Cottrell's Air-spring Two-roller Press.—This drum-cylinder press, made of various sizes, covers the necessities of a large share of work done in nearly every 'printing office. This press, and also the two-revolution press, contains Messrs. Cottrell & Sons' patent air-spring with governor attachment, which bears on an easy cushion for the bed, and can be readily adjusted for different speeds. This air-spring not only forms a cushion to arrest the momentum of the bed as it passes the center. but with the assistance of the governor and vacuum valves aids in starting the bed on its return movement, and relieves the gearing of all undue strain. By the governor valve, in the air-pipe connected with both of the hol low piston rods, the amount of spring pres sure is controlled. the gale being kept either wholly or partially open or closed, accord ing to the position of the governor balls as affected by the speed of the press.
The Potter Flat-bed Perfecting Press (Fig. 5).—This im p r oved pr ess combines the well-known ad van tages of the Potter two revolntion press and the perfecting press, which print from fiat forms, call& type or plates, a high-grade work , economically and profitably.
The general me chanical movements of this press are the same as those of the Potter two-revolu lion press. The driving mechan ism and the patented method for controlling the raisin& and lower ing, of the cylinders and regulating the im pression, are identical with the two-revolu tion presses. Som e of the distinguishing points of this press are: The feeding and cutting device for roll feed: as will be seen in engraving, the paper is taken from a roll at the end of the press and led into for warding rollers, which in turn carry it between the cutting cylinders, thence on through an other pair of rollers, which have the web under full c on trol until the sheet is cut and seized by the grip pers of the feeding cyl inder. The cutting and feeding mechan ism, claimed to be the only one by w hi c h sheets of various sizes can be cut and carried positively to the grip „ pers : the changes ne cessary for cu tt ing sheets of different lengths are easily and quickly made, all gears being plainly marked so as to correspond with a graduated scale on the frame. By this means, in connection with an index finger on the adjustable carriage of the cutting cylinders, the relative position of the cutting cylinders to the feeding cylinder, as the size of sheet is varied, is easily deter mined and accurately adjusted. The adjustable carriage of the cutters allows tapes to be
dispensed with, and ensures positive control of the sheet at all times. The press is not limited, however, to roll feed, but may be fed by hand as well to the same guides, and with no change of mechanism save the adjustment of a simple clutch. The registering segments on the cylinders not only engage with the usual racks on the type-bed, but with each other at each revolution. In addition to this, Messrs. C. Potter, Jr., & Co have a newly patented device by which the cylinders are driven at all times in full gear, despite their rise and fall, which, combined with their patent bed driving rack, insures accurate register.
The distribution is that of a four-roll, two-revolution press, with rack screw, table and cylindrical distribution. There has been added to the regular table distribution of the four-roller press, the vi brating cylinder and riders of the stop cylinder.
Cottrell's Two - revolution Press (Fig. 6).—This press embodies a patent "front sheet delivery," brought out by C. B. Cottrell & Sons. It dispenses entirely with the fly, and no tapes or strings are used in its construction or op eration. It takes the printed sheet from the cylinder by grippers, a positive motion, carries it rapidly through the air, and deposits it on the pile table, printed side up, over the fountain. It requires no adjustment for large or small sheets. Another great advantage claimed over other methods of delivery is the convenience with which the forms and rollers can be handled. The rear of the press is, oNourse, left en tirely unobstructed for the placing of forms. The deliv ery is placed sufficiently high above the bed to be entirely out of the way, and as there are no tapes or strings what ever in front of the cylinder, it will be seen that the forms may be placed or corrected and the rollers easily handled from either side of the ma chine. The feed-board is so constructed and hinged that it may be lifted entirely away from the cylinder, leaving free access to the whole print ing surface, and giving ample room from either side of the press for making ready. This press also has a " power back ing-up motion and a trip," enabling the operator to throw off the Impression at will, or to roll the form any number of times, and also has a patent reel and fly delivery.