US2964605A - Fluid pressure operated circuit breaker pole units - Google Patents

Description

Dec. 13, 1960 R. SCHULZ FLUID PRESSURE OPERATED CIRCUIT BREAKER POLE UNITS Filed Sept. 19, 195,6

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FLUID PRESSURE OPERATED CIRCUIT BREAKER POLE UNITS Filed sept. 19, 195e 2 sheIs-*sheet z L" Y raaf /9 ,9&3

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United States Patent C M FLUID PRESSURE OPERATED 'CIRCUIT BREAKER POLE UNITS Richard Schulz, Friedberg, Germany, assignor to Voigt & Haelfner Aktiengesellschaft, Frankfurt, Germany Filed Sept. 19, 1956, Ser. No. 610,868

`Claims priority, application Germany Sept. 22, 1955 9 Claims. (Cl. 20G-148) This invention relates to high voltage circuit breakers wherein each pole unit is provided with a plurality of pairs of cooperating relatively movable contacts adapted to form multibreaks upon separation thereof. In circuit breakers of this type operation of the pairs of relatively movable contacts is preferably elfected by fluid under pressure, e.g. air under pressure, and in circuit breakers of this type the series arcs formed upon separation of pairs of cooperating contacts may be extinguished by blasts of air.

Regarding the operation of pairs of relatively movable contacts, this can be achieved by fluid pressure responsive means maintaining such pairs of contacts'separated as long as a predetermined pressure level prevails at the pressure responsive contact-operating means, and causing engagement of pairs of relatively movable contacts if and when the pressure at the pressure responsive contact-operating means drops below said predetermined pressure level.

If, in a circuit breaker of this type, the pressure at the pressure responsive contact-operating means drops accidentally below the aforementioned pressure level say, on account of a defect causing loss or leakage of air under pressure, the circuit breaker closes the circuit into which it is connected. Such accidental closings may result in serious damage to the system, and endanger human lives.

It is, therefore, one object of this invention to provide circuit breakers having serially related multibreak-forming contact means in each pole thereof, and having pressure-responsive operating means for said contact means closing said contact means upon a reduction in pressure, wherein accidental closing of the circuit as a result of a defect in the compressed uid operating system is positively precluded.

Another object of the invention is to provide a circuit breaker operating system wherein accidental losses of fluid under pressure are localized, and thus precluded from causing a drop of pressure throughout the system which would result in a faulty operation of the circuit breaker.

Another object of the invention is to provide a circuit breaker operating system comprising automatic valve means responsive to fluid leakage for selectively isolating defective portions of the system from the portions thereof which are intact.

Still another object of the invention is to provide a circuit breaker operating system having selective automatic leakage responsive valve means and having, in addition thereto, manually operable control means for causing opening of said valve means in spite of the prevalence of low pressure conditions normally causing automatic closing of the aforementioned valve means.

`In prior art circuit breakers having serially related contact means for establishing multibreaks in eachV pole and having a plurality of spring-biased iiuid motors each for operating a pair of cooperating contacts and each adapted to open a pair of cooperating contacts in the,

2,964,605 Patented Dec. 13, 1960 presence of a predetermined pressure and each adapted to close said pair of cooperating contacts in the absence of said predetermined pressure said plurality of fluid motors are being supplied with operating fluid from a common storage tank. If the pressure drops in such a tank as a result of a defect or leakage, all serially related contact means close, i.e. one pole unit is being closed.

lt is another object of the invention to provide means resulting in selective closing of but a portion of the serially related contacts provided in a pole unit of a circuit breaker having a pneumatic operating system.

These and other general and special objects of the invention and advantages thereof will more clearly appear from the ensuing particular description of the invention, as illustrated in the accompanying drawings, wherein Fig. 1 shows a circuit-breaker pole unitin part in side elevation and in part in vertical section,

Fig. 2 shows mainly a vertical section through one of the housings 2 of Fig, l, some of the parts included in Fig. 2 being shown in side elevation, and

Fig. 3 is a top-plan view of the structure of Fig. 2 showing the association of two housings 2 of Fig. 1 with one common supporting column.

Referring now to the appended drawings, and more particularly Fig. l reference numeral 1 has been applied to indicate three hollow insulating columns of which each supports two operating mechanism receiving cham-4 bers or cases 2 on the top portion thereof. The parts accommodated in cases 2 are more fully shown in Fig. 2. Each of the operating mechanisms housed in each of the chambers or cases 2 may comprise a uid motor of the cylinder-and-piston-type. Each chamber or case 2 supports a hollow horizontal insulator 2a as shown in Fig. 3 and the contact operating mechanisms in the two cases on top of each column 1 are adapted to operate two pairs of relatively movable contacts forming two breaks in series upon separation thereof. The pole structure illustrated comprises three insulating columns 1, two times three, i.e. six, operating mechanism cases 2, and six horizontal insulators 2a. All pairs of relatively movable contacts are serially connected by connecting studs 2c. Reference numerals 2d have been applied to indicate the terminals of the pole structure illustrated. It will be apparent from the foregoing that this structure comprises 3 2=6 pairs of relatively movable contacts, and that one operating mechanism in each of the cases 2 is adapted to operate one of the aforementioned six pairs of contacts. As long as a predetermined tluid pressure, e.g. air pressure, is being maintained at the top of the respective column 1, each operating machanism maintains the one pair of contacts being operated by it, open or separated. When the fluid pressure drops below a predetermined level, the pair of contacts under the control of one contact operating mechanism are automatically closed. Contact operating fluid motors adapted to maintain pairs of contacts separated in presence of a predetermined pressure, and closing pairs of contacts in the absence of a predetermined pressure, and such mo tohs have been shown in Fig. 2 and are describedbelow in connection with that figure. Each supporting insulator 1 is mounted upon a separate storage tank 3 for air under pressure. Manifold 5 is connected to a source of fluid under pressure (not shown), such as a compressor system, and provided with three tap conduits 4, each connected to one of tanks 3. Each conduit 4 is controlled by an automatic valve 6 adapted to be operated by motor means associated with it, eg. fluid motors 8. Each fluid motor 8 comprises a piston 7 having a piston rod for operating one of valves 6 and a spring 7a biasing piston 7 downwardly, i.e. to the valve open position thereof. Each piston 7 is provided with a stem 7b supporting a contact bridge for an auxiliary switch 13..'

Each auxiliary switch 13 controls the circuit of a signalling device A13a indicating whether valves 6 are in the open or closed position thereof. Probe or venting conduits 9v connect the space of each cylinder of each fluid motor 8 situated above piston 7 to the lower end of each of the insulating columns 1. Manifold 10 is adapted to supply to the space of each cylinder of each uid motor 8 situated below piston 7 fluid under pressure derived from manifold 5. To this end manifolds and are connected by a valve or cock 11. Valve or cock 11 is a manually operable three-way-valve. Normally valve 11 is in the position shown, admitting air under pressure from manifold 5 to manifold 10. By operation of valve 11 manifold 5 may be sealed off, and manifold 10 vented to atmosphere. If desired, the circuit breaker may be provided with a pneumatic control system for effecting manual opening and closing and for automatic tripping thereof. The air under pressure required for such a control system is taken from the right end of manifold 10, indicated by reference numeral 12. Reference numeral 14 has been applied to indicate a pressurel relief valve, and reference numeral 15 has been applied to indicate a pressure gage both connected to manifold 5.

The-operation of the above structure is as follows:V

Assuming all the contacts to be initially open or separated, and the portion of the circuit between terminals 2d interrupted at six points of break. This condition can be maintained only as long as there is sufficient pressure in insulating columns 1 and at the operating mechanisms in cases 2. Assuming now that a serious leak develops at the insulating column on the left end of the pole unit shown in the drawing, resulting in Fig. 1 of a substantial drop in pressure inside said column. As a result, the two pairs of contacts under the control of the fluid motor in casing 2 on colunm 1 on the left side of Fig. 1 will be closed. It is now vitally important to preclude closing of the other contacts of the pole unit which would result in a faulty closing operation. The leak. causing closing of the contacts situated on the top of the left supporting colunm 1 results also in a substantial drop of pressure at the polnt where the probe conduit 9 is connected to the lower end of colunm 1. Therefore the pressure on top of piston 7 of the Huid motor 8 on the left side of Fig. 1 of the drawing is substantially reduced, making it possible for the pressure on the bottom, or in back, of piston 7 to overcome the bias of spring 7a, thus closing valve 6. Closing of valve 6 in duct 4 to the left of Fig. 1 of the drawing precludes further leakage of air under pressure out of manifold 5. Consequently the pressure level in manifold 5 will be substantially maintained, thus precluding closing of the contacts associated with the two columns 1 on the right of Fig. 1.

Upon repair of the defect which had caused closing of one of the valves 4 the system will again be air-tight, but there will be no pressure in the left column 1 of Fig. 1 and at the lower end thereof where probe conduit 9 is connected to it. To re-open valve 4 and re-open the contacts on the top of the left column 1, the threeway-Valve 11 is manually operated to seal of manifold 5 and to vent manifold 10. The latter enables spring '7a to move piston 7 downwardly to the valve-open-position thereof shown in Fig. 1. As long as manifold 5 is sealed-off and manifold 10 vented, no compressed air can be supplied from the latter to the part of the pneumatic control system for effecting manual closing. Hence any attempt to effect manual closing before the pressure build-up in columns 1 is sufficiently high is ineffective. No manual closing operation can be effected unless the pressure is so high as to permit an arcextinguishing air blast to be established during any opening operation following a closing operation.

Referring now to Figs. 2 and 3, the structure shown therein is prior art disclosed in British Patent 713,798 and ULS. Patent 2,724,757. The insulating column 1v supports two chambers 2v made of metal, one arranged in front and one arranged on the rear of column 1. Chambers 2 are connected in series. As shown in Fig. 3 the left side of the front chamber 2 and the right side of the rear chamber 2 are provided with bushings 2a through which connector studs 2d extend into the inside of chambers 2. The axially inner ends of studs 2d support fixed contacts 16 adapted to cooperate with movable tubular contacts 17. Each movable contact 17 supports a piston 18 biased by a helical spring 19 tending to move the contact to the closed position thereof, i.e. into engagement with contact 16. Blast valve 20 is adapted to be operated by a fluid motor comprising cylinder 31 and piston 21 under the bias of helical spring 22 tending to move blast valve 21B to the closed position thereof. Numeral 23 has been applied to indicate an orlce in housing 2 through which air under pressure forming an arc-extinguishing blast may escape upon separation of contacts 16, 17 and opening of blast valve 20. Piston 21 may be operated by air under pressure admitted to it through control conduit 24 which may be connected to manifold 12 (see Fig. 1) by means of a trip and venting valve (not shown). The space 25 to the right of piston 18 is connected by duct 26 to a dual position valve 27 operable by means of rod 29. In the position of valve 27 and rod 29 shown in Fig. 2 valve 27 connects duct 26 with pipe line 28 and, therefore, the pressure in the above-mentioned space 25 is equal to the pressure in that part of chamber 2 adjacent contacts 16, 17, i.e. that part of chamber 2 which is separated from the other part by the cylinder structure inside of which piston 18 operates. In that particular position of valve 27 the tap-like movable valve element thereof closes a venting port provided in the housing of valve 27. Rod 29 is under the control of a pressure responsive element 30 causing the rod to move from right to left if there is pressure in pipe lines 24 and 24a. There will be pressure in pipe lines 24 and 24a incident to any opening operation, and under such conditions rod 29 will be moved from right to left, causing closing of pipe line 28r and venting of duct 26. An adjustable needle valve 32 connects pipe line 24a with that portion of cylinder 31 situated to the left of piston 21. Needle valve 32 thus controls the flow of air under pressure from pipe lines 24, 24a to the left end of cylinder 31. Numeral 33 has been applied to indicate a check valve for venting the part of cylinder 31 situated to the left of piston 21 when the pressure in control pipe line 24 drops incdent to a closing operation of the circuit breaker pole unit.

In the closed position of contacts 16, 17 shown in Fig. 2 there is pressure in chamber 2 and there is no pressure in control pipe line 24. Since there is no pressure in pipe line 24 blast valve 20 is in the closed position thereof. Opening is caused by admitting air under pressure to pipe line 24, causing piston 21 to move against the bias of spring 22 from right to left. Pressure in pipe line 24 causes also rod 29 to be moved from right to left, resulting in venting of space 25 through duct 26 and valve 27. Hence the pressure lthen acting upon the left face of piston 18 by far exceeds the pressure then acting upon the right face thereof. As a result, piston 18 and contact 17 are jointly moved from left to right against the bias of spring 19. Now an arcextinguishing blast of air is allowed to escape from chamber 2 through hollow contact 17 and venting port 23. Leakage `of air through needle valve 32 causes a gradual equalization of pressure to both sides of piston 21. Therefore piston 21 will move from left to right after lapse of a predetermined period of time required for the above-mentioned equalization of pressure, and this movement of piston 21 causes re-closing of blast valve 20. As long as there is pressure in pipe line 24, valve 27 remains in the ventingy position thereof and space 25 remains vented. AslongV as space 25 remains vented',

contacts 16, 17 remain separated by virtue of the excess pressure acting on the left face of piston 18.

Closing of the circuit breaker pole unit is effected by p venting pipe line 24 to atmosphere. This results in moving control rod 29 from left to the right position shown in Fig. 2, whereby air under pressure is admitted to space Z5 through pipe line 28, valve 27 and duct 26. As a result, piston 18 and movable contact 17 are moved from right to left, i.e. to the closed position shown in Fig. 2.

It will be understood that the invention is not limited to the prior art structure shown in Figs. 2 and 3, the latter having been shown merely for the purpose of better illustrating the gist of the invention shown in Fig. 1. Other structures might be substituted for that shown in Figs. 2 and 3 as long as such other structures have operating characteristics which are the same as, or similar to, the operating characteristics of the structure of Figs` 2 and 3.

It will also be understood from the foregoing that my invention comprises pressure-responsive means including a'valve to selectively sever the faulty portion of a pneumatic circuit breaker operating system from the sound portion thereof. The probe conduit 9 may be connected to any point where a drop'in pressure will occur as a result of loss of uid under pressure. Probe conduit 9 might be connected directly to chamber 2, or to tank 3. To connect probe conduit 9 to the bottom of column 1 is preferable since this is the point at ground potential closest to chamber 2. It will also be understood that the selectivity which I have achieved is predicated on associating a plurality of separate systems of iluid under pressure with each pole unit of the circuit breaker, each of said plurality of separate systems of tluid under pressure comprising a separate storage tank 3.

While this invention is not limited to air blast circuit breakers, it is preferably embodied in circut breakers of that type. To establsh an arc extinguishing air blast air under pressure is supplied directly from the top of hollow columns 1 to the space in chambers or cases 2 where cooperating contacts 16, 17 are arranged.

It will also be understood that I have illustrated and described herein a preferred embodiment only of the invention and that various alterations maly be made in the details thereof without departing from the spirit and scope of the invention as dened in the appended claims.

I claim as my invention:

1. In a high voltage circuit breaker pole unit the combination of a plurality of pairs of cooperating separable contacts adapted to be serially connected into an electric circuit, a plurality of systems of fluid under pressure, a plurality of fluid-pressure-responsive contact operating means each adapted to be supplied with fluid under pressure from one of said plurality of systems, each of said plurality of contact operating means being operatively related to at least one of said plurality of pairs of contacts and adapted to maintain said one of said plurality of pairs of contacts separated in the presence of a predetermined tluid pressure in one of said plurality of systems and to close said one of said plurality of pairs of contacts in the absence of said predetermined uid pressure in said one of said plurality of systems, a plurality of tanks each forming part of one of said plurality of systems, a manifold for supplying fluid under pressure to each of said plurality of tanks, a plurality of valves each connecting one of said plurality of tanks to said manifold, and a plurality of controls one for each of said plurality of valves, each of said plurality of controls being responsive to the fluid pressure prevailing in one of said plurality of systems and each of said plurality of controls causing instant closing of one of said plurality of valves upon occurrence of a smaller fluid pressure in one of said plurality of systems than said predetermined uid pressure.

2. In a high voltage circuit breaker pole unit the combination of a plurality of storage tanks for air under pressure, a plurality of hollow insulating columns eachv mounted on one` of said plurality of tanks, pairs of cooperating separable contacts adapted to be serially connected into an electric circuit, supported by said plurality of columns, a plurality of air-pressure-responsive contact operating means each arranged on and connected to one of said plurality of columns, each of said plurality of contact operating means being operatively related to at least one of said pairs of contacts and each adapted to maintain said one of said pairs of contacts separated in the presence of a predetermined air pressure at one of said plurality of columns and to close said one of said pairs of contacts in the absence of said predetermined air pressure at said one of said plurality of columns, a manifold for supplying air under pressure to each of said plurality of tanks, a plurality of valves each connecting one of said plurality of tanks to said manifold, a plurality of valve operating motors one for each of said plurality of valves, a plurality of air pressure sensing conduits one connected to each of said plurality of columns each by-passing one of said plurality of tanks and one of said plurality of valves, a plurality of pressure responsive control means each associated with one of said plurality of motors, the end of each of said plurality of pressure sensing conduits remote from said plurality of columns being connected to one of said plurality of control means to cause one of said plurality of motors to close o-ne of said plurality of valves upon occurrence of a predetermined drop in air pressure in one of said plurality of columns.

3. In a high voltage circuit breaker pole unit the combination of a plurality of pairs of cooperating separable contacts adapted to be serially connected into an electric circuit, a plurality of contact-operating fluid motors each operatively related to one of said plurality of pairs of contacts, each of said plurality of fluid motors being adapted to maintain said one pair of contacts separated in the presence of a predetermined amount of fluid pressure, means for closing each of said plurality of pairs of contacts in the absence of said predetermined amount of fluid pressure, a plurality of storage vessels for fluid under pressure each connected to one of said plurality of contact-operating uid motors, a source of iluid under pressure for supplying fluid under pressure to each of said plurality of vessels, a plurality of valves each connecting said source to one of said plurality of vessels, a plurality of valve-operating fluid motors one for each of said plurality of valves, each of said plurality of valve-operating lluid motors comprising a differential piston having a valve-open-position and a valve-closed-position and normally maintained in said valve-open-position, and a plurality of venting conduits each connecting. one of said plurality of contact-operating fluid motors to one of said plurality of valve-operating uid motors to cause said differential piston of one of said plurality of valve-operating lluid motors to move to said valve-closed-position thereof in response to accidental venting of one of said plurality of contactoperating fluid motors.

4. In a high voltage circuit breaker pole unit the combination of a plurality of pairs of separable contacts adapted to be serially connected into an electric circuit, a pluarlity of contact-operating fluid motors each operatively related to one of said plurality of pairs of contacts maintaining said one of said plurality of pairs of contacts separated in the presence of a predetermined fluid pressure and closing said one of said plurality of contacts in the absence of said predetermined fluid pressure, a source of uid under pressure, means for supplying uid under pressure from said source to said plurality of contact-operating uid motors, said fluid supplying means comprising a plurality of valves each controlling the supply of fluid under pressure from said source to one of said plurality of contact-operating uid motors,

a plurality of valve-operating uid motors one for each of said plurality of valves, a plurality of differential pistons each in one of said plurality of valve-operating uid motors, each of said plurality of differential pistons being movable to a valve-open-position and to a valveclosed-position, a plurality of springs each biasing one of said plurality of differential pistons to said valve-openposition thereof, a plurality of conduits for fluid under pressure each connecting one of said plurality of contactoperating fluid motors to one of said valve-operating uid motors tending to equalize the uid pressure at one of each of said plurality of contact-operating uid motors and at one of each of said plurality of valve-operating fluid motors, and conduit means for admitting fluid under pressure from said source to each of said plurality of differential pistons tending to move each of said plurality of differential pistons to said valve-closed-position thereof.

5. A high voltage circuit breaker pole unit as specified in claim 4 comprising a plurality of auxiliary switches each under the control of one of said plurality of differential pistons.

6. In a high voltage circuit breaker pole unit the combination of a plurality of pairs of cooperating separable contacts adapted to be serially connected into an electric circuit, a plurality of contact-operating fluid motors each operatively related to one of said plurality of pairs of contacts maintaining said one of said plurality of contacts separated in the presence of a predetermined iiuid pressure and closing said one of said plurality of contacts in the absence of said predetermined iluid pressure, a plurality of storage vessels for fluid pressure each connected to one of said plurality of contact-operating fluid motors, a manifold for supplying fluid under pressure to each of said plurality of vessels, a plurality of valves each controlling the supply of fluid under pressure from said manifold to one of said plurality of storage vessels, a plurality of valve-operating iiuid motors one for each of said plurality of valves, a plurality of pistons one in each of said plurality of valve-operating fluid motors, each f said plurality of pistons having a valve-open-position and a valve-closed-position, a plurality of springs each biasing one of said plurality of pistons to said valve-open-position thereof, a plurality of fluid conduits each connecting one of said plurality of contact-operating iluid motors to one of said plurality of valve-operating fluid motors each tending to equalize uid pressure at one of said plurality of contact-operating fluid motors and at one of said plurality of valve-operating fluid motors, conduit means for admitting iluid under pressure to each of said plurality of pistons tending to move each of said plurality of pistons to said valve-closed-position thereof, and a dumping valve for dumping fluid under pressure from said conduit means to maintain said plurality of pistons in said valve-open-position thereof irrespective of the amount of fluid pressure prevailing in each of said plurality of uid conduits.

7. In a high voltage circuit breaker pole unit the combination of a plurality of pairs of cooperating separable contacts adapted to be serially connected into an electric circuit, a plurality of contact-operating fluid motors each operatively related to one of said plurality of pairs of contacts maintaining said one pair of contacts separated in the presence of a predetermined uid pressure and closing said one pair of contacts in the absence of said predetermined uid pressure, a plurality of storage vessels for uid under pressure each connected to one of said plurality of contact-operating tluid motors, a first manifold for supplying fluid under pressure to said plurality of vessels, a plurality of valveseach connecting said first manifold to one of said plurality of storage vessels, a plurality of valve-operating uid motors one for each of said plurality of valves, a plurality of pistons one in each of said plurality of valve-operating fluid motors, each of said plurality of pistons being movable to a valve-open-position and to valve-closedposition, a plurality of fluid conduits each by-passing one of said plurality of valves, each connecting one of said plurality of contact-operating fluid motors to one of said plurality of valve-operating tluid motors, and each tending to equalize iiuid pressure at one of said plurality of contact-operating iiuid motors and at one of said plurality of valve-operating ud motors, a second manifold for admitting fluid under pressure to each of said plurality of valve-operating uid motors tending to move said plurality of pistons to said valve-closed-position thereof, valve means for admitting fluid under pressure from said rst manifold to said second manifold, and valve means for dumping fluid under pressure from said second manifold.

8. A high voltage circuit breaker pole unit as specified in claim 7 comprising a three-way valve adapted to supply said second manifold with uid under pressure from said first manifold and to dump iluid under pressure from said second manifold.

9. A circuit breaker comprising a plurality of pairs of co-operating contacts, means for serially connecting said plurality of pairs of contacts into an electric circuit, a plurality of systems containing fluid under pressure, one associated with each of said plurality of pairs of contacts, a common supply of fluid under pressure for said plurality of systems, a plurality of automatic valves each controlling the admission of iiuid under pressure from said source to one of said plurality of systems, a plurality of fluid motors each operatively related to one of said plurality of pairs of contacts, each of said plurality of iiuid motors being adapted to maintain said one of said plurality of pairs of contacts separated in the presence of a predetermined pressure in one of said plurality of systems and each of said plurality of fluid motors comprising means for closing said one of said plurality of pairs of contacts in the absence of said predetermined pressure, and a plurality of pressure-sensing means each associated with one of said plurality of systems and each controlling one of said plurality of automatic valves to cause selective closing thereof in response to a reduction of pressure in one of said plurality of systems.

References Cited in the file of this patent UNITED STATES PATENTS 2,148,410 Wait Feb. 2l, 1939 2,387,960 Webb et al. Oct. 30, 1945 2,472,070 Garretson June 7, 1949 2,491,112 Jansson Dec. 13, 1949 2,747,055 Forwald May 22, 1956 2,748,226 MacNeill et al. May 29, 1956 FOREIGN PATENTS 718,401 Great Britain Nov. 10, 1954 UNITED emma-s PATENT oFFICE CERTIFICATIN 0Fy CURRECTION Patent *Nov ZWQQQOS December l3le 1960 Richard Schulz It is h'ereby certified that errorappears in the above numbered patent requiring correction and 'that the said Letters Patent should read as corrected below.

Column 2v line 50, for "mechanism" read m mechanism nm; lines 58 and 5% for "motohs'l read me motors mi; column 3y line 33V for "shown in the drawingl resulting in Figu l of a substantiel read shown in Fig. l of the drawing, resulting in a substantial Signed and sealed this 23rd day of May l9l (SEAL) finest:

ERNEST W.. SWEDER DAVID L. LADD Attesting @fficer i Commissioner of Patents Ummm sufra-s PATENT orales @EfllllCllN F QRECTMN Patent, No 2964g605 December 13l 1960 Richard Schulz It is hereby certified that error appears in the abo-ve numbered patent requiring correction and lahat the said Letters Patent should read as corrected below Column 2 line 50, for gmachanism" read me mechanism m'- lines 58 and 5% for "motohs" read fw motors Lm; column 3 line 33 or "shown in the drawing, resulting in Figu l of a substansial" read @m shown in Fig l of the drawing, resulting in a substantial Y Signed and sealed this 23rd day of May 1961 (SEAL) Attest:

ERNEST W. SWDER DAVID L. LADD Atlesting @fficer Commissioner of Patents

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