US3519970A - Current limiting fuse oil switch cut-out assembly - Google Patents

Description

July 7, 1970 y G. E. LusK ET AL 3,519,970

CURRENT LIMITING FUSE OIL SWITCH CUT-OUT ASSEMBLY Filed oct. 51, 1967 4 sheets-sheet 1 Z] I .Z1

July 7, 1970 @.E. LUSK ETAL 3,519,970

CURRENT LIMITING FUSE OIL SWITCH CUT-OT ASSEMBLY Filed Oct. 3l, 196'? 4 Sheets-Sheet 2 IJuly '7, 1.970 G. E. LUsK ET AL 3,519,970

CURRENT LIMITING FUSE OIL SWITCH CUT-OUT ASSEMBLY July 7, 1970 G, E, LUSK ET AL CURRENT LIMITING FUSE OIL SWITCH CUT-OUT ASSEMBLY 4 Sheets-Sheet 4 Filed oct. 31, 19's? 5 2 5 M @l o J wg gw ,w y@ J 0, J

61907' l 5, @9462206 [Maen United States Patent Officey 3,519,970 Patented `luly 7, 1970 VVi 3,519,970 CURRENT LIMITING FUSE OIL SWITCH l CUT-OUT ASSEMBLY George E. Lusk, Downers Grove, and Clarence L. Welter,

Alsip, Ill., assignors to G & W Electric Specialty Company, Blue Island, Ill., a corporation of Illinois Filed Oct. 31, 1967, Ser. No. 683,082 Int. Cl. Htllh 9/20, 85/22, 85/56 U.S. Cl. 337--5 8 Claims ABSTRACT 0F THE DISCLOSURE The present switch structure is housed within an oillled tank or container and a spring energized toggle mechanism opens the switch when the toggle mechanism is tripped by operation of a current limiting fuse due to overload currents in the circuits being protected. However, the toggle mechanism can be tripped by manual trip means independently of fuse operation. When the current limiting fuse is swung out of the oil-lilled tank for fuse replacements or repair both ends of the fuse are disconnected and visually separated from the power terminals. Safety features are also provided, in the form of interlocks between the cover of the oil-filled tank and the toggle mechanism.

The invention relates to electric switch apparatus housed within an oil-filled tank or container and has reference in particular to switch structure wherein spring energized toggle mechanism is provided for actuating the switch and wherein a current limiting fuse is employed for tripping the toggle mechanism and effecting an actuation of the switch into an open circuit position in the event the fuse detects an over load or fault current.

The current limiting fuses and the flXed contacts electrically connected to the respective ends of each fuse comprise a unit and which is carried by a carriage for each phase of the circuit and wherein each carriage unit is pivotally mounted for movement into and out of the oil filled container or tank. By this pivotal mounting of the carriages as contemplated by the invention the fuses can be readily and easily swung out of the oil lilled container or tank for inspection or for fuse replacement with both ends of the fuse totally disconnected and visually separated from the power terminals.

Another object is to provide switch structure as described wherein fuse operation is accompanied by the projection of a striker pin from one end of the fuse and which is transmitted by linkage to the spring energized F toggle mechanism eifecting a release thereof thereby opening the switch contacts. In the event an opening of the switch is desired separate from a fuse operation it is only necessary for the operator to trip the spring energized switch mechanism by means of a manually actuated trip lever.

Another object of the invention resides in the provision of safety means which requires that the cover of the container be closed before the spring energized toggle mechanism is unlocked for operation. As a further safety measure the invention provides an interlock between the cover and the toggle mechanism to prevent the cover from being opened unless the switch is located in an open circuit position. Once the cover is opened the switch cannot be actuated into a closed circuit position.

A still further object of the invention is to provide a switch structure of the spring energized toggle actuated type wherein only one operating handle is provided for two shafts, one comprising the main switch operator and the other shaft comprising the manual trip shaft. The operating handle can be removed from the main switch operator shaft only when the switch is in reset position.

This two-shaft, one-handle feature builds into the device a time delay so that the operating personnel cannot close the switch into a fault that the fuse would clear and then abort the fuse clearing `by immediately tripping the switch by the manual trip release.

With these and various other objects in view the invention may consist of certain novel features of construction and operation, as will be more fully described and particularly pointed out in the specification, drawings and claims appended thereto.

In the drawings which illustrate an embodiment of the device and wherein like reference characters are used to designate like parts- FIG. 1 is a vertical sectional view taken through the oil lled container and showing parts of the present switch structure in a cover closed, switch open position;

FIG. 2 is an end elevational View of the switch structure of FIG. l, with the cover being shown in an open dotted line position and with one fuse carriage uint also being shown in dotted lines in an elevated position for fuse inspection or for fuse replacement;

FIG. 3 is a vertical sectional View similar to FIG. 1 but showing a fuse carriage in an elevated out of container position such as illustrated by the dotted lines in FIG. 2;

FIG. 4 is an elevational view, parts being shown in section, of the main operating shaft of the switch with the spring energized toggle mechanism having location at the left hand end thereof;

FIG. 5 is an end elevational view taken on line 5 5 of FIG. 4 and showing the spring energized toggle mechanism in a tripped position with the movable switch contacts in the circuit open position;

FIG. 6 is an end elevational view similar to FIG. 5 but showing the toggle mechanism in a latched position ready for reset, and with the movable switch contacts in a circuit closed position;

FIG. 7 is an end elevational view similar to FIG. 6 with the toggle mechanism being latched but wherein the mechanism has been reset to compress and store energy in the power coil spring;

FIG. 8 is a fragmentary detail view of the trip shaft and tripping lever for actuating the same;

FIG. 9 is a fragmentary detail view of line 9--9 of FIG. 8 showing a current limiting fuse and the linkage connecting the same to the trip shaft;

FIG. 10 is a fragmentary detail view on line 10-10 of FIG. 8 and which illustrates the manner of manually actuating the trip shaft; and

FIG. 11 is an elevational view showing the means for rotating the handle on the main switch operating shaft.

Referring t0 FIG. l it will be observed that the switch structure of the invention is wholly contained within a tank or container 10, the same being lled with au oil or other suitable dielectric liquid medium and having a cover 11 pivoted at 12 to a side wall 14, FIG. 2. The insulated conductors 15 and 16 of the electric circuits to be controlled by the switch enter the "bottom wall 17, being sealed with respect thereto, and the container 10` is completed by the other side wall 13 and by the front and rear walls 18 and 20. When the cover is closed it can be locked in closed position by the locking nuts 21 which are located in spaced relation around the four sides of the cover. When unlocked the cover can be pivoted into an open dotted line position as shown in FIG. 2. With the cover of the container open and out of the way the carriage units for the current limiting fuses can be rotated into an elevated, inoperative position as shown in FIG. 3 and which will be described in detail as the description proceeds.

The apparatus as disclosed in the drawings has been designed for a three phase circuit and thus three of each of the insulated conductors and 16 are provided. Each insulated conductor 16 is electrically connected by the flexible conductor 22 to a terminal 23 which is fixedly held and positioned by the transverse bar 24 of insulating material. 'Ihe bar 24 is, in turn, supported at 25, FIG. 2, at its respective ends 'by the side walls 13 and 14. The connections for the insulated conductor 15 are similar in most respects to that as described. A liexible conductor 26 electrically connects each supply conductor 15 to a contact rod 27 which in this case is movable, being iixedly secured to the rotatable shaft 28. Each of the movable contact rods 27 project from the formed of insulating material all as best shown in FIG. 4. Said shaft at 30 is journalled for rotation from the side wall 14. The opposite end of shaft 28 is xedly secured at 31 to the spring energized toggle mechanism indicated in its entirety by the numeral 32. The flexible conductors 26 are connected 'by the bolts to the movable contact rods 27 and each contact rod extends through an insulating sleeve 34 in the shaft 28 to project from the opposite side of the shaft. The bolts 35 additionally secure to the shaft a guide 36 for the striker pin to be presently described.

The carriage unit for the current limiting fuses 37 and 38 is shown in FIGS. 1 and 3. One or two fuses may be provided for each phase of the electric circuit to be controlled by the switch. The carriage essentially consists of a supporting channel 40 which is pivoted at 41 within the container and immediately below the cover 11. When the carriage is operatively positioned within the tank or container the free end opposite the pivot is locked by the spring locking means 42. The standolf insulators 43 and the contact supports 44 and 45 are provided for suspending the fuses 37 and 38 from the supporting channel 40. The contact supports 44 at the striker pin end of the fuses 37 provide the stationary contacts 46 for coaction with the contact rods 27. At the opposite end of the fuses the supports 45 provide the stationary contacts 47 for c0- action with the lixed terminals 23.

When the carriage units are located within the container and in the event the contact rods 27 have been actuated to engage the stationary contacts 46, it will be understood that the circuits from insulating conductors 15 and 16 are closed. An opening of the circuits occurs when the contact rods 27 are disconnected from the stationary contacts 46. The invention provides an interlock such as the rod for preventing actuation of the spring energized toggle means in a direction to close the switch when the cover is open. The rod is spring biased in an upward direction by the coil spring 51 and the rod at its base end connects with a stop lever 52 pivoted at 53 and adapted to engage the stop `54. When the cover lis open the coil spring 51 moves the rod 50 and thus the lever 52 upwardly against the stop 54. The lever 52 is now located in the path of the cocking lever 64 of the toggle mechanism, thus preventing actuation thereof to cause a closing of the contact rods 27. However, upon closing the cover 11, the rod 50 is depressed thus moving the lever 52 out of the path of the cocking lever 64 of the toggle mechamsm.

A further safety feature is provided for locking the cover 11 in closed position when the spring energized toggle switch is in closed position. This prevents the opening of the cover when the electric circuits are closed. The locking plate member 67 of the toggle mechanism has the link 55 pivoted thereto at 56. The other end of the link is pivoted to the lever 57 which is rotatable on the pivot axis 41 and which provides the locking linger 58. The latch 59 is fixed to the underside of the cover and the latch depends into the path of the finger 58. When the switch is open, the right hand end of the locking plate member 67 is elevated as best shown in FIG. 5, and the plate member is depressed when the switch is closed, FIG. 7. This movement of the locking plate member of the toggle mechanism is employed to unlock and lock the cover.

The journalling structure tor the toggle mechanism includes the fixed stationary plate 60 which is anchored by the member 61 to the side wall 13, FIG. 4. The left end of shaft 62 extends through the side wall 13 for receiving the crank handle 63, FIG. 11. Rotation of shaft 62 will rotate the cocking lever 64, since the lever is xedly secured to the shaft. The cocking lever has an inwardly directed ilange 65 at one end and a camming portion 66 is formed at its opposite end. The lever is located on the side of the supporting plate 60 adjacent the wall 13. The shaft at its inward terminal end journals one leg of the locking plate member 67. The other leg of said U-shaped locking plate member is iixed to shaft 28 as shown in FIG. 4. The locking plate member 67 is thus operatively associated with the toggle mechanism, but the unitary locking plate is free to rotate independently of the shaft 62. The irst mentioned leg portion of the locking plate member is general- 1y circular and ratchet teeth 68 and 70 are formed on the periphery of said plate leg and disposed in spaced relation around the edges thereof as clearly evident from FIGS. 5, 6 and 7. The spring energized toggle mechanism shown in said figures is similar to that as disclosed and claimed in the Lusk et al. Pat. 3,211,870, Oct. 12, 1965 and reference is made to that patent for a more particular description of said toggle mechanism.

The guide block 72 is located between the leg portions of the locking plate member 67 and the guide block is rotatably mounted, being journalled by pins which project from the guide block and enter openings provided for the same in the leg portions of the locking plate. The toggle arrangement is completed by the power coil spring 73 which has encircling relation with the guide rod 74. The outer end of the gude rod adjacent the flange 65 has the spring seat 75 fixed thereto and this outer end of the coil spring 73 engages this seat. The opposite end of the coil spring 73 engages the seat 76 which is free as regards the rod 74 and the remaining projecting end of the lguide rod extends through a passage formed in the guide block 72. The guide rod may move freely in said passage in the guide block and may also move freely of the seat 76.

The locking plate member is adapted to be releasably locked to prevent rotation in a counterclockwise direction FIGS. 5, 6 and 7, by means of the latching lever 80, the said latching lever coacting with the ratchet tooth 68. Also, said locking plate member is releasably locked to prevent rotation in a clockwise direction by the latching lever 181 which coacts with the ratchet tooth 70. The lever 81 is pivoted at 82 to the stationary plate 60 and said lever is yeldingly biased in a locking direction by the coil spring 83. The latching lever A is mounted and pivotally connected to an arrangement of links and levers so as to form a toggle. The lever 84 is pivoted at 85 to the plate 60 and at its opposite end the same is pivoted to the latching lever at 86. The link 87 is pivoted to the latching lever at 88 and at this pivot junction the lever 90 is also connected, the same being pivotally mounted at 91 and yeldingly biased by the coil spring 92. The link 87 can be actuated to make and break the toggle and upon breaking the toggle the latching lever is lifted from contact with the ratchet tooth 68 with very little force being required.

The toggle mechanism is shown in FIG. 5 in tripped or released position with the contact rod 27 out of contact with the stationary contacts 46. The circuits are open and the operator can open the cover should he desire to inspect the fuses 37 and 38 or to replace a fuse. In order to cock the toggle mechanism and store energy in the coil spring 73 the operator applies the handle 63 to the projecting end of the operating shaft .162. The cocking lever is accordingly rotated from its position as shown in FIG. 5 to the intermediate position shown in FIG. `6. When the cocking lever moves beyond a dead center position the locking plate member Wou1d be caused to move except that it is held by the latching lever 81. Continued rotation of the cocking lever counterclockwise beyond dead center will cause its camming end 66 to engage the latching lever 81 and release the locking plate which thereupon rotates in a Iclockwise direction to the position of FIG. 6. Since the shaft 28 is fixed to and unitary with the locking plate member 67 the contact rods 27 are caused to snapr into a circuit closed position with the stationary contacts 46. Thus the toggle mechanism produces a rapid closing of the switch contacts.

When the contact rods engage their stationary contacts, further clockwise movement of the locking plate member 67 is prevented. However, the rotation of the same has been sucient to locate the ratchet tooth 68 beyond the latching lever `80 allowing the lever to drop into position for holding the locking plate mem-ber 67 against counterclockwise movement. The final resetting operation can now be made by the operator which requires additional rotation of the cockinlg lever, but this time in a clockwise direction so as to store energy in the coil spring 73. With the locking plate member being held by the latching lever 80 the clockwise rotation of the cooking lever will store energy in the coil spring and the parts are finally positioned as shown in FIG. 7. This is the reset position of the toggle mechanism and the handle 63 can now be removed from the shaft 62.

When the toggle mechanism is in a fully cocked, reset position, the same can be tripped for opening the switch contacts by operation of one of the fuses 37, or the toggle mechanism can be tripped by the operator by using the manual trip means. For tripping the toggle mechanism by operation of a fuse, reference is made to FIG. 9. The fuse such as 37 contains a pin 94 which is propelled by a powder charge within the fuse when the fuse melts due to overload currents or fault currents occurring in the electric circuits. Projection of the pin 94 from the fuse 37 will actuate the striker rod 95, an insulator, in a direction towards the left. The striker rod is pivoted at 96 to the striker rod lever 97 which is mounted on and fixed to the trip shaft 98. The said trip shaft is rotatably mounted at its respective ends as at 100, FIG. 8, at the end walls 13 and y14. The trip shaft is thus rocked by actuation of the striker pin 94 and this movement of the trip shaft is imparted to the trip shaft lever 102 which is also fixed to the trip shaft 98. The upper end of the trip shaft lever has the link 87 pivotally connected thereto as at 101. Accordingly the rocking movement of the trip shaft, which will be in a clockwise direction, will produce movement of the link 87 in a right hand direction to break the toggle arrangement formed by the lever 90 and by the latching lever 80. The latching lever is thus released from the locking plate member 67 thus allowing the coil spring 73 to take over and due to the energy stored in the spring the locking plate member is snapactuated in a counter-clockwise direction. The shaft 28 is rotated in the same direction so that the contact rods 27 are disconnected from the stationary contacts 46, thus opening the switch. K

The manual trip shaft 105, FIG. 8, is journaled by the bushing 106 in the front wall 13 of the container, and the said manual trip shaft passes through the plate 107 to project beyond both the bushing and the plate. The plate is supported by the bolts 108 from the wall 13 and said plate anchors one end of a coil spring 110 which is anchored at its other end by the pin 111. The coil spring 110 yieldingly biases the manual trip shaft 105 in a direction to hold the pin 111 in contact with the stop bracket 112 as shown in FIG. l0. One end of the shaft 105 projects beyond the bushing for receiving the crank handle 63. The trip lever 113 is fixed to the other end of the manual trip shaft 105 and it will be observed that the trip lever is adapted to coact with the depending end 103 of the trip shaft lever 102.

When the spring energized toggle mechanism has been reset with the locking plate member 67 locked by the latching lever 80 as shown in FIG. 7, the link 87 is so positioned that the trip shaft lever 102 is approximately vertically disposed. With the toggle mechanism thus reset and should the operator desire to trip the toggle mechanism for opening the switch it is only necessary for the operator to rotate the trip shaft 105 to cause the trip lever 113 to engage the portion 103 and oscillate the trip shaft 98 in a clockwise direction, FIG. l0. Such rotation of the trip shaft will actuate the link 87 in a direction towards the right and accordingly the toggle arrangement formed by the lever and the latching lever 80 is broken. With the elevation of the latching lever the locking plate member 67 is released.

The handle 63 cannot be removed from the shaft 62 except in the tripped position and in the reset position of the toggle mechanism. This safety feature of the invention is shown in FIG. ll wherein it will be observed that the handle 63 has a projection 69. In certain positions of the handle the projection 69 will be located under the fixed ledge 1-15, and considering the connection of the handle to the shaft such a location of the projection will prevent the operator from removing the handle. However, when the toggle mechanism is in a tripped position or in a reset position, the handle can be removed since in these positions it will be noted that the projection 69 is free of the ledge 115. In the reset position of the toggle mechanism, for example, the operator can remove the handle from shaft 62 and apply the handle to the trip shaft in the event it is desired to manually trip the toggle mechanism.

What is claimed is:

1. In switch structure for controlling an electric circuit, in combination, a container, a rotatable shaft within the container and journalled thereby, a movable contact carried by the rotatable shaft, one terminal of said electric circuit having a fixed location within the container and the other terminal of said circuit being electrically connected to the movable contact, a current limiting fuse and a stationary contact at each end of the fuse in electrical connection therewith, a carrier on which the current limiting fuse and said stationary contacts are mounted as a unit, means located within the container for mounting the carrier for pivotal movement from an operative position inside the container to an inoperative position outside the container and return, said movable contact having coacting relation with one of said stationary contacts and the other stationary contact having electrical connection with the said one terminal of the electric circuit when the carrier is positioned inside the container, and said carrier when positioned outside the container effecting a disconnection and visual separation of the stationary contacts and thus the current limiting fuse from the movable contact and also from said one terminal of the electric circuit.

2. Switch structure for controlling an electric circuit as defined by claim 1, wherein spring energized toggle mechanism is provided for effecting rotation of the rotatable shaft to cause movement of the movable contact, whereby to effect said coacting relation of the movable contact with said one of the stationary contacts.

3. Switch structure or controlling an electric circuit as defined by claim 1, wherein spring energized toggle mechanism is provided for effecting rotation of the rotable shaft to cause movement of the movable contact, whereby to effect said coacting relation of the movable contact with said one of the stationary contacts, and strip means for tripping said spring energized toggle mechanism to disconnect the movable contact from said one of the stationary contacts, said trip means being actuated by fuse operation when the fuse detects an overload or fault current occurring in the electric circuit.

4. Switch structure 'for controlling an electric circuit as defined by claim 1, wherein spring energized toggle mechanism is provided for effecting rotation of the rotatable shaft to cause movement of the movable contact, whereby to effect said coacting relation of the movable contact with said one of the stationary contacts, trip means for tripping said spring energized toggle mechanism by fuse operation when the fuse detects an overload or fault current occurring in the electric circuit, and said switch structure additionally including separate trip means capable of manual operation for manually tripping the spring energized toggle mechanism independently of the first mentioned trip means.

5. In switch structure for controlling an electric circuit, in combination, a container, a rotatable shaft within the container and journalled thereby, a movable contact carried by the rotatable shaft and having movement upon rotation of the shaft, a current limiting fuse and a stationary contact at each end of the fuse in electrical connection therewith, spring energized toggle mechanism for actuating the rotatable shaft to cause movement of the movable contact, said movable contact upon movement thereof coacting with one of the stationary contacts to close and open the said electric circuit, means for tripping the spring energized toggle mechanism by fuse operation when the fuse detects an overload or fault current occurring in the electric current, whereby to` disconnect the movable contact from said one of the stationary contacts, said tripping means including a striker rod having a linkage connection with the spring energized toggle mechanism, a striker pin incorporated in the current limiting fuse and which is projected from one end of the fuse when fuse operation takes place whereby to effect actuation of the striker rod, and additional means including separate trip means for manually tripping the spring energized toggle mechanism independently of the first mentioned trip means.

6. Switch structure yfor controlling an electric circuit as defined by claim `5, wherein said spring energized toggle mechanism includes a locking plate member which is spring tensioned when the toggle member is in a fully cocked re-Set position, a latching lever adapted to engage the locking plate member to hold the same in said cooked re-set position, said striker rod having a linkage connection with the latching lever whereby when said striker rod is actuated the same effects release of the latching lever and a tripping of the toggle mechanism, and wherein said linkage connection which the striker rod has with the latching lever includes a toggle arrangement, the Said latching lever forming one element of the toggle arrangement.

7. In switch structure for controlling an electric circuit, in combination, a container, a cover for the container, a rotatable shaft Within the container and journalled thereby, a movable contact carried by the rotatable shaft and having movement upon rotation of the shaft, a current limiting fuse and a stationary contact at each end of the fuse in electrical connection therewith, spring energized toggle mechanism for rotating the shaft and having a cocking lever, said movable contact having coacting relation with one of the stationary contacts for controlling an electric circuit, means for tripping the spring energized toggle mechanism whereby to disconnect the movable contact from the said one of the stationary contacts, interlocking means between the cover and the toggle mechanism, said interlocking means effecting a locking of the cover in closed position when the movable contact is in circuit closed position with said one of the stationary contacts, additional means including a looking lever associated with the toggle mechanism, and spring means yieldingly biasing the locking lever into an operative position in the path of the cooking lever of the toggle mechanism when the cover is open, whereby said locking lever in its operative position prevents movement of the cocking lever of the toggle mechanism in a direction for energizing the said toggle mechanism.

8. 'In switch structure lfor controlling an electric circuit, in combination, a container, a cover for the container, a rotatable shaft within lthe container and journalled thereby, a movable contact carried by the rotatable shaft and dapted to have movement upon rotation of the shaft, a current limiting fuse and a stationary contact at each end of the fuse in electrical connection therewith, a carrier on which the current limiting fuse and said stationary contacts are mounted as a unit, means located within the container for mounting the carrier or pivotal movement from an operative position inside the container to an inoperative position outside the container and return, said movable contact having coacting relation with one of said stationary contacts when the carrier is positioned within the container for controlling an electric circuit, said carrier when positioned outside of the container effecting a disconnection and visual separation of the stationary contacts and thus the current limiting fuse from the structure within the container, spring energized toggle mechanism for rotating the rotatable shaft, means for tripping the spring energized toggle mechanism by fuse operation when the fuse detects an overload or fault current occurring in the electric circuit whereby the movable contact is disconnected from said one of the stationary contacts, additional means including separate trip means for manually tripping the spring energized toggle mechanism independently of the rst mentioned trip means, and interlocking means between the cover and the toggle mechanism, said interlocking means effecting a locking of the cover in closed position when the movable contact is in circuit closed position with said one of the stationary contacts.

References Cited UNITED STATES PATENTS 3,400,353 9/196'8 Schockelt 337-7 3,277,251 10/1966 Daly.

3,211,859 10/ 1965 Kobryner 337-11 3,211,870 10/1965 Lusk et al. 200-70 XR i3,054,867 9/1962 Rimmer.

1,731,489 10/1929 Frank.

1,383,808 7/1921 Horton et al. 200-3 OTHER REFERENCES German Printed Application DAS 1,126,976, April 1962, H. Heidenreich.

BERNARD A. GILHEANY, Primary Examiner D. M. MORGAN, Assistant Examiner U.S. Cl. X.R.

ZOO-50.1; 337-9, l1

Patent No. 3,519,970 nan-.d september 28, 1970 Invcnms) GEORGE E. LUSK and CLARENCE'L. WELTER It is certified that error appears in the above-identified p;:'-ont and that said Letters Patent are hereby corrected as shown below:

Column 2, line 19 "uint" `should 'ao uuni-t-` Column 3, line 12 after "the" inserl. the V following:

--shaft 28, beln-gfixdly-scred to the shaft and which :Ls--

, line 33 "'gudre" Ashould read l-g1i`l1de..-

l. line 19 "or" .should read "four-- r l SMDIANL SAL| uvam@ EvndlLl'lemhegJr. l l l n Mision- `of Patnta

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