US39867A - Improvement in lithographic presses - Google Patents

Description

lINiTnD STATES PATENT Onricr;D

JOHN TAGGART, OF ROXBURY, MASSACHUSETTS, ASSIGNOR TO HIMSELF ANI) STEPHEN O. THAYER, OF SAME PLACE.

IMPROVEMENT IN LITHOGRAPHI PRESSES.

Specification forming part of Letters Patent No. 39,867',` dated September 8, 1863..

To all whom it may concern:

Be it known that I, JOHN TAGGART, a resident of Roxbury, in the county of Norfolk and State of Massachusetts, have invented an Improved Lithographie Press; and I do hereby declare the same to be fully described in the following specification, and represented in the accompanying drawings, of which- Figure l is a top View, Fig. 2 a side elevation, Fig. 3 a rear end elevation, Fig. 4 a longitudinal and vertical section, and Fig. 5 a transverse section, of it.

In the said drawings, A denotes the frame for supporting the main operative parts, and particularly the bed B, on which the lith0 graphic stone G reposes and is sustained during the operations of printing with the press. The said bed and stone are stationary, while the scraper, which is shown at D, is moved across the stone in a direction from end to end of it, the scraper being first moved forward and next backward. To this end the scraper is hung on journals a a, arranged at its two upper corners, (see Fig. 4,) and so as to be capable of swinging within a carriage, E, which spans the frame A, and at each end is supported on a horizontal rail, c, by means of rollers b b. The bearings of the journals of the scraper should be so made as to admit of the scraper being moved vertically or gaged to the stone by means of a screw, e, which screws through the arch or cross-bar f of the carriage E. Fur thermore, two arms, g g, project from the scraper and receive at their outer ends two de pressors, h 71 each of which hangs from one of the arms, and at its lower part is bent at right angles and enters a channel or groeven?, made in the side of the frame A. The two depressors are connected by a cross-bar, lc, (see Fig. 4,) and extend through guide arms or struts l Z, projecting from the carriage. A helical spring, m, encompasses each depressor, rests on its guide-arm, and presses upward against one of the arms g g.

The groove i, of which there is one in each side of the press-frame, is formed of two horizontal and parallel grooves arranged at a short distance asunder and provided vwith lateral openings oppl of communication, theybeing arranged as shown in Fig. 2. The passage o is a vertical one and connects the two forward extremities of the two horizontal grooves. A switch, q, is applied to each of the other passages, pp p2. This switch turns on a center pin, 1^, and is provided with a spring, s, for depressing it. passages p p2 there is a gate, t, which turns vertically on a pin, u, and is arranged with respect to the passage and lower groove and formed as shown in the drawings. The purpose ofthe gate is to close the lateral passage, so as to prevent the entrance of the depressor into it while the carriage may be advancing and the depressor may be in the lower part of the groove i and in the act of passing across `the said passage.

The purpose of each switch is to guide the depressor from the upper into the lower of the horizontal portions of the groove 0J at or just after'the period .of commencement of an ad- Vance movement of the scrapercarriage. Under these circumstances the switch will be borne up against the upper side of the upper horizontal portion of the groove i, and when the foot of the depressor may be moved into contact with and be moving past the switch the latter will cause the depressor to move downward and to pull down the scraper in a manner to turn it and canse it to press the tympan T toward the stone.

I employ more4 than'one of the lateral vpassages p p p2 on account of adapting the press `to the use of stones of different sizes or lengths,

and so as not to be obliged to move the scrapercarriage farther back than would suffice for the scraper to pass entirely off the stone and effect the elevation of the tympan. There is also another spring, o, oneach of the depressors, it beingplaced above the arm of thescraper and serving to enable the scraper while passing over the stone to accommodate itself to the varying thickness of the stone, the tympan, and its appliances. A cranked shaft, w, extends across the lower part of the scrapercarriage, and carries at its middlea pinion, x, which engages with a stationary rack, y. By laying hold of the crank e of the shaft w and revolving the shaft the carriage may be moved over or across the stone and either forward or backward.

The tympan T is hinged to the frame or table for supporting the stone, or, in other words,

Furthermore, to each of the extends from a shaft, a', whose journals b b turn in eyes or bearings c o. Near to one of its journals the front side of the shaft is provided with a dog, d', which at its lower end is hinged to the shaft, such dog being furnished with a spring, e', for elevating it into or nearly into a vertical position.

There may be one or more other sets of eyes or bearings, c2 c2, for the tympan, they being arranged so as to enable it to be adjusted to stones of different sizes. A spring-latch, f, extends from the scraper-carriage in manner as shown in Figs. l and 2, its purpose being to catch and hold up the tympan after it may have been raised up by the action of the scraper against the spring-dog d. During the advance of the scraper-carriage the scraper will be depressed or turned down upon the tympan, and will be there held until completion of the advance movement of the carriage, which, having taken place, the depressors of the Scrapers will be forced -up into the upper parts of their grooves During the rearward movement of the scraper-carriage the scraper, relieved from pressure on the tympan, will be carried into contact with the springdog d', and by pressure against it will elevate the tympan oft` the stone or the paper which may be thereon, and such tympan will be caught and held up by the spring-catch. f. While the scraper may be advancing it will press against the dog, which will give way and allow the scraper to pass freely over it.

, In the common lithographie press the stone itself is moved underneath the scraper; but in my improved press the stone is stationary and the scraper is moved across it. On several accounts this is preferable to having the stone movable underneath the scraper.

I claim- 1. The improved lithographie press as made, not only with the stationary bed B, but with the scraper D, supported by a movable carriage, E, and provided with mechanism, substantially as described, (or its equivalent,) for operating the scraper or depressing it upon and relieving it from the tympan and stone, the whole being as and to operate as specified.

2. The said mechanism or combination for operating the scraper during the reciprocating rectilinear movements of its carriage, the same consisting not only of the channels t' and their switches q and gates t, constructed and arranged substantially as described, but of the arms Z, the depressors h, and vthe elevatingsprings m, arranged as set forth.

3. The combination of the spring-latch f', applied to the carriage E, and the movable or spring dog d', applied to the tympan-shaft, with the tympanshaft, the scraper, and its carriage, the whole being as and for the purpose set forth. y

JOHN TAGGART.

Witnesses:

R. H. EDDY, F. P. HALE, Jr.

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