US2681720A - Power case-shift mechanism - Google Patents

Description

June 22,1954 c. YAEGER POWER CASE-SHIFT MECHANISM Original Filed Dec. 5, 1950 2 Sheets-Sheet l INVENTOR .HARRY C VAEGER ATTORNEY H. C. YAEGER POWER CASE-SHIFT MECHANISM 2 Sheets-Sheet 2 Original Filed Dec. 5, 1950 R m W w m ii i A N NQ Patented June 22, 1954 POWER CASE-SHIFT MECHANISM Harry G. Yaeger, West Hartford, Conn., assignor to Underwood Corporation, New York, N. Y., a

corporation of Delaware December 5, 1950, Serial No. and this application Novem- Serial No. 258,853

Original application 199,306. Divided her 29, 1951,

3 Claims. 1

This invention relates to typewriting machines and more particularly to case-shifting mecha" nisms for such machines. It is a division of my application Serial No. 199,306 filed December 5, 1950, directed to a noiseless typewriter.

In most typewriting machines the type-bearing instrumentalities are case-shiftable relatively to paper supporting means, in order to condition the machine for typing by diiierent case types. Whether such relative shift is accomplished by a shift of the paper supporting means or a shift of the type-bearing instrumentalities, there exists the problem of quickly setting in motion and arresting a considerable case-shift mass in an interval of time which must be very short for speedy operation of the machine. Furthermore, it is most desirable to effect the case-shifts with a minimum of attendant shock and noise.

It is therefore an object of the invention to provide an efiicient, quickly and quietly acting power case-shifting mechanism.

It is a further object of the invention to provide a power-operated, case-shift mechanism which will operate with a minimum of applied motor power and substantially noiselessly.

Also an object of the invention is to provide in efficient cooperation with a motor-operated case-shift means an efficient case-shift cushioning device which during cushioning action is adapted to store energy, and which is eiiiciently controlled to apply the stored energy in useful work aiding in the succeeding motor-operated case-shift operation.

A still further object of the invention is to provide for efiicient control of a case-shift crank to execute motor-driven, substantially noiselessly terminated, rotary case-shirt actuating steps.

Other objects and features of the invention will be in part obvious and in part pointed out particularly as the following description of a preferred embodiment of the invention proceeds.

The invention is illustrated in association with a pressure printing typing mechanism which is the subject of the aforementioned patent application, and which embodies a pivotally caseshiftable type carrier system.

Turning now specifically to the drawings:

Figure 1 is a fractional right-hand side elevation of a typewriting machine showing the power case-shifting mechanism of the invention in its normal, idle condition,

Figure 2 is a fractional side elevation similar to Figure 1, but the power case-shifting mechanism is shown in an upper case condition,

normal, lower case position in Figure 1.

Figure 3 illustrates two parts of a spring supporting device.

Referring now more particularly to Figure 1, the machine to which the invention is applied comprises two main side plates or Walls 18. Between these side walls there is case-shiftably supported on pivot studs 34 provided on the opposite machine walls l8 a body or unit 30 having thereon a system of type carriers 50. The individual type carriers 40 are selectively operable under key control to type against a usual work-sheet supporting platen :24. The case-shiftable body 30 includes adjacent the inside of each machine wall i8 2. side plate 33, these plates being connected by various members including one numbered I88.

The said case-shift body 30 is shown in its In this position an arm I8l of each side plate 33 of the case-shiftable body 30 abuts an eccentrically adjustable normal case stop I82, each such stop being carried on the adjacent side wall l8 of the machine. In the stated normal case position of the case-shift body 30, the type carriers 40 are selectively operable to type by either of two lower case types 5!, as indicated by dot-and-dash lines.

In Figure 2 the case-shift body or unit 3%! is shown in upper, that is in capital case position. The arms l8! abut each upwardly against a capital case stop I83 which is similar to and adjustably supported in the same manner as the stop !82. In the stated capital case position of the body the type carriers 49 are selectively operable to type by either one of two upper case types 5lc, as indicated by two dotand-dash lines in Figure 2.

For moving the case-shift body 30 to and from case-shifted position there is provided a noiselessly operating power mechanism which in some respects is similar to a mechanism disclosed in the U. S. patent to Helmond, No. 2,275,759. This power mechanism includes a normally quiescent eccentric I95 having: associated therewith, by means of-a ring of balls 19?, a connecting rod I96, said balls being accommodated in opposite ball races provided in the eccentric I95 and the connecting rod I96, whereby said eccentric is turnable with a minimum of friction in the connecting rod and the latter is retained on the eccentric. The connecting rod has a pivotal connection with a rocker 598 that is pivotally carried at 200 on the left side wall it of the machine frame. The rocker has adjustable abutments 20! straddling a pin 202 extending laterally from a dowmreaching portion of the left end plate 33 of the case-shift body 3%. The pin 2&2 extends through a clearance hole in said side wall I8. The eccentric I95 is turnably mounted on a shaft 263' which is constantly rotating when the machine is in use and carries fast on the outer end thereof, adjacent the eccentric H5, at toothed clutch wheel 2%. Provision is made to couple the eccentric 595 to said toothed wheel 2% to turn therewith a half turn upon downward operation of a shift key 285 and to turn another half turn upon restoration of such shift key. A clutch pawl 295 pivotally carried on the eccentric 195 is normally held free of the toothed wheel 29% by a control dog 26? that normally engages an outreaching nose of the pawl. A compression spring 205 carried in a thickened portion of the eccentric engages a tail of the pawl 265 and thereby tends to swing the pawl inwardly into coupled association with the wheel 2%. Diametrically opposite to the control dog 26? there is another control dog 2MB which when the case-shift key is in normal position is clear of the orbit of the pawl 29%. The two dogs 25?, 230 are each pivotally carried as at ZIZ on a bracket 2! I. A link 25% connects the two dogs. The case-shift key 205 is borne on a lever 2% fast on a shaft 2H1 and when said key is operated an arm 2E5 on the left end of the shaft 2M draws a link 2; forwardly. The latter has a pivotal connection with the dog ZIB and upon operation of the shift key 205 will swing the dog am into the orbit of the out-reaching nose of the pawl 205. At the same time due to the link ZIB which connects the two dogs, the dog 20'! will swing clear of the nose of the pawl 206, wherefore the eccentric I95 becomes coupled to the toothed wheel 254 to turn therewith. At the end of a half turn the connecting rod I85 will be in the rearward position seen in Figure 2, and through operation of the rocker I98 will have displaced the case-shift body 353 to the upper case position. The half turn of the ecentric is terminated by engagement of the outreaching nose of the pawl 205 with the hooked end of dog 2), such engagement resulting in a limited outswinging movement of the pawl to free the latter from the toothed wheel 254 as shown in Figure 2. At the release of the case-shift key 265 the dogs 291, 2H3, under the tension of a spring 2|! associated with the link 2I5, return to their normal positions seen in Figure 1. Con sequently the pawl 256 will reengage the toothed wheel 2% for a second half turn of the eccentric I35, such half turn being terminated as the pawl 2235 is intercepted by the dog 28'! and swung clear of the wheel 294. During such second half turn the connecting rod I96 is driven forwardly by the eccentric and through restoration of the rocker I98 will restore the case-shift body 38 to the normal case position seen in Figure l. The motion imparted to the connecting rod I55 is of harmonic characteristic and thus the case-shift body 30 is picked up and deposited in each posi tion without substantial shock and noise. Disengagement of the pawl 2% from the wheel 26 with concomitant arrest of the eccentric I95 is achieved without shock and noise. To this end provision is made for the dogs 251, 21a to yield slightly when engaged by the pawl 2G6. Specifically, as shown, the stop faces of the dogs are afforded by leaf springs 2H8 of gooseneck form. As shown in reference to the dog 20'! the gooseneck spring 2H8 may be backed up by an abutment 220 normally spaced slightly from Said spring. The opposite range of movement of the dogs is controlled by two stop pins 2 I9. Due to the resiliency of the gooseneck springs 2I8, the eccentric I95 has a tendency to rebound in reverse direction as the pawl 206 is intercepted at each half turn of the eccentric. To control this rebounding tendency, the eccentric W5 carries fast thereon a two-lobe member 223 with which there cooperates a spring pressed pawl 224.

While the machine is in use, the shaft 203 is continuously motor driven at a desired caseshift speed.

The case-shift body 30 with the mechanism supported thereon represents an appreciable aggregate mass which must be set in motion and stopped rapidly, and yet such operation should be quiet. It is conceived to associate means with the case-shift body 30 whereby the initial caseshift movement of said body from one to the other position is aided by energy stored in the preceding case-shift operation, the motor-operated case-shift mechanism, hereinbefore described, constituting a controlling agent for said energy. To this end the machine has at least on the side of the power operable case-shift rocker I98 a spring device 228, comprising an upper and a lower link member 22?, 223 having forked portions 230, see Figure 3, interfitting one another to allow their distension lengthwise. The upper link member 221 has a pivotal joint with the overlying arm I81 of the case-shift body as at 23!, while the lower link 228 has a forked lower end fitting in a notched bottom of an opening 232 in the side plate It of the machine. Each of the two links 221, 228 is shouldered as at 233 for spring seating elements 234 to abut thereagainst. A relatively light spring 235 is interposed in compression between the two seats 234 of the spring device 226, and thereby exerts an upward force on the case-shift body 39. The spring 235 balances the greater portion of the weight of the case-shift body and the parts supported thereby. The spring device 226 also embodies between the two spring seats 234 a relatively heavy'compression spring 236 loosely surrounding the lighter spring 235. This heavy spring 236 is shorter than the space between the two spring seats 234 and becomes strained only after an appreciable part of the downward movement of the case-shift body 30 from upper case to lower case position has taken place. In being so strained the spring 256 stores a certain amount of energy which in the initial movement of the case-shift body 39 from normal case to capital case position assists such movement. It will be noted that the eccentric I95 forces the case-shift body against the resistance of the spring 236 to normal case, lower position, thereby snubbing' such movement, and at the end of such movement the case-shift body 35 is held stationary because the eccentric I85 reaches and is arrested in a dead center position, and because the check pawl 224 in cooperation with the lobe member 223 then prevents backward rotation of the eccentric.

Since the lighter spring 235 does not fully balance the weight of the case-shift body and the mechanism supported thereon, it follows that in a power operated case-shift movement of said body to upper, capital case position the eccentric I works against the unbalanced portion of the weight of the body 30. The body upon arrival in upper case position is held thereat due to the dead center position of the eccentric I95 reached, see Figure 2. When the eccentric receives a half turn to case-shift the body 30 down to the normal position seen in Figure 1, then the unbalanced weight of the case-shift body 30 aids initially such movement. Due to the structure described the motor power can be kept to a minimum and the case-shift movement gets under way very rapidly. Furthermore, since the movement of the body to either position is opposed during the last part of each such movement, the arrest of the case-shift body is accomplished with a minimum of shock and noise. Additionally, the initial case-shift movement of the body from either position is aided, resulting in this connection also in a reduction of noise and shock. Obviously-the eccentric stops I82, I83 associated with the arms IBI of the caseshift body are adjusted for proper throw of the latter and the abutments I on the rocker I98 which is operated by the connecting rod are adjusted for proper correlation with the stops I82, I83.

Obviously the invention is not restricted to case-shifting a pivotally mounted case-shift body, nor to case-shifting a type system instead of a carriage, and variations of the structure may be resorted to within the scope of the invention, and portions of improvements may be used without others.

What is claimed is:

1. In a typewriter or the like comprising a body shiftable oppositely to two different case-shift positions, a continuously rotated clutch wheel,

an element coaxial with said clutch wheel and normally quiescent, means to place said body in two different case positions by rotation of said element to two different positions, a clutch pawl carried on said element, spring means continuously urging said pawl into engagement with said clutch wheel, an interceptible member adapted to rotate with said element and having connection with said pawl so that by respectively being intercepted and freed said pawl will respectively be forced clear of said wheel and urged into engagement with said wheel, a control element for said member at each of two diametrically opposite locations thereof controllable for one such element to move to an operative position while the other one is moved to an inoperative position and reversely for the other to move to operative position while said one is moved to an inoperative position, resiliently strainable means caused by movement of either of said control elements to operative position to occupy with respect to the operative control element and the said member a relation for softly and noiselessly halting said member, said resiliently strainable means after halting said member exerting a resilient force tending to rotate the pawl carrying element reversely and thereby tending to reengage said pawl with said clutch wheel, and means to hold said pawl carrying element against reverse rotation under the resilient force of said strainable means.

2. In a typewriter or the like comprising a body shiftable oppositely to two different caseshift positions, a toothed, continuously rotated clutch wheel, an element coaxial with said clutch wheel and normally quiescent, means to place said body in two different case positions by rotation of said element to two opposite positions, a clutch pawl carried on said element, spring means continuously urging said pawl into engagement with said clutch wheel, an interceptible member adapted to rotate with said element, and having connection with said pawl so that by respectively being intercepted and freed said pawl will respectively be forced clear of said wheel and urged into engagement with said wheel, and two stop elements for said member at diametrically opposite locations thereof and controllable to move either one to an operative position and concomitantly to move the other to an inoperative position, each stop element com prising a resiliently strainable means for it to softly and noiselessly intercept said member, each said resiliently strainable means after straining exerting a force tending to rotate the pawl carrying element reversely and thereby tending to reengage said pawl with said clutch wheel, and means to check said pawl carrying element against reverse rotation by the resiliently strained means.

3. In a typewriter or the like comprising a body shiftable oppositely to two different case shift positions, a toothed, continuously rotated clutch wheel, an element coaxial with said clutch wheel and normally quiescent, means to place said body in two different case positions by rotation of said element to two opposite positions, a clutch pawl carried on said element, spring means continuously urging said pawl into engagement with said clutch wheel, an interceptible member adapted to rotate with said element, and having connection with said pawl so that by respectively being intercepted and freed said pawl will respectively be forced clear of said wheel and urged into engagement with said Wheel, two stop elements for said member at diametrically opposite locations thereof and controllable to move either one to an operative position and concomitantly to move the other to an inoperative position, each stop element comprising a resiliently distortable portion for it to softly and noiselessly intercept said member, and abutment means on at least one of said stop elements to limit the magnitude of distortion of its distortable portion.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,275,759 Helmond Mar. 10, 1942 2,289,531 Thompson July 14, 1942 2,383,259 Kittel Aug. 21, 1945

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