US2824914A - Contact structure - Google Patents

Description

Feb. 1953 E. F. KLEINSCHMIDT ETAL 2,824,914

CONTACT STRUCTURE Original Filed June 14, 1951 3 Sheets-Sheet l \NVENTORS EDWARD F. KLEmscHMmT CARL F. ANDERSON AT TO RN EYS Feb. 25, 1958 E. F. KLEINSCHMIDT ETAL 2,824,914

I CONTACT STRUCTURE Original Filed June 14, 1951 3 Shets-Sheet 2 INVENTORS EDWARD F. KLElNSCHMlDT CARL P ANDERSON ATTORN EYS Feb. 25, 1958 E. F. KLEINSCHMIDT ETAL CONTACT STRUCTURE 3 Sheets-Sheet 3 Original Filed June 14, 1951 \NVENTORS EDWARD F Kuamscumor CARL E ANDERSON w/yflm AT TORN EYS United States Patent CONTACT STRUCTURE Edward F. Kleinschmidt, Wilmette, and Carl P. Anderson, Evanston, Ill., assignors to Kleinschmidt Laboratories Inc., Deerfield, 11L, a corporation of Delaware Original application June 14, 1951, Serial No. 231,554,

now Patent No. 2,754,364, dated July 10, 1956. Divided and this application October 10, 1955, Serial No. 539,489

8 Claims. (Cl. 200-) This invention relates to contact apparatus in transmitters for printing telegraph systems and is a division of and entitled to the filing date of Serial Number 231,554, filed June 14, 1951, application for Keyboard Transmitters.

The preferred embodiment of this invention is adapted for use with a telegraph system of the start-stop type, wherein the signals comprise permutations of impulses corresponding to two different line conditions extending throughout a definite number of time intervals. The selecting intervals or impulses of each signal are preceded by a starting interval or impulse of uniform line condition and followed by a stopping or rest impulse or interval which is always the same and of opposite line condition from that of the starting interval or impulse.

The two different line conditions are customarily referred to as intervals during which marking or spacing impulses are transmitted. The marking impulses correspond to intervals during which current is transmitted and the spacing impulses correspond to intervals during which current is not transmitted. Usually the start interval consists of a spacing impulse and the stop or rest interval consists of a marking impulse. In certain instances polarized systems are used wherein the telegraph signals are formed by reversing the direction of current flow instead of interrupting the current flow. Thus the marking impulse will comprise a current flow in one direction and the spacing impulse a flow of current equal in value but in the opposite direction. Ordinarily the Baudot code is used in telegraph printer systems. It consists of a start pulse, five permutated impulses, and a stop pulse. Other systems use a six or seven unit code in addition to the start and stop impulses.

In signal transmitters for printing telegraph apparatus it has become increasingly important, as the speed of operation increases, to provide mechanism that will accurately space the signals according to a pattern and prevent any bounce of the electrical contacts so that perfect make and break or positive and negative signals may be transmitted at high speed. The transmitters of the prior art, such as the multi-contact type transmitter disclosed in U. S. Patent No. 2,135,377 to Dirkes et al., worked fairly satisfactorily with telegraph printers limited to receiving fifty or sixty words per minute. However because of the tremendous demand for the use of telegraph lines, and because of the rapid advances made in the associated arts and the need for increasing the speed of conveying intelligence in regard thereto, such a rate of speed is no longer satisfactory particularly where the machines are used by the Armed Forces of the United States. Accordingly we have developed a keyboard transmitter which operates with a telegraph printer which will print one hundred words per minute and which has been accepted by the Signal Corps of the United States Army as its standard telegraph printer.

In telegraph printers in the past the transmitter comprised either a distributor having a rotating arm or brush which passed over a series of contact segments, or a group 2,824,914 C6 Patented Feb. 25, 1958 of contact springs equal in number to the impulse units of the particular code in use. For many reasons such transmitters were unsatisfactory especially when operated at high speeds. In the distributor type the brush was a constant source of trouble, and in the multi-contact type the many contacts required constant adjusting and introduced difficulties in producing accurately spaced signals free from the effect of bouncing contacts.

We have overcome the difficulties inherent in such transmitters by providing for page and tape printers a single pair of positively actuated contacts of novel anti-bounce construction, having a single contact operating bail which is common to all of the code selecting levers. With this construction we have eliminated the necessity of constantly adjusting many sets of contacts and the poorly spaced signals so frequently caused thereby. It has also been customary in the prior art transmitters to have the rotatable member make a complete revolution for each code combination of impulses transmitted. When faster operation was desired the entire machine was speeded up to make the rotatable member turn at a higher speed with the result that the machine parts became unable to withstand the increased strain and wear. We have overcome the above problem by increasing the number of code transmissions made in one revolution, thus maintaining reasonable speeds while accomplishing more work per revolution. This has been accomplished by providing relatively large cam sections each having two or more cam lobes so that at least two characters may be transmitted in the course of one complete revolution of the cam sections as will be more fully explained hereinafter. Thus, without materially increasing rotational speeds and strains the output and efficiency of our transmitter is greatly increased by taking advantage of the increased lengths and peripheral speeds of the cam sections.

Accordingly, it is a primary object of this invention to provide signal transmitting mechanism transmitting contacts which are operated by a positive motion under control of an operator and to provide means to prevent bounce when a contact is made or broken.

A further object of this invention is to greatly simplify the construction, operation, and maintenance of a keyboard and transmitter by providing a single set of contacts for controlling the line condition, thereby eliminating the formerly used plurality of transmitting contacts.

Another object of this invention is to provide a keyboard and transmitter having electrical contacts operated by a set of levers having two different mechanical motions and sequentially operated by one-half revolution or less of a rotatable member to send current impulses corresponding to an actuated key lever.

A more complete and thorough understanding of the invention may be had from the following detailed description in conjunction with the accompanying drawings forming a part of this specification showing preferred embodiments thereof in which like reference characters indicate like parts and in which:

Figure 1 is an end elevation of a preferred embodiment of the invention;

Figure 2 is a perspective view of the transmitter and code bars of the invention;

Figure 3 is a fragmentary elevation showing the essential parts in position to transmit a marking impulse;

Figure 4 is similar to Figure 3 but positioned to send a spacing impulse;

Figure 5 is a front elevation partly in section of the transmitter of the invention;

Figures 6, 7, and 8 are vertical sectional views of a portion of the apparatus showing various operative positions assumed by the mechanism; and

Figure9'is a cross sectional view showing the details of 'thecontact mechanism.

In order to simplify the drawings, a considerable portion of the frame structure has been omitted. Also various springs'which would normally be employed for restoring various operating parts to normal have been omitted or-shown schematically in order to avoid complicating the drawings; lt'isto be understood, however, that suitable supporting means'may be provided for the transmitter mechanism, and that suitable springs may be provided wherever necessary for assisting in the operation of parts and for restoring the various parts to normal.

Keyboard transmitter The. preferred embodiment of-this invention utilizes an electrical transmitting device comprising a single set of contacts, insteadof the usual distributor member, operatedpby a; rotatablecamdrum whichis'released for onehalf; revolution ata time by the actuation of any of the keys. During. thisone-half revolution of the cam drum thewcontactsare.actuated to transmit a code group of impulses which. representthecharacter of the key actuated. The rotatable cam member is stopped and started for each character code group. transmitted and a non-repeat mechanism is provided to preventrepeated transmittal of the same code group if the key is held depressed for too long a time. However, another mechanism is providedto render the non-repeat mechanism inoperative when the spacebar is actuated so that the spacing operation will be repeateduntil the space-bar is released. The rotatable cam drum is normally prevented from rotating by a stop latch which is controlled by a universal bar that operates each time a key or the space-bar is depressed, and means are provided for regulating the amount of, movement between the universal bar and the. stop latch. Otherv meanscontrolled by the cam drum during. its, rotation return the stop latch to its normal positionso that it will be effective to stop the rotation of the cam drum upon its completing one half revolution. The keys, key levers and transmitter are assembled as a complete unit on a framewhich is secured to the printer frame in a manner to permit its easy removal to allow the interchange of;

keyboard and printer units.

The rotatable camdrum actuates selector levers in one of two varieties of motion to open or close the associated electrical contacts. These selector levers or fingers as well as certain other partsare identical to parts disclosed in copending application Serial No. 190,359, cited hereinbefore, and the same principles ofoperation are applied in both mechanisms. These same parts are designed for member 54, keyboard frame member 56 and a rear frame.

comb member 58 (see Fig. l). The keyboard may be removably secured to the printer frame in any suitable manner. Springs 60 are secured between the key levers 52 and a turned over portion of comb member 58and cooperate withnotches in the upper edge. of the key levers to position them in the slots and to pull them upwardly in a manner well known in the art. A stopstrip 62 is securedon the back of comb 54 and abovethe key levers 52 to restrain the key levers in their upward movement. When a key 50 is depressed against the tension of a spring 60 the associated key lever 52 positions a series of'permutation bars 64, 66', 68, 70.and 72 in various combinations which represent, according to a predetermined arrangement, the character assigned to the particular key 4 depressed. The permutation bars 64, 66, 68, 70 and 72 are provided with beveled notches 74 (Fig. 2) cut therein in a manner well known in the art which allow the bars to be cammed into position by the operation of a key lever 52.

The permutation bars have elongated slots 76 at their ends which surroundmountingstuds 78; secured in the frame in any suitable manner and provided with spacing.

collars 80for positioning the bars, so that the bars are free to move transversely under the key levers 52 to either one of two positions. The notches 74- in each bar have variously arranged inclinedfaces, one suchvface being provided on each bar for each key lever 52, so that each baris adapted to be movedto its right hand position by some of the keys and to its left hand position by the other keys to set the bars into different combinations. A universal bar 82 mounted adjacent the first permutation bar 64 is provided with notches 84, each having a similarly inclined face, so that the universal bar 82 is always moved to its right hand position whenever any key 50 is actuated.

Each permutation bar is provided at its right end with a notch 86 (Fig. 4) in its upper edge which engages the lower end of a corresponding blocking latch 88 as shown in Fig. 2. The five blocking latches or levers 88 extend upwardly and are mounted upon a common pivotal support 90 secured to the frame 56. The blocking latches 88 control a set of contact operating selector levers 92 and each is provided with a hooked lug 94 at its upper end which, as the associated permutation bar is shifted, is rocked into or out of position above the hooked end 96 of the coresponding selector lever 92 to block or unblock the lever'and thereby determine the subsequent movement imparted to the lever by the cam with which it is associated as will be later explained. A. bracket 98 having a turned up comb portion for supporting and guiding the blocking latches 88 is secured by some suitable means as screws 99 to the keyboard frame member 56.

A transmitter cam shaft 100 is journalled in a boss 102 of the frame member 56 and connected through a friction clutch 104, of a type well known in the art, to a shaft 106 (see Fig. 1) rotatably connected to a constantly rotating drive shaft of an electric motor (not shown). The motor is provided with a suitable governor for maintaining the motor speed constant, the governor being provided with suitable means by which the speed of the motor may be regulated. Such a governor is disclosed in. copending application Serial Number 160,687, filed May 8, 1950, by Carl P. Anderson, now U. S. Patent No. 2,617,904.

Securedto the camshaft 100 (Fig. 5) is a cam drum 108 provided with a series of cam sections arranged helically around the drum to successively engage and operate the selector levers 92. In the particular embodiment of the invention herein disclosed, seven selector levers 92 are provided, one for the start impulse, fivev for the code impulses, and one for the stop impulse. A cam: section is provided for each of the selector levers 92, and in addition a restoring cam section and a latch cam section are provided for purposes hereinafter disclosed. It is to be understood thatthe number of permutation bars, blocking levers 88, selector levers 92, and'cam sections is not limited to the number disclosed herein but that the number is variable and determinedby the number of current impulses-comprising the particular code in use. Each of the cam sections has a pair of diametrically opposed raised portions or cam lobes 110 which, due to the helical arrangement of the cam-sections on the cam drum 108, successively engage their associated selector levers 92 once. during each. one-half revolution of the cam drum. This in turn permits the transmittal of code signals for two characters during each revolution of. the

cam drum 108. It will be understood, of course, that it is possible to. transmit morethan two characters per revolution of the cam drum by providing more than two cam lobes 110 for each cam section.

Referring to Figures 2 and 58, the mechanism for controlling rotation of the cam drum during signal transmission, including a device for blocking repeat transmissions by inadvertent holding down of a key lever, and a device for disenabling the repeat blocking means by depressing the space bar for repeat transmission of spaces, will be described. The transmitter camshaft 100 and cam drum 108 are normally held against rotatable movement by a latch or yieldable stop 112 which is pivoted on pivot post 114 and has shoulder 116 arranged to engage either of the two stops 118 formed in the front cam section of the cam drum 108 preventing drum rotation and causing friction clutch 104 to slip. A spring 120 fastened between the machine frame and the latch 112 tends to bias the latch out of the path of stop 118 and thereby permit the cam drum 108 to rotate, but latch movement under spring bias is normally restrained by the end 121 of the latch which is turned sideways and engages the blocking lug 122 of a clutch release lever 124 pivoted on a stud 126 secured in the keyboard frame 56. An adjusting screw 128 is in threaded engagement with the clutch release lever 124 and the end of the screw engages the universal bar 82 to permit the lever 124 to be adjusted relative to the universal bar 82. A spring 130 fastened between a turned over edge 132 of the lever 124 and the frame 56 tends to force the universal bar 82 to the left and to maintain the blocking lug 122 of lever 124 under the end 121 of the yieldable stop 112 as shown in Figs. 2 and 5 of the drawings. The adjusting screw 128 permits the release lever 124 to be adjusted relative to the universal bar 82 whereby the amount of movement of the universal bar 82 necessary to effect the operation of the tripping means may be made variable and extremely slight. A repeat blocking lever 136 is pivoted on pin 126 with the clutch release lever 124 and also has a blocking lug 134 substantially coextensive with the release lever blocking lug 122 but extending a few thousandths of an inch higher than the top of lug 122. Locking lever 136 is biased by a spring 138 connected between an ear 140 on the blocking lever and an ear 142 on the release lever 124 so its blocking lug 134 normally engages the adjacent side of blocking lug 122, shown in Figure 5.

As explained above, when a key 50 is depressed its associated key lever 52 engages the inclined face in a notch in the universal bar 82 which invariably moves to the right.

This movement of the universal bar 82 pivots the release lever 124 together with the blocking lever 136 counterclockwise against the tension of spring 130. The blocking lug 122 of release lever 124 moves to the left away from blocking engagement with the yieldable stop latch end 121. Since the blocking lug 134 of the repeat blocking lever 136 extends slightly above blocking lug 122, continued movement of lever 136 to the left is prevented by engagement with the side face of the stop latch end 121, as shown in Figure 7, however its spring connection with the release lever continues to bias the repeat blocking lever 136 counterclockwise. When blocking lug 122 has been moved out from under the stop latch end 121, the stop latch 112 can move clockwise under the bias of spring 120 a short distance which while still maintaining engagement with and preventing further clockwise movement of the repeat blocking lever 136 is suflicient to remove the shoulder 116 from engagement with the stop 118 on the cam drum 108 which will rotate due to its connection thru the friction clutch 104 to the constant- 1y rotating motor. As the cams on the cam drum 108 are double, 1. e., have diametrally disposed raised portions, a transmission of code signals is accomplished during each one-half of a cam drum revolution. The stop latch 112 as will now be described, is arranged to be automatically reset to stop the drum rotation at the end of each one-half revolution.

When the five code cams have completed their functions cycle, described hereinafter, a cam follower 190 one locking bail 186 integral with the stop latch 112, is engaged by a restoring cam lobe on the cam drum (Figure 5) causing a counterclockwise pivoting of the latch 112. As latch 112 moves counterclockwise against the bias of spring its shoulder 116 is moved into the path of a cam drum stop 118 to thereupon stop the rotation of the cam drum by friction clutch 104. Since there are two restoring cam lobes and two cam drum stops the function just described occurs during each one-half revolution of the drum. Restoring movement of the stop latch 112 raises its end 121 above the top of blocking lug 122 on the clutch release lever 124. If the depressed key 50 has been released by the operator the spring will move release lever 124 in a clockwise direction on the pivot post 126 since the universal bar under bias of a spring 192, secured between the machine frame and the universal bar 82, is moved to the left to a normal position whenever the depressed key is released and regardless of the position of latch 112 and lever 124. Clockwise movement of lever 124 upon raising of the stop latch end 121 will again place blocking lug 122 under end 121 to hold the stop latch 112 in position to lock the cam drum 108 against further rotation. The arrangement of the universal bar spring 192 makes the universal bar operation more positive since it is not dependent for movement upon lifting of the latch 112 near the completion of rotation of the cam shaft. Furthermore an early return of the universal bar 82 to its normal position assures its readiness for a subsequent operation of another key. Depression of a subsequent key will again move the universal bar 82 to the right pivoting the release lever 124 counterclockwise to release its blocking action on the stop latch 112 again initiating cam drum rotation.

Repeat transmission block A second or repeat transmission of the same set of code signals cannot be accomplished by holding the key in a depressed position. Such repeat signals are pre vented by the repeat blocking lever 136. If key 50 is still depressed when the transmitter completes a code signal transmission, the universal bar 82 will still be in its operated position and the blocking lug 122 of the release lever 124 will be maintained in its operated position as shown in Figure 7. As the end 121 of the stop latch 112 is raised by the action of the restoring cam, as explained above, the repeat block lever 136 will no longer be engaged by latch end 121 hence it will be pulled counterclockwise by spring 138 to the position shown in Figure 8 which positions the blocking lug 134 under the end 121 of stop latch 112 to prevent the stop latch end 121 from moving downwardly under spring bias to release its stop shoulder 116 from the cam drum stop 118. A subsequent release of the key 50 will permit springs 192 and 130 to return the universal bar together with the release lever 124 to their normal positions, as shown in Figure 5, with the end 121 of stop latch 112 again resting on the release lever blocking lug 122. It is thus seen that to accomplish a repeat transmission of a character it will be necessary to release the operated key 50 and then reoperate it to start another cycle of transmission operation similar to that described in the foregoing paragraphs.

Repeat transmission for space bar The space bar 194 (Figure 1) is supported by arms 196, secured thereto in any suitable manner, which are pivoted upon a rod 198 fastened on the cone 54. A space bar operating bar 200 is slidably pivoted at one end 202 on one arm 196 and is otherwise positioned and mounted like any key bar 52 and performs similar functions. When space bar 194 is depressed the bar 200 moves the universal bar 82 and permutation bar 68 to the right and bars 64, 66, 70 and 72 to the left in accordance with the Baudot code.

This will permit the cam 7 drum. 108 to 10133161 to transmit the proper code signals forcthe. spacing operation. The operation will be the same-as described above until the restoringcam operates the restoring lever 186 toraise the end 121 of the latch 112. Whenthe space bar operating bar 261) was depressed-it engages-an off-set end 294, Figures through 8, of arepeat lever 206 and moved it counterclockwise (-Figure 6) about the pivot 208. This action raises the toe210 of a leg portion of lever 2116 into engagement with an car 212 integrally formed on the repeat blocking lever 136 and will thus hold the repeat blocking lever againstithepull of spring 138 when the end 121 of stop latch 112 is-raised away from holding engagement with the. repeat blocking lug 134 by action of the restoring cam. Consequently, when the restoring cam lobe passes the cam follower l9it'the latch 112 will again be operated by, the pull of spring 121) and its end 121 will again be positioned between the blocking lugs 122 and 134 as seen in Figure 6. The spacing operation will be repeated so longas-the spaced bar 194 is held depressed and when it is released theuniversal bar 62 is moved to its left by the stored energy of spring 192 and spring will pivot the lever 124 to again place the blocking lug 122 under the latch end 121 to hold the latch 112 in a stop position thus preventing continued rotation of the cam drum 168.

The selector levers 92 each have upturned portions 144 and 146 (Figs. 3 and 4) adjacent their respective ends, acam follower 148, and depending portions 150 and 152 which fit around a squared shoe 153 on pivot post 114. A spring 154 is secured between the machine frame 3 and the portion 152 of each lever 92 to normally hold the lever against the shoe 153 on the pivot post 114 and a stop 156 secured to frame 56. The turned up portions 144 and 146 engage and position a contact bail 158 pivoted at 161 and provided with a pair of contacts 162 and 164 which cooperate with contacts 166 and 168 respectively to control the condition of the line circuit of the associated telegraph system.

Contact supports'170. and 172 (Fig. 9) are adjustable screwswhich are externally threaded sleeve members with an apertured lower end wall engaging terminals 173 which are internally threaded sleeves or ferrules fitted into an insulated supportingblock 174. The contacts 166 and 168 are plungers which are. pressed forward by coiled springs 175. positioned between shoulders 176 formed on the contact plungers and apertured guide plugs 177 screwed into the upper portion of the contact supports and 172. The contact supports may be turned in and out until the contacts 166 and 168 are in the proper relationship with the contacts 162 and 164 and set screws 178, only one of which is shown, may be set to maintain theadjustment. It is to be noted that the contact bail 158 is not biased or spring pressed in one direction as is usual in mechanism of this type but is operated solely by positive mechanical means which assures positive operation in the. manner desired. The contact bail 158 is engaged near its ends by the upturned portions 144 and 146 of the transmitter, levers respectively with just sufiicient clearance to permit thelevers and contact bail to pivot under the control of blocking levers 88 and cam drum 108.

In mechanically operated transmitting contacts, particularly where, such contact mechanisms are operated at highspeedsas required in printing telegraph signal transmitting apparatus, the prevention of contact bounce has presented serious difiiculties. The contact mechanism herein disclosed overcomes these difi-lculties by the use ofthe novel construction of contactmechanism which is described as follows: The rocking contact bail 158 is positively pressed by selector levers 92 against plunger contact members 166 and'168 which are spring pressed and slidably and frictionally mounted in adjusting screws. Exhaustive testshave demonstrated that the friction of the contact plungerinitsbearing will absorb any bounce duev to-impact of thelrocking contact bail 158 against contact 1 266 n 6 As the contact162or 164 israised and meets its as sociated contact 166 or 168 the initial shock of meeting is cushioned or absorbed by the coiled spring which compresses as the plungerv moves upwardly into theguide plug 177. The distance which the contact on the bail 15% moves after it first engages its associated contact until it reaches its full extent of movement must .be inter-- related with the initial tension of the spring 175 and the adjusted position of the contact support 170 or 172 so that the contacts will remain in engagement throughout their prescribed movement without any intermittent opening and closing of the contacts which has become known as bounce. The initial tension of spring 175 is fixed by its. being positioned between the shoulder 176 on the contact and the guide plug 177. This tension is. not changed when the contact support is adjusted in the block 174 to determine the normal position of the contact 166 or 163 in relation to the associated contacts 162 or 164, and is sufficient to cause the contact to remain in engagement with the bail contact during its upward movement. The contact arrangement disclosed prevents any undesired or unauthorized opening of the contacts due to bounce such as is usual in spring pressed contacts because. the

mechanical arrangement is such that the contacts, once.

closed, are held firmly together until the next operation begins.

In the embodiment of the invention shown herein we provide two sets of contacts for use in a telegraph system of the polarized current type. In such a system the contacts 162 and 164 are connected in parallel by means.

of the flexible conductor 179 (Figs. 3 and 4) and terminal 180 to the telegraph line, and the contact 166 is connected to a current source of a certain polarity while,

the contact 168 is connected to a current source having the opposite polarity to that connected to contact 166. Thus when contacts 162 and 166 are engaged current of the first polarity is connected to the telegraph line and when contacts 164 and 163 are engaged current of the opposite polarity is connected to the line. The contact bail 158 is of sufficient width to be operated by each of the selector levers 92 which are capable of motion in two directions under the control of blocking levers 88 and cam drum 108 to determine which contacts will be engaged. Thus, if a blocking lever 88 blocks the end 96 of its associated lever 92 (Fig. 3) as the latter is engaged by its cam, the opposite end will raise upon the pivot post 114 to engage contacts 164 and 168. If the blocking lever 88 does not block the end 96 of the selector lever 92 (Fig. 4), it will pivot upon the shoe 153 and post 114 and raise the end 144 to close contacts 162 and 166. When the transmitter is associated with a system having only one source of current the contact 166 or the external electrical connections to contact 166 will be omitted as is well known in the art.

In a polarized system it is necessary that one or the other of the movable contacts be in engagement with its associated contact at all times to maintain current of the proper polarity on the line and therefore cams and selector levers 92 must be provided for the start and stop positions of the transmitter. The front or first cam section in Fig. 5 cooperates with the latch 112; the second cam operates a restoring lever, to be described; the third, fourth, fifth, sixth, and seventh cams operate the five code selector levers; the eighth cam controls the start selector lever and the ninth cam operates the stop tacts 164 and 168 to connect a marking current to the telegraph line.

The first movement of the cam drum. 108 causes thelobe 110 of the stop cam to disengage the camfollower 148 of the stop selector lever 92 and immediately thereafter the lobe 110 of the start cam engages the cam follower 148 of the start selector lever 92 and as there is no blocking or latching member provided for the start selector lever it will invariably pivot on post 114 raising its right (Fig. 4) or unblocked end to cause the up turned portion 144 to press the contact bail 148 upwardly, as in Fig. 4. Bail 158 will pivot at 160 to close contacts 162 and 166 and open contacts 164 and 168 and thereby place the associated telegraph line in a start condition. The cam drum 108 continues to rotate and successively operates the five code selector levers 92 to control the position of the contact bail 158 in accordance with the blocked or unblocked condition of the levers.

Thus if the key 50 which corresponds to the letter Y" is depressed permutation bars 64, 68, and 72 will be moved to the right and bars 66 and 70 will be moved to the left. The blocking levers or latches 88 associated with the respective bars assume corresponding positions with the first, third, and fifth levers in their latching or blocking position and the second and fourth in their unblocking position. The blocking levers 88 are held in their respective positions by a knife edge 184 (Figs. 1 and formed on the end of the restoring locking bail 186 which is an integrally formed angularly displaced portion of the latch 112. The knife edge 184 is moved by the pivotal movement of the latch 112 into engagement with the ears 188 on the ends of the respective blocking levers 88 to hold them in position until a complete code is sent by the transmitter. The depression of another key 50 will not be effective to set up another code as the blocking levers 88 cannot move until the code for the first character is completely transmitted.

As the cam drum 108 continues to rotate the first code cam engages the cam follower 148 on the first code selector lever 92 which has its right end blocked by the first latch 88 (Fig. 3) so as its cam follower 148 rides up on the lobe 110 of the cam the right end of the lever will be held down to act as a pivot whereby the portion 146 will press the contact bail 158 upwardly to close contacts 164 and 168 and open contacts 162 and 166 which were previously closed by the operation of the start selector lever 92. By the time the cam follower 148 of the first code selector lever 92 is engaged by its associated cam the cam lobe 110 for the start lever has passed beyond the start cam follower so the contact bail 158 is free to move under the influence of the first code lever. The second code lever 92 does not have its end blocked (see Fig. 4) and therefore pivots on the post 114 to raise the right end of contact bail 158 to open contacts 164 and 168 and close contacts 162 and 166 to place the line in a space condition. As the code levers 92 are successively engaged they will operate the transmitter contacts to alternatively (for the letter Y) place marking or spacing current (or current or no-current) on the telegraph line in accordance with the blocked or unblocked condition of the levers. Immediately upon the operation of the final, in this case the fifth, code selector lever 92 the restoring cam lobe 110 engages the cam follower 190 (Figs. 2 and 5) on the restoring locking bail 186 which pivots on post 114 and disengages the knife edge 184 from the ears 188 of the blocking levers 88 so that they may be moved by the depression of a key 50 to set up the transmitter for the sending of another code signal. The restoring bail 186 as previously described, is integrally formed with latch 12 and as latch 112 is pivoted by the restoring bail its shoulder 116 is moved into the path of the cam stop 118 to stop the rotation of the cam stop 108 upon their engagement. At this time the stop selector lever 92 is in an operated position and contacts 164 and 168 are closed to place the line in a mark condition.

From the foregoing description it will be apparent that the novel invention disclosed herein provides a reliable keyboard transmitter mechanism operating at a compara- 10 tively slow speed but transmitting code signals at high speed. At the same time the transmitter iscompact and very durable and provides a novel construction and arrangement of elements which overcome to a large extent the difliculties and drawbacks of the prior art.

The invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. The present embodiment is therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.

What is claimed and desired to be secured by United tates Letters Patent is:

1. In an electric switch: a rotatable switch operating member; means for rotating said member; a freely pivotable unbiased bail disposed in the proximity of said rotatable member and mounted on an axis intermediate its ends to be positively moved in both directions by force applied to one or the other side of said pivot axis; a first contact fixed on said bail in insulated relation thereto; a second spring biased contact; means fixing said second contact in the path of movement of said first contact; a bail operating member disposed between said rotatable member and said bail and operable by said rotatable member to engage said bail on one or the other side of its pivot axis to positively move said first contact into and out of engagement with said second contact, dependent upon direction of bail pivoting.

2.-In an electric switch: an insulating support; a plunger having a contact portion; a sleeve support having an apertured end wall and retaining said plunger with its contact portion extending through the aperture of said end wall; means adjustably mounting said sleeve support to said insulating support; a shoulder on said lunger disposed within said sleeve and adapted to abut said end wall; resilient biasing means between said plunger and said sleeve support urging said plunger toward said end wall; a freely pivotable member, with no normal position, pivotally mounted on an axis inter- I mediate its ends adjacent said insulating support with a second contact fixed thereto and movable with said pivotable member into or out of engagement with said plunger contact portion.

3. In an electric switch: a support; an insulating member rigid with said support; a pivotable member having no normal position and freely pivotally mounted on an axis intermediate its ends to said support with a portion of said pivotable member on one side of its axis movable toward and away from said insulating member upon pivotal movement of said pivotable member; a first contact fixed on said portion of said pivotable member; a second spring biased contact means mounted, for damped movement, to said insulating member and disposed to be engaged and to remain engaged by said first contact when said pivotable member is moved to and past a predetermined pivotal position.

4. In an electric switch wherein a first movable contact, which has no normal position, is movable into engagement with a second contact in such a manner as to abut and impart movement to the second contact, said second contact comprising: a sleeve member having an apertured end wall; a plunger having an intermediate shoulder disposed in said sleeve member with one portion of said plunger projecting through the aperture in said end wall with a close fit and having an apertured guide plug fixed in said sleeve on the opposite side of the shoulder of said plunger from said end wall with the other portion of said plunger passing through the aper ture of said guide plug with a close sliding fit; and a resilient biasing means of suflicient strength to overcome sliding friction of said plunger disposed between said 11 piun er and said sleeve member urging the lunger toward said end wall.

5. For use in combination with an electric switch having at least two relatively movable engageable contacts, a contact mounting structure comprising: a sleeve member having external threads for adjustable engagement in a support member, and an apertured end wall at one of its ends; a plunger structure with an intermediate shoulder, disposed in said sleeve member with one of the end portions of said plunger structure including a contact surface and projecting through the aperture in said end wall with a close sliding fit; an apertured plug fixed in the opposite end of said sleeve member with the other end portion of said plunger structure projecting through the plug aperture with a close sliding fit; and resilient means in said sleeve member urging the plunger shoulder toward said end wall.

6. A contact structure for use in combination with an electric switch device comprising: a support; means providing an internally threaded hole through said support; an externally threaded sleeve having an apertured wall at one end, adjustably screwed in said threaded hole; a plunger structure with an intermediate shoulder, one end portion of said plunger structure including a contact surface and projecting through the aperture in said end wall with a close sliding fit; an apertnred guide plug fixed in the opposite end of said sleeve member with the opposite end portion of said plunger structure passing through the guide plug aperture with a close sliding fit; and resilient means in said sleeve member urging the plunger shoulder toward said end wall.

7. The contact structure as defined in claim 6, wherein said support is an insulated member and the means 12 providing a threaded hole through said support is an in- 'ternally threaded terminal sleeve fixed in a hole through said insulated member.

8. An electric switch device comprising: a frame; at least two spring biased contacts fixed in said frame in spaced apart insulated relation; a pivotable contact bail, freely pivotally mounted on said frame on an axis transverse to a line between said two contacts, said bail having no normal position; at least two contacts on said bail, one of which is disposed on the opposite side of the bail pivot axis from the other and is movable, upon bail pivotal movement, in a path to engage one of said spring biased contacts and the other being movable, upon bail pivotal movement, in a path to engage the other spring biased contact; whereby said bail can be positively moved in one direction to engage a set of contacts which will inherently remain in a position of contact engagement and said bail can be positively moved in another direction to engage a second set of contacts and disengage said first set of contacts and said second set of contacts will remain in contact engagement.

References Cited in the tile of this patent UNITED STATES PATENTS 253,442 Starr Feb. 7, 1882 1,113,592 Wright et al Oct. 13, 1914 1,222,714 Baehr Apr. 17, 1917 l,4i5,l14 Price May 9, 1922 1,459,756 Stahl June 26, 1923 1,702,075 Chireix et al Feb. 12, 1929 1,764,8l9 Anderson June 17, 1930

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