A pair of concentrically mounted drive shafts are rotatable with respect to one another. Each drive shaft engages and drives at least one endless chain upon which lugs are mountable. A driven power shaft directly drives one of the drive shafts. The other drive shaft has a coaxially-mounted gear wheel that intermeshes with a pinion wheel that is rotatable and is interconnected with the driven power shaft such that when the pinion wheel is inhibited from rotating power is delivered from the driven power shaft through the locked pinion gear to the gear wheel and drive shaft affixed thereto.

BACKGROUND OF THE INVENTION
 Technical Field
 The invention relates to continuous-motion packaging machines, and, more
 particularly, to a phase-adjustment mechanism for modifying the phase
 relationship between carton lugs in such a machine.
 Continuous-motion cartoning machines are useful for packaging multiple
 articles such as beverage cans in cartons or other packaging components.
 An example of a continuous-motion cartoning machine is shown in U.S. Pat.
 No. 5,241,806 to Ziegler et al.
 In cartoning machines (also known as packaging machines) endless chains are
 often used to transport lugs which in turn translate cartons or other
 objects along the length of the machine. The distance between lugs is
 generally referred to as "phase" or "pitch." It is often desirable to use
 a packaging machine to package cartons of different sizes at different
 times. The phase, or pitch, of the carton transport mechanism must be
 modified to accommodate cartons of a different size. It is important that
 phase/pitch modification not be too difficult or time consuming. Thus, it
 can be appreciated that it would be useful to have a means for rapidly and
 easily adjusting the phase/pitch of a carton transport.
 Various phase-adjustment methods and structures are disclosed in U.S. Pat.
 No. 5,560,473 to Ivansco, Jr. et al., U.S. Pat. No. 5,544,738 to
 Klopfenstein, U.S. Pat. No. 5,394,975 to Bernhard, U.S. Pat. No. 5,339,599
 to Risnes, U.S. Pat. No. 5,328,021 to Calvert et al., U.S. Pat. No.
 5,282,530 to Neri, U.S. Pat. No. 5,241,806 to Ziegler et al., U.S. Pat.
 No. 5,238,101 to Ota et al., U.S. Pat. No. 5,145,053 to Krieger et al.,
 U.S. Pat. No. 4,718,540 to Greenwell et al., U.S. Pat. No. 3,857,474 to
 Hutson et al. and U.S. Pat. No. 2,736,421 to Bell.
 BRIEF SUMMARY OF THE INVENTION
 A phase-adjustment mechanism in accordance with a preferred embodiment of
 the invention includes a pair of concentrically mounted drive shafts which
 are rotatable with respect to one another. Each drive shaft engages and
 drives at least one endless chain upon which lugs are mountable. A driven
 power shaft directly drives one of the drive shafts. The other drive shaft
 has a coaxially-mounted gear wheel that intermeshes with a pinion wheel
 that is rotatable and is interconnected with the driven power shaft such
 that when the pinion wheel is inhibited from rotating power is delivered
 from the driven power shaft through the locked pinion gear to the gear
 wheel and drive shaft affixed thereto.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT
 Throughout the drawings the same reference numerals are used to denote the
 same or like features of the invention.
 Referring first to FIG. 1, therein is illustrated the context of a
 continuous-motion cartoning machine M, suitable for incorporating therein
 a phase-adjustment mechanism in accordance with a preferred embodiment of
 the invention. In the machine, the carton hopper 10 receives collapsed
 cartons C stacked in substantially upright condition as shown. Cartons C
 are withdrawn from the carton hopper 10 by the adjustable carton feeder 20
 and then deposited in substantially erect condition at the beginning of
 the carton conveyor 30. As cartons are continuously engaged and translated
 through the machine M, articles, such as beverage cans, to be packaged in
 the cartons C are also translated through the machine in synchronous
 motion with the cartons. An article conveyor 40 and article lane
 arrangement 50 form an article transport that urges the articles into the
 cartons C. Article-engaging wheels 60 complete the process of placement of
 the articles into cartons C. Side-flap folding wheels 70 (partially
 obstructed in FIG. 1) engage and inwardly fold the side flaps of cartons
 having side flaps. Glue is applied to the cartons C at a gluing station
 80. At a sealing station 90, end flaps of the cartons C are pressed and
 held into contact with glue that has been previously applied. Packaged,
 sealed cartons are ejected from the machine at the ejection station 100.
 Referring now to FIG. 2, therein is shown in partial cut-away view, an
 isometric illustration of a phase-adjustment mechanism 800 in accordance
 with a preformed embodiment of the invention. A drive shaft 820 (for
 convenience of reference referred to as a "first" drive shaft 820) has
 structure 823 for engaging at least one endless chain. The structure 823
 in the preferred embodiment illustrated is a sprocket for an endless
 chain. Although each of the drive shafts 820,840 may drive more than one
 endless chain, in FIG. 2 structure 823, 842, 843 for engaging only one
 endless chain per respective drive shaft 820, 840 is shown for convenience
 of clarity. In FIG. 3, structure for driving two endless chains per drive
 shaft is shown.
 Referring now to FIG. 2 and FIG. 3 simultaneously, a second drive shaft 840
 is concentrically and rotatably disposed within the first drive shaft 820.
 Typical bushings or bearings 825 for concentrically mounted shafts are
 shown. The second drive shaft 840 has structure 842, 843 for engaging at
 least one endless chain. As previously noted, only on structure 842 in the
 form of a drive sprocket with radially extending teeth 843 is shown in
 FIG. 2 for convenience of clarity while structure 842 for engaging a pair
 of endless chains is shown in FIG. 3. A gear wheel 850 having gear teeth
 852 for engagement with a pinion (described below) is coaxially affixed to
 the second drive shaft 820.
 A driven power shaft 860 is concentrically and rotatably mounted within the
 second drive shaft 840. Typical bushings or bearings 845 are disposed
 between the driven power shaft 860 and the second drive shaft 840. A
 pinion gear 870 having pinion gear teeth 872 is rotatably intermeshed with
 the gear wheel 850 and gear teeth 852 of the second drive shaft. The shaft
 874 of the pinion gear 870 is supported by and rotatable within a
 connecting member 880 which is affixed to the driven power shaft 860. A
 lock for the pinion gear 870 is formed by a lock member 882 which is
 affixed to the pinion shaft 874 and which has an aperture 884 therethrough
 for receiving a pin (pin not shown). The pin is inserted through the
 aperture 884 of the lock member 882 and a second locking aperture 886
 (shown in FIG. 3 only) to inhibit rotation of the pinion gear 870. Other
 methods of inhibiting rotational motion of a structure are contemplated by
 the invention.
 Referring now also to FIG. 4, the first drive shaft 820 is interconnected
 to the driven power 860 shaft by means of a fastener 810 which passes
 through a radial slot 846 in the second drive shaft 840. The driven power
 shaft 860 is driven or powered by known driving or powering means such as
 a motor mechanically connected to the power shaft 860.
 In operation, the first drive shaft 820 is always turned as the power shaft
 860 turns because of the interconnection between the two by the connecting
 member 820. Although other means may be used to interconnect the power
 shaft 860 and first drive shaft 820, the use of the connecting member 810
 passing through the first drive shaft 820, then through the radial slot
 846 of the second drive shaft 840 and ultimately screwed into the power
 shaft 860 is simple. When the pinion gear 870 is prevented from rotating
 as described above, the pinion gear 870 and the gear wheel 850 do not
 rotate with respect to one another but instead serve as a mechanical link
 for transmission of power from the power shaft 860 through the pinion
 connecting member 880 through the pinion gear 870 to the gear wheel 850
 and ultimately to the second drive shaft 840. When the pinion gear 870 is
 so inhibited from rotation the first drive shaft 820 and second drive
 shaft 840 move together with the power shaft 860. In turn, the endless
 chains that are engaged by each drive shaft 820, 840 through the
 respective sprocket structures 823, 842, 843 travel in synchronous motion.
 The phase, or pitch, of lugs attached to the chains is constant.
 The phase/pitch is adjusted by unlocking the pinion gear 870 (by removal of
 the pin from the aperture 886) so that the pinion gear 870 rotates freely,
 particularly with respect to the gear wheel 850. When the pinion gear 870
 is allowed to rotate freely no power is transmitted to the second drive
 shaft 840 by the power shaft 860. As previously mentioned, the first drive
 shaft 820 always turns in conjunction with the power shaft 860 because of
 the interconnected previously described. Thus, the phase, or pitch, is
 adjusted by turning the power shaft 860 (which, in turn, turns the first
 drive shaft) clockwise or counter-clockwise a desired amount to achieve
 the desired spacing between lugs or other structures mounted upon the
 endless chains which are in turn engaged by the respective first 820 and
 second 840 drive shafts. Thus, asynchrounous movement of the two drive
 shafts 820, 840 is limited to the angle subtended by the radial slot 846.
 Modifications may be made in the foregoing without departing from the scope
 and spirit of the claimed invention.