U.S. patent number 3,709,485 [Application Number 05/146,329] was granted by the patent office on 1973-01-09 for control circuit for sorting system.
This patent grant is currently assigned to Xerox Corporation. Invention is credited to Thomas J. Acquaviva, Jr..
United States Patent |
3,709,485 |
Acquaviva, Jr. |
January 9, 1973 |
CONTROL CIRCUIT FOR SORTING SYSTEM
Abstract
A control circuit for a high speed copier sorting system having
a plurality of sheet conveyors each having an associated motor
drive for driving a predetermined one of the sheet conveyors for
transporting sheets along a predetermined path past trays into
which the sheets are distributed in accordance with a predetermined
control logic. A jam detection circuit times signals received and
is coupled to the motor drive to de-energize same in the event of a
jam condition. A first circuit for supplying signals to the jam
detection circuit indicative of the transit of sheets along the
conveyor path. A second circuit for supplying signals to the jam
detection circuit indicative of the transit of sheets leaving the
conveyor path and entering a predetermined tray. A third circuit
for counting reference signals representative of the number of
copies produced by a copier. A fourth circuit for counting signals
of the second circuit. A fifth circuit for comparing counts of the
third circuit and fourth circuit and supply a reset signal to the
fourth circuit during normal sorting. In addition, the fourth
circuit is coupled to the jam detection circuit to indicate a jam
in the absence of a reset signal.
Inventors: |
Acquaviva, Jr.; Thomas J.
(Penfield, NY) |
Assignee: |
Xerox Corporation (Stamford,
CT)
|
Family
ID: |
22516874 |
Appl.
No.: |
05/146,329 |
Filed: |
May 24, 1971 |
Current U.S.
Class: |
271/259; 271/297;
377/30; 270/58.2; 271/290; 377/8 |
Current CPC
Class: |
B41L
43/16 (20130101); B65H 39/115 (20130101) |
Current International
Class: |
B41L
43/00 (20060101); B41L 43/16 (20060101); B65H
39/115 (20060101); B65H 39/10 (20060101); B65h
007/00 () |
Field of
Search: |
;271/64,57 ;270/58,56
;340/259 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Knowles; Allen N.
Claims
What is claimed is:
1. A control circuit for a sorting system comprising:
motor means for driving a conveyor transporting sheets along a
predetermined path past trays into which the sheets are distributed
in accordance with a predetermined control logic,
a jam detection circuit for detecting sheet jam conditions,
including timing means,
first circuit means for supplying signals to said jam detection
circuit indicative of the transit of sheets along the conveyor path
and for setting said timing means,
second circuit means for supplying signals to said jam detection
circuit indicative of the transit of sheets leaving the conveyor
path and entering a predetermined tray and for resetting said
timing means,
said jam detection circuit being coupled to said motor drive means
and responsive to signals supplied from said first and second
circuit means for de-energizing said motor drive means in the event
of a jam condition,
third circuit means for counting reference signals representative
of the number of copies produced by a copy processor,
fourth circuit means for counting signals of said second circuit
means,
fifth circuit means for comparing counts of said third with said
fourth circuit means,
said fifth circuit means supplying a reset signal to said fourth
circuit means during normal sorting operation,
said fourth circuit means being coupled to said jam detection
circuit to indicate a jam condition in the absence of the reset
signal.
2. The control circuit of claim 1 wherein said second circuit means
sets other timing means of said jam detection circuit and then
resets said other timing means in the event of no jam.
3. The control circuit according to claim 1 wherein said motor
drive means includes at least two motors, at least a one of said
drive motors operating individually and consecutively with another
of said drive motors depending upon the length of the sorting
run.
4. The control circuit according to claim 3 wherein each of said
drive motors is associated with a sorting module.
5. The control circuit of claim 4 including sheet deflection means
associated with said modules for directing sheets to a
predetermined one of said modules for setting a memory device, said
memory device also receiving an input signal from said first
circuit means, said fifth circuit further supplying a signal to
reset said memory device.
6. The control circuit according to claim 4 wherein said jam
detection circuit includes lamp means to identify the module at
which a jam occurs.
7. The control circuit according to claim 1 including by-pass
switching means for by-passing said jam detection circuit.
Description
This invention relates to apparatus for sorting documents and more
particularly to a control circuit for a high speed modular
apparatus for sorting documents.
Sorters for copying machines are of several types. One type shifts
copy receiving trays relative to a fixed sheet feed path as
described, for example, in U. S. Pat. No. 3,356,362. Another type
feeds copy sheets to a plurality of modular assemblies in a serial
fashion as described, for example, in U. S. Pat. No. 3,484,101.
With the advent of high speed copier machines where sheet jams may
become more frequent, it is desirable to control the routing of the
copy sheet material and to facilitate the detection of sheet jams
both along the transport path and in the vicinity of the trays.
Heretofore, control circuits were such as to detect certain jam
conditions but not altogether satisfactory in ensuring detection
under various conditions.
It is therefore an object of the present invention to improve the
sorting of sheet material.
It is another object of the present invention to improve jam
detection of sheets supplied to high speed sorting apparatus.
It is a further object of the present invention to enable jam
detection of sheet material in the transport path as well as in the
vicinity of the trays.
It is a further object of the present invention to interrogate a
counting sheet system for jam detection.
These objects as well as others will become more apparent upon
considering the following description which is to be read in
conjunction with the accompanying drawings in which:
FIG. 1 is a perspective view of a copying machine incorporating a
sorting apparatus according to the present invention;
FIG. 1(a) is a view of the control panel of the sorting
apparatus;
FIG. 2 is an isometric view of the exterior of the sorting
apparatus;
FIG. 3 is a front sectional view of the sorting apparatus;
FIG. 3(a) is a front view of the sorting apparatus with cover open
illustrating certain details of the latch assembly.
FIG. 4 is an isometric view of the drive mechanism of the sorting
apparatus;
FIGS. 5 and 6 are end and front sectional views of the trays and
stacking control apparatus;
FIGS. 7(a) through 7(d) are front views illustrating sequential
operation of the stacking control apparatus;
FIG. 8 is a block diagram of the control circuitry for the sorting
apparatus;
FIG. 9 is a circuit diagram of the motor circuit of the control
circuitry; and
FIG. 10 is a circuit diagram of the jam detection circuitry.
GENERAL
For a general understanding of reproduction apparatus with which
the present invention may be incorporated, reference is made to
FIG. 1 wherein various components of a typical electrostatic
printer system are illustrated. It should be understood, however,
that any type of printer system could be used with the present
invention and not necessarily the printer system described herein.
The printer system is of the xerographic type and is generally
designated with the reference numeral 10. As in all xerographic
systems, a light image of an original to be reproduced is projected
onto the sensitized surface of a xerographic plate to form an
electrostatic latent image. Thereafter, the latent image is
developed with toner material to form a xerographic powder image
corresponding to the latent image on the plate surface. The powder
image is then electrostatically transferred to a record material
such as a sheet or web of paper or the like to which it may be
fused by a fusing device whereby the powder image is caused
permanently to adhere to the surface of the record material.
The xerographic processor indicated by the reference numeral 11 is
arranged as a self-contained unit having all of its processing
stations located in a unitary enclosure or cabinet. The printer
system includes an exposure station at which a light radiation
pattern of a document to be reproduced is positioned on a glass
platen 12 for projection onto a photoconductive surface in the form
of a xerographic belt 13.
Imaging light rays from the document as flash illuminated by lamps
18 are projected by a first mirror 20 and a projection lens 21 and
another mirror 23 onto the belt 13 at the focal plane for the lens
21 at a position indicated by the dotted line 25.
As an interface structure and for unobstructive optical
projections, the side of the cabinet is formed with an enlarged
rectangular opening to permit the projection of image light rays
from the lens 21 to the mirror 23. Similarly, the cabinet
supporting the document plane is formed with a corresponding
rectangular opening that mates with the opening in the printer
cabinet when the two cabinets are operatively joined together for
copy/duplicating purposes. Suitable light-type gaskets may be
utilized adjacent the exterior of each opening in the cabinets in
order to minimize the leakage of unwanted extraneous light. The
xerographic belt 13 is mounted for movement around three parallel
arranged rollers 27 suitably mounted in the frame of processor 11.
The belt may be continuously driven by a suitable motor (not shown)
and at an appropriate speed corresponding to the discharge
responsive the photoconductive material that comprises the belt and
the intensity of the imaging light rays from the document. The
exposure of the belt to the imaging light rays from the document
discharges the photoconductive layer in the area struck by light
whereby there remains on the belt an electrostatic latent image of
configuration corresponding to the light image projected from the
document. As the belt continues its movement, the electrostatic
latent image passes a developing station at which there is
positioned a developer apparatus 29 for developing the
electrostatic latent image. After development, the powdered image
is moved to an image transfer station whereat record material or
sheets of paper just previously separated from a stack of sheets 20
is held against the surface of the belt to receive the developed
powder image therefrom. The sheet is moved in synchronism with the
movement of the belt during transfer of the developed image. After
transfer, the sheet of paper is conveyed to a fusing station where
a fuser device 31 is positioned to receive the sheet of paper for
fusing the powder thereon. After fusing of the powder image, the
sheet is conveyed through an opening in the cabinet to a sorting
apparatus 32 for distributing into trays or bins in a manner as
will be described more fully hereinafter. The sheets are separated
from the stack and fed from the top of the stack by means of a
separator roll device 33 and timed sequence of the movement of the
developed images on the belt 13.
Further details of the processing devices and stations in the
printer system are not necessary to understand the principles of
the present invention. However, a detailed description of these
processing stations and components along with the other structures
of the machine printer are disclosed in copending application Ser.
Nos. 731,934, filed May 24, 1968, and 756,598, filed Aug. 30, 1968,
which are commonly assigned with the present invention.
It will be appreciated that the printer system may be operated in
conjunction with a roll converter unit indicated by the reference
numeral 35. The roll converter unit 35 is adapted to convert a
relatively large roll of paper 36 into various sizes of sheets of
paper by means of a cutter device 37 and a suitable control system
(not shown) arranged to control cutting and feeding of the
individual sheets into operative cooperation is assured between the
various units operating with the printer system by the physical
association of the cabinets for the units and the matching openings
which enable full cooperation of the imaging light rays and sheet
transport path between the units. In this regard, locking clamps
may be provided on all the units for preventing the inadvertent
movement of such units during use and interlocks which is an
alignment device may be utilized on each unit for ensuring upper
alignment and to terminate or suspend operation in the event
misalignment or separation of the units occur. For facility and
needs of operation, each of the units provided with caster wheels
and locking brakes thereby aiding in the movement of the units into
and out of cooperative engagement.
SORTING APPARATUS
Referring now to FIGS. 2-6, sorting apparatus 32 comprises a base
frame 51 which supports upper and lower sorting assemblies 53, 55,
respectively. Lower sorting assembly 55 includes a unitary
framework 57 defining a series of bins or trays 59 which receive
copy sheets in a downward direction. Similarly, upper sorting
assembly 53 has a unitary framework 57 which defines a series of
trays or bins 59 for receiving copy sheets.
Sheets enter the sorting apparatus through an opening 61 formed in
the frame of the lower sorting assembly 55. The sheets pass through
guides 63 to a pair of pinch rolls 65 and 67 which direct their
travel to a horizontal transport 69 which is made up of a plurality
of horizontal driving belts 71 which are above the sheet path and
free wheeling rollers 73 positioned below the sheet path. Above
rollers 73 are rollers 74 which are positioned within belts 71 and
are spring loaded downward to ensure proper traction between the
belts and sheets being transported. The sheets traveling on the
horizontal belts are deflected downward into an appropriate tray by
fingers or gates 76 actuated into the sheet path by an associated
solenoid in accordance with the control logic. The control logic is
triggered by the passage of a sheet from the horizontal transport
into a tray which causes the breaking of the light beam between a
light source 78 and a photo-transistor 80. The breaking and then
re-establishment of the light beam results in the open gate closing
and the next gate opening which continues until the last copy is
received in the appropriate sorting assembly.
The upper sorting assembly 53 includes a transport 115 made up of
horizontal belts 117 which moves above the sheet path and free
wheeling rollers 119 positioned below the sheet path. Above rollers
119 are rollers 121 which are positioned in belts 117 to ensure
proper traction as in the case of rollers 74. Fingers or gate
members 123 serve to deflect the copy sheets into the bins or trays
when actuated by the control logic which includes a light source
125 and phototransistor 127.
To transport the copy sheets into the upper sorting assembly, there
is provided a vertical transport 129 made up of vertical belts 131
which moves against rollers 133. The vertical transport 129
receives the sheets when solenoid actuated sheet deflector 135 is
positioned so as to direct the sheet upwardly in accordance with
control logic as will be described hereinafter.
Horizontal belts 71 are received and supported in a pivotable cover
137 connected to the frame by one or more hinges 139. Similarly,
horizontal belts 117 are received in and supported by a pivotable
cover 141 connected to the frame by one or more hinges 139. By this
arrangement, if a jam occurs within the transport path, the belts
71 and 117 may be raised clear from the transport path by pivotable
movement of the covers 137 and 141, respectively. Torsion springs
143 extend along the length of covers 137 and 141 and serve to
facilitate raising of the covers. In the event that a jam occurs in
the vertical transport 129, a hinged cover 145 is provided for easy
access to the transport path. It will now be appreciated that if a
jam occurs anywhere along the sheet path, the sheet may be cleared
expeditiously by opening of the covers 137, 141 or 145 to a
displaced position away from the sheet path sufficiently so that an
operator's hand may be inserted and the jammed sheet removed from
the sheet path. A latch assembly 147 including spring biased pins
149 serves to maintain each of the covers 137 and 141 in a raised
position to prevent inadvertent closing on the hand of an operator.
Handle 151 operates to retract the spring biased pins for closing
of the covers.
Sheets may be sorted by either the lower sorting assembly 55 or the
upper sorting assembly 53 or both together for long runs. The lower
sorting assembly includes a drive motor 153 which drives transport
belts 71 through a timing belt 155 (FIG. 4). Transport belts 71
drive gears 157, 159 which, in turn, drive pinch rolls 67 through a
timing belt 161 which is mounted on a pulley 163 driving shaft 165
carrying the pinch rolls 67. It will be appreciated that by virtue
of the flexibility of belt 161, that transport belts 71 which are
housed in cover 137 may be pivoted away from and into the sheet
path. A spring 169 connected to the frame and a link member 201
maintains proper belt tensioning during operating conditions. The
pinch rolls 67 desirably are driven at a speed or rate slightly
lower than the speed at which the belts 71 are moving so that the
paper is pulled smoothly along its transport path rather than being
pushed or jerked.
Upper sorting assembly 53 includes a drive motor 167 which drives
the transport belts 117 through a timing belt 209. Transport belts
117, in turn, drive transport belts 131 through a timing belt 211
mounted on pulleys 213 and 214 and a belt 203 which is mounted on
pulleys 215 and 216 which serve to drive shaft 217 drivingly
connected to the belts 131. It will be appreciated that belt 203 is
able to flex when belts 117 and cover 141 are raised above the
sheet path. A spring 205 connected to link 207 maintains proper
belt tension for accomplishing the desired drive operation. It will
be noted that a shaft 219 which is at the lower extent of the
transport belts 131 is drivingly connected to a pinch roll 67
through an O-ring 221 which is received on a pulley 223 mounted on
a shaft 225 which carries gear 227 which meshes with a gear 229
mounted on a shaft 165.
The driving mechanism described above enables the vertical
transport to be driven by motor 167, and pinch rolls 67 to be
driven through the upper or lower sorting assemblies by motors 153
and 167, respectively. To accomplish this operation, a pair of
overrunning clutches 231 and 233 are mounted on shaft 165. The
shaft 165 may then be driven through either the upper sorting
assembly drive motor or the lower sorting assembly drive motor. It
will now be appreciated that when clutch 231 is in driving relation
that clutch 233 overruns and vice versa. By virtue of this driving
arrangement, the pinch rolls 65 and 67 may be operated to provide
alternate sorting paths into the two sorting assemblies. Thus, in
the event that drive motor 153 becomes inoperative, the pinch rolls
are driven by drive motor 167 through clutch 233. Furthermore, by
virtue of the flexibility of belts 161 and 203, the transport belts
may be moved out of the sheet path to remove sheet jams
expeditiously.
STACKING CONTROL APPARATUS
Associated with each of the trays 59 is a stacking control
apparatus 250 which serves to ensure that the sheets when received
in a tray do not bounce to interrupt the light beam and assures
proper stacking alignment of the sheets. The stacking control
apparatus comprises a roller assembly 251 which includes an
X-shaped frame 253 with loop portions 255 engaging wire framework
57. Suspended from X-shaped frame 253 is a roller member 257. It
will be noted that the configuration of frame 253 is such that a
crimped or offset portion 259 is located in the vicinity of roller
member 257 to enable sheets to enter tangentially to the roller. By
this structure the sheet acceleration is controlled to prevent
bouncing of the sheets off the tray bottom back into the light
beam.
The sheets are aligned in the trays to form desirable stacks.
Associated with roller assembly 251 is a plurality of hanging wire
devices 265 which serve to retard the velocity of an incoming sheet
and further compress the top of the stack being formed in its tray.
It will be noted that pairs of hanging wire devices are suspended
from framework 57 symmetrically on each side of the sheet
centerline. It will be further noted that each of the hanging wire
devices has generally W-shaped portions 267 and loop portions 269
for free pivoting on the framework as they are impacted by incoming
sheets. By this structure, the top of a stack formed is compacted
to assure clearance in the sheet path for the next incoming sheet.
The hanging wire devices are easily mounted on the framework due to
the cooperation between W-shaped portions 267 and loop portions 269
with the framework. It has been found that the hanging wire devices
which are made of a conductive metal contribute to the dissipation
of static electricity normally imparted to the sheets being
transported along their path.
SORTING APPARATUS CONTROL CIRCUIT
A description of the control circuitry for the sorting apparatus
may best be understood in connection with the control panel of FIG.
1a, the block diagram of FIG. 8, the motor drive circuit of FIG. 9,
and the jam detection circuit of FIG. 10. The mode of operation for
the sorting apparatus is determined by pressing a one of switches
S1, S2, or S3 on the control panel which then set a mode selector
circuit 301 for upper sorting assembly 53, lower sorting assembly
55, or off condition, respectively. If S1 is closed an output from
mode selector circuitry 301 is supplied to a motor logic circuit
303 which, in turn, supplies a signal 305 to a motor drive circuit
307 for energizing motor 167. By closing switch S2, motor logic
circuit 303 supplies a signal 309 to motor drive circuit 307 which
operates to energize motor 153. FIG. 9 illustrates the motor drive
circuit in detail. It will be noted that motor 153 has a triac Q1
and a power source 311 connected across its terminals and that
motor 167 also has a triac Q2 and power source 311 connected across
its terminals. It will be appreciated that a signal 309 serves to
energize a relay K1 causing Q1 to conduct which then provides a
conductive path for power source 311 to cross motor 153. In similar
fashion, signal 305 serves to energize relay K2 which causes Q2 to
conduct thereby enabling power to be placed across the terminals of
motor 167. It will be further noted that motor logic circuit 303
provides a signal 313 to sheet deflector 135 at the entrance of the
sorting apparatus to assure a sheet path consistent with the motor
drive circuit.
The sheets are transported along their selected path and enter a
first tray of the selected sorting assembly. Phototransistors 80
and 127 detect each sheet being deflected into its tray by fingers
76 and 123, respectively, and signal counters 315 and 317,
respectively. Counters 315 and 317 supply an input to decoders 319
and 321, respectively. Decoders 319 and 321 serve to energize the
selected solenoid driver of solenoid driver circuits 323 and 325,
respectively, which, in turn, energize the proper solenoid of the
solenoid matrix 327 and 329, respectively.
At the same time, signals 330 from the processor which are taken
from the pulsing of flash lamps 18 or any other suitable processor
reference count are received by a counter 332 and signals 331
supplied to comparison circuits 333 and 335, respectively.
Comparison circuits 333 and 335 also receive signals from counters
315 and 317, respectively. If the counters of the processor and
sorting assemblies agree, then reset signals 337 and 339 are
supplied to counters 315 and 317, respectively.
A jam detection system of the control circuitry of the sorting
apparatus enables detecting different types of jams which may occur
while the sheet is on a belt transport or upon entering a
particular tray. A jam detection circuit 345 (FIG. 10) serves to
detect jams in the vicinity of the trays by timing the duration of
signals 349 and 351 supplied by phototransistors 80 and 127,
respectively. Jam detection circuit 345 supplies a signal 347 to
motor logic circuit 303 to de-energize whichever motor is in
operation at the time. If a jam occurs while the sheet is on the
transport belts, then a timing signal 353 supplied from a sensor
355 (FIG. 3) located at the entrance of the sorting apparatus is
received by the jam detection circuit 345 and compared with signals
349 and 351. In this manner, jams are detected both during the
transport of the sheets on the belts as well as in the vicinity of
the trays as they are deflected by the fingers associated
therewith.
As a special jam detection feature for the sorting apparatus,
counters 315 and 317 are interrogated by jam detection circuit 345
at the completion of the run to ascertain if all sheets were
actually received in the trays. By this arrangement if a last sheet
has not been received a count will remain and as a result a jam
signal 347 supplied to motor logic circuit 303 for de-energizing
the appropriate sorting assembly.
In operation, sheets entering the sorting apparatus pass sensor 355
generating signal 353. With the sorting apparatus energized by
depressing S1 or S2 and a sheet arrives at the apparatus a signal
400 is produced at the output of a gate 401 which is then inverted
by a gate 402. This signal causes a sharp pulse at the output of a
pulse forming network 403 which sets a flip-flop 408 to start a
timer 410. Timer 410 is preset for a predetermined time which is
slightly greater than the time it takes for the first sheet to
enter the furthest bin in the sorting apparatus.
If a sheet breaks the light beam in the lower sorting assembly 55
of the sorting apparatus, phototransistor 80 produces signal 349
which is converted into a pulse by a pulse forming network 404. The
output of network 404 produces a pulse to reset flip-flop 408 which
causes the timer 410 to stop timing. Likewise if a sheet is
directed to the upper sorting assembly 53, phototransistor 127
produces signal 351 which is converted into a pulse by a pulse
forming network 405. The output of network 405 produces a pulse
which resets flip-flop 408 which causes timer 410 to stop timing. A
gate 413 serves to direct initializing and reset pulses to the
flip-flop 408.
If a sheet jams on either transport of the sorting assemblies,
signals 349 and 351 do not occur, and timer 410 will time out
producing a pulse at gate 425. This generates a jam signal 347 at
the output of gate 426 which is supplied to the motor logic circuit
303 to stop the motors.
If a sheet jams in the vicinity of the trays, i.e., in the path of
light beams from light sources 78 and 125, signal 349 or signal 351
is continuously present. This leaves a signal on a gate 417 which
signals a gate 418 to start timer 422. Timer 422 is set for a
predetermined time which is greater than the time for a sheet to
pass the light beam. If the sheet jams, the timer 422 times out and
a jam signal is produced at a gate 425 which causes the motors to
stop.
A further method of jam detection is to interrogate the sheet
counters 315 and 317 at the completion of a run to ascertain if all
sheets were actually received in the trays. An interrogation
circuit 429 interrogates counters 315, 317. If a count remains in
counters 315, 317 there will be a signal at the output of a gate
429. When the processor completes a run, a signal 310 is supplied
to one input of gate 430. The output of gate 430 will signal gate
425 enabling a jam signal 347.
Another jam situation which may be detected is if the last sheet or
sheets jam in the upper transport while sorting continues in the
lower sorting assembly. This may happen, for example, if another
copy run commences prior to completing a previous copy run. When a
sheet enters the sorting apparatus, signal 400 is produced and is
inverted by gate 402 and supplied as an input to gate 432. If the
sheet deflector 135 is operated, signal 313 will appear at other
input gate 432 after being inverted by a gate 433. The output from
gate 432 is inverted by a gate 435 and sets a flip-flop 437.
Normally, at the completion of the run in the upper sorting
assembly 53, flip-flop 437 is reset by the delivered coincidence
signals 337 or 339. If signals 337 or 339 do not occur due to a jam
in the upper sorting assembly, and if the beam of the lower sorting
assembly is broken by the first sheet of the next run, signal 349
will be supplied as an input to a gate 439 which results in a jam
signal 347.
In order to enable location of a jam condition there are provided
jam indicator lamps L1 and L2. If there is a jam in the sorting
apparatus and the sheet deflector is not operated, or a count
remains in counter 315, then a signal 445 will appear at the input
of a lamp driver circuit 450 causing lamp L1 to be energized. Also,
when a jam, or a count remains in counter 317 or the beam of the
upper sorting assembly is broken, there is a signal to lamp driver
circuit 451 causing lamp L2 to be energized. It should be
understood that the jam detection circuit can be by-passed by
activating the jam by-pass switch S4 which energizes a relay
K3.
While the invention has been described and illustrated herein as
preferred form of the invention, it will be apparent to those
skilled in the art that changes and modifications may be made
thereto without departing from the spirit and intent of the
invention which is to be limited only to the scope of the appended
claims.
* * * * *