US 3052465 A
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Description (OCR text may contain errors)
p 4, 1962 B. F. DAVID 3,052,465
SHEET SEPARATING APPARATUS Filed Nov. 3, 1960 2 Sheets-Sheet 1 INVENTOR BRUCE F. DAVID BY 5022s ATTOR EX Sept. 4, 1962 B. F. DAVID 3,052,455
SHEET SEPARATING APPARATUS Filed Nov. 3, 1960 2 Sheets-Sheet 2 Patented Sept. 4, 1962 3,052,465 SHEET SEPARATING APPARATUS Bruce F. David, Vestal, N.Y., assignor to International Business Machines Corporation, New York, N.Y., a corporation of New York Filed Nov. 3, 1960, Ser. No. 67,029 9 Claims. (Cl. 271-36) This invention relates to sheet separating apparatus and more particularly to improvements in apparatus for separating sheets of random varying thicknesses and delivering such sheets singly and in their original order.
It has hereto-fore been proposed to provide a sheet separating apparatu comprising a high friction separator wheel or belt which cooperates with a run of a lower friction restraint belt to define a throat into which sheets of varying thicknesses, such as bank checks, are advanced by picker means from a hopper. A suitably anchored helical spring pulls on the shaft of an idler pulley to maintain the restraint belt taut and bias the run of said belt into contact with the periphery of the separator wheel. However, as checks are fed into the throat, said run can give against the action of this spring bias automatically to expand the width of the throat as necessary to pass checks of differing random thicknesses. This automatic expansion of the throat is necessary because checks in current use vary in thickness from about .003 to .013".
While such apparatus works satisfactorily under normal operating conditions, there are some conditions under which jamming of checks in the throat and/or feeding of more than one check at a time by and past the separator wheel have occurred. This is intolerable in high speed reader-sorter machines for bank checks which are capable of processing over 1600 checks per minute, because one such jam every ten minutes or, in other words, every 16,- 000 checks would seriously reduce the throughput or output of the machine due to the down time necessary to clear the jam or misfeed. It has been found, for instance, -that when a number of checks have been creased transversely or a number of adjacent checks have checkprotection embossments, the picker means will advance a batch of such checks to the separator wheel as a superposed group, rather than in partially overlying shingleli-ke fashion. When this occurs, the group of superposed checks can and will wedge in the throat and exert a wedging force higher than normal on the restrain belt. Since a relatively small increase in such wedging [force creates a vastly multiplied increase in belt tension, it can be seen that even a slight increase in wedging force will create an increase in restraint belt tension sufiicient to overcome the bias effect of the restraint-belt-tensioning spring and thus undesirably widen the throat to an extent where a jam or multiple feed can occur. Since the bias force of said spring must be limited to a value which can be overcome during normal operation to permit checks of varying thicknesses to pass singly past the separator wheel, the above-described condition cannot be overcome merely by increasing the bias value of said spring.
Also, in apparatus wherein a spring is used to maintain the restraint belt taut or tensioned, the tensioning force is not constant as the belt stretches or wears during use because springs have a pick-up rate and their bias effects vary according to the degree they are extended or compressed. Hence, as the spring takes up slack in the restraint belt, the tensioning force exerted by the spring, and hence the force with which the run of the restraint belt pinches against the separator wheel, progressively reduces to the point where more than one check may pass through the throat.
The principal object of this invention is therefore to provide an improved apparatus for separating sheets of random varying thicknesses and lengths and embodying means for positively preventing the above-described undesirable over-expansion of an automatically expandable throat, thereby to assure that sheets will always be fed by and past the separator one at a time even under the batch-feed condition above described.
Another object is to provide, in a .separtor apparatus of the type embodying a separator wheel and a belt which cooperate to define and automatically expandable throat, novel means to maintain a constant tension on said belt despite wear-produced variations in the thickness of the restraint belt and separator wheel belt or stretching of the restraint belt during use.
According to these objects, there is provided an improved sheet separating apparatus comprising two separator elements, one preferably in the form of a wheel surrounded by a high-friction belt, and the other in the form of a driven restraint belt of lower friction providing a run on which the separator wheel belt impinges; and a mechanism for automatically maintaining a constant tension on the restraint belt and positively preventing said belt from giving more than a limited degree. This mechanism comprises, briefly, a weight carried at the outer end of an arm that is pinned to a suitably supported shaft. A sector cam is also pinned to said shaft and bears against a pin-like follower that is carried by a rockable arm and carries one of the idler rolls or pulleys for the restraint belt. As the restraint belt wears, the weight slowly descends and exerts a moment of force on the shaft to turn the latter and correspondingly rotate the cam one way. The cam is of such configuration that, as it is rotated, it exerts a force on the follower and hence on the idler roll which is constant over the entire working surface of the cam thereby to maintain a constant tension on the restraint belt. Also, the pressure angle is very low, to prevent the cam from rotating back against the action of the weight when an external force is applied to the restraint belt and hence prevent the throat between the wheel belt and restraint belt from widening more than the limited degree corresponding to the inherent give of the restraint belt. Thus, the mechanism acts automatically to tighten the restraint belt but prevents loosening of said belt, such as could otherwise occur if a batch of sheets were to wedge in the throat. Manually operable means is provided to rotate the cam the opposite way to permit untensioning of the restraint belt.
The foregoing and other objects, features and advantages of the invention will be apparent from the following more particular description of a preferred embodiment of the invention, as illustrated in the accompanying drawings.
In the drawings:
FIG. 1 is a side elevation view of a sheet separating apparatus embodying the invention;
3 FIG. 2 is an enlarged section view taken along the line 22 of FIG. 1;
FIG. 3 is a fragmentary section taken along the line 3-3 of FIG. 2, more clearly to show some of the structure shown dotted in FIG. 1.
Description As illustrated in FIG. 1, the sheet separating apparatus embodying the invention comprises a wheel 16, a restraint belt 11, and a mechanism designated generally 12 for automatically maintaining a constant tension on said belt irrespective of belt stretch or wear during use and preventing the belt from being forced more than a predetermined limited degree away from the wheel if a bunch of superposed sheets of varying thickness such as bank checks 13, are concurrently delivered by a picker means 14 to a throat 15 between said wheel and belt.
As illustrated, the separator wheel 10 comprises a hub encircled by a disc 21 that is perforated to reduce weight and inertia and has a thickened rim about which is non-slippably mounted a belt 22 of material, such as rubber, having a high coefficient of friction. Belt 22 preferably has uniformly spaced transversely extending reoesses 23 in its outer periphery, the non-recessed part of said periphery constituing the driving surface of said belt. As illustrated, belt 22 impinges on a run R of restraint belt 11 to provide arcuate (rather than merely linear) frictional contact of said belts with a check 13 while a check is interposed in the throat 15 between said belts. Belt 22 is adapted to be driven clockwise, as viewed in FIG. 1, at a predetermined peripheral speed by suitable drive means including a pulley driven or geardriven drive shaft 24 journaled in bearings (not shown) carried by a back plate 25.
Restraint belt '11 is composed of a material, such as rubber-impregnated fabric, having a coefiicient of friction which is somewhat less than of belt 22 but greater than the maximum coeflicient of friction between any of the checks 13. Belt 11 preferably has longitudinally extending serrations and runs around a driven pulley or roll 26 and idler pulleys or rolls 27, 28, 29, 30. As illustrated in FIG. 1, roll 26 is driven clockwise by suitable drive means including a shaft 31 that is journaled in bearings (not shown) carried by the back plate so as to drive belt 11 at a uniform speed which is a small fraction of the speed of separator wheel belt 22. Rolls 27, 29, are supported on studs 32, 33, 34, respectively, carried by back plate 25.
Referring now to FIGS. 1 to 3, mechanism 12 comprises a shaft 41 journaled in ball bearings 42, 43 press fit into a bearing support 44. This support has a flange that is abuttingly secured by screws 45 and an elongated stop stud 46 to a plate 47 that, in turn, has elongated slots for accommodating screws 48 whereby said plate is adjusbably secured to the front face of back plate 25. The unflanged part of support 44 is carried within a bore 49 through plate 45 and extends with radial clearance through an opening in, and through the rear face of, back plate 25.
A weight 50 laterally abuts and is bolted to the outer part of an arm 51 which at its opposite end is secured to a hub 52 that, in turn, is pinned to the rear part of shaft 41. Adjacent the flanged front end of support 44 is a sector cam 53 secured to a hub 54 which is pinned to shaft 41 so that as weight 50 descends, it will operatively rock said shaft clockwise, as viewed in FIG. 1, and thereby correspondingly rock said cam. As the cam 53 is thus rocked clockwise, its cam surface 55 will ride over a cylindrical pin like follower 56 and bias it downward against resistance of a helical bias spring 57 that is anchored to a projection on plate 47. To support the follower 56 and constrain it to move in a defined arcuate path, the follower is carried at one end of a follower arm 58 that is rockably supported at its opposite end on a pin 59 carried by plate 47. The arm 58 is mounted between a collar 69 and a spacer 61 on follower 56; and a ball bearing cage 62, that is press fit into a bore through idler roll 28, is mounted over the follower and clamped against said spacer by a stud 63. Thus, the idler roll 28 is supported on the follower 56 so that as the weight 50 moves down and rocks the cam 53 clockwise, the follower will be rocked down relative to pin 59 to maintain restraint belt 11 taut.
Manually operable means, designated generally 65, is provided to permit the cam 53 to be rocked counterclockwise, as viewed in FIG. 1, and thus untension the belt 11. Means 65 comprises a radial finger 66 secured about the rear end of a sleeve 67 that loosely encircles shaft 41. Sleeve 67 and thereby finger 66 can be rotated relative to shaft 41 by a handle 68 secured about the front end of said sleeve and preferably having a handle knob 69. The finger 66 can laterally engage stop stud 46 and/ or either of two circumferentially spaced shoulders 70, 71 provided at the front end of cam hub- 54.
The separating apparatus herein disclosed is especially adapted for use with the picker means, impositively driven separator wheel and take-away means disclosed in the copending application of David and Dimmenna, U.S. Serial No. 66,821 filed November 2, 1960, assigned to the assignee of the present invention. However, for sake of simplified illustration, the picker means 14 is illustrated as a roller 73- having an encircling belt 74 formed of material with a high coefficient of friction, such as rubber, and driven clockwise as viewed in FIG. 1, by suitable drive means including a drivensh-aft 75. The picker belt 74 is disposed above the top of a stack of checks 13 which are supported on a platform 76 of a hopper. Suitable means (not shown because well known in the prior art) is provided automatically to elevate the platform 76 as necessary to maintain the top check on the stack positioned so that successive top checks can be picked continuously by the picker belt 74 and fed between suitable guides 77, 7 8 into the throat 15 between the separator belts 22, 11. As the checks 13 are fed singly through the throat 15 and past the belts 22, 11 in the manner presently to be explained, they are guided by guides 89, 8 1 into a take-away means which, as illustrated, comprises a driven roll 82 and an idler roll 83 that start the separated check moving through the machine to which the separating apparatus is applied.
Operation Assume initially that the cam 53 and follower 56 are latched in the positions shown by broken lines in FIG. 1 and in which a recessed surface of the cam is held in contact with the stop pin 46 by the action of spring 57 which has rocked the follower upward against the leftmost part of cam surface 55. Under this condition, the restraint belt 11 is untensioned because the idler roll 28 carried by follower 56 has been moved upward to ward run R. Stop pin 46 limits the degree of counterclockwise movement of cam 53 to assure that the follower 56 cannot move up along the left radial edge 91 of the cam and thus prevent unlatching of the cam and follower in the manner now to be described.
To condition the separating apparatus for operation, the restraint belt 11 must first be tensioned. The operator moves handle 68 clockwise about shaft 41 to the abnormal position in which it is shown in FIG. 1 and in which finger 66 abuts stop pin 46. During this movement and before hitting stop pin 46, the finger 66 will abut and act through shoulder 71 to drive the cam assemblage 54, 53 clockwise about shaft 41 and thereby cause cam surface 55 to drive follower 56 down a limited extent. Further clockwise movement of handle 68 will be stopped when finger 66 hits pin 46. Thereupon, the weight 50 will descend and operatively rotate shaft 41 and thereby cam 53 clockwise a greater extent until the belt 11 is tensioned to a predetermined degree, whereupon the parts will be in the relative positions in which they are shown in FIG. 1. The particular point along cam surface 55 which contacts the follower 56 and the distance shoulder 71 is spaced from finger 66 at this time will of course depend upon the degree of stretch and/or wear of belt 11 and the adjusted position of plate 47 relative to drive shaft 31 and studs 32, 33, 34. The operator then releases handle 68 and permits gravity to rotate sleeve 67 relative to shaft 41 to a normal position in which the handle 68 and finger 66 are vertical.
It is to be noted that the profile of cam surface 55 is such that the belt 11 will be tensioned said predetermined degree irrespective of what point of said surface contacts the follower, said profile being cut so as to compensate for the changing moment of force exerted by weight 50 as it descends and for the changing position of follower 56.
Assume now that, with the belt '11 tensioned said predetermined degree, the operator supplies power to a motor (not shown) to drive the picker means 14, shaft 24 of separator wheel 10, drive shaft 31 for pulley 26, and take-away roll 82. As the checks 13 are fed by the picker means 14, they will generally accumulate in partially overlying shingle-like fashion at the entry end of the throat due to the continuous feeding action of the picker means. The high friction separator wheel belt 22 rotates to drive any check in direct contact therewith in a check-advancing or leftward direction, as viewed in FIG. 1; whereas the lower friction restraint belt 11 tends to drive any check in contact therewith in the opposite direction, thereby assisting in separating checks which accumulate at the throat 15 and assuring that checks will be fed one at a time to the take-away rolls 82, 83. Also, since belt 11 moves, it presents a changing surface for engagement by the checks (or by the rapidly moving belt 22 if no checks are in the throat) thereby distributing wear evenly over the entire outer surface of the long belt 11.
. The run R, which extends from roll 29 to roll 30, has a limited amount of inherent give or resiliency which is sufiicient to permit the throat 15 to widen far enough to'enable passage therethrough of a check of maximum thickness. However, mechanism 12 positively prevents the belt 11 from being forced more than this limited amount away from belt 22 and thus prevents throat 15 from being widened enough to permit multiple feeding of checks or cause a jam, as will now be explained.
Assume now that a batch of say ten to twenty-five checks 13 had been creased or folded transversely before being put on platform 76 or that a batch of adjoining checks which have check protection embossments are presented to the picker means 14. It has been found that, due to the interlocking of these checks and irrespective of the type or" picker means used, the picker means will usually feed these checks to the throat 15 as a batch in superposed fashion like a stacked deck of cards, rather than in the usual fan-like or partially overlying shingle-like fashion. When this occurs in previously proposed apparatus employing a bias spring to maintain the restraint belt 11 tensioned, the batch of checks exerts a consequent increased wedging force on run R suflicient to widen the throat 15 enough to cause multiple feeding of checks or jamming of checks in the throat. This results from the fact that any increase in the normal wedging force exerted by a check and tending to push run R of belt 11 away from contact with belt 22 will create a greatly multiplied increase in the tension force on the restraint belt 11, easily overcome the bias spring and permit the throat 15 to widen enough to cause the multiple feeding or jamming above described.
With the improved separating apparatus herein disclosed, however, run R of belt 11 cannot give more than the limited amount corresponding to its inherent resiliency, irrespective of the magnitude of any such wedging force which may be exerted by a batch of checks at the entry end of the throat, because the follower 56 on which idler roll 28 is mounted cannot move upward when the cam 53 is in the normal position in which it is shown in FIG. 1. Follower 56 cannot move upward because of the very low pressure angle such as a maximum of about 4, provided between the cam 53 and follower 56, which prevents the cam 53 from being rotated counterclockwise by the follower against the opposition of the moment of force exerted by weight 50 on shaft 41. Hence, since the batch of superposed checks cannot become wedged in the throat .15 because of the positively limited give of belt 11, they will accumulate at the entry end of the throat and be fed singly through throat 15 by separator wheel belt 22.
As the belts 11, 22 wear or belt 11 stretches during use and tend to create slack in the belt 11, the weight 50 will descend and thus correspondingly rock shaft 41 and hence cam 53 clockwise to move the follower 56 and thereby the idler roll 28 down in a belt-tensioning direction as necessary to constantly bias belt 11 with the aforementioned predetermined degree of tension against belt 22. As already noted, the profile of cam surface 55 is cut to take into account the changing eifective moment of force exerted by the weight 50 as it descends and the changing position of follower 56 and provide this predetermined degree of tension irrespective of where said surface contacts the follower 56 during the period the cam 53 is normally conditioned. Thus the belt 11 will the maintained under a constant predetermined degree of tension over a wide range of belt slack or wear due to the length of cam surface 55.
To untension belt 11, such as to replace the same, the operator rocks handle 63 counterclockwise, as viewed in FIG. 1, from its normal depending position to cause finger 66 to act through shoulder 70 to rock the cam assemblage 54, 53 and hence shaft 41 and weight 50 counterclockwise to a latched position. In this position cam surface abuts stop pin 46, and follower 56 is pulled up by spring 57 to a position where the point of junction of cam surfaces 55, 91 is slightly to the right, as viewed in FIG. 1, of a plane passing vertically through the centers of the follower and shaft 41 so that the cam 53 will be latched with a toggle-like over-center locking action. Stop pin 46 prevents the cam from being rocked counterclockwise far enough to run cam surface 55 off the follower 56, because if this were permitted the cam could not be restored to normal condition by handle 68 in the manner.
Normal variations in the length of a new belt 11 can be compensated for by adjusting the position at which plate 47 is secured by screws 48 to the back plate 25 so that when a new belt 11 is normally conditioned, the cam 53 will assume the position in which it is shown in FIG. 1, rather than a position in which a point nearer the middle of ca m surface 55 contacts follower 56.
It will thus be seen that in the improved sheet separating apparatus a constant tension of a predetermined amount corresponding to the selected magnitude of weight 50 is maintained on the restraint belt 11 automatically as the belts 11, 22 wear or belt 11 stretches during use. However, belt 11 cannot become loosened when subjected to an external force applied such as at the throat 15; and hence the throat, which is defined between belts 11, 22, cannot be widened more than the limited amount permitted by inherent resiliency of the belt 11. These two factors minimize the possibility of checks becoming jammed in the throat or fed other than one at a time past the separator belts 22, 11.
While the invention has been particularly shown and described with reference to a single preferred embodiment thereof, it will be understood by those skilled in the art that changes in form and details may be made therein without departing from the spirit and scope of the invention.
What is claimed is:
1. In an apparatus for separating and singly delivering sheets of varying random thicknesses, the combination of two elements providing respective contactable surfaces aoaaees defining a throat therebetween, means for normally feeding sheets in shingle-like overlapping fashion to the entry end of said throat, means for driving one of said surfaces in a sheet-advancing direction to cause the sheet in contact with said one surface to be advanced thereby and out the exit end of said throat, and mechanism operatively acting on the other element to maintain the other of said surfaces biased with a constant tension toward contact with said one surface and also positively prevent said surfaces from being wedged apart more than a limited extent corresponding substantially to the maximum thickness of any one of the sheets, whereby even if a bunch of superposed sheets accumulates at said entry end only one sheet at a time will be delivered through said throat by said one surface.
2. In an apparatus for separating and singly delivering sheets of varying random thicknesses, the combination of a separator wheel having a surface, a restraint belt having a run on which said surface impinges to define a throat of expandable width therebetween, means for normally feeding sheets in shingle-like overlapping fashion to said throat, means driving said surface in a sheet-advancing direction to cause the sheet in contact with said surface to be fed thereby through said throat, and mechanism for biasing the belt toward said surface with a constant force and positively limiting the extent said belt can be forced away from said surface if a bunch of superposed sheets should accumulate at the throat, thereby positively to prevent the throat from being opened enough by said bunch to permit delivery of more than one sheet at a time by and past the surface of said separator wheel.
3. In an apparatus for separating and singly delivering sheets of varying random thicknesses, the combination of a wheel having a rim formed of material having a high coefficient of friction and driven in a sheet-advancing direction, a belt formed of material having a lesser coefficient of friction and having a run on which said rim impinges to define a throat of expandable width therebetween, means normally feeding sheets in shingle-like overlapping fashion to the entry end of said throat, means including rotatable idlers and a rotating driver for driving said belt in a sheet-retarding direction to assist in separating the sheets as they enter the throat so that only the sheet contacting said rim will be fed thereby through said throat, and mechanism acting through one of said idlers to maintain a constant tension on said belt and positively limit the extent said throat can expand thereby positively to prevent the throat from being wedged open enough to pass more than one sheet even if a bunch of superposed sheets should accumulate at said entry end.
4. In an apparatus for separating and singly delivering sheets of varying random thickness, the combination of a wheel having a rim formed of material having a high coefiicient of friction and driven in a sheet-advancing direction, a belt formed of material having a lesser coefiicient of friction and having a run on which said rim impinges to define a throat of expandable width therebetween, means normally feeding sheets in shingle-like overlapping fashion to the entry end of said throat, a plurality of belt-supporting members one of which is movable to tension and untension said belt, a follower carrying said one member, a rotatable cam for engaging said follower, and a weight operatively secured to said cam eccentrically of its axis of rotation, said weight acting to progressively rotate the cam one way as said belt wears or stretches as necessary to bias said belt with a constant tension via said follower and one member against said rim, said cam having a pressure angle low enough to prevent rotation of the cam the opposite way and untension said belt if a bunch of sheets should attempt to wedge open the throat more than the limited extent corresponding to the inherent resiliency of said belt, thereby to assure that sheets will be fed singly through the throat by said rim.
5. The combination according to claim 4, including means manually operable to rotate said cam said opposite I cient of friction and driven in a sheet-advancing direction,
a belt formed of material having a lesser coefficient of friction and having a run on which said rim impinges to define a throat of expandable width therebetween, means normally feeding sheets in shingle-like overlapping fashion to the entry end of said throat, means including rotatable idlers and a rotating driver for driving said belt in a sheetretarding direction to assist in separating the sheets so that the sheet contacting said rim will be advanced through said throat, follower means including a support on which one of said idlers is rotatably mounted, means permitting said follower means to oscillate relative to a fixed pivot, a shaft, a cam carried by said shaft for engaging said follower means, a weight secured to and carried eccentrically by said shaft, said weight being adapted to descend and rotate said shaft progressively as the belt wears or stretches during use thereby operatively to rotate said cam one way a corresponding degree for applying a tensioning force to said one idler via said follower means, said cam being configured to maintain said tensioning force constant as said weight descends and provide a pressure angle low enough to positively prevent rotation of said cam the opposite way to prevent loosening of said belt, thereby positively to limit the give of said belt to prevent the throat from being wedged open enough to pass more than one sheet at a time.
7. The combination according to claim 6, including means having a lost motion connection with said cam and manually operable to rotate said cam said opposite way to effect loosening of the belt.
8. In an apparatus for separating and singly delivering sheets of varying random thicknesses, the combination of a wheel having a rim formed of material having a high coefiicient of friction and driven in a sheet-advancing direction, a belt formed of material having a lesser coefficient of friction and having a run on which said rim impinges to define a throat of expandable width therebetween, means normally feeding sheets in shingle-like overlapping fashion to the entry end of said throat, means including rotatable idlers and a rotating driver for driving said belt in a sheet retarding direction to assist in separating the sheets as they enter the throat so that only the sheet contacting said rim will be delivered thereby through said throat, and mechanism acting through one of said idlers to apply a constant tension to said belt despite stretch or wear during use and also positively limit the extent said throat can expand thereby positively to prevent the throat from being wedged open far enough to pass more than one sheet event if a bunch of superposed sheets should accumulate at said entry end, said mechanism comprising a cam follower operatively connected to said one idler, a cam acting on the follower to apply a tensioning force via said one idler to said belt, and means including a weight for progressively rotating the cam as belt slack and wear increase, said cam being configured to maintain said tensioning force constant through all rotative positions of said cam and provide a pressure angle low enough to lock said one idler against movement in a belt-loosening direction when external forces are applied to said belt.
9. The combination, with a belt driven by a rotating driver around rotatable idlers, of follower means including a pin on which one of said idlers is rotatably mounted, means carrying said follower means and constraining the latter to move in a defined path, a shaft rotatable within a fixed support, a cam carried by said shaft for engaging said follower means, a weight carried eccentrically by said shaft, said weight being adapted to descend and rock said shaft progressively as the belt wears or stretches during use thereby operatively to rotate said cam one way a corresponding degree for applying a tensioning force to said one idler via said follower means, said cam being configured to maintain said tensioning force constant as said weight descends and provide a pressure angle low enough to positively prevent rotation of said cam the opposite way by external forces applied to said belt and thereby prevent loosening of said belt.
References Cited in the file of this patent UNITED STATES PATENTS Raky Dec. 5, 1893 Borton Nov. 26, 1901 Harber et a1 Apr. 14, 1931 Sturgess Apr. 21, 1942 Johnson Jan. 12, 1954 La Bombard Apr. 5, 1955 Herrick et al May 10, 1960