US2865331A - Cam type retractable mechanisms - Google Patents

Description

Dec. 23, 1958 J. MARCOTTE CAM TYPE RETRACTABLE MECHANISMS 2 Sheets$heet 1 Filed Aug. 17, 1953 m y Ll, %w a i 1;

Dec. 23, 1958 J. L. MARCOTTE CAM TYPE RETRACTABLE MECHANISMS 2 Sheets-Sheet 2 Filed Aug. 17. 1953 N m M Feb-mag! peda /an JNVENTORL KIM/IE5 L. MAQco'r ATTORNEY- United States Patent CAM TYPE RETRACTABLE MECHANISMS James L. Marcotte, Lawndale, Califl, assignor, by mesne assignments, to Paper Mate of Puerto Rico, Inc., Salinas, Puerto Rico, a corporation of Puerto Rico Application August 17, 1953, Serial No. 374,497

17 Claims. (Cl. 12042.03)

This invention relates to writing implements of the ball point type and has to do more specifically with a novel projecting-retracting mechanism whereby the writing point of such implements may alternately be projected out of and retracted back into the implement.

Ball point writing implements, as manufactured heretofore, normally employ a replaceable cartridge comprising a tubular ink reservoir and a writing tip assembly carried by one end of such reservoir, the writing tip assembly including a rotatable ball which picks up ink supplied from the reservoir and then deposits such ink from the surface of the ball onto the surface upon which the ball is rolled during the writing operation. The small size and long life and large ink supply of these pens are an important and valuable characteristic. Most prior attempts to make ball point pens with a retactable point (to thereby facilitate carrying of the pen without staining garments with ink from the point, and without the use of a removable cap on the pen) necessitated the use of a shorter cartridge, the reduction in length being caused by the complexity and extent of mechanism employed for selectively projecting and retracting the writing tip. The use of a standard or normal cartridge was not feasible because its length plus the space occupied by most prior retracting mechanisms rendered the instrument excessively large and long. The reduction in length was obtained at the expense of the tubular ink reservoir, thereby reducing its capacity and the writing life of the pen.

Since most manufacturers desire to make non-retractable and retractable pens, it was necessary to carry at least two styles of cartridges: dealers had to carry two styles of refill or replacement cartridges in stock, and many instances of confusion were bound to arise by selling a refill cartridge of improper length for the customers pen. Manufacturing, shipping and selling difficulties were thus encountered.

The present invention permits the use of cartridges of normal or standard length (as used in non-retractable pens) in a pen body which is'no larger and embodies an efficient, selectively operable retracting and projecting mechanism which is self-locking.

One of the objects of my invention is to provide in a ball point pen a projecting-retracting mechanism of simple and rugged construction which is economical to manufacture and unlikely to get out of order.

Another object is to provide a writing implement of the type described which is composed of a minimum number of parts, which parts are of simple and sturdy design and are easy to assemble and disassemble.

It is another object to provide such a mechanism which is easy to operate, positive and dependable in operation, inherently incapable of jamming or binding, and capable of withstanding a large number of operations without failure.

It is a further object of the invention to provide such a mechanism, wherein a writing unit is held in an extended or in a retracted position without a separate latching mem- 2,865,331 Patented Dec. 23, 1958 ber and wherein no independent latching means is required.

It is a further object of the invention to provide a writing implement of an improved construction so that nonmetallic materials such as suitable plastics may be used for the construction of almost the entire device.

The invention may be further characterized as a mechanism which incorporates camming means associated with an operating plunger, and a cam follower associated with the upper end of a writing unit, which co-act upon successive depressions of the operating plunger to impart axial and lateral motion to the writing cartridge and thus extend and hold the writing tip in extended position and retract and hold the tip in retracted position at the will of the operator.

These and other objects, advantages, and particular characteristics of the invention will become apparent from the following description and accompanying drawings in which:

Fig. 1 is an enlarged longitudinal sectional view of one exemplary form of retractable writing instrument, with the tip in projecting position.

Fig. 2 is an enlarged longitudinal section of the upper body.

Fig. 3 is a fragmentary longitudinal sectional view similar to Fig. 2, showing a depressed position of the pronged plunger when retraction is initiated.

Fig. 4 is a view similar to Fig. 3, showing the position of the parts an instant later than that illustrated in Fig. 3.

Fig. 5 is a transverse section taken along plane VV of Fig. 2.

Fig. 6 is an enlarged longitudinal section similar to Fig. 2, illustrating a fully retracted position of the cartridge.

Fig. 7 is an enlarged longitudinal section taken along the line VII-VII of Fig. 5, showing the position of the pronged plunger and the cam follower immediately following a successive depression of the operating plunger to initiate projection of the cartridge.

Fig. 8 is a longitudinal section taken along plane VIHVIII of Fig. 5, illustrating movement of parts from the position shown in Fig. 7, toward project position.

Fig. 9 is a diagrammatic representation showing a sequence of various positions A to F of the cam follower during the sequential operation illustrated in Figs. 1-8; and

Fig. 10 is a longitudinal sectional view of the upper body of a writing implement, showing another modification of the invention.

Generally stated, the exemplary writing instrument illustrated in the drawings consists of a shell or housing containing a writing cartridge and operating means whereby the cartridge may be selectively moved from a projected position to a retracted position and vice versa, the cartridge being inclined to one side of the axis of the instrument when in projected position, and being inclined to the opposite side of the axis when in retracted position. This new mode of operation is accomplished by novel and simple means, and permits the use of long,

high capacity cartridges. In order to facilitate understanding, the essential elements comprise a cam follower tip carried by the upper end of an ink cartridge within the barrel of a writing instrument, a fixed body element within the barrel, said body element having a downwardly directed face provided with two adjacent means for receiving the cam follower tip, and a pair of oppositely inclined surfaces, each such inclined surface being inclined toward only one of said follower tip receiving means, and a camming means connected to an actuating plunger and movable through the body element into contact with the cam follower tip to move such tip into an inclined surface which then guides the follower tip to the other follower tip receiving means. When the follower tip is at one of-saidtip receiving means the cartridge is in writing position and when the follower tip is at the other receiving means the cartridge is in retracted position.

The exemplary retractable writing instrument illustrated includes a writing cartridge 11 which is shown as a cylindrical ball point pen unit having an upper, tubular ink reservoir portion 12 and alowcr writing tip 13 of reduced diameter. The 'c-artridge'll is slidably positioned in a longitudinally extending bore or chamber of a lower case '14-and anupper .body element '15, the latter being permanently encased in a shell "16. It isbiased toward a retracted position and into operating engagement with an upwardly directed cam follower '17 by a retracting spring 18, which bears against a retaining shoulder 19 provided in the lower portion of the case 14 and a shoulder or projection of'the cartridge. As clearly shown in Fig. 2, the cam follower 17, which is movably but permanently retained within the body element 15, has an upwardly directed tip '21and a lower cap portion 22, to loosely fit over the upper end of the cartridge and thereby permit lateral motion of the cam follower.

The longitudinally extending chamber 20 in the body portion 15 is adapted to loosely receive the cartridge 11 so that the-cartridge may move laterally as well as longitudinally. The upper end of the body 15 is provided with an enlarged chamber 23 in which the cam follower 17 is movably retained. The diameter of the cap 22 of the carnfollower 17 is slightly larger than the bore 20. The upper and enlarged chamberj23 contains a stationary body element 24, this element forming the upper end of the chamber 23 and being held in position by a press fit and.

the constricting action of the outer shell 16. Body elements 15 and 24 can therefore be considered as a unit.

Mounted within the shell 16 above intermediate body portion 24 is an operating plunger'25 which includes an operating button 26 extending axially of the pen through a port in the shell and camming means shown in the form of-two downwardly directed parallel and adjacent prongs, a retracting prong '28 and a projecting prong 29. The prongs or 'camming means forming the inner end of the plunger are longitudinally but non-rotatably slidable in the adjacent bores 30 and 31 which jointly constitute aperture means extending through the stationary body portion 24 and communicating with chamber 23 and lower face/36 of the body 24. The plunger is biased upwardly by spring 32 resting on the body portion 24 and is retained within the ,shell 16 by a stop shoulder 27 carried by the plunger and bearing against the inner surface of the shell. It will be noted that prong 28 and bore '30 are on one side of the axis of the instrument, whereas prong 29 and its bore 31 are on another, 0pposite side of the axis.

It will be noted that the rounded tip of the cam follower is received in tip-receiving bore 30 when the cartridge is in writing position (Fig. l) and such earn follower tip is received in tip-receiving bore 31 when the cartridge is in retracted position ('Fig. 6 Body portion 24 is provided with a downwardly facing project position shoulder or holding means 34 against which the end of cartridge 11 or its cam follower cap may rest (as shown in Fig. 2) and a retract-position face 36 against which the endofcartridge 11 or its cam follower cap may rest (as shown in Fig. 6). This shoulder 34 and face '36 form a part of the body and an upper end of enlarged chamber 23 which movably retains the cam follower 17. It maybe noted that the Project position shoulder 34 is formed adjacent to and radially away from the retracting prong 28 and its bore 30. Shoulder 34 lies in a plane spaced from face 36 a-distance adequate to cause the writing tip of the cartridge to be moved .or

-displacedlongi udinally a-sui abledi ta e- The length f m foll wer t p 1 i sl ght y gr er than the distance separating the transverse planes of shoulder 34 and face 36.

The operating means for moving the cam follower and cartridge longitudinally and laterally'comprise the prongs 28 and 29, a cam follower 17 (or its tip 21) and inclined surfaces which guide the upper end of the cartridge (through the cam follower or a tip) from projected to retracted position and vice versa. The detailed means shown in the exemplary drawings include camming means or surfaces formed in the ends of prongs 28 and 29. .Retracting prong 28 is provided with an inclined, preferably concave camming surface 38 and projecting prong 29 is provided with an oppositely in=clined,. preferably concave camming surface 39. These carnming surfaces are adapted to contact and impart directionalmovement to tip 21 of cam follower 17.

Adjacent the lower opening of the bores or apertures 3t and 31, face 36 of the body portion 24 is Provided with two transversely extending, oppositely inclined surfaces, herein referred to as a retracting incline 48 and a projecting incline 4-9. These inclines are preferably concaved to receive and guide the end of tip 21. Retracting incline 48 is well shown in Fig. 2 and leadsfrom a position adjacent bore30 into bore 31. It is inclined 'or descends toward bore 31 so that end of tip 21, when first received into'the incline from bore 30, would be urged (by retracting spring 18) to slide alongthe incline toward and enter bore 31.

The prong 28 has been referred to as .a retracting prong since it contacts the tip '21 of the cam follower 17 on the retracting depression of the operating button and the camming surface 38 moves said tip onto retracting incline 48. The prong 29 has been referred to as a projecting prong since .it contacts the tip 21 of the cam follower 17 on the projecting depression of the operating button and the camrning surface 39 moves tip 21 from a position in bore 31 onto projecting incline 49 leading back to bore 30. However, it is to be noted that the bore 31) in which the retracting prong 28 moves can be more properly referred to as a project-position bore, because the tip 21 of the cam follower 17 moves into this bore when the writing tip of the cartridge is projected, and the bore 31 can be more properly referred to as a retract-position bore, because the tip 21 of the cam follower 17 moves into this bore when the writing unit is retracted. Finally, the retracting incline 48 has been so designated because its inclined surface leads into the retract-position bore 31, and the projecting incline 49 has been so designated because its inclined surface leads or descends into the project-position bore 30.

The operation of my retractable writing instrument will now be described, starting with the writing unit 11 in its normal projected writing position, as clearly shown in Fig. 2. In this position the writing unit 11 is held projected against the retracting influence of the spring 18, because the upper face of the cap 22 of the cam follower 17 is in engagement with the project-position shoulder 34 of the body element 15, and the tip 21 of the cam follower 17 is partly within the project-position bore 30.

When the operating button 26 is depressed to retract the writing unit 11, the plunger 25 moves downward to cause the retracting prong 28 to contact the tip 21 of the cam follower 17 and urge the writing unit 11 axially downward. The axial movement is continued until the prong 28 has carried the tip 21 to the level of the lower opening of the project position bore 30. This position of the parts is shown in Fig. 3.

Fig. 4- shows the parts an instant later when with the further depression of the operating button 26 the tip .21 of the cam follower '17, under the influence-of the spring 18, has been carried by or cammed laterally by the retracting cam surface 38 of the prong'23 and onto a relatively high point of the adjacent retracting incline .48.

Tip v21 tends to move 'down the incline toward bore 31 (being urged by retracting spring 18.) but as long as plunger .25 isdepressed the tip will not enter here 31 because the cylindrical side of the prong 29 is contacting the cylindrical side of the tip 21.

However, (when the operating button 26 is released the plunger 25 and the prong 29 move axially upward under the restoring action of the spring 32, and as the prong 29 is withdrawn back into the bore 31, the tip 21 of the cam follower 17 is freed and under the influence of the spring 18 is caused to cam on the retracting incline 48 and into the retract-position bore 31, and move axially upward within the bore, until the upper face of the cap 22 of the cam follower 17 engages the retractposition face 36. When the parts are so positioned, as shown in Fig. 6, the writing until 11 is fully retracted.

The above-described retracting sequence of operation is further elucidated schematically in the diagrams A-B--C--'D of Fig. 9, the movement of the tip 21 being shown from writing position (projected position) as in diagram A onto incline 48 (diagram B), along the incline toward bore 31 (diagram C) and into retracted position wherein the tip is in bore or aperture 31 (diagram D). It is to be understood that the axial and lateral motions of tip 21 are transmitted by the tip, through the cap 22 of the cam follower to the upper end of the cartridge. The inclined camrnin surfaces form a unit-directional path for the cam follower.

When the operating button 26 is again depressed with the parts in the positions shown in Fig. 6, the plunger 25 moves downward to cause the projecting prong 29 to contact the tip 21 of the cam follower 17 and urge the writing unit 11 axially downward. The axial movement is continued until the prong 29 has carried the tip 21 to the level of the lower opening of the retract position bore 31. This position of the parts is shown in Fig. 7, a section taken along a broken plane VIL-VII of Fig. 5.

Fig. 8 shows the parts an instant later when with the further depression of the operating button 26 the tip 21 of the cam follower 17, under the influence of the spring 18, has been cammed by the projecting cam surface 39 of the prong 29 and on to a relatively high point of the projecting incline 49. As is clear from the figure, the tip 21 will be held in this position as long as the plunger 25 is so depressed because the cylindrical side of the prong 28 is contacting the cylindrical side of the tip 21.

Now when the operating button 26 is released, the plunger 25 and the prong 29 move axially upward under the restoring action of the spring 32, and as the prong 28 is withdrawn back into the bore 34), the tip 21 of the cam follower 17 is freed and under the influence of the spring 18 is caused to cam onto the projecting incline 49 and into the project position bore 30. Movement of tip 21 along incline 49 moves the upper portion of cartridge 11 laterally, such lateral movement ceasing when tip 21 engages bore 30. Such lateral movement in the device illustrated also places the cap 22 under the shoulder 34.

' moved laterally from one lateral position wherein the writing unit was retracted to another lateral position wherein the writing unit was projected, an axial movement occurring simultaneously with the lateral movement, the axial movement being limited by longitudinally displaced portions of the stationary body member.

The above-described projecting sequence of operation is further elucidated schematically in the diagrams D-E-F-A of Fig. 9. Diagram D shows tip 21 within bore 31, such tip being moved onto incline 49 in diagram E, moving along the incline in diagram F and into projected or writing position in diagram A.

Thus, if the. writing tip is projecting, depression and release of the button effects retraction of the writing tip whereas if the writing unit is retracted, similar depression and release of the button causes the writing unit to be projected.

When a cam follower such as 17 is used in the body of the pen, a standard, open-ended cartridge can be used as a refill. The operating mechanism is extremely compact and maximum ink capacity can be used in a pen of short external length. By making the axial bore 20 larger (as indicated at 20 in the modification shown in Fig. 10) so as to permit greater lateral movement to the cartridge, body 15 and portion 24' can be made as a single unit and the cartridge -11' may have its upper end provided with a tip or cam follower 21' which is attached to the cartridge or made an. integral part thereof before the cartridge is inserted into the instrument. Portions of the species of body member 15', illustrated in Fig. 10, which are counterparts of portions of the earlier described species of body member 15, have been designated by similar but primed reference numerals; namely, face 36', shoulder 34, bore 31, and bore 30'. The operation of the pen is substantially identical to that described hereinabove.

It is to be understood that various changes and modifications may be made without departing from the inventive concepts here disclosed, since the drawings illustrate but an example and details of construction may be varied.

I claim:

1. In a writing instrument including a writing cartridge having a downwardly directed writing tip, the provision of: a plunger provided with a pair of downwardly directed prongs; a body element including two longitudinally extending, parallel bores adapted to slidably receive the prongs of the plunger, said bores being on opposite sides of the axis of the instrument, said body element having a downwardly directed project-position shoulder adjacent one of said bores, a retract-position face, and a pair of inclined surfaces in such face, each one of said pair leading to and being inclined in the direction of a respective one of said bores, said surfaces: being oppositely inclined; an upwardly directed cam follower adapted tocontact said surfaces and partly enter said bores, said cam follower being in operative engagement with the upper end of a writing cartridge; and camming means carried by the end of each of said prongs to impart axial motion along one of said bores and lateral motion along one of said transversely extending, inclined surfaces to the cam follower and the upper end of the writing cartridge upon axial movement of the plunger.

2. A Writing instrument of the character stated in claim I 1, wherein each of said inclined surfaces extends from adjacent one of the bores.

3. A writing instrument as stated in claim 1, wherein each of the inclined surfaces is concaved to receive and guide an end of the cam follower.

4. A writing instrument of the character stated in claim 1, wherein the cam follower is connected to the upper end of the cartridge.

5. A writing instrument of the character stated in claim 1, wherein the cam follower is movably retained in the writing instrument, and has a cap portion adapted to receive the upper end of a cartridge.

6. In a writing instrument including a barrel having a writing tip aperture at its lower end, and containing a laterally and axially movable ink cartridge having a writing tip adapted to project through the writing tip aperture when in writing position, and a spring normally biasing the cartridge and writing tip into retracted position, the com bination of: a cam follower having an upwardly directed rounded end carried by the end of the cartridge within the barrel; a stationary body element provided with a downwardly directed face and adjacent bores extending through 7 said element and in, communication with said face, said adjacent bores being adapted to receive the upwardly directed rounded end of the cam follower; said body element being further provided with guiding surfaces formed in saidjface and inclined in the direction of a respective one of said bores to facilitate movement of the cam follower end from one bore to another; and camming means including adjacent prongs provided with camming surfaces, each of said prongs being slidably mounted in a respective, one of said adjacent bores into contact with said cam follower end to eject it from a bore and direct it onto a guiding surface leading to the adjacent bore.

7. In a writing instrument as stated in claim 6, wherein the: guiding surfaces in said face are two in number, said guiding surfaces being oppositely inclined and such guiding surfaces being on opposite sides of said adjacent bores.

8. In a writing instrument as stated in claim 6, wherein the guiding surfaces are two in number, said guiding surfaces being oppositely inclined and concaved and on opposite sides of said adjacent bores, and the camming surfaces of the camming means are oppositely inclined.

9. In a writing instrument as stated in claim 6, wherein the camming means are connected to a plunger extending from the barrel and the guiding surfaces provided in the face are two in number, said guiding surfaces being oppositely inclined and concaved and on opposite sides of said adjacent bores, and the camming surfaces of the camming means are oppositely inclined.

10. In a retract-project mechanism for a writing instrument including a barrel having a writing tip aperture at its lower end, an ink cartridge having a writing tip adapted to project through the writing tip aperture when in writing position, a spring normally biasing said cartridge and writing tip into retracted position, and an outwardly biased plunger extending from the upper end of the barrel, the combination of: a cam follower adapted to be carried by the end of an ink cartridge within the barrel, said cam follower being provided with an upwardly directed rounded end; a stationary body element provided with a downwardly directed face, said face being provided with two adjacent apertures for the reception alternately of said upwardly directed rounded end of the cam follower; said body element having a face having inclined surfaces formed therein andleading to each of said cam follower end receiving apertures, said inclined surfaces being oppositely inclined and in the direction of their respective apertures; and camming means, having oppositely inclined camming surfaces, movable through said body element into contact with the rounded end of the cam follower when said cam follower is in one of said two cam follower end receiving apertures to move the end of the follower onto an inclined surface leading to the other and adjacent follower end receiving aperture.

11. A writing instrument having an elongated tubular barrel, a writing cartridge slidable therein and provided with a writing tip atone end thereof and a laterally movable cam follower having an upwardly directed tip carried on the end of the cartridge opposite the writing tip, a mechanism for shifting the cam follower from one tothe other of two laterally spaced positions and selectively retaining the follower in such position, including a stationary body element provided with a downwardly directed faceand aperture means formed in the body elementand communicating with said face, the face being piovided with two concaved, oppositely inclined surfaces, one on each side of the aperture means, said oppositely inclindedsurfaces constituting guiding surfaces to facilitate movement of the cam follower tip from one of said laterally spaced positions to the other; and camming me I movable longitudinally through the aperture means in th'e 'ody elernent and having oppositely inclindedcarn; m1 sa d upisiii one or said positionsin theaperture means toniove the tip' from said one position onto the respective surfaces for contactingjtheicam follower, tip when.

concaved, inclinded surfaces to guide the tip to. other position. v

12 A writing instrument as stated in claim 11 wherein the stationary body element is provided with a holding means to engage and hold the cam follower in one of the lateral positions of the follower to prevent the cam follower tip from extending fully into the aperture means when the cam follower is in such lateral position.

13. A writing instrument as stated in claim 11 wherein the stationary body element is provided with a laterally displaced holding means in a plane spaced from the face of the body element, said holding means engaging and holding the follower when said. follower is in one of the lateral positions to hold the writing tip of the cartridge in writing position.

14. A writing instrument having an elongated barrel, a writing cartridge slidable therein and provided with a writing tip at one end thereof, a cam follower adapted v to engage the end of the cartridge opposite the writing tip, said follower having an upwardly directed tip laterally movable within the barrel, a mechanism for shifting: the cam follower from one to the other of two laterally spaced positions and selectively retaining the follower in such position, including a stationary body element provided with a downwardly directed face and aperture means formed in the body element and communicating with said face, the face being provided with two oppositely inclined surfaces, one on each side of the aperture means, said oppositely inclined surfaces constituting guiding surfaces to facilitate movement of the cam follower tip from one of said laterally spaced positions to the other; and camming means movable longitudinally through the aperture means in the body element and having oppositely inclined, laterally disposed camming surfaces for contacting the cam follower tip when said tip is in one of said lateral positions to move the tip from said one position onto the respective inclined surfaces to guide the tip to the other lateral position.

15. A Writing instrument having an elongated barrel, :1 writing cartridge slidable therein and provided with a writing tip at one end thereof, a cam follower adapted to engage the end of the cartridge opposite the writing tip, said follower having an upwardly directed tip laterally movable within the barrel, a mechanism for shifting the cam follower from one to the other of two laterally spaced positions and selectively retaining the follower in such position, including a stationary body element provided with a downwardly directed face and aperture means formed in the body element and communicating with said face, the face being provided with two oppositely inclined surfaces, one on each side of the aperture means, said oppositely inclined surfaces constituting guiding surfaces to facilitate movement of the cam follower tip from one of said laterally spaced positions to the other; a holding means forming a part of the stationary body element for limiting movement of the cam follower when said follower is in one of the laterally spaced positions, at least part of said follower tip extending into the aperture means when the cam follower is in the other laterally spaced position; and camming means movable longitudinally through the aperture means in the body element and having oppositely inclined, laterally disposed camming surfaces for contacting the cam follower tip when said tip is in one of said lateral positions to move the tip from said one position onto the respective inclined surfaces to guide the tip to the other lateral position.

16. In a writing instrument having an elongated barrel adapted to receive a writing cartridge for axial movement therein from and to projected writing position and a retracted position and including a spring normally biasing the cartridge into retracted position, the provisior of: a plunger, having an outer portion and an inner portion; a cam. follower. adapted to engage the upper end of a writing cartridge in the barrel; a stationary intermediate member within the'barrel, said intermediate member being provided with aperture means extending therethrough to slidably but non-rotatably receive the inner end portion of the plunger for longitudinal reciprocation in said aperture means; said inner end portion having two laterally disposed camming means inclined in opposite directions; said intermediate member being provided with two oppositely inclined cam surfaces adjacent the aperture means, each of said cam surfaces sloping toward an opposite lateral side of said aperture means; said cam surfaces defining a unidirectional cam path for said cam follower whereby, by successive reciprocation of the plunger in said aperture means, said follower is engaged by and cammed by the camming means onto said cam surfaces in succession and laterally shifted.

17. A writing instrument as stated in claim 16 wherein the stationary intermediate member is formed with a holding means to limit longitudinally directed movement of the cam follower when said follower is in one of the laterally spaced positions, said cam follower having 'a tip extending into the aperture means when the cam follower is in the other laterally spaced position.

References Cited in the file of this patent UNITED STATES PATENTS

Images