US2118696A - Changeable letter sign - Google Patents

Description

May 24, 1938. D BQNETT] 2,118,696

CHANGEABLE LETTER SIGN Filed Sept. 30, 1955 2. Sheets-Sheet 1 ATTORNEYS May 24, 1938. D, BONE-r11 2,118,696

' CHANGEABLE LETTER SIGN Filed Sept. 30, 1955 2 Sheets-Sheet 2 OQOOGQGGQ ATTORNEYS'.

Patented May 24, 1938 UNITED STATES PATENT GFFICE 4 Claims.

This invention relates to changeable letter signs, and relates more particularly to signs which are equipped with a plurality of members whereby to change the legend upon the sign to any desired grouping of letters.

It is an object of this invention to provide a sign having a plurality of members carrying a plurality of alphabetical arrangements of letters.

It is another object of this invention to provide a sign which is capable of being changed within denite limits to make up any combination of numbers or letters.

It is another object of this invention to provide a sign which can be changed from one legend to another rapidly and quickly.

It is another object of this invention to provide a sign which can be changed from one legend to another without the necessity for removing letters and replacing the same.

It is another object of this invention to provide a sign which can be changed from one legend to another by remote control.

Numerous other objects and advantages will more fully appear during the course and progress of the following specification.

Figure 1 is a perspective view of a preferred embodiment of the present invention showing the front face thereof.

"0 embodiment of the present invention shown in Figure l showing the rear side view.

Figure 3 is a cross-section View of the preferred embodiment shown in Figure 1 about line 3 3 of Figure 1.

Figure 4 is a perspective detail View of the roller member of the preferred embodiment shown in Figures l, 2, and 3.

Figure 5 is a cross-sectional view of a preferred 40 embodiment substantially similar Yto the preferred embodiment shown in Figures 1, 2, and 3, showing an interlocking feature.

Figure 6 is a cross-section view of a preferred embodiment of the present invention substantially similar to the preferred embodiment shown in Figures l, 2, and 3, but having a reverse winding arrangement for the letter carrying member.

Figure 'l is a plan View of another preferred embodiment of the present invention, this embodiment being equipped with remote control mechanism.

Figure 8 is` a cross-section View of the upper letter carrying track of the embodiment shown in Figure 7 about line 8-8 of Figure 7.

Figure 2 is a perspective view of the preferredv Figure 9 is a cross-sectional view of the preferred embodiment shown in Figure 7 about line 9-9 of Figure '7 showing the motor and chain drive assembly in detail.

Figure 10 is a cross-sectional view of the preferred embodiment shown in Figure l about line IIL-II) of Figure 7 showing in detail the roller drive mechanism.

Figure 11 is a cross-section View of the roller drive selector mechanism in return position.

Figure 12 is a perspective view of the separator clip which may be used between the rolls in any of the embodiments of the present invention.

One preferred embodiment of the present invention comprises a metal plate I shown in Figure 1. This metal plate is preferably provided with inwardly bent flanges 2, 3, 4, and 5 which extend b-ackwardly perpendicular to the plane of the face of the plate I so as to form a very shallow box-like member. 'Ihe plate may be provided with any Words or letters painted on the face thereof such as the Word PRICE' shown at 6, and the word EACH shown at 1. The plate is provided with a plurality of parallel slots 8, 9, I0, and Il, the slots 8 and 9 being parallel and lying ldirectly one above the other in spaced apart but coextensive relation to the other. Similarly the slots IIJ and II are parallel and lie directly one above the other in spaced apart coextensive relationship. 'I'he slots 8 and I0 also lie substantially in the same straight line. Similarly the slots 9 and II lie substantially in the same straight line.

Bracket members I2, I3, I4, and I5 are mounted on the back of the plate I, the brackets being provided with holes through which rods I6 and IT may pass. Obviously the holes in the brackets I2 and I3 are aligned so as to permit the rod I6 to pass therethrough parallel to the surface of the plate I and at the same time parallel to the plane of the flange 3. Similarly the holes in the bracket members I4 and I5 are aligned so as to permit the rod Il to pass therethrough and lie substantially in the same plane as the rod I6 and parallel thereto. The rods I6 and I'I are held in position by suitable terminal fastening means I8 and I9, and 20 and 2| respectively. On the rod I6 and between the brackets I2 and I3 are mounted a plurality of roller members 22, 23, and 24 respectively. Similarly on the rod II and between the brackets I4 and I5 are mounted a plurality of roller members 25, 26, and 21 respectively. The roller members on the rods I6 and I'I are capable of revolving freely there-around. The roller members 22, 23, 24, 25, 26, and 21 are substantially identical in structure. An enlarged Adetail view of these roller members is shown in Figure 4. The roller member comprises a central spindle member 28 and terminal guide members 29 and 3G respectively. Both of the terminal guide members 29 and 30 are circular discs rigidly mounted on the spindle 28 having a diameter substantially larger than the diameter of the spindle 28. One of these terminal guide members is preferably knurled at its outer periphery to provide a surface to which manual power may be applied in turning the roller member about the shaft I6.

A long continuous strip of flexible material 32, preferably Cellophane, is wound about the roll 22 and threaded down through the slot I and then through the slot Il, and finally around the roll 25. Any literal characters may be inscribed at spaced intervals along the surface of this roll. such as numbers or the letters of the alphabet. A similar strip 33 is wound about the roll 23 and threaded through the slots in similar fashion and ultimately wound about the roll 26. Similarly a strip 34 is placed in identical position upon the pair of rollers 24 and 21 respectively.

It has been found desirable to interpose washers 35 and 36 between the roller members 22 and 23, and 25 and 26 respectively. These washers may be made of fairly soft rubber or ungreased leather, or even rough metal and fashioned in any way designed to create a certain amount of friction so that when the roller members are Y turned there will be a small amount of resistance against turning such as that when the force inducing the turning is removed the roller member stops immediately and does not tend to coast past the desired stopping point. It has also been found that spring clip means such as the V-shaped clip shown in Figure l2 may also be inserted between the respective rollers to pro- Vide this friction.

It has been found preferable to have each of the Cellophane strips carry a duplicate set of literal characters. Thus if the sign is to be used as a price marker numbers from zero through nine would be printed on each strip. In order to set the sign the roll 24 is then turned by applying tangential force to the knurled guide member thereon so as to rotate it about the shaft I B and roll up the Cellophane strip onto the roller member 24 and off of the roller member 21, ultimately bringing the figure 2 into view. Thus the price of two dollars may be fixed upon the sign as illustrated in the preferred embodiment shown in Figure l. If the item upon which the sign is to be placed is to cost two dollars and forty-five cents for example, the second roll, i. e., roller member 23, is similarly rolled up bringing the figure 4 into View. Likewise the third roller member, i. e., 22, is rolled up to bring the figure into view. If the next item upon which the sign is to be used is to cost two dollars and forty-one cents for instance it would only be necessary to apply the rolling movement to the roller member 25, thereby rolling the Cellophane strip back up upon the roller member 25 until the figure l is brought down into View ofi` of the roller 22, whereupon the sign will read 2.41.

If it is desired to have a number of signs which fit together the flange member 3 may be made of extra width and bent back upon itself to form a member of U-shaped cross-section such as that shown at 3l in Figure 5. The opposite ange 5 is made alittle shorter than normal and is adapted to t into a similar U-shaped portion on an adjacent sign member 38.

It is also possible to avoid the use of knurled guide members if this be desirable. The Cellophane strips may be rolled up on the roller members in the reverse direction as shown in Figure 6, whereupon the manual pressure may be applied to the back of the Cellophane strip directly without fear of dirtying the face portion of the Cellophane strip.

Another preferred embodiment of the present invention is shown in Figure '7. This embodiment of the invention is capable of being controlled from a distance and is therefore particularly applicable for use on the front of moving picture theaters and in the face of the canopies which extend out in front of the movie theater over the street. At the present time in these movie canopies it is customary to have a series of channels into which are fitted glass plates carrying the letters. 'I'he words making up the legends on the sign are composed of a series of glass plates fitted into the channels and slid together. A trough behind the glass plates carries a plurality of light bulbs or some other light producing member so that light shines through the glass plates. It also makes the letters thereon clearly visible. It is necessary therefore in changing these signs to crawl out on a cat-walk or mount a ladder and remove the individual letters and replace them or rearrange them in the course of changing the legend on the sign. This is extremely bothersome, time consuming, and even dangerous. In addition to this the glass letters frequently crack and are constantly being replaced, all of which constitutes an extreme expense in the upkeep of the canopy or sign. In adapting the present invention to this use it has been found possible to provide a device capable of remote control whereby the necessity for climbing around in dangerous places and handling frangible materials is entirely obviated.

The embodiment shown in Figure '7 comprises a sign board 40 carrying a plurality of rows of letters 4| and 42. Each of the rows 4I and 42 may have any number of separate letters spaces. The embodiment shown happens to contain nine spaces for letters. The face of the sign board 40 is substantially similar to the embodiment shown and described in connection with Figure l and consists of a plurality of slots, a pair of parallel superposed coextensive slots being arranged for each letter space. A pair of roller members similar to the roller members shown in connection with the embodiment shown and described in Figure 1 are arranged adjacent to the slots and on the back of the sign board for each letter space. Thus as shown in the cross-section view of Figure 8 one letter space would consist of the face portion of the sign board 40 with a roller member 43 and a roller member 44 mounted on axle members 45 and 45 respectively. The axles 45 and 46 respectively are supported by suitable bracket members 4l and 48 respectively. The roller` member 43 is provided with a driving gear 50 at one extremity thereof. Similarly the roller member 44 is provided with a driving gear member 5| at one extremity thereof. Meshing with the roller drive gears 50 and 5l respectively are the power driven gear members 52 and 53 respectively, which are mounted on the drive shafts 54 and 55 respectively. Obviously therefore when it is desired to roll the Cellophane strip upon the roller member 44 this may be accompnsned oy applyilio ing motor power to the shaft 55 which in turn rotates the gear 53 which meshes with the gear and rolls the roller member 44 about the axle member 46. If it is desired to roll up the Cellophane strip on the roller member 43 the shaft 54, power driven in similar fashion causes rotation of the member 5|! and causes the Cellophane strip to be rolled up thereon and off of the roller member 44. It has been found that in signs the circumference of the roll of Cellophane on the roller members increases or de creases depending on whether the roll is being rolled on 'or off of that particular roller memu ber. It has been found necessary to drive the top and bottom roller member of each letter position individually so that when the strip is being rolled up on the upper roller member the driving mechanism in connection with the loWer member runs free and idle, and conversely when the strip is being rolled up upon the lower member the driving mechanism associated with the upper member will roll free and idle.V Similarly only one row of letters can be conveniently changed at a time. Therefore it is desirable that all the driving mechanisms for the Various rolling shafts be powered by one motor. This can be accomplished by mounting a motor 56 at a convenient point and connecting it to driving sprockets 51, 58, 59, 6U, and 6| through the flexible drive chain 69 as shown in Figure 9. Thus by reversing the direction in which the chain passes over the respective sprockets the direction of rotation of these sprockets can be or-dered in such a manner that the rotary motion transmitted to the roller members will be in the proper direction.

The sprocket 6| is merely an idle sprocket whereby the alignment of the sprocket members 51, 58, 59 and 60 may not be disturbed. Obviously as the motor revolves all of the sprockets are turned. Therefore it is necessary to provide clutch members 52, B3, 64, and B5 respectively for each of the drive shafts shown. These clutch members are solenoid operated so that by closing the circuit to a given solenoid a given clutch member may be engaged while all the other clutch members remain disengaged. Therefore only one selected driving shaft will be in motion thereby causing rotation of only one row of letters.

It is also necessary that each of the yseparate letter places be capable of separate operation. For instance, the particular embodiment shown in Figure '1 shows the letters TUE & WED in the upper row 4|. It might be desirable to change the rst word in this sign to T I-I E. This would necessitate moving only the roll or strip on which the letter U is mounted rolling it down upon the bottom roll thereof until the letter H is brought into view. To this end a selective mechanism must be provided. A preferred form of this letter selector mechanism is shown in cross section at Figure 10. This comprises a clutch member B2 which is operated by the solenoid 85 through the operating bar 81. This clutch may be of any conventional design. The idle side of the clutch 58 is connected to the inner driving shaft 10. An outer driving shaft 1| is slidably mounted over the inner driving shaft 1b so as to slide longitudinally along the inner drive shaft 19. A long key-way 12 in the inner shaft is adapted to engage a` key on the outer shaft 1! whereby to allow the shaft 1| 'to be rotated with the rotation of the shaft 10 and still be translatable longitudinally therealong. On the shaft 1| are mounted a plurality of power driven gears 13, 14, and respectively. These gears are adapted to engage the driving gear members 16, 11, and 18 which are rigidly mounted on the roller members of the device- The outer driving shaft 1| is considerably longer than the inner driving shaft 10 and is closed off at its further extremity 89, thereby providing a cylindrical space 8| inside its further extremity between the end 8i! of the shaft 1| and the end 82 of the shaft 18. A spring 83 is located in this space and normally urges the shaft 1| longitudinally along the shaft 1D so that the end '88 of the shaft 1| tends to move away from the end 82 of the shaft 18. The forward end 84 of the shaft 1| passes through a suitable bearing and support member 85 which is mounted on the selector member 85. The selector block 86 is provided with a chamber 81 into which the end 84 of the shaft 1I ts loosely. The selector block is also provided with a plurality of stop plates 90, 9|, 92 and 93 which pass across the chamber 81 in a plane perpendicular to the longitudinal axis of the shaft 1|. These stop members may operate in a vertical plane so as to be normally urged by gravity downwardly, thereby to rest on the bottom of the chamber 81 and extend upwardly there-across or they may be spring urged into such position. Each stop member is also provided with complementary solenoid members 94, 95, 96, and 91 respectively. 'Ihese solenoid members will retract the stop members respectively when the solenoids are appropriately en ergized so as to draw the given stop member upwardly out of the chamber 81. The driving gears 13, 14, and 15 which are mounted on the shaft 1| are spaced along the shaft a distance less than the distance between the roller driving gears 16, 11 and 18 respectively. That is to say, the distance between corresponding points on gears 13 and 14 is less than the distance between corresponding points on the gears 16 and 11 by an amount slightly greater than the thickness of the gear 11. Similarly the distance between the stop member 98 and the stop member 9| is equivalent to slightly greater than the thickness of the gear 11.

The stop plates 99, 9|, 92 and 93 are provided with holes |80, |91, |92, and |03 respectively. The selector carrying member 88 carries a solem noid |94 at one end. Through the solenoid passes a return setting rod H which is adapted to enter the chamber 81. The rod |65 has a diameter considerably smaller than the diameter of the chamber 81' and considerably smaller than the diameter of the driving shaft 1|. This rod is normally urged out of the chamber 81 by the spring member |05. The holes |90, IUI, |92, and |93 in the stop plates 98, 9|, 92, and 93 respectively, are large enough to allow the rod |05 to pass therethrough and come into Contact with the end 89 of the drive shaft 1| and yet not allow the end 80 of the drive shaft 1I to pass backwardly into the chamber when the given stop plate is in downwardly extending position. When the solenoid |84 is energized the return setting rod |05 will be forced through the chamber 81 passing through the holes |93, |82, and IGI successively in the respective stop plates and impinging upon the end 88 of the drive shaft 1| urging it backwardly out of the chamber 81 against the action of the spring 83. As the rod |05 reaches the extremity of its movement the end 89 of the drive shaft 1| will have passed outwardly beyond the limits of the stop plates, whereupon the stop plate 90 will drop downwardly behind the upper portion of the end 80 of the shaft 1| and against the top of the return setting rod |05, As the return setting action of the rod is completed the current to the solenoid |04 may be interrupted and the spring |85 will retract the return setting rod |65 out of the chamber 81'. This will permit the stop plate 5t' to drop completely down across the chamber 8l and rest against its bottom, completely stopping the shaft 1|. 'I'he completed travel of the return setting rod |85 is shown more specifically in Figure 11. This return setting action is suicient to translate the driving shaft 'll longitudinally along the inner drive shaft 10 a distance sufficient to move the gear 13 backwardly toward the clutch member 68 a distance sufficient to bring it out of operative contact with the gear 76. When it is desired to move the first roll of letters electrical connection to the solenoid 94 is completed whereby the stop plate 90 will be retracted out of the chamber 81. The spring 83 will then urge the driving shaft forward into the chamber 8T until it comes to rest against the stop plate 9|. This longitudinal movement of the shaft will bring the gear 'I3 transversely along the shaft 'l5 and into engagement with the gear '56. Meanwhile the gear T4 will be just short of engagement with the gear Tl.

The electric circuit to the solenoid 66 may then be closed bringing the clutch 68 into engagement and the circuit in the motor completed whereby the sprocket 6G will be set in rotation and the shaft turned. This will cause the gear T3 to turn, which in turn operates the gear 'I6 and imparts rolling action to the roller wherebythe Cellophane strip thereon is rolled up upon this roller. After the proper letter has been brought into view on this roller it may be desirable to roll up the letters on the second roller to A. To accomplish this the electrical circuit to the solenoid S5 is completed, whereupon the stop plate Sil is retracted out of the chamber 81. The spring 83 thereupon urges the shaft 1i forward into the chamber 87 until it comes to rest against the stop plate 92. This transverse movement of the shaft 1| will cause the gear 13 to be moved one space further forward and out of contact on the other side of the gear 1E. Meanwhile the gear T4 will be moved forward one position and brought into operative engagement with the gear T'i', whereupon the clutch circuit and motor circuit may be completed as before and the rotation of this roller accomplished. Similarly the third roller may be rotated by completing the electric circuit in the solenoid 9.5i whereupon the stop plate 92 will be retracted, allowing the shaft ll to travel forward until it comes to rest against the stop plate 9S. This will move both gears '|3 and 'I4 forward one more position, whereby the gear |3 will be two positions away from the gear 16, the gear 'i4 will be one position away from the gear and the gear 'l5 will be moved forward to its third position at which it is in operative engagement with the gear T8, whereupon the circuits to the clutch and motor may again be completed and the rotation of the third roller accomplished. It will be seen that in this fashion each roller may be selectively rotated.

In case only the first few letters of the legend need changing in a particular instance it is ol vious that the shaft l will not have moved the entire distance into the selector chamber. Therefore in resetting the mechanism the holes |362, iSl, |52, and 53 in the stop plates are provided so that the return setting rod |l5 may pass therethrough and impinge upon the end 80 of the shaft 'll forcing it into reset position without the necessity of having to permit it to traverse the entire distance along the selector chamber. In order to return the apparatus to its original position for subsequent changing of the letters the circuit to the solenoid |04 is closed and the return setting rod |05 brought into play, whereupon the shaft 'l'l' is pushed all the way back to its original starting position where it is held by the stop plate 96 which will have dropped into place as previously described. Obviously the rollers carrying the Cellophane strips must not rotate too freely otherwise there would be a tendency to coast past the desired point. In order to overcome this diiculty it has been found desirable to provide V-shaped clips such as those shown at |01 in Figure l2. These V- shaped clips may be inserted in between the rollers as shown in Figure l0, whereby to provide suicient friction to prevent any coasting.

Obviously it is desirable to move the Cellophane strips downwardly as well as upwardly er in other words cause the Cellophane strips to roll up on the bottom rolls as well as to roll up on the top rolls. To this end a rolling mechanism IME is provided. This rolling mechanism Hi8 is identical with the rolling mechanism described in connection with Figure 10. This mechanism may be provided with a selector similar to the selector described above or it may be possible to provide one selector for the entire rotation, top and bottom, the selector being connected to the top and bottom drive shafts respectively through a yoke member H as shown in Figure 11, provided with coupling means IIE. Thus in changing the legend on the sign shown in Figure '7 one would press a button raising the first stop plate in the selector, allowing the rst drive gear to contact with the rst roller member and then close either the clutch 62 or 63 depending upon whether it was desired to roll the strip upwardly or downwardly, and then close the circuit to the motor to impart the rotating action to the roll, stopping when the desired letter comes into view. The next successive letter will be set by closing the circuit which will raise the second stop plate in the selector mechanism allowing the gears on the second set of rollers to enmesh, repeating the previous action to impart rotary motion thereto. This process is continued successively down the individual letter places rolling upwardly or downwardly as the case may be until the proper letters come into view. Where a long rack of letters is employed the spring 83 in the shaft must be rather strong. In order to smooth out the action of such a spring it has been found that air cushioning may be used as shown in Figure l1. This comprises a small bore duct ||2 which opens into the chamber 8l. The duct ||2 is closed at its outer end by a set valve ||3. This valve may be adjusted to allow the air to pass therethrough at any desired rate. A collar lill is placed about the shaft 'El where it enters the chamber 87 and this collar is provided with a stufling ring whereby to make a fairly airtight seal. Thus the movement of the shaft 7| into the chamber 8l must force the air therein out through the duct ||2 and the valve ||3. By regulating the speed of air ow at the valve I3, the cushioning effect can be obtained.

Various multiplicaticns of the various electric circuits involved in the above embodiment may be applied thereto so that three corresponding rolls of letters on three different sides or faces of a theater canopy, for instance, could be changed at the same time by the action of one motor so that the signs on all sides of the canopy would read the same. Similarly two different canopies facing on different streets over different entrances to the theater could be so wired in parallel circuits that legends in comparable positions on both canopies could be changed by the same action. 1n addition to this a small representative canopy or miniature device could be constructed in the control room for the entire mechanism and wired in parallel so that the operator might observe what changes are taking place on the signs in front of the theater without being within vision thereof.

Modifications of this device could be provided so as to serve as score boards at baseball and football games. Still other modifications of the above invention could be made to provide signs in central depots announcing the departure of trains by remote control.

It should be noted that the Cellophane strips or similar material are transparent. The face of the frame member 4i) may be provided with a plurality of apertures or windows lll positioned behind the Cellophane strips in letterspace position, so that the light normally generated in the trough behind the signs on the movie canopy or similar structure will shine through and make the letters clearly visible. If Cellophane strips are to be used it is thought preferable to use neon tubes in the light trough rather than ordinary electric bulbs since the neon tube produces much less heat and therefore has less deteriorating effect upon the Cellophane strip. The Cellophane strips have been found to be proof against normal weathering action and capable of rendering long service under the conditions to which they are put.

It is also possible in constructing the hand operated changeable letter sign rst described above to substitute toothed wheels on the rollers in place of the knurled terminal members 29, and provide suitable gear means to mesh with these gear' toothed members so that the rotation of the rollers might be accomplished by the turning of a small crank. This crank might be detachable. Similarly in a modification of the present invention to be adapted to large signs such as those used in movie cano-pies it might be desirable to have a plurality of small worm members associated with the roller gear members 43 in place of the driving gear members 52. These worm members could extend through the front face of the sign and be operated by a crank or key which might be either permanently or detaohably mounted thereon. In such a case the operator of the sign could insert the key or crank and turn each set of letters into position.

It is thought that the invention and numerous of its attendant advantages will be understood from the foregoing description and it is obvious that numerous changes may be made in the form, construction and arrangement of the several parts without departing from the spirit or scope of my invention, or sacrificing any of its attendant advantages, the form herein described being a preferred embodiment for the purpose of illustrating my invention.

Having thus described my invention what I claim as new and desire to secure by Letters Patent is as follows:

1. A changeable sign comprising a face element, a plurality of roller elements associated with said face element, a plurality of movable elements having literal characters thereon associated with said roller elements, power driven means associated with the roller elements whereby to rotate said roller elements, said power driven means comprising a solenoid operated clutch, a primary shaft operably connected to the clutch, a secondary shaft slidably connected to the primary shaft, a plurality of gear means mounted at spaced intervals along the secondary shaft, and drive gear means on each roller adapted to engage one of the gears on the secondary shaft.

2. A changeable sign comprising a face element, a plurality of roller means associated with the face element, a plurality of movable elements associated with the roller means and moved thereby, drive means on each of the roller means, and power driven means for rotating each of the rollers selectively comprising a solenoid operated clutch, a primary shaft operably connected to the clutch, a secondary shaft slidably connected to the primary shaft, a plurality of power transmitting means mounted at spaced intervals along the secondary shaft, said power transmitting means being so located on the shaft as to engage predetermined driving means of the roller means,

and means associated with the secondary shaft to move the secondary shaft longitudinally along the primary shaft, and selectively slidable stop means associated with the secondary shaft to arrest its longitudinal movement at a predetermined point.

3. A changeable sign including a face element, a plurality of rows of spaced-apart, axially alined rollers associated with the face element, movable elements having literal characters thereon associated with said rollers, and V-shaped frictioncreating means disposed in each of the spaces between adjacent axially alined rollers with the arms of the V-shaped means resiliently engaging the sides of adjacent rollers whereby to restrict the freedom of rotation of the rollers.

4. A changeable sign comprising a face element, a plurality of roller elements associated with said face element, a plurality of movable elements having literal characters thereon associated with said roller elements, power driven means associated with the roller elements whereby to rotate said roller elements, said power driven means comprising a solenoid operated clutch, a primary shaft operably connected to the clutch, a secondary shaft slidably connected to the primary shaft, a plurality of gear means mounted at spaced intervals along the secondary shaft, and drive gear means on each roller adapted to engage one of the gears on the secondary shaft at only one selected position of the secondary shaft.

DANTE BONETTI.

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