US2184746A - Typewriting machine - Google Patents

Description

Dec. 26, 1939.

e'. F. KUROWSKI TYPEWRITING MACHINE Filed Jan. 11, 1937 3 Sheets-Sheet l a Q x INVENTOR 5 Sheets-Sheet 2- A. G. F. KuRow'sKl TYPEWRITING MACHINE Filed Jan. 11, 1957 Dec. 26, 1939.

INVENTOR ATT NEY 1939- A. G. F. KUROWSKI' 3 TYPEWRITING MACHINE Filed Jan. 11, 19:57

3 Sheets-Sheet 5 Patented Dec. 26, 1939 UNITED. STATES PAT T TYPEWRITING MACHINE- Application January 11, 1937, Serial No. 119,945

13 Claims.

This invention relates to typewriters, and more especially to those having a letter-space feed rack on the carriage and a pinion-ratchet escapement mechanism on the frame. An occasional overthrow of the carriage, when the carriage is returned and banked against the rightend margin-stop, thereby causing the first type impression in a line on a copy-sheet to be made one letter-space to the left of the vertical line on the worksheet predetermined by the marginstop setting, takes place when the carriage attains an unusually great momentum during return. Sometimes also, when the carriage is returned and banked against the right-end margin-stop, the carriage-rack jumps oii from the escapement pinion and falls back into engagement with the pinion one tooth away from the original contact tooth and therefore the carriage is left in such a position that the initial type impression is made one letter-space to the right of the initial letter-space predetermined by the margin-stop setting. This error of setting to the extent of one letter-space at the beginning of a line sometimes occurs in typewriters having an electrical automatic carriage return and a large carriage having rearward extensions in which a twisting movement of the carriage may take place when banking.

A feature of this invention is'broadly a device to assure that every return of the carriage on a typewriter is exactly to the initial letter-space at the beginning of a line predetermined by the setting of a margin-stop.-

Another feature of this invention is a mechanism automatically actuated by a margin-stop for locking concomitantly the escapement pinion against overthrow of the carriage when the carriage is returned, or in other words against setting the carriage for type impressions one letterspace to the left of the position predetermined by the margin-stop for the succeeding line of by this margin-stop forthe first letter-space in the next succeeding line of typing.

Another feature of the invention is the provision of means concurrently operated by a margin-stop for both locking the escapement pinion against overthrow and for locking the carriage letter-space feed' rack in mesh with the pinion to retard jumping of the rack, orin other words to prevent the carriage return to a position either one letter-space to theleft or one letterspace to the right of the printing position at the left of a copy-sheet predetermined by the margin-stop.

Another feature of the invention is a device, including a margin-stop that is movable with the carriage in letter-space feeding direction, which is actuated by the margin-stop and which includes a pawl movable into engagingposition with a ratchet'wheel on the escapement pinion shaft and which includes a hook that simultaneously lockingly engages the letter-space feedrack to hold the rack in mesh with the escape ment pinion.

One embodiment of the invention is applied to a typewriter having an electrical automatic carriage return and in which a margin-stop may be mounted on a banking rod that moves a bellcrank to actuate the electrical return mechanism. A crank-shaft may extend rearwardly from the pivot mounting of the bell-crank in the frame to the rear and actuate a slidable arm which in turn actuates both apawl that locks the escapement pinion against overthrow and a hook that holds downthe carriage letter-space feedrack in mesh with the pinion, to prevent jumping of the carriage. A ratchet wheel may be mounted on the inner or forward end of the escapemen't pinion shaft for engagement with the locking pawl and may have a tooth for each letter-space on the typewriter.

Other features and advantages will after appear.

In the accompanying drawings, Figure 1 is a perspective view with parts of the typewriter broken away.

Figure 2 is a front elevation of the escapement mechanism with the carriage in the extreme return position before the carriage drops back.

Figure 3 is a side elevation with parts broken away.

Figure 41s a front elevation of the escapement mechanism showing in normal position a part of the supplemental ratchet wheel mounted on the pinion shaft and the locking pawl which is hereinengageable with this supplemental ratchet to lock the pinion against overthrow, with parts broken away.

Figure 5 is a sectional elevation of the escapement pinion and the carriage-overthrow prevention ratchet wheel.

Figure 6 is a perspective View of one embodimerit of the invention and the cooperating parts of a typewriter, in looking engagement.

Figure '7 is a diagrammatic view of a carriage in banking position showing the twisted position, exaggerated in dot-and-dash outlines, due to great carriage-return momentum.

Figure 8 is a view similar to Figure 6 but showing only the left end of the devicein nonlocking relationship to the escapement pinion and the carriage rack.

A heavy duty typewriter frame I!) is mounted on the usual feet H and supports a reciprocatorily mounted platen carriage I2 in which is rotatably mounted a cylindrical platen 53, over which is fed a copy-sheet l4 upon which upper and lower case type l5 imprint when keys it are struck by an operator. A spring drum I! winds a strap i8, fastened on an arm 8| depending from the carriage l2, to feed the carriage l2 in writing direction. The frame I9 has a letter-space scale bar 29 across the front which is formed at the rear into a track 2| for a roller 22 mounted on an arm 29 extending forwardly from and sup porting the front of the carriage l2. At the rear is a heavy round cross-rod 24 mounted in the frame ill on which is slidingly supported a cylindrically socketed arm 25 depending from the rear of the carriage l2. The carriage I2 is made rigid by an obtuse-angled cross-bar 26 at the rear and a right-angled cross-bar 21 at the front. A front cross-rod 28 in the frame I!) supports at the left a usual line-end margin-stop 29 provided at the rear with a dual cam 39 for depressing a toothed arm 36 which actuates a signal and a key-lock (not shown). Knobs 3! are mounted on the ends of the platen i3 and may rotate the platen. Letter-space feeding of the carriage I2 is procured by means of a rack-bar 32 supported at the ends on arms 33 which are pivotally mounted in the sides of the carriage 12 on pivot pins 34 (only one of the arms 33 being shown), the right arm 93 being rigidly connected with acarriage-releaselever 35 by means of which, against the tension of a spring 44, the bar 32, which has letter-spacing teeth forming a rack 37, is lifted out of meshing engagement with an escapement pinion 38 which together with a cylindrical collar 39 is mounted rotatably on a shaft 43 (see Figure 4) in the. escapement mounting frame 49 of a wellknown construction. A ratchet wheel 4|, fixed on the escapement shaft, has a tooth 42 for each letter-space. The pinion 38, as clearly shown in Figures 6 and 8, is rotatable forwardly or clockwise With reference to the ratchet wheel 4! but the pinion 38 is prevented from rotation in the counter-clockwise direction with reference to the wheel 4!, or in other words the ratchet wheel 4! controls the feed of the bar 32 from right to left, under control of the spring drum H, but the bar 32 is free to move to the right with the pinion 38, to the right being in the carriage-return direction; means permitting the foregoing relative motion and locking are a pair'of pawls l5 oppositely disposed and pivotally mounted on the front side of the ratchet wheel 4| to engage the pinion 39 at an angle inclined in the clockwise direction. Each pawl 45 is held in yielding engagement in the clockwise rotation of the pinion and in looking engagement in the counter-clockwise rotation of the pinion 38 by loop springs 46 on one end of each bearing on the back of a pawl 45 and the other end being held by a stud 41 on the front side of the ratchet wheel 4|. A dog rocker 4B is pivotally mounted in the escapement mounting frame 40 and supports the usual fixed dog 49 and the usual limber dog 50 to which is attached a pull spring 5! which tends to draw the limber dog 59 into engagement with a letter-space positioning stop arm 52 mounted on the rocker 48. A check dog 59 (see Figure 4) is pivoted on the rocker 48 to the right of the fixed dog 49 and is held in a vertical position, but yieldable away from the dog 49 along the guide arm 55 mounted on the dog 49, when engaged by the right side of a tooth 42, but also exactly stopping the ratchet wheel when the latter is advanced clockwise one letter-space. A thumb-piece 56 may be used for the facile return of the carriage l 2 to the banking position in which a counter-stop 57', mounted on a lever 58 pivoted on a screw 59 on the cross-bar 2? of the carriage l2 and held in engageable position by a spring 69, engages a margin-stop 6| adjustably mounted on the rod 28 and a banking rod 952, both of said rods being mounted in the front of the frame I 0. An arm 63, releasable by the finger-piece 64, has teeth 65 which engage notches GB in the rod 62 to secure the marginstop of in any adjusted position on the rod.

Referring now to Figure 7, when the carriage I2 is returned to the banking position it has attained often considerable momentum when it has reached the banking position, this momentum tending to move the carriage after stops 51, 6| are engaged at'the front, thereby carrying along the rear of the carriage l2 to produce a twisting of the carriage to the position shown in Figure 7 in dot-and-dash lines. Such a twisting motion carries along the rack-bar 32 also and causes herein applied to a typewriter equipped with an electrically operated automatic carriage return.

Referring to Figure 1 a motor 10 drives a shaft 1! on the end of which, within a housing 12, is

mounted a worm-gear 13 which meshes with and To overcome rotates a gear wheel 14 fixed on the rear end of a shaft 75 journaled in a bearing 16 which is supported in the frame ID. A clutch comprises a rear jaw Tl pinned against turning on the shaft 35 and a front jaw 18 rotatably and slidably mounted on the shaft 15. The jaw 18 mounts a er end on the rock-shaft 84 which is journalecl transversely in the lower front end of the bearing '26. A depending arm 86 is fixed on the rockshaft 84 and by means of a link 81 actuates an arm 88 fast on a rock-shaft 89 transversely mounted on the frame H]. An arm 90 depends from and is fast on the rock-shaft 89 and at its lower end is pivotally connected with a rearwardly extending arm 9| which opens and closes a switch 92 in the electrical circuit to the motor 19.

As shown in Figure 3 the switch 92 is open as well as the clutch 11, 18. To the lower end of the arm 88 is pivotally connected a forwardly extending keeper arm 94 which passes through a slot 95 in v the transverse keeper plate 96 and which is secured in the forward position shown in Figure 3 by a notch 91 in the lower edge of the arm 94 and a spring 98 pinned to the arm 94 and to the inside of the frame I9. A key 99 is pivotally mounted in the frame I9 on a lever I99 which has an upstanding inner end IN, on which a spring I22 is positioned to hold the key 99 in the upright position with the rear edge of the inner end IIII engaging a stop pin I92 mounted in the frame I9. A second stop-pin I93 limits the depression of the key 99. It is apparent that, when the arm 94 is locked, in the position shown, by the keeper 96, the switch 92 is broken and the clutch 11, 18 is open, but when key 99 is depressed I and the upper end of arm I9I engages a cam II9 96, the

rear end of a lever I 99 rockingly mounted in a frame bracket I91 by means of a pivot rod I96. On the forward end of the rocking lever I96 is mounted a vertical link I99 the upper end of which is twisted into the vertical transverse plane and is apertured by a central vertically elongated slot I I9 which slidably confines a screw II I which is fastened in the lower arm of a bell-crank II2, pivotally mountedon an arm II3 which in turn is mounted in the end arms II4 of a bracket H5 by means of screw-set collars H9. The bracket H5 is mounted on the frame I9. It is now clear that when the key 99 is depressed the notch 91 is lifted from the keeper 9% (see Figure 3) the switch 92 is made and the clutch 11, 13 is engaged, but that when the bellcrank I I2 is moved clockwise to the extreme right position shown in Figure 6 the switch 32 and the clutch 11, =9 are broken and the carriage stopped in an initial letter-space. A forwardly extending pin H1 mounted on the banking rod 62 is locked for movement in and with a slot H8 in the top of bell-crank II2. A spring I29 tied to a depending post HI and to the frame I9 tends to hold the banking rod 62 in the extreme left position. Y

The rod or arm I I3 which is fixedly secured to the bell-crank H2 and is rockable in the bracket arms II I may be extended rearwardly and downwardly in the form of a crank I25 the upper rear end I23 of which terminates below the bearing axis of the rod H3 so that a transversely and horizontally positioned arm I21 pivoted on the upper rear end I25 of crank I25 is moved to the left when the banking rod 62 moves to the right to rotate the bell-crank .2. In other words as the counter-stop 51 and counter-stop BI engage in banking position the arm I21 is moved to the left, and the reverse is also true so that as the bell-crank II2 oscillates the arm I21 moves in the opposite direction.

In Figures 1 and 6 it is seen that the banking rod 32 carries a fixed collar I28 on a reduced extension I24 of the banking rod 62, the extension having a slidable bearing in a round aperture in the top of the frame I9. The collar I28 is spaced to the left of the frame I9, as shown in Figure 1, when the stops 51, 9| are in the initial engaging position, so that the banking rod 62 can slide to the right until the collar I28 engages the side of the frame I9 as shown in Figure 6. This motion causes an opposite or leftwards motion in the arm I21 to actuate my improved mechanism for preventing a faulty setting of the carriage I2 when returned to banking position with excessive carriage momentum. The arm I21 has an elongated central slot I29 and terminates at the left in a narrower extension I39 which has near its outer end an upstanding stop I3I. A top ear I33 and a bottom ear I33 are fast on the top and bottom of an arm I34 and secure the arm I34 and the extension I39 together slidably one to the other. Another top ear I35 to the right of ear I32 and another bottom ear I36 on the arm I34 secure the arm I21 in sliding contact with arm I34. The arm I34 also has an elongated slot I31 shorter than the slot I29, the left end wall of which has a short central projection I39 to the right and the right end wall of slot I29 in arm I21 has a central projection I39 to the left longer than the projection I38. A coil spring M9 is mounted in the two slots I29, I31 and secured in position by pushing the ends of the coil spring I49 over the opposed extensions I39, I38 so that the ends of the coil spring I49 press against opposite ends of the slots I29, I31,

thereby tending to extend the arms I21, I34 with reference to each other, but on the other hand.

the arm I34 can slide back to the right on the arm :21 against the tension of the spring I49. The ear I32 engages the stop I3I and limits the extension of the arms I21, I 34. The left end of the arm I34 is secured by a pivot screw I42 to a pawl I43 which is pivoted on the escapement mounting 99 by a pivot screw I44. It is now ob- Vious that as the arms I21, I34 move to the left the pawl I43 moves into engagement with a ratchet-tooth wheel I 45 to prevent rotation of the wheel I45 in a clockwise direction. The wheel I45 which is fixed on the outer end of the cylindrical collar 39 and is therefore rotatable with the pinion 38 is locked against slipping off the end of the escapement shaft 43 by means of the head of a screw I46. The pinion 38, the collar 39, and the ratchet I45 form an integral rotatabie unit. The pawl I43, when engaged with the ratchet wheel I45, therefore locks the escapement pinion 38 against clockwise or carriage-return rotation, and when engaged after the manner of my invention concurrently and concomitantly with the arresting of the carriage by the engagement of the carriage and frame margin-stops in banking position it prevents overthrow of the pinion 38 and therefore overthrow of the carriage I2 one letter-space to the right of letter-space position predetermined by the setting of the margin-stop 6|. The effect of this carriage overthrow is shown in, Figure 7 where a type I5 is shown striking one letter-space to the left of the predetermined margin indicated by the extreme left X s in the two imprinted lines on the copy-sheet I4.

On the other hand if the carriage-rack 31 is altogether disengaged in the banking position so that the rack'31 no longer meshes with the pinion 3B the carriage may come to a final stop one letter-space to the left of the initial banking position predetermined by the stops 51, 6I. The effect of such a jumping of the carriage would be to have the first letter-imprint in a line in the second letter-space position from the left shown on the copy-sheet M. To prevent the disen gagement of the carriage-rack 31 from the pinion 53 a hook Hit, which may overlie the rack-bar is provided on an arm l5l, the latter being pivotally mounted on a screw I52 which is secured on a support I53 in the frame Hi. The pivotal mounting of the hook I is such that it normally lies to the rear of the rack-bar 32 so that the rack 31 may be lifted clear of the pinion by depressing the carriage release lever 35. A pin 5 3 is secured in the lower horizontal end of the arm iii! and projects forwardly into thro gh an inclined slot i55 in the arm I34 the inclination of which is upwardly to the left and downwardly to the right so that when the arm its is moved to the left the top of the slot cams down the pin i and therefore the hook Hill to lock the rack-bar 32 against rising (the free position of the rack-bar 32 being shown in Figures 1 and 3 and the locked position in Figure 6). When the arm 53 is restored to the right the lower edge of the slot I55 cams up the pin I54.

The spring Mil holds the pawl M3 in engagement with the ratchet wheel i 55 irrespective of slight irregularities from precision in manufad ture and furthermore prevents any stresses strains on the parts in case of an unusually great banking thrust which compresses the spring i $3.

The spring $8 and the spring are tend to restore the pawl i4 3 and the hook 558 to inoperative position by moving the upper rear end W3 of the crank 325 to the right.

Referring to Figure 4, the check pawl is shown in the normal vertical position in which it is maintained, yieldabiy to the right, by the spring 54. As the carriage-rack 3i feeds to the left the pinion-313 is rotated counter-clockwise and so likewise the ratchet wheel ti, under control of the escapement dogs id, 59, turns counterclockwise in letter-space feeding of the rack 3'! to the left. Each tooth 42 engages the pawl 53 on the ieft side and t' ts it back to the right as it passes over the pawl 53.

Referring to Figure 2 the ratchet wheel 45 is shown in the condition obtaining when the car riage-rack 3'! is at the extreme right, when the initial margin-stop 5i is engaged by the carriage stop 5?, in which condition the spring-retracted limber-dog 5S engages the right side of a tooth 42 to check counter-clockwise rotation of the ratchet-wheel l! and the paw engages the left side of another tooth 42 to check clockwise rotation of the ratchet-wheel ll, thereby assuring that when the rack 31 drops back to the left, the letter-space and a fraction provided by the ad iustment, the position of the platen-carriage i2 is always uniform with reference to the banking margin-stop M. The letter-space drop is provided by the rotation of the wheel ll a single tooth, and the fraction of the play between the pawls G5 and th engaging teeth of the pinion 3t.

Variations may be resorted to within the scope of the invention, and portions of the improvements may be used without others.

Having thus described my invention, I claim:

1. In a typewriter having a frame and a carriage reciprocatorily mounted thereon, in combination, an escapement pinion rotatably mounted on the frame, a rack mounted on the carriage and normally engaging said escapement pinion, a margin-stop adjustable on the frame, a counterstop on the carriage, said stops determining the initial letter-space position of a line of typing,

means actuated by the margin-stop for; locking the escapement pinion against overthrow of the carriage to a printing position to the left of the initial predetermined letter-space position, and means for concomitantly locking the rack in mesh with the pinion. 4

2. In a typewriter having a frame and a carriage reciprocatorily mounted thereon, in combination, an escapement pinion rotatably mounted on the frame, a rack mounted on the carriage and normally engaging said escapement pinion, a margin-stop adjustable on the frame, a counterstop on the carriage, said stops determining the initial letter-space position of a line of typing, and means for preventing faulty operation of the mechanism in which the initial position of the carriage does not correspond with the setting of the margin-stop, comprising a pivoted arm oseillatable from a position over a carriage-rack away from the carriage-rack and means actuatahle by said margin-stop for oscillating said arm.

3. In a typewriter having a frame and a carriage reciprocatorily mounted thereon, in combination, an escapement pinion rotatably mount ed on the frame, a rack mounted on the carriage and normally engaging said escapement pinion, a margin-stop mounted for limited movement on the frame, a counter-stop on the carriage, said stops determining the initial 1etter-space position of a line of typing, and means actuated by the frame margin-stop for securing the carriage against faulty initial banking positioning to initial printing position at either side of the initial predetermined letter-space position, comprising a, pawlmovable into and out of locking engagement with the escapement-pinion, an arm for locking the carriage-rack in mesh with the escapement pinion, and an arm for concurrently moving said pawl and said first-mentioned arm.

4. In a typewriter having a frame and a carriage reciprocatorily mounted thereon and having a feed-rack, in combination, an escapement having a shaft mounted in the frame, a ratchet r0- tatably mounted on the shaft, a pinion fixed on the shaft, a pawl pivoted on the ratchet and engaging said pinion to permit independent rotation of the pinion and the shaft clockwise only, a ratchet fixed to turn with the escapement pin ion, a pawl movable into engagement with said last-named ratchet to stop carriage-return rotation of said pinion, a margin-stop on the carriage, a margin-stop on the frame, and a device actuated by the engagement of the carriage margin-stop and the frame margin-stop to move said last-named pawl into engagement with said lastnamed ratchet.

5. In a typewriter having a frame and a carriage mounted for reciprocatory movement thereon, in combination, an escapement pinion rotatably mounted on the frame, a rack mounted on the carriage and normally in mesh with said escapement pinion, a margin-stop mounted for limited movement on the frame, a counter-stop on the carriage, said stops determining the initial letter-space position of a line of typing, and means actuable by movement of said margin-stop for locking said rack in mesh with said escapement pinion.

6. In a typewriter having a frame and a carriage mounted for reciprocatory movement thereon, in combination, an escapement pinion rotatably mounted on the frame, a rack mounted on the carriage and normally in mesh with said escapement pinion, a margin-stop mounted for limited movement on the frame, a retractile spring for said margin-stop, a counter-stop on the carriage, said stops determining the initial letter-space position of a line of typing, and means actuable by advance movement of said margin-stop for momentarily locking said rack in mesh with said escapement pinion, said looking means being releasable by retraction of said margin-stop.

'7. In a typewriter having a frame and a carriage mounted for reciprocatory movement thereon, in combination, an escapement pinion rotatably mounted on the frame, a rack mounted on the carriage and normally in mesh with said escapement pinion, a margin-stop mounted for.

limited movement on the frame, .a retractile spring for said margin-stop, a counter-stop on the carriage, said stops determining the initial letter-space position of a line of typing, and means actuable by advance movement of said margin-stop for locking the escapement pinion against overthrow of the carriage to a printing position to one side of the initial predetermined position, said locking means being releasable by said spring incident to the retraction of said margin-stop.

8. In a typewriter having a frame and a carriage mounted for reciprocatory movement thereon, in combination, an escapement pinion rotatably mounted on the frame, a rack mounted on the carriage and in mesh with said escapement pinion. a margin-stop mounted for limited movement on the frame, a counter-stop on the carriage, said stops determining the initial position of a line of typing, a power-actuated carriagereturn mechanism including control means, and means actuated by said margin-stop for concomitantly operating said control means to disable said carriage-return mechanism and looking the escapement pinion against overthrow of the carriage to a printing position to one side of the initial letter-space position.

9. In a typewriter having a frame and a carriage mounted for reciprocatory movement thereon, in combination, an escapement pinion rotatably mounted on the frame, a rack mounted on the carriage and in mesh with said escapement pinion, a margin-stop mounted for limited reciprocatory movement on the frame, a counterstop on the carriage, said stops determining the initial position of a line of typing, a power-actuated carriage-return mechanism including manually settable control means resettable by said margin-stop and means actuated by said marginstop for concomitantly operating said control means to disable said carriage-return mechanism and locking the escapement pinion against overthrow of the carriage, said locking means being releasable during retraction of said margin-stop, said disabling and locking means having a lostmotion connection to permit retraction of said margin-stop with said control means in reset condition.

10. In a typewriter having a frame and a carriage mounted for reoiprocatory movement thereon, in combination, an escapement pinion rotatably mounted on the frame, a rack on the carriage and normally engaging said pinion, a margin-stop mounted for limited movement on the frame, a counter-stop on the carriage, said stops determining the initial letter-spacing position of a line of typing, and means actuated by move ment of said margin-stop for securing the carriage against faulty initial banking position, said means comprising an arm swingable to abut said carriage-rack for locking same in mesh with said escapement pinion.

11. In a typewriter having a frame and a carriage mounted for reciprocatory movement thereon, in combination, an escapement pinion rotatably mounted on the frame, a rack on the carriage and normally engaging said pinion, a ratchet wheel rotatable with said pinion, a, margin-stop mounted for limited movement on the frame, a counter-stop on the carriage, said stops determining the initial position of a line of typing, a crank arm actuable by said margin-stop, a link actuated by said crank arm, a member movable into and out of engagement with said rack, and a pawl swingable to engage said ratchet wheel, said link being operatively associated with said pawl and rack-locking member to concomitantly actuate same.

. 12. In a typewriter having a frame and a carriage mounted for reciprocatory movement thereon, in combination, an escapement pinion rotatably mounted on the frame, a rack on the carriage and normally engaging said pinion, a ratchet wheel rotatable with said pinion, a margin-stop mounted for limited movement on a frame, a counter-stop on the carriage, said stops determining the initial position of a line of typing, a crank arm actuable by said margin-stop,

, a link actuated by said crank arm, a member movable into and out of engagement with said rack, and a pawl swingable to engage said ratchet .wheel, saidlink being operatively associated with said pawl and rack locking member to concomitantly actuate same, said link being yieldable in one direction whereby to yieldably urge said pawl and locking member into engagement.

13. In a typewriter having a frame and a carriage mounted forreciprocatory movement there-

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