thereafter through the weaker spring in order to give an addimovable member to open position and pneumatic means operated by the spring to pro-' tional impulse to the piston for giving a quick operation of the blow-out nozzle, and a blow-out'nozzlefor directing the air compressed by the inward movement of the piston upon the switch contact when they separate.

39; In combination, a pair of, switch members one of said members being movable, a

cylinder having a piston connected to said movable switch member, a housing of reduced diameter mounted upon said cyhnder, I

a, spring in said housing for opposing the closing movement of the piston, a stationary contact mounted along the side of the housing, and a movable wiper connected to the movable switch member. 7

40. In combination, a switch having a relatively stationary and a relatively mov able member, a spring for throwing the they are separated. I

41. The combination of a main switch ject a'blast of air between the members as having means for closing-the same, a spring for opening the same,*a latch for holding the main switch in closed position, the, closing means for the main switch comprising the main switch in closed position, the closing means for the switch comprising a piston and cylinder and an auxiliary reservoir forholding said main sw tch closed for a predetermined time only, a latch for holding the switch closed for an indefinite time, means for tripping out the latch, and a blowout nozzle connected with the cylinder, the

inward movement of the piston under the influence of the spring causing a flow of air through said blow-out nozzle.

43. In combination, a main switch, a blow-out nozzle for the main switch, an operating cylinder for closing said main switch, means for 1 admitting fluid under.-

pressure to said cylinder to close the switch,

a mechanical detent. for holding the switch in closed position, a spring for moving the piston in said cylinder to open the switch, means adapted to release saiddetent and valve means for connecting the cylinder with the blow-out nozzle.

442 In an electric controlling device for controlling'a motor operated pump, a motor circuit, a circuit changer for said circuit, a pressure cylinder for operatin said circuit changer, a valve controlling t e admission of pressure to said cylinder, a connection between said valve and said cylinder, and

means in said connection for permitting a free flow of fluid out of said cylinder.

45. In an electric. controlling device for controlling the electric motor circuit of a motor operatedpump,'a circuit controller, a pressure actuated motor for actuating the circuit controller, a valve, eontrollingthe motor,a connection between-the valve and the-motor, and means in the connection retarding the flow from the valve to the motor but permitting a free fiow from the motor.

46; In an electric controlling device, the.

combinationof'a circuit controller, a pressure actuatedmotor for actuating the cir-v cuit controller, a valve controlling the motor,

a connection between the valve and the mo tor, and means in the connection retardingthe iiowfrom the valve to the motor and permitting a free flow from the motor.- 4L7. In combination, a switch, a cylinder for closing the switch, a pressure controlled valve, a fluid pressure connection between the valve and the cylinde'r,,and a quick release valve for said cylinder for quick open ing of the switch when the pressure in the cylinder decreases below a predetermined value.

48. In combination, a switch having a contact, a blow-out for the contact, a'pressure operated cylinder for closing the switch contact, a s ring for opening said contact, a connection ibr fluid pressure to the cylinder, and a nick release valve for the cylinder for connecting said cylinder with said blowout.

49. In combination, a switch having a con tact, a blow-out for the switch contact, a fluid pressure operated cylinder for closing the switch contact, a fluid pressure connection for the cylinder for closing said switch contact, and a quick release valve connecting the cylinder and the blow-out.

50. In combination, a switch, a fluid pressure operated cylinder for closing the switch, means for admitting a charge of fluid pressure to the cylinder for holding it closed for a predetermined time, a leakage port for dissipating said charge and a quick release valve for permitting the switch to open quickly after the fluid pressure has been depleted to a predetermined point.

51. In combination, a switch, a fluid pressure operated cylinder for closing the switch, means for admitting a charge of fluid pressure to the cylinder for holding it closed for a predetermined time, a leakage port for dis-' sipatin said charge, and a quick release valve for permittin the switch to open quickly after the fluid pressure has been depleted to a predetermined point, and a blowout for the switch'connected to the cylinder throu h said quick release valve.

52. In combination, a swit h having a stationary and movable contact, a cylinder having a piston connected to the movable contact, a spring for moving the piston and 'movable contact, a fluid pressure connection forthe cylinder, a leakage port tending to deplete the pressure in said cylinder and a quick release valve for said cylinder. v 53. In combination, a switch having a stationary and a movable contact, a cylinder for operating the movable contact, means i tending to open the movable contact, a fluid pressure connection for the cylinder, and a quick release valve for exhaustin the pressure in the cylinder when said pressure drops below a predetermined value.

54. In combination, a switch having a stationary and a movable contact, a cylinder for operating the movable contact, means tending toopen the movable contact, a fluid pressure connection for the cylinder, and a quick release valve for exhausting the pressure in the a cylinder when said pressure drops below a predetermined value, a blowout for the switch contact, and a connection between said blow-out and saidquick release valve. i

55. In combination, a main switch, a cutout switch, a first fluid pressure operated cylinder for the mainswitch, a leakage port and a quick acting release valve for said cylfor closing said main switch, a cut-out switch, in series with a main switch, means for closing the cut-out switch and means controlled by the cutout switch for holding said main switch closed, and means controlled by said holding means for automatically opening the main switch.

57. In combination, a main switch, means for closing said switch, a spring for opening said switch, a latch for holdingsaid main switch closed, a cut-out switch in series with a main switch, a spring for opening the second switch, means for hol ing the second switch closed, said latchfor the main switch being tripped by opening of the cut-out switch.

58. In combination, a plurality of switches, means for closing said switches in a predetermined order, means for each switch individually tending to open it, means for holding said switches closed and means con- .trolled by opening of one switch for disabling the holding means of an adjacent switch. e

59. In combination, a plurality of switches, means for closing said switches in a predetermined order, means for each switch individually tending to open it, means for holding said switches closed, said means be-' ing operable only in a different predetermined order from that of closing the switches.

60. In combination, a first switch, a second switch, means for closing the first switch, means for closing said second switch after the closing of the first switch, spring means for throwing the first switch open automatically, means for throwing the second switch open automatically and holding means for the first switch adapted to be tripped out by the opening of the second switch.

61. In combination, a first switch, a second switch, pneumatic means for closing the first switch, spring means tending to open the first switch, fluid pressure means for closing the second switch, spring means tending to throw the second switch open, mechanical holding means for holding the first switch closed, said holding means being tripped out by opening of the second switch and a valve controlling the opening of the second switch.

62. In combination, a first switch, a sec ond switch, pneumatic means for closing the first switch, spring means tending to throw said switch open, a quick release valve for permitting rapid opening of the first switch,

mechanical detent means for holding the first switch closed, a second switch, fluid pressure means for closing the first switch, spring means tending to open said first switch, a'quick release valve for permitting rapid opening of said second switch and means on. thesecond switch controlled by opening of said second'switch for tripping .out the mechanical holding means for the first switch.

63. In combination, a pair of switches,

fluid pressure means for closing the switches in predetermined order and detent means for the switch first'closed for compelling .opening of the switches in the reverse of said predetermined order. I

645-111 combination, a pair of switches, fluid pressure means for closing; the said switches in a I predetermined order, detent I meansfor the switch first closed for compelling opening of the switches in the reverse order, andquick release valves for said fluid pressure means for permitting rapid opening of each ofsaid switches.

65. In combination, aswitch, a cylinder having a piston 'for operating said switch, aniaux-iliary- .reservoir,means for connecting the auxiliary reservoir to said, switch cylinder, means for bleeding away the' pressure of said. auxiliary reservoir and said switch cylinder-, ancl means for, recharging; I

opened.

the auxiliary reservoir when'the switch is 66.111 combination, a' switch,a cylinder having-a piston for operating said switch,

a main reservoir, an auxiliary reservoir,-

and said switch? cylinder, fa. mechanical pressure themain reservoir for tripping said mechanic alfdetent and for recharging said auxiliary reservoir, I I I In witness whereof I hereunto subscribe n y name this 30th day of October'l9l9. BURTON s. AIK AN.

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