US1308867A - Telephone-exchange system - Google Patents

Description

J. N. REYNOLDS. TELEPHONE EXCHANGE SYSTEM. APPLICATION FILED NOV. 2, I917. 1,308,867. Patented July 8,1919.-

3 SHEETS-SHEET I.

"al Tm-"I'm I r IIIINlllflilllllllllillll In wn for: John Arwbrrry Reynolds.

APPLICATION f lLED m 2, I917.

Patenced J My 8, 1919,

F/y. l0. \\\\\X JW 5 m m 00 v y I m m m f A E V. M A H n M W WW e n M I" H m J V K WV WW wcwm siding at Greenwich, field'and State of Connecticut, have invented certain. new and useful Improvements in 'Tel'e'phone Exchange Systems, of which the .No; 158,190, filed 1 exchange systems. vWhenusedin connecgroup. of lines,

1 STATES A PATENT OFFICE..-

JOHN unwn'nanr nEYno ns, or GBEENWICH, CONNECTICUT, assrcnon 'ro wns'rnnn ELECTRIC comm, nconrona'rnn, OF NEW YORK, N. Y., A ccmeonn'rron or NEW YORK.

REYNOLDS, acitizen of the United States, re.- in the county of Fairfollowin'g'is a full, clear, concise, and exact description. 1

'aThis invention relates -toautomatic switching apparatus for'tel ephone exchange systems, and'zparticularly' to apparatus including means whereby a largenumber of lines are quickly, and efficiently served with a mini- Inum'expenditure of time and wear. on the apparatus. This apparatus is especially adapted to connection with multiple contact banks of the type shown-and de.-' scribed in my oopending application, Serial March 29, 1917, telephone tion with the contact bank described in this- *prior application, a brush is moved .up to the'level desired and'then moved in across the line terminals either in a hunting or directed movement. volved in the: present invention .is adapted to be used with a plurality of groups of lines of the'type set forth in the above mentioned application, so that it becomes necessary first to select a brush serving the desired which, when properly operated, will be moved up to the desired level and then in as just one of the lines in thatlevel. To effect-this, means are provided whereby the calling party,i through well-known electrical devices'," operates .a, shaft connected. with that i in a novel arrangement of parts whereby 'whic carries the brushih'olders. is second of latching memiven numberof steps a particular brought into osition to engagewith a desired brush older to: move" contacts of the selected level. r "Another feature of the invention resides Specification of Letters Patent.

brush mountingandoperating scribed in my application,

The mechanism indescribed to contact with "stepping magnet 12.

the selected brush outwardly into. engagement w th the TELEPHONE-EXCHANGE sY's'rEM.

Patented July 8,1919.

.' Application filed November 2, 1917. serial No. 199,862.

the latch means is restored to normal at the end, of the operation.

The invention is best illustrated in the 'drawings,lin which Figure 1 is an elevation of the'switch operating means; a

' Fig. 2. is a section on the'line 2--2. of

Fi -1. Fig. 3 is a view, partly in section, taken on the line 3-'-3 of Fig. 1; Fig. 4 is a view, partly 1; Fig. 5 is an elevation of the upper part of the switch shaft carrying the brushesand their holders;,Fig. 6 is a view of the inner latch-carryin' shaft; Fig. 7 is a view, partly in section, ta en on'the line 7 7" of Fig. 1; Fig. is a section,'-taken on line 88 of'Fig. 9;..F1g.'9 is a. view, partly in section taken on'line 9 '9 of Fig. 5 and Fig. 10 is a diagrain of the circuits involved in the operation of the switch in accordance with my in vention. a 1

As illustrated in the drawings,,,thc bank contacts 1,-

, Serial No. 158,190, filed March 29, 1917, telephone exchange systems. 1 I I 'The brush operating.mechanism, which is illustrated in detail in Figs. 1 to 9, inclusive, is designed to first select the brush serving the desired group of lines, then. to move'the brushes step by step to the several levels of the contact bank until the desired level is reached-and then transversely there of .toy certain contacts of the level. Asshown in the drawing 2 designates two of a plu-' rality 0f brushes,each mounted upon a'carriage'3, which is secured to a hollow shaft 4. The shaft 4 is 'slidable in guide members 5 and G and secured to a frame plate 8. Located adjacent to the shaft 4 is a toothed bar 9, adapted tobe engaged by a stepping .pawl- 10, carried by an armaturev 11 of a supported by collars 13 and 14, which are slidable upon the shaft 4, but there is s'ecured to the shaft 4 a spring-pressed locking member 15, adapted, in of the shaft 4 and the toothed bar 9, to engage a notch 16 in said toothed bar 9 -to lock it to said shaft 4. Within and extend ing' throughout thel'ength of hollow shaft 4 and movable therein is a shaft 17, which, at

insection, taken on line 4-4 of Fig.

1 are of the typev clearly de- The toothed bar 9 is the normal position of successive slots isequal its lower end below shaft 4, is embraced by a sleeve 18, to which it is connected by a slot and key. Keyed to sleeve 18 is a ratchet wheel 19, to which isattached one end of a spring 20, the other end of which is fastened to a guide member 21. Ratchet wheel 19 is adapted to be acted upon by pawl 22, carried by armature 23 of rotary magnet 24. A locking pawl 25 engages the pinion 19 opposite pawl 22, pawl 25'being pivoted at 26 and held in engagement with pinion 19 by a spring 27. The pawl 25 is adapted to be released from engagement with pinion 19 by the engagement with its rear shoulder 28 of a release bar 29, carried by a collar 30 on the lower end of shaft 4, which bar 29 normally rests against the back of shoulder 28 in a position'slightly ofi perpendicular. lVhen drawn up with shaft 4, bar 29 as: sumes a perpendicular position, and, when dropped its lower end strikes shoulder 28 to release pawl The upper portion of shaft 17 is reduced in cross. section just below each brush holder and a slot 31 is provided in each such reduced section, each slotbeing cut-through shaft 17 at a different angle from the other slots, so that the angle between the planes to the angle through which the shaft 17 is rotated per step by rotary magnet 24. Mounted in each slot is a latch le er 32 pivoted near its upper end and provided with a hooked lower end 33, which, in its normal position remains within slot 31. The upper end of latch lever 32 normally projects out of slot'31 slightly. The brush mounts 37 are fastened to shaft 4 by means of set screws 38, the inner ends 38 of which project slightly into the space formed between the inner wall of the shaft 4 and the reduced portion of shaft 17. As the shaft 17 is moved upwardly, it carries with it the lever 32, the upper end of which contacts with the end of set screw 38, thus forcing the lower end of the lever 32 out of slot 31. Vertical slots 39 are formed in shaft 4, which are adapted to register with slots 31 in shaft 17 when slots 31 are moved into the position when the latch lever is adapted to operate. Positioned near the lower end of slot 39 is the lower end of a bell-crank lever 40, mounted on the brush mount 37, the upper end of lever 40 being connected to the brush carriage 3. lVhen shaft 17 is moved up within shaft 4 and the hooked end of lever 32 is moved out of slot 31, it engages the lower end of lever 40, and any further movement of shaft 17 moves the brushes 2 out over the contacts. shaft 17 is dropped back into normal position within hollow shaft 4, the levers 32. are returned to normal position within their slots by the engagement of the lower sloping edge 35 thereof with the lower edge 36 of the opening 39 in the hollow shaft 4.

When the In the first movement of the apparatus in response to 'impulses sent through rotary stepping-magnet 24, the pawl 22 will engage the pinion 19and rotate shaft 17 to bring a particular one of the slots 311opposite the corresponding slot 39 in the shaft 4 thus positioning thelevers 32 to be ready to engage the lever 40 connected to the desired brush carriage. I

At the cessation of the first set of impulses through the rotary magnet 24 a side-switch magnet 41 will be caused to operate. 1 This magnet by its armature 42 and a pawl :fnd ratchet connection 43, 44 controls the operation of cam disks 45 and 46. These cam disks have two sets of'surfaces, each set adapted to control a switch movement through a complete cycle of operations. Cam disk 45 operates the side-switch arm 47 by means of rollers 48,- 48 and progressively advances the side switch step by step. Normally, an antifriction roller 49, secured to a pivoted lever 50, rests in an opening 51 between adjacent sets of surfaces on cam disk 46. .At the first deenergization of the mag net 41, the cam disk 46 will be moved one step around in the direction ofv the arrow, as indicated in Fig. 7, and the side-switch arm 47 will be moved from first'to second positions. The opening 51, in cam disk 46, however, has such acircumferential length that this movement does not affect the roller 49 but leaves it in position ready to engage the first surface of cam disk 46.

ln-the second movement of in response to impulses through the stepping magnet 12 the pawl 10 will engage the toothed bar 9 to move said bar 9 and the shafts 4 and 17 upwardly in steps equal in length to the distance between two ,successive teeth on the bar 9 until the brushes selected have been moved into a position opposite the desired level.

At the cessation of the second series of impulses which are transmitted through stepping magnet 12, the side-switch magnet 41 will again be caused to deenergize to move cam disk 45 one step and the side-switch arm 47 from second to third position. Likewise, cam disk 46 is moved forward one step and'a sloping cam surface 52 will be moved under roller 49to push the lever 50 to the left, as shown in Fig. l; at a third step of the magnet 41 a straight surface 53 will be moved under the roller 49 to hold said lever 50 in its outward position; at the fourth, fifth and sixth steps of cam disk 46 the roller 49 will still be on the straight surface; at the seventh step the roller will be moved to the right as shown in Fig. 1 by sloping surface 54, to release the pivoted bar 50; and at the eighth step the roller will be moved into the next open space 51. .During these steps of cam disk 46, cam disk 45 has been advancing side-switcharm47 step by step the apparatus 100- time the operation fri'nn one position to the next. \Vhenthe cam disk, 45 makes the eighth and last step oi its cycle the rollers 48 pass off the rear edge of cam disk 45 and swing back to starting position again, due to the weighted rear end. 47' of theswitch arm 47. 1

The second step e 'T the magnet 41, as above set forth, brings sloping cam surface 52 pingklistance of the brushes in a manner clearly set forth in my co-pending appl1ca- After the toothed tion, above referred to. bar 9 has been released from shaft4 in this well known manner, the magnet 12 receives a third series of impulses, either directed or automatic, which moves the brushes 2, transversely of the contacts.

This is effected as follows; Y

To the upperend of bar 9 is attached collar 14 which loosely embraces shaft 4. A

set screw passes through this collar and into a slot in shaft 4 and its end restsin a circumferential groove in a collar 17 fastened to inner shaft 17 (see Fig. 2). Thus when the toothed bar 9 is new steppedupby magnet 12, the shaft 17 is carried with it. -As.soon as the shaft 17 startsto move, the latch lever 32 which has been selected is moved out'to grip thelower end of lever 40 and thereby w the samej to release pnnoir19, which then,

winder act on, of sp.r1ng 20, 1noves n ove'the brushes, as desired.

This first step of the brush carriage 37 s sufficient to bring the brushes 2 into engagement with the first set of contacts of the selected level. bar 9, 7 however, magnet 12 will be only half those which arecaused'by the caused by the impulses of the previous series so that thefsubsequentmovement of the brushes 2 will be only the-distance between successive setsof contact surfaces.

The magnet l2 is, then automatically operated to move thebrushes 2 into engagement with an idle set ofterminals in the level selected by the second set ofqimpulses. At

the end ofthis hunting action, the magnet 41 willbe again deenergized to cause the cam disk to make one step. During this step the straight surface 53 of the cam'disk 46 will still be under the roller 49 and it has .no further effect on thelever 50. This step of the magnet tl also moves-the side-switch arm 47 to the. fourth position, at Which time the two subscribers; lines are connected.

The parts will remain in this position with the side-switch arm 47 in engagement with the fourth position contact during the conversational period,'at the end of which of making a disconnect-ion will; use the automatic operation of the magnet 41 to advance the cams "'45 and .46 to releasingposition. This movement of the cam 46 will move the cam .surfaceai gage the teeth ofthe toothed bar 9 tore 1 reach the limit The succeeding steps of the i the distance of I back to tli' firstposi a. subscriber, say at a substation ,B,

of er the roller 49. The movement of the cam surface 54- over the roller-49 turns the lever 56 backwardly to the right; as-viewed in Fig.1, until a finger 55 thereon engages the finger 56 on a bracket member .57 pivoted on therod 57 and which "arriesh holding pawl normally adapted to ch:

it in its elevatedposition. Thus the b'ai 1 ward movement of the lever 50 carries with 7 5 it-pivoted bracket 56 to release the holding pawl bSfroin the btlfgp This will causeth'e bar 9 to drop-by gravity, and cause the brush. carriage toinove out ardly as. .tl byspring 3' to draw the in %s 2 cl the contact strips 1 1,

\ Asthe bari) moves dovjvnwardly, thesbaft 4 remains locked in the manner clearly set forth-in'my prior application, above noted. This action carries shaft-17 down with bar 9 until bar 9 and shaft 4 locktogether again,

.at-which time the shaft 17 hasfch'opped a distance sufficient to move the hooked lower 1 end of lever 32 below the lower end, of lever 40 and thus permitof their disengagement. -9,0 As this happens lever. is returned to normal by the" engagement 0f its lower beveled; edge 35. \v-ith,tlie,,.lower edge 36 of the slot 39. l l hen the shaft 4-, and the bar-9 of their rams merit, the lowerendiof the bar ,wil s the rear shoulder- 2$ of the pawl '25 toicanse the inner shaft-17 back to normal xposition; At-this time, the i n'agnetfl llv will again be operated to move; the cam disk another step; The last step of the cam disks. will bring the roller 49 into the next'openaspace ofithe cam disk 46 and will bring the-rollers 48 into the next open space of the cam. disk whereupon thesideswitch armsy iue to, Weight of the end47" thereof,- willlbefswnng- In Fig. 10 theswiteli, invention s shown connected in a c rcuit function as a selector, although it isffobvljo" that the device is not: mited togthis 'peci fi Referring to'Fig. 10,, A may represent-a calling SUlOSCI'IbGI S station, the line for which is connected with 'linefinder termii 11 1, 111, adapted to be engaged by mov le contacts 112, 112. Assuming "that the sub scriber at, stationtA desires connection with i r w ation will be as followsu'lhe snbsc iberg yi, upon removal of his receiver from ,the; switchhook, will automatically have hi'sdinel connected vv ith the inov'able conta'cts 'll, 112, in a ten knowmway through. the oper ation ofthe linefinder, Following the sure of the line finder contacts, a relay 115 will be energized over a line circuit, through ,positibn l-of the side-switch wipers 1 1 6- J 1171 mechanism of this 1ft?"- tract controlled by the selector switch embodying the features of this invention. The energization of relay 115 will cause it to open back contact 121 and close its front contact 122 to ground, thereby completing a circuit including a slow release relay 123. Relay 123 is energized and attracts its armatures, putting ground on lead 124 through its left armature, and putting ground on the lead 138 so that, when said switch wiper 139 reaches the fourth position, the magnet 125' is energized toxclose the line contacts 125, 125. When the calling subscriber operates his sender impulses are sent which break the circuit through the magnet 115, causing it to reits armature. This momentarily breaks the circuit of magnet 123, but being slow to release it will maintain its armatures attracted. When the armature of magnet 115 is retracted, a circuit is formed from ground, armature and back contact of magnet 115, inner right armature and front contact of magnet 123, magnet 126, side-switch wiper 127 in first position, magnet 24 to battery and ground. -Magnet 24 thereupon steps shaft 17 around to select the desired brush. Upon the cessation of the first set of impulses, magnet 115 remains energized and breaks this circuit at its back contact. Upon the first retraction of the armature of magnet 115 the magnet 126 was energized and remains energized during the sending of im pulses, being a slow relay, but when its circuit is broken for a longer period of time it releases. By pulling up, magnet 126 closes a circuit through ground, its armature, sideswitch wiper l28 in the first position, escape magnet 41,-battery and ground. Magnet 41 pulls up and holds during the sending of the first set of impulses. At the end of the first set of impulses, magnet 126 releases and opens this last named circuit, causing magnet 41 to release and advance the side-switch wipers into second position.

During the sendlng of the second set of impulses by the calling subscriber, the following circuit is intermittently closed and opened from ground, armature and back contact 121 of magnet 115, inner right armature of magnet 123, magnet 126, side-switch wiper 127 in second position, magnet 12, battery and ground. Through this circuit the magnet 12 is now caused to operate and steps up shafts 4 and 17. At the end of the set of impulses magnet 41 advances the earns 45 and 46 to third position as before through the circuit through side-switch wiper 128.

Through side-switch wiper 129 in second position a new circuit is prepared from ground, outer right armature and back contact of magnet 123, wiper 129, armature 42, magnet 41, to ground. This circuit is introduced to cause an automatic action of the magnet 41 to more the cams 45 and 46 around to normal position and is put in at this time so that if circuit conditions should cause magnet 115 to become permanently deenergized the mechanism would be automagnet 115, side-switch wiper 132 in third position, magnet 131 to battery and ground. Magnet 131 pulls up and locks itself over a circuit from ground, battery, magnet 131, its armature, side-switch wiper 133 in the third position, normal contact 134, to ground. As soon, however, as magnet 12 commences to operate and step up shaft 17, the ground on magnet 131 through normal contact 134 is removed by the opening of said contact and transferred to test brush 2 and this ground is maintained as long as the test brush engages test terminals of busy line. When magnet 131 is first energized by the movement of the side-switch wiper 132 to third position an automatic stepping circuit is established from ground, inner right armature and front contact magnet 131, armature 11 of magnet 12, magnet 12, battery and ground. The automatic action of magnet 12 causes the brushes 2, to hunt out an idle line, the bar 9 having previously been released from shaft 4 as described heretofore. As soon as the brushes 2, contact with an idle line the ground or magnet 131 is removed and it deenergizes, breaking circuit for magnet 12 at its right contact, thus stopping magnet 12. Also when magnet 131 'pulls up a circuit for magnet 41 is established from ground, outer right armature 135 of magnet 131, magnet 41, to battery and ground. Thus when magnet 131 deenergizes magnet 41 is caused to move the side-switch wipers to fourth position. In this position the two subscribers lines are connected and the wipers remain in this position until conversation has ceased. All the magnets are in normal condition eX- cept 115, 123 and 125 which are pulled up. When conversation ceases, magnet '115 deenergizes, causing 123 to be deenergized and retract its armatures. Thus at the outer right armature of magnet 123 circuit for magnet 125 is broken, causing it to disconnect the lines at 125, 125, and at the back contact of the outer right armature a circuit is established through side-switch wiper 129 causing magnet 41 to automatically step around the cam disks 45 and 46. .lVhen the cam disk 46 reaches its seventh position it causes the release and restoration of the shafts and brushes as previously described and then is moved to eighth position. When the shafts reach their normal position, normal contact 136 is closed, which, because magnet 123 has retracted its armatures, establishes a circuit for magnet 41 from for magnet 12 1.sos,sav

ground, out of right armature of magnet 123, side-switchwiper 129 in eighth position,

. sume normal position 1.

armature i2, magnet ll to battery and ground, causing one more step of magnet $1 to cause the side-switch wipers to as- When the sideswitch w per I37 returns to normal position ground" is taken off lead 124, which nis'm shown but not described operate in sub-' causestherelease of the line finder in a known manner; The partsof the mechastantially the same manner .as set forth in my copending application above referred to.

What is claimed, is:

1. In an automatic switch, a contact bank comprising terminal sets arranged in sections and groups, a brush-carrying shaft, an

auxiliary shaft, means to operate said auxil iary shaft to control the selection of the de sired section, means to operate said brushcarrying shaft and said auxiliary shaft simultaneously to control the selection of the desired group, and means to again oper ate said auxiliar-ysha'ft to control the selection of a desired terminal set.

2. In an automatic switch,

a contact bank comprising terminal sets arranged in sec} tiple contacts,

tions and groups,

a brush-carrying auxiliary shaft, means to rotate said auxiliary shaft to control the selection of a desired section,

means to advance said brush carrying shaft and said auxiliary shaft simultaneously in a and means to operate said-auxiliary shaft in a longitudinal. directionfto control the selection of a desired terminal set.

3." In an. automatic switch, the combinationwith a contacttbank comprising terminal sets arranged sections and groups,

each section comprising a plurality of unit layers of multiple contacts, said layers being mounted in superimposed relation to each of termr othe'r,,each layer forming agroup nal sets, a brush-carrying shaft, an auxiliary shaft, mean'sto operate said auxiliary shaft to control the selection of a desired section, meansto operate said brush-carrying shaft and said auxiliary shaft simultaneouslyto control the selection of a. desired group, and means to again ope ate said auxiliary shaft to'control the selection of a desiredterminal set in said group.

' layers of multiple contacts, well in a longitudinal brush in-over the terminalsets of the selected.

shaft, an

I longitudinal direction .to control the selection of a desired group,

superimposed layers of muleach layer forming a group of group and means :iary shaft to move the selected brush in over the terminal sets of the selected group.

5. In an automatic switch, the combination with a contact bank comprising terminal sets arranged in sections and groups,

to again operate said auxil each section comprising a plurality of unit each. layer co1n re g 'agro'up of terminal sets, I a h g A; of brushes on said-shaft servingu said sections, an auxiliaryshaft, meansto rotate said auxiliary shaft to control the selection' of a desired brush, means .to advance of a. shaft,

said brush-carrying shaft and said auxiliary I shaft simultaneously in longitudinal direction to move the brush to adesired group, and means to operate said{auxiliary shaft direction; to move said group. s i

6. An automatic switch comprising a con-.

carried by but. capableof 'pendcntly of'sa'id shaft, brush. sets mounted on said carriages, an auxiliary shaft cooperating with said brush-carrying shaft, operating membe'rs carried by'wS fll Cl r a-uxiliary shaft, means, for operating said aux-i iary shaft to position one of said members in op erative relation to a desired brush carriage,

means for simultaneously" ,advancingsaid brush, carriages and said shafts toia desired level, and means for disengaging-saidshafts and for operating said auxiliaryr slraftto. cause the selected brush carriagetobe engaged and to advance its associated brush 'set over the terminal sets in the selected level. I v

T. An automatic switch comprising a con.- tact bank having terminal sets arranged in levels, a hollow shaft having a series of slots in its wall, a plurality of brush carriagcs carried by but capable of movement I independently of said sha t, brush sets mounted on said carriages, an auxiliary shaft movable within said hollow shaft, op erating members on said auxiliary shaft, means for operating said auxiliary shaft to position one of said members opposite a slot in operative'relation to a desired brush carriage, means fer advancing said brush carriages and said shafts toa desired level, andmeans for disengaging said shafts and for operating said auxiliary-shaft to cause the selected brush carriage to be engaged and to tact bank having terminaljsets arranged levels, a shaft, a plurality of brush carr ages movement uncle-- advance its associated brush setover the terminal sets in the selected level.

8 An automatic switch comprising a contact bank having terminal sets arranged in levels, a hollow shaft having a series of slots in its wall, a plurality of'brush carriages carried by but capable of movement independen'tly of said shaft, an auxiliary shaft movable within said hollow shaft, a series of slots in said auxiliary shaft, operating levers in said last mentioned slots; means of said hollow shaft in operative relation to the desired brush carriage, means for stepping the brush carriages and said shafts up to the desired level, means for disengaging said shafts, means for 0 crating said aux- .iliary shaft independent y of said hollow shaft, and means for causing the selected operating lever to engage the desired brush carriage when the auxiliary shaft moves relatively to the hollow shaft.

9. An automatic switch comprising a contact bank having terminal sets arranged in levels, a hollow shaft having a series of slots in its wall, a plurality of brush carriages carried by but capable of movement independently of said shaft, an auxiliary shaft movable within said hollow shaft, a series of slots in said auxiliary shaft, an operating lever in each of said last mentioned slots, each operating lever adapted to cooperate with a particular brush carriage, means for moving the auxiliary shaft with respect to the hollow shaft, and means on said hollow shaft to cause the selected operating lever to engage its brush carriage when such movement takes place.

10. An automatic switching system comprising a contact ban]; having terminal sets arranged in levels, a longitudinally movable shaft, a plurality of sets of movable contacts carried by said shaft, an auxiliary shaft cooperating with said movable contact-carrying shaft, operating members on said shaft, means for operating the auxiliary shaft to position one of said members in operative relation to a desired set of movable contacts, means for disengaging said shafts, and a single means for stepping the movable con: tacts and the shafts up to a desired level and for operating said auxiliary shaft after such disengagement to cause the selected set of contacts to move in over the stationary contacts.

-11. In an automatic switch, a. shaft, a second shaft cooperating therewith, a

-'atcl1et wheel connected with said second shaft for rotation therewith but arranged to permit relative longitudinal. movement between the shaft and ratchet wheel, means for locking said ratchet wheel, and means on said first shaft to engage said locking means and release the 'atchet wheel when the first shaft moves toward the ratchet wheel.

12. In an automatic switch, a. hollow shaft, a rod within said shaft, a ratchet wheel connected with said rod but not movable longitudinally therewith, a pivoted pawl engaging said ratchet wheel, said pawl having a shoulder rearwardly of the pivot point, and an arm on the lower end of said hollow shaft adapted to strike said rear shoulder and release the pawl from the ratchet wheel when the hollow shaft approaches said ratchet wheel.

In witness whereof, I hereunto subscribe my name this 27th day of October A. D., 1917.

JOHN N EWBERR-Y REYNOLDS.

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