US3215805A - Unitary lead support molding including an integral chamber for puffer, buffer assembly - Google Patents

Description

Nnv. 2, 196 G. A. WILSON ETAL 3,

UNITARY LEAD SUPPORT MOLDING INCLUDING AN INTEGRAL CHAMBER FOR PUFFER, BUFFER ASSEMBLY Filed March 1, 1962 4 Sheets-Sheet 1 INVENTOR5 GEO F65 ,4. W/A .S'UIV is 7801 E/we, 598 52, 6am Jaw-z Nov. 2, 1965 G. A. WILSON ETAL 3,215,805

UNITARY LEAD SUPPORT MOLDING INCLUDING AN INTEGRAL CHAMBER FOR PUFFER, BUFFER ASSEMBLY Filed March 1, 1962 4 Sheets-Sheet 2 Nov. 2, 1965 G. A. WILSON ETAL 3,215,805 7 UNITARY LEAD SUPPORT MOLDING INCLUDING AN INTEGRAL CHAMBER FOR PUFFER, BUFFER ASSEMBLY 4 Sheets-Sheet 3 Filed March 1, 1962 INVENTORS 62056! 4 W/[JO Oar/904.51%, 59852, Gsea f ana-w 477272445250 G. A. WILSON ETAL Nov. 2, 1965 UNITARY LEAD SUPPORT MOLDING INCLUDING AN INTE CHAMBER FOR PUFFER, BUFFER ASSEMBLY Filed March 1, 1962 594952. 6 44 Jung/v United States Patent UNITARY LEAD SUPPORT MOLDING INCLUDING AN INTEGRAL CHAMBER FOR PUFFER, BUFF- ER ASSEMBLY George A. Wilson, Media, and Frank J. Pokorny, Hatboro, Pa., assignors to I-T-E Circuit Breaker Company, Philadelphia, Pa., a corporation of Pennsylvania Filed Mar. 1, 1962, Ser. No. 176,556 4 Claims. (Cl. 200-148) This invention relates to circuit interrupters, and more particularly to a novel unitary molding for circuit interrupters which incorporate the functions of both the lead support means and the puffer assembly means into a single unitary structure.

Circuit interrupters presently in use employ single unitary panel members which are formed of an insulating material and which serve the purpose of the rear panel and terminal lead support for the circuit interrupters. One such panel support structure is set forth in US. application Serial No. 10,625, now US. Patent No. 3,096,423, entitled Unitary Multiphase Terminal Support, filed February 24, 1960, by G. A. Wilson, and assigned to the assignee of the instant invention.

The support means of the type set forth in the aforementioned U.S. application provides adequate support for the lead terminals of circuit breakers of the draw-out switch gear type.

In circuit breakers which employ means for transferring an are which forms between the circuit breaker cooperating contacts during the tripping operation, means are employed to rapidly remove the are from the cooperating contacts to an arc extinguishing means such as, for example, an arc chute assembly. One such means pres- .ently employed in the circuit breaker assemblies is a puffer assembly means which is designed so as to generate a puff or blast of air in the region between the cooperating contacts as they begin to separate in order to blow out or remove the are from the cooperating contact surfaces.

In circuit breakers which employ such puffer assemblies, it becomes highly advantageous to eliminate as many of the elements of the puffer and assembly as is possible while retaining all the functions performed by these elements.

The unitary molded structure set forth in the instant application performs this function by combining the necessary lead support structure and pufier assembly housing into a single unitary molding. This is highly advanponents which make up the circuit breaker structure.

It. is, therefore, oneobject of this invention to provide a novel unitary structure for draw-out switchgear.

Another object of this invention is to provide a simple and economical means of positioning and supporting the lead terminals of a circuit interrupter by means of a unitary molded assembly. 7

Another object of this invention is to provide a novel unitary molded member for positioning and supporting the lead terminals of a circuit interrupter, and for incorporating into the same. unitary member the housing structure for a puffer assembly means.

Still another object of this invention is to provide a 'novel unitary molded member which is designed to perform the function of positioning and securing the lead terminals of a circuit interrupter and which further in- "cludes a novel configuration fora circuit breaker puffer assembly.

Patented Nov. 2, 1965 These and other objects of this invention will become apparent from the following description when taken in connection with the drawings, in which:

FIGURE 1 shows a perspective view of one embodiment of the novel unitary molding.

FIGURE 2 is a side plan view of a circuit interrupter employing an alternative embodiment of the unitary molding member shown in FIGURE 1.

FIGURE 3 is a side plan view of a portion of the unitary molding showing an arrangement which is slightly modified from that of the arrangement of FIGURE 2.

FIGURE 4 is a side plan view of one embodiment of the unitary molding shown in FIGURE 1.

FIGURE 5 is a side plan view of another embodiment of the unitary molding of FIGURE 1.

Referring now to the drawings, FIGURE 1 shows a novel unitary molding 10 which is provided with integral tubular members 11, 12, 13, 14 and 15 which extend through the rear panel section 17 and are provided with support flanges to render the tubular members more rigid on either side of rear panel 17. Each of the integral tubular members 11 through 15 has openings such as opening 18 in tubular member 11 which extend completely therethrough and are adapted to receive conductive members, as will be described hereinafter.

Also integral with unitary molding 10 are two interphase barriers 19 and 20 which are adapted to extend between the stationary contact structures of the multiphase circuit breaker of the switch gear assembly.

Although FIGURE 1 shows a unitary molding which is adapted to position and secure lead supports for the upper and lower terminals of a three-phase circuit interrupter, it should be understood that the unitary molding shown in FIGURE 1 may be employed to adequately posi- .tion and secure lead terminals for a greater or lesser number of phases, as the number of phases for which the unitary molding is designed lends no novelty to the instant invention.

At the base of the molding 10, an opening 26 is provided for receipt of the push rod (not shown) which is connected to a bridge (not shown) carrying the movable contact of the circuit interrupter. An arrangement similar to that of the molding shown in FIGURE 1 is set forth in detail in the aforementioned US. application Serial No. 10,625, and that application is hereby incorporated herein by reference.

Each phase of the multiphase molding 10 has projecting from its rear panel 17 an opening 27 which is designed to house the piston and piston rod components (not shown) of the circuit breaker puffer assembly which will be considered in greater detail with reference to the remaining figures. This assembly provides adequate positioning and securement for the puffer assembly, whilefurther performing the function of the piston chamber which confines the gas contained therein during the opening and closing operations of the circuit interrupter associated with this unitary molding.

FIGURE 2 shows a side plan view of the unitary mold- :ing together with the circuit interrupter structure for .for the circuit interrupter structure shown in- FIGURE 2.

The opposite end of conductor 30 is electrically connected to a substantially U-shaped stationary contact structure 31 which cooperates with movable contact 32 mounted to movable bridge member 33 which is pivoted to rotate about pivot point 34. Lower tubular member 12 receives lower lead conductor 35 through an opening pror 3- vided therein, the opposite end of conductor 35 being secured to conductive member 36 to which movable bridge 33 is rotatably secured.

A triangular shaped non-insulating member 37 is fastened to movable bridge 33 at pivot 34 and at a second pivot 38 which serves a dual function, as will be more fully described.

An aperture 39 is provided at one apex of the triangularly shaped member 37 for linkage with the circuit interrupter operating rod (not shown) which rod is adapted to move the movable bridge 33 between its engaged and tripped positions.

An aperture 40 is provided in unitary molding for receiving a threaded member 41 which is secured at one end to unitary molding 10 by threaded member 42 which threadedly engages member 41. The opposite end of member 41 has a head 43 which secures piston chamber 44 employed in the putter assembly 45 to the support molding.

Puffer assembly 45 is comprised of a piston 46, slidably mounted within piston chamber 44 for reciprocating movement between the piston walls 43a and 47. A tubular member 48 is secured at one end to an aperture 49 provided in piston chamber wall 47. A nozzle member 50 is secured to the opposite end of tubular member 48 for the purpose of directing a blast or puff of air between the cooperating contacts 31 and 32 in a manner to be more fully described.

A solid cylindrical member 51 is rigidly secured at one of its ends to piston member 46. A second aperture 52 is provided in the piston chamber wall 47 which is adapted to slidably engage tubular member 51. Connecting member 53, which is pivotally secured at one of its ends to pivot point 38 on movable bridge 33 and which is secured at its opposite end to tubular member 51, is employed 'for the purpose of imparting translational movement to the solid cylindrical member 52 under control of rotational movement of the movable bridge 33.

The operation of the puffer assembly 45 is as follows:

Upon the occurrence of a short circuit or overload condition, the circuit breaker push rod (not shown) which is linked to 'triang'ularly shaped member 37, urges member 37 clockwise about pivot point 34. Member 37 which is secured to movable bridge 33 imparts this clockwise rotation to bridge 33 causing cooperating contacts 31 and 32 to move to a disengaged position. Member 53, which is pivotally connected to movable bridge 33 at pivot point 38, urges solid cylindrical member 52, which is also known as a piston rod member, in the direction shown by arrow 54. This translational movement is imparted to piston 46 which compresses the air contained between piston 46 and piston chamber wall 47 forcing the air out of this confined area through tubular member 48 and nozzle 50. The blast, or pull, of air is directed by the nozzle 50 into the immediate region of the cooperating contacts 31 and 32, urging any are which may form between these cooperating contacts towards separation from the contact surfaces upward so as to be transferred to an arc chute assembly such as the arc chute assembly 60 shown in FIGURE 2.

It should be noted that the puffer assembly 45 is pivotally mounted to the unitary molding 10 in order to compensa'te for the vertical movement which will be imparted to cylindrical member 52 due to the rotation of movable bridge 33.

The vertical movement which will occur can clearly be seen from consideration of FIGURE 3 which shows the movable bridge 33 in both the closed and partially tripped positions. The phantom lines 61 show the general region of the air blast which is created upon initiation of the tripping operation, and the dotted lines 62 show the general region of the air blast an instant later. It can be seen that the air blast follows the movement of the arc and, therefore, acts upon the arc in the region between the contact surfaces which is the most advantageous region for urging the arc upward and away from the cooperating contacts 31 and 32.

As an alternative embodiment FIGURE 4 shows a portion of the unitary molding 10 having an aperture 27 provided therein, which performs the function of the puffer assembly piston chamber. The piston 46 is housed within the chamber 27 for reciprocating movement between the end surfaces 7 0 and 71 of the molding 10. A piston rod 72 is secured at one end to piston 46; the other end of piston rod 72 being secured to a nozzle assembly 73. It should first be noted that the unitary molding 10 is designed so as to incorporate the piston chamber 27 within the molding itself.

The embodiment shown in FIGURE 4 further ditfers from that of FIGURES 2 and 3 by the employment of a piston rod 72 which is hollow so that it contains an opening 74 through its entire length, which opening cooperates with the substantially L-shaped opening 75 provided in nozzle member 73 which communicates directly at one of its ends with the opening 74 in piston rod 72. The opposite end of the hollow chamber 75 in nozzle 73 is positioned in the immediate region of the circuit breaker cooperating contacts 31 and 32.

An aperture 76 is provided at a point along piston rod 72 for the purpose of permitting the gas compressed in the piston chamber to pass through aperture 76 into the hollow chamber 74 of piston rod 72, and the hollow chamber 75 of nozzle 73 into the region of the cooperating contacts 31 and 32.

The operation of the puffer assembly of FIGURE 4 is V as follows:

As the movable bridge 33 rotates clockwise about pivot point 34, this rotational movement is imparted to nozzle member 73 by the link 77 which is pivotally connected to movable bridge 33 and nozzle member 73 at pivot points 78 and 79 respectively. Link 77 is adapted, under the control of the rotational movement of movable bridge 33, to impart translational movement to nozzle member 73 causing nozzle 73 to move in the direction shown by arrow 80. This translational movement is imparted to piston rod 72 and piston 46 causing the gas confined in the region bounded by piston 46 and chamber 27 to pass from this region through aperture 76, hollow chamber 74 in piston rod 72, and hollow chamber 75 in nozzle 73 so as to generate a blast or puff of air in the immediate region of the cooperating contacts 31 and 32.. The region which this blast occupies is shown by the dotted lines 82.

As the movable bridge 33 continues its rotational movement, the nozzle 73 moves further to the right, as shown by the dotted configuration 73 of the nozzle. Thus, it can be seen that the blast or puff of air generated by the puffer assembly moves horizontally to the right so as to urge the arc upward, while staying in a position which is approximately intermediate the cooperating contacts 31 and 32 during the entire tripping operation. The region of the air blast at this time is shown by the dotted lines 83.

As the aperture 76 moves to the position shown at 7 6', it is no longer positioned within the piston chamber, and it becomes sealed by the right-hand wall 71 of the piston chamber 27, thereby preventing the flow of any more compressed air in the region defined by the piston chamber 27 and piston 46, causing any air contained therein at this time to remain in this region. The air contained therein, therefore, substantially impedes the further movement of piston 46 in the direction of arrow 80.

This rapid deceleration of piston 46 is imparted, in turn, to piston rod 72, nozzle 73, link 77 and movable arm 33, thereby performing a buffer action which substantially decreases the movement of these elements immediately prior to movement of these elements to their fully tripped positions.

This is an advantageous feature, since it cushions the shock which would be imparted to these elements in making the transition from a condition of high velocity movement to an abrupt standstill position.

FIGURE 5 shows a unitary molding arrangement which is substantially the same as that of FIGURE 4 which is employed in a circuit breaker arrangement having main and arcing cooperating contact structures 90-91 and 92-93 respectively. Circuit breaker contact structures of this type are set forth in detail in US. application Serial No. 79,425, entitled Stationary Contact Structure for SHV, filed December 30, 1960, by F. J. Pokorny et al. and assigned to the assignee of the instant invention.

It should be understood that the contact structure described in the aforementioned US. application and shown in FIGURE 5 of this application is merely exemplary and lends no novelty to the unitary molding assembly of the instant application. The puffer assembly 45 employed in the circuit breaker structure of FIGURE 5 is produced by casting the pufferbuffer cylinder arrangement consisting of piston 96 and piston rod 97 integral with the unitary molding 10.

The puffer assembly shown herein operates in a manner similar to that of the assembly of FIGURE 4, namely, that upon rotation of movable bridge 33, movement is imparted to the piston rod 97 by link 77 which is pivotally connected to nozzle 73' and movable arm 33 at pivot points 79' and 78' respectively. Movement of hollow piston rod 97 towards the right causes the piston 96 to compress the air confined in the region between piston 96 and hollow piston chamber 27 urging the compressed air through aperture 76' and hollow chambers 74' and 75' of piston rod 97 and nozzle 73' respectively, outward into the region of cooperating arcing contact pair 92-93.

As piston rod 97 moves further towards the right, aperture 76 is sealed by the projecting wall portion 100 of unitary molding 10, causing the remaining air confined in the region between piston 96 and piston chamber 27 to continue to be compressed, causing the movement of piston 96 to be greatly impeded, thereby performing a butter operation in a manner similar to that described with reference to FIGURE 4.

It can, therefore, be seen that I have provided a unitary molding which provides means to adequately position and secure circuit breaker terminal leads and to further provide means for housing the circuit breaker pufier assembly within the same unitary molding, thereby producing a greatly simplified overall structure.

Although this invention has been described with respect to its preferred embodiments, it should be understood that many variations and modifications will now be obvious to those skilled in the art, and it is preferred, therefore, that the scope of this invention be limited not by the specific disclosure herein but only by the appended claims.

The embodiments of the invention in which an exclusive privilege or property is claimed are defined as follows:

1. In circuit interrupters having a contact pair comprising a first relatively fixed and a second relatively movable cooperating contact, wherein said second contact is movable between an engaged and a tripped position, the improvement comprising a unitary member having means for mounting said member to a rigid support, said unitary member having a pair of first and second apertures for receiving first terminal leads; puffer means including an enclosure formed within said unitary member intermediate said first and second apertures for generating a gaseous blast in the region of said contact pairs to extinguish an electric arc drawn between said cooperating contacts upon separation thereof, said puffer means being controlled by and having means mechanically linked with said relatively movable cooperating contact, said putfer means including buffer means for impeding the movement of the second contact a predetermined time before said second contact reaches its tripped position; said unitary member having a chamber for mounting said puffer means, said chamber being the enclosure for the puffer means, said puffer means further comprising a piston mounted for reciprocal movement in said enclosure; said unitary member having a third aperture providing a passageway from said enclosure to the exterior of said unitary member; a piston rod being positioned by said third aperture and being movable relative to said unitary member; said piston rod having a first end linked to said piston and a second end linked to said second contact, said piston rod being a hollow tubular member having an aperture positioned along its surface adjacent the first end of said piston rod; a nozzle having a chamber extending therethrough mounted to said piston rod second end, said nozzle chamber communicating with said hollow tubular member and said piston rod aperture, said hollow tubular member and said nozzle chamber cooperating to direct the gas blast of said puffer means in the region of said cooperating contacts when said second contact is moved toward its tripped position.

2. In circuit interrupters having a contact pair comprising a first relatively fixed and a second relatively movably cooperating contact, wherein said second contact is movable between an engaged and a tripped position, the improvement comprising a unitary member having means for mounting said member to a rigid support, said unitary member having a pair of first and second apertures for receiving first terminal leads; puffer means including an enclosure formed within said unitary member intermediate said first and second apertures for generating a gaseous blast in the region of said contact pairs to extinguish an electric are drawn between said cooperating contacts upon separation thereof, said puffer means being controlled by and having means mechanically linked with said relatively movable cooperating contact, said puffer means including bufier means for impeding the movement of the second contact a predetermined time before said second contact reaches its tripped position; said unitary means having a chamber for mounting said puffer means, said chamber being the enclosure for the puffer means, said puffer means further comprising a piston mounted for reciprocal movement in said enclosure; said unitary member having a third aperture providing a passageway from said enclosure to the exterior of said unitary member; a piston rod being positioned by said third aperture and being movable relative to said unitary member; said piston rod having a first end linked to said piston and a second end linked to said second contact, said piston rod being a hollow tubular member having an aperture positioned along its surface adjacent the first end of said piston rod; a nozzle having a chamber extending therethrough mounted to said piston rod second end, said nozzle chamber communicating with said hollow tubular member and said piston rod aperture, said hollow tubular member and said nozzle chamber cooperating to direct the gas blast of said puffer means in the region of said cooperating contacts when said second contact is moved toward its tripped position; said piston compressing the gases contained in said enclosure when said second contact is moved towards its tripped position; the third aperture in said unitary member sealing the aperture on said piston rod surface to prevent the compressed gases in said piston chamher from leaving the enclosure prior to the time said second contact reaches its tripped position.

3. In circuit interrupters having a contact pair comprising a first relatively fixed and a second relatively movable cooperating contact, wherein said second contact is movable between an engaged and a tripped position, the improvement comprising a unitary member having means for mounting said member to a rigid support, said unitary member having a pair of first and second apertures for receiving first terminal leads; puffer means including an enclosure formed within said unitary member intermediate said first and second apertures for generating a gaseous blast in the region of said contact pairs to extinguish an electric are drawn between said cooperating contacts upon separation thereof, said puffer means being controlled by and having means mechanically linked with said rela- 7 tively movable cooperating contact, said puffer means including buffer means for impeding the movement of the second contact a predetermined time before said second contact reaches its tripped position; said unitary member having a chamber for mounting said puffer means, said chamber being the enclosure for the puffer means, said puffer means further comprising a piston mounted for reciprocal movement in said enclosure; said unitary member having a third aperture providing a passageway from said enclosure to the exterior of said unitary member; a piston rod being positioned by said third aperture and being movable relative to said unitary member; said piston rod having a first end linked to said piston and a second end linked to said second contact, said piston rod being a hollow tubular member having an aperture positioned along its surface adjacent the first end of said piston rod; a nozzle having a chamber extending therethrough mounted to said piston rod second end, said nozzle chamber communicating with said hollow tubular member and said piston rod aperture, said hollow tubular member and said nozzle chamber cooperating to direct the gas blast of said puffer means in the region of said cooperating contacts when said second contact is moved toward its tripped position; said piston compressing the gases contained in said enclosure when said second contact is moved towards its tripped position; the third aperture in said unitary member sealing the aperture on said piston rod surface to prevent the compressed gases in said enclosure from leaving the chamber prior to the time said second contact reaches its tripped position; a connecting link having fourth and fifth apertures for pivotal engagement with said piston rod second end and said second contact respectively for controlling the movement of said piston rod by said second contact.

4. In multiphase circuit interrupters each of said phases having a contact pair comprising a first relatively fixed and a second relatively movable cooperating contact wherein said second contact is movable between an engaged and a tripped position, the improvement comprising a unitary member having means for mounting said mem ber to a rigid support, said unitary member having a pair of first and second apertures for receiving first terminal leads of each phase; puffer means including an enclosure for each phase formed within said unitary member inter-. mediate said first and second apertures for generating a gaseous blast in the region of said contact pairs to extinguish an electric are drawn between said cooperating contacts upon separation thereof, said pufier means being controlled byv and having means mechanically linked with said relatively movable cooperating contact; said puffer means including buifer means for impeding the movement of the second contact a predetermined time before said second contact reaches its tripped position; said unitary member having a chamber for mounting said puffer means, said chamber being the enclosure for the puffer means; barrier means extending from and integral with said unitary member for providing an insulating barrier between the cooperating contacts of each phase, said puffer means further comprising a piston mounted for reciprocal movement in each enclosure, said unitary member having third apertures providing a passageway from said enclosure to the exterior of said unitary mem:

ber; a piston rod being positioned by said third aperture and being movable relative to said unitary member; said piston rod having a first end linked to said piston and a second end linked to said second contact.

References Cited by the Examiner UNITED STATES PATENTS 2,734,971 2/56 Lingal 200148 2,775,670 12/56 Geiger 200148 2,913,558 11/59 Bottonari 200148 3,086,097 4/63 Delevoy et a1 200-144 3,096,423 7/63 Wilson 200-168 KATHLEEN H. CLAFFY, Primary Examiner.

ROBERT K. SCHAEFER, BERNARD A. GILHEANY,

Examiners.

Claims (1)

1. IN CIRCUIT INTERRUPTERS HAVING A CONTACT PAIR COMPRISING A FIRST RELATIVELY FIXED AND A SECOND RELATIVELY MOVABLE TOOPERATING CONTACT, WHEREIN SAID SECOND CONTACT IS MOVABLE BETWEEN AN ENGAGED AND A TRIPPED POSITION, THE IMPROVEMENT COMPRISING A UNITARY MEMBER HAVING MEANS FOR MOUNTING SAID MEMBER TO A RIGID SUPPORT, SAID UNITARY MEMBER HAVING A PAIR OF FIRST AND SECOND APERTURES FOR RECEIVING FIRST TERMINAL LEADS; PUFFER MEANS INCLUDING AN ENCLOSURE FORMED WITHIN SAID UNITARY MEMBER INTERMEDIATE SAID FIRST AND SECOND APERTURES FOR GENERATING A GASEOUS BLAST IN THE REGION OF SAID CONTACT PAIRS TO EXTINGUISH AN ELECTRIC ARC DRAWN BETWEEN SAID COOPERATING CONTACTS UPON SEPARATION THEREOF, SAID PUFFER MEANS BEING CONTROLLED BY AND HAVING MEANS MECHANICALLY LINKED WITH SAID RELATIVELY MOVABLE COOPERATING CONTACT, SAID PUFFER MEANS INCLUDIONG BUFFER MEANS FOR IMPEDING THE MOVEMENT OF THE SECOND CONTACT A PREDETERMINED TIME BEFORE SAID SECOND CONTACT REACHES ITS TRIPPED POSITION; SAID UNITARY MEMBER HAVING A CHAMBER FOR MOUNTING SAID PUFFER MEANS, SAID CHAMBER BEIONG THE ENCLOSURE FOR THE PUFFER MEANS, SAID PUFFER MEANS FURTHER COMPRISING A PISTON MOUNTED FOR RECIPROCAL MOVEMENT IN SAID ENCLOSURE; SAID UNITARY MEMBER HAVING A THIRD APERTURE PROVIDING A PASSAGEWAY FROM SAID ENCLOSURE TO THE EXTERIOR OF SAID UNITARY MEMBER; A PISTON ROD BEING POSITIONED BY SAID THIRD APERTURE AND BEING MOVABLE RELATIVE TO SAID UNITARY MEMBER; SAID PISTON ROD HAVING A FIRST END LINKED TO SAID PISTON AND A SECOND END LINKED TO SAID SECOND CONTACT, SAID PISTON ROD BEING A HOLLOW TUBULAR MEMBER HAVING AN APERTURE POSITIONED ALONG ITS SURFACE ADJACENT THE FIRST END OF SAID PISTON ROD; A NOZZLE HAVING A CHAMBER EXTENDING THERETHROUGH MOUNTED TO SAID PISTON ROD SECOND END, SAID NOZZLE CHAMBER COMMUNICATING WITH SAID HOLLOW TUBULAR MEMBER AND SAID PISTON ROD APERTURE, SAID HOLLOW TUBULAR MEMBER AND SAID NOZZLE CHAMBER COOPERATING TO DIRECT THE GAS BLAST OF SAID PUFFER MEANS IN THE REGION OF SAID COOPERATING CONTACTS WHEN SAID SECOND CONTACT IS MOVED TOWARD ITS TRIPPED POSITION.

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