System for controlling warp let-off motion of weaving machine during machine downtime

A weaving machine has a first drive means which has a speed change transmission and drives a warp beam during normal weaving operation, and a second drive means for driving the warp beam independently of the first drive means when the weaving machine is moved by inching or by hand during downtime operation. A first sensor senses the weaving cycle of the weaving machine, and a second sensor senses the warp beam rotation. A warp beam rotation control system determines the angular displacement of the warp beam per weaving cycle during normal weaving operation, and controls the warp beam rotation during downtime operation in accordance with the determined angular displacement per weaving cycle.

BACKGROUND OF THE INVENTION 
The present invention relates to a system for controlling a warp let-off 
motion of a loom during downtimes, that is, a system for controlling the 
rotational movement of a warp beam when the loom is not in a normal 
weaving operation but moved by inching or by hand in a forward or reverse 
direction. 
Let-off motions of looms, especially of a fluid jet type which is operated 
at high speeds, are usually provided with stepless speed change devices to 
guarantee a uniform warp tension from full to empty warp beam. One example 
of such stepless speed change devices is disclosed in Japanese patent 
examined publication No. 45-37180. 
In this stepless speed change device, rotational movement of an input shaft 
is converted to movement of link means, and then the movement of the link 
means is converted again to rotational movement of an output shaft by the 
aid of a one-way clutch disposed between the link means and the output 
shaft. Therefore, the output shaft is rotated only in one direction 
whether the input shaft is rotated in forward direction or reverse 
direction. 
If a malfunction such as a mispick is found during weaving operation, a 
loom in trouble is stopped for mending. However, a mispick is usually 
detected at a beating step following a weft inserting step especially in 
high speed jet looms, and there is a delay in subsequent response due to a 
time lag of a control circuit and/or delay in braking action. For these 
reasons, it is usual that a loom actually stops at the next weft-inserting 
step. Therefore, in order to remove a wrongly-inserted weft, it is 
necessary to rotate the loom in the reverse direction. In this case, the 
reverse rotation of the loom causes a reverae rotation of a woven fabric 
take-up motion because the take-up motion is connected with a driving 
shaft of the loom by a gear train. At the same time the reverse rotation 
of the loom causes a warp let-off motion to rotate in a forward direction 
because the let-off motion has a stepless speed change device of the above 
mentioned type. By these movements of the take-up motion and the let-off 
motion, the cloth fell is moved out of position, so that it is necessary 
to set the cloth fell in position again to restart the loom. Such a 
setting operation is necessary for preventing an undesired mark which is 
formed in the fabric at the position of the cloth fell when the weaving 
operation is restarted. However, this setting operation requires skill, 
and accordingly there is a strong demand for an automatic mechanism for 
doing such a setting operation automatically. 
To meet this problem, Japanese patent provisional publication No. 56-68140 
discloses a warp let-off mechanism which is provided with means for 
reversing the direction of output shaft rotation of a stepless speed 
change device in accordance with the direction of the loom rotation. 
However, this mechanism utilizes a worm gear, so that it requires a force 
increased by one and a half times to obtain the reverse rotation. 
Accordingly the construction of the stepless speed change device must be 
made strong enough to endure such an increased force, with the result of 
an increase of the manufacturing cost. 
SUMMARY OF THE INVENTION 
It is an object of the present invention to provide a weaving system which 
can control the relation between the weaving machine movement and the warp 
beam rotational movement when the weaving machine is moved by inching or 
by hand during downtime. 
It is an object of the present invention to provide a weaving system which 
can automatically set the cloth fell at a correct position to restart the 
weaving operation in the case the weaving machine is moved in the reverse 
direction by inching or by hand during downtime. 
According to the present invention, a weaving system comprises a warp beam 
and a main mechanism which is combined with the warp beam, and moves 
periodically so as to repeat a weaving cycle. "Main weaving mechanism" as 
used herein and in the appended claims is intended to mean the balance of 
a weaving apparatus apart from the warp beam proper and its attendant 
driving and control mechanisms. Thus, the main weaving mechanism normally 
comprises a shedding mechanism, a picking mechanism, and a beat-up 
mechanism. The main mechanism has a normal weaving operation mode and a 
slow operation mode. The weaving system further comprises a driving shaft 
which is driven in synchronism with the periodical movement of the main 
mechanism, and first and second drive means. The first drive means drives 
the warp beam in the normal operation mode by transmitting power from the 
driving shaft to the warp beam. The first drive means includes speed 
change means capable of changing the speed of the warp beam rotation. The 
first drive means further includes first clutch means for connecting and 
disconnecting the driving connection between the driving shaft and the 
warp beam through the first drive means. The second drive means drives the 
warp beam in the slow operation mode by transmitting power from the 
driving shaft to the warp beam independently of the first drive means. The 
second drive means includes second clutch means for connecting and 
disconnecting the driving connection between the driving shaft and the 
warp beam through the second drive means. The weaving system further 
comprises first sensing means, second sensing means, and control means. 
The first sensing means senses the periodical movement of the main 
mechanism, and the second sensing means senses the rotational movement of 
the warp beam. The control means is connected with the first and second 
sensing means. The control means determines, during the normal operation 
mode, a quantity indicative of an angular displacement of the warp beam 
per weaving cycle in accordance with signals produced by the first and 
second sensing means. The control means stores the determined value of the 
quantity, and controls the warp beam rotation during the slow operation 
mode by controlling the second clutch means in such a manner that the warp 
beam rotates only through an angle equal to the stored value when the main 
mechanism is moved through one weaving cycle during the slow operation 
mode.

DETAILED DESCRIPTION OF THE INVENTION 
One embodiment of the present invention is shown in FIGS. 1 to 5. An input 
shaft 1 rotates in synchronism with a reed of the loom. That is, the input 
shaft 1 rotates by one revolution each time the reed completes one beating 
step. A V-belt pulley 2 is fixedly mounted on one end of the input shaft 
1. A chain sprocket wheel 3 is fixedly mounted on an intermediate portion 
of the input shaft 1. An arm 5 having an iron piece 4 is fixed to the 
intermediate portion of the input shaft 1. A proximity switch 21 is 
disposed so as to face the iron piece 4 when the arm 5 is in a 
predetermined angular position. The arm 5, the iron piece 4 and the 
proximity switch 21 constitute a reference rotation detecting means 20. A 
stepless speed change transmission 6 has an input shaft 7 driven by the 
input shaft 1. A V-belt pulley 8 is fixedly mounted on the input shaft 7 
of the stepless speed change transmission 6. The V-belt pulleys 2 and 8 
are drivingly connected together by a V-belt 9. An output shaft 10 of the 
stepless speed change transmission 6 is connected to a first 
electromagnetic clutch 12 through gears 11. The first electromagnetic 
clutch 12 is connected to one end of an output shaft 15. A bevel gear 15a 
of a bevel gearing 13 is fixedly mounted on the other end of the output 
shaft 15. The output shaft 15 has a chain sprocket wheel 17 and a rotary 
disc 18a which are fixed thereto between both ends. The rotary disc 18a is 
a component member of an encoder 18 which is a means 19 for detecting warp 
beam rotation. The rotary disc 18a is formed with a plurality of slits 
arranged circumferentially along the periphery. The number of the slits of 
the rotary disc 18a amounts to 2000, for example. A detector 18b of the 
encoder 18 detects the slits of the rotary disc 18a one by one. The bevel 
gearing 13 is in direct contact with a worm gearing 14 to transmit driving 
torque. The worm gearing 14 has a worm 14a. The worm gearing 14 drives a 
shaft 31 of a warp beam 30 through gears 29. There is further provided a 
secondary shaft 25, which is in parallel with the input shaft 1 and the 
output shaft 15. One end of the secondary shaft 25 has a chain sprocket 
wheel 26 fixed thereto, and the other end of the secondary shaft 25 has a 
chain sprocket wheel 27 fixed thereto. The secondary shaft 25 has a second 
electromagnetic clutch 28 disposed between the chain sprocket wheels 26 
and 27. The chain sprocket wheel 26 is drivingly connected with the chain 
sprocket 3 by an endless chain 32. The chain sprocket wheel 27 is 
drivingly connected with the chain sprocket wheel 17 by a chain 33. 
During the normal weaving operation, the rotational movement of the input 
shaft 1 is transmitted to the warp beam 30 to rotate warp beam 30 in the 
same direction by way of the V-belt 9, the stepless speed change 
transmission 6, the gears 11, the first electromagnetic clutch 12, the 
output shaft 15, the bevel gearing 13, the worm gearing 14, the gears 29. 
During this, the stepless speed change transmission 6 changes the 
rotational speed of the input shaft 1 to such a speed as to provide an 
optimum warp letting off rate. In addition to this line for transmitting 
driving torque from the input shaft 1 to the warp beam, there is provided 
a secondary line through which driving torque can be transmitted from the 
input shaft 1 to the warp beam 30 without passing through the stepless 
speed change transmission 6. In this secondary line, driving torque is 
transmitted by way of the chain 32, the secondary shaft 25, the second 
electromagnetic clutch 28, the chain 33, and the output shaft 15. This 
secondary line is used when the weaving machine is stopped. 
A control circuit is shown in FIG. 2. The proximity switch 21 is connected 
to a first divider circuit 40 so that the first divider circuit 40 
receives an output signal of the proximity switch 21. The detector 18b of 
the encoder 18 is connected to a second divider circuit 50 so that the 
second divider circuit 50 receives an output signal of the detector 18b. 
The first divider circuit 40 is connected to a switching circuit 43 
through a rotary switch 41 and a movable contact 42a of a second relay 42. 
An output signal of the first divider circuit 40 is inputted to the 
switching circuit 43 through the rotary switch 41 and the movable contact 
42a. The second divider circuit 50 is connected to a counting circuit 52 
through a rotary switch 51 and a movable contact 42a of the second relay 
42. Thus, an output signal of the second divider circuit 50 is inputted to 
the counting circuit 52 through the rotary switch 51 and the contact 42a. 
The counting circuit 52 is connected to a storage circuit 53 and a 
comparator circuit 54 so that an output signal of the counting circuit 52 
is sent to the storage circuit 53 and the comparator circuit 54. The 
storage circuit 53 is connected to the comparator circuit 54 so that the 
comparator circuit 54 further receives an output signal of the storage 
circuit 53. An output signal of the comparator circuit 54 is inputted to a 
reset terminal R of a flip-flop circuit 55. The switching circuit 43 is 
connected to a set terminal S of the flip-flop circuit 55. The switching 
circuit 43 is further connected to the counting circuit 52, the storage 
circuit 53, and the comparator circuit 54, individually. Each of these 
circuits 52, 53, 54 and 55 receives a signal from the switching circuit 
43. An output terminal Q of the flip-flop circuit 55 is connected to a 
driver circuit 56 so that an output signal of the flip-flop circuit 55 is 
supplied to the driver circuit 56. 
The driver circuit 56 is connected to first and second contacts 59a and 59b 
of a first relay (not shown). The second relay 42 is connected in parallel 
with a first actuating circuit 57 for actuating the first electromagnetic 
clutch 12. The driver circuit 56 is connected in series with a second 
actuating circuit 58 for actuating the second electromagnetic clutch 28, 
through the second contact 59b. The parallel combination of the relay 42 
and the first actuating circuit 57 is connected to a junction point 61 
through the first contact 59a, and to a junction point 62 so that this 
parallel combination is interposed between the junction points 61 and 62. 
The series combination of the driver circuit 56 and the second actuating 
circuit 58 is interposed between the same pair of the junction points 61 
and 62, so that the parallel combination 42 and 57 and the series 
combination 56 and 58 are in parallel. One terminal of a power source 60 
is connected to the junction point 61, and the other terminal is connected 
to the junction point 62. 
When a main switch (not shown) of the weaving machine is turned on to start 
the manual weaving operation, the first relay (not shown) closes the first 
contact 59a and opens the second contact 59b. Accordingly, the second 
relay 42 becomes operative and connects the contacts 42a with the 
terminals 41a and 51a of the rotary switches 41 and 51, respectively, as 
shown in FIG. 2 which shows the state of the normal weaving operation. 
The proximity switch 21 produces a P.S. (proximity switch) signal 
indicative of the weaving cycle of the loom. That is, the proximity switch 
21 produces a pulse each time the loom repeats one weaving cycle. The 
first divider circuit 40 divides the pulse repetition frequency of the 
P.S. signal of the proximity switch 21 by a predetermined number. In this 
embodiment, the predetermined number is five. That is, the first divider 
circuit 40 allows one pulse to pass therethrough each time the first 
divider circuit 40 receives five pulses. The first divider circuit 40 is 
helpful for improving the accuracy of the control. However, it is not 
necessary to use the first divider circuit 40. The pulses allowed to pass 
through the first divider circuit 40 are supplied to the switching circuit 
43 through the rotary switch 41 and the contact 42a of the second relay 
42. The switching circuit 43 sends signals to the counting circuit 52, the 
storage circuit 53, the comparator circuit 54 and the flip-flop circuit 55 
each time the switching circuit 43 receives one pulse from the first 
divider circuit 40. 
While the loom is running, the detector 18b of the encoder 18 produces an 
A.S. (angular sensor) signal consisting of pulses indicative of the 
angular displacement of the output shaft 15. The second divider circuit 50 
divides the pulse repetition frequency of the pulse train sent from the 
detector 18b by a predetermined number. In this embodiment, the 
predetermined number is five. That is, the second divider circuit 50 
allows one pulse to pass therethrough each time it receives five pulses. 
The pulses sent from the second divider circuit 50 are supplied to the 
counting circuit 52 through the rotary switch 51 and the contact 42a of 
the second relay 42. The counting circuit 52 counts the number of the 
pulses received during the interval between two consecutive pulses of the 
P.S signal. That is, the counting circuit 52 is reset to zero to start the 
counting again, by the switching circuit 43 each time the switching 
circuit 43 receives one pulse from the first divider circuit 40. The 
storage circuit 53 stores the count of the counting circuit 52. Upon each 
receipt of a pulse from the first divider circuit 40, the switching 
circuit 43 sends signals to the counting circuit and the storage circuit 
53, commands the counting circuit 52 to transfer the count to the storage 
circuit 53 before resetting the counting circuit 52, and commands the 
storage circuit 53 to store the newly-transferred count in place of the 
old count already stored. Accordingly, the storage circuit 53 always 
stores the newest information of the count. During this normal weaving 
operation, the first electromagnetic clutch 12 is engaged, and the second 
electromagnetic clutch 28 is disengaged, so that the warp let-off 
mechanism drives the warp beam through the stepless speed change 
transmission 6 in the normal manner. 
When the main switch of the loom is turned off, and the loom is stopped, 
the first relay (not shown) is deenergized, so that the first contact 59a 
is opened, and the second contact 59b is closed, as shown in FIG. 3. 
Because the first contact 59a is opened, the first actuating circuit 57 is 
deenergized, and the first electromagnetic clutch 12 is disengaged. At the 
same time, the second relay 42 is deenergized, so that the contacts 42a of 
the second relay 42 are disconnected from the terminals 41a and 51a, and 
instead connected with the "one" terminal of the first and second divider 
circuits 40 and 50, respectively. Although the second contact 59b is 
closed in this state, the second actuating circuit 58 is not energized, 
and the second electromagnetic clutch 28 is not engaged until the driver 
circuit 56 makes the connection between the second actuating circuit 58 
and the power source 60. The driver circuit 56 does not make the 
connection between the second actuating circuit 58 and the power source 60 
until a pulse is supplied from the first divider circuit 50 to the 
switching circuit 43. The storage circuit 53 stores the count counted by 
the counting circuit 52 just before the loom is stopped, and maintains the 
then-stored count unchanged. 
If the loom is moved in the forward direction or in the reverse direction, 
by inching or by hand, the proximity switch 21 and the detector 18b of the 
encoder 18 supply pulses to the first and second divider circuits 40 and 
50, respectively. The thus-supplied pulses can pass through the "one" 
terminals which allow free passage of pulses. Thus, the first and second 
divider circuits 40 and 50 do not perform their dividing functions. 
Accordingly, the counting circuit 52 counts the number of pulses produced 
by the encoder 18 during an interval required for one revolution of the 
input shaft 1. The thus-obtained count bypasses the storage circuit 53, 
and is sent to the comparator circuit 54. The storage circuit 53 is not 
set, so that it maintains the count counted just before the loom is 
stopped. The comparator circuit 54 supplies its signal to the reset 
terminal R of the flip flop circuit 55 when the count of the counting 
circuit 52 becomes equal to the stored count of the storage circuit 53. 
The switching circuit 43 supplies its signal to the set terminal of the 
flip flop circuit 55 each time the switching circuit receives the pulse of 
the proximity switch 20. When the signal is applied to the set terminal of 
the flip flop circuit 55, the output of the Q terminal becomes "1". When 
the signal is applied to the reset terminal R of the flip flop circuit 55, 
the output at the Q terminal becomes "0". When the output at the Q 
terminal of the flip flop circuit is "one", the driver circuit 56 makes 
the connection between the power source 60 and the second actuating 
circuit 58. When the output at the Q terminal of the flip flop circuit 55 
is "zero", the driver circuit 56 breaks the connection between the power 
source 60 and the second actuating circuit 58. 
Thus, the warp beam 30 is driven through the secondary shaft 25 and the 
second electromagnetic clutch 28 when the loom is moved by inching or by 
hand while the main switch remains in its off state. In this case, the 
driver circuit 56 allows the warp beam 30 to rotate in a warp let-off 
direction or in a reverse direction through an angle corresponding to an 
angular displacement of the warp beam per weaving cycle, measured just 
before the loom is stopped. If the loom is moved through two weaving 
cycles in the reverse direction, this system repeats the above-mentioned 
process two times. In this case, the switching circuit 43 supplies its 
signal to the comparator circuit 54 and sets the comparator circuit 54 to 
an initial state to restart the comparison. 
Thus, this system can provide an accurate control of the warp beam 
rotation, and prevent an undesired mark of the woven fabric due to a loom 
stoppage. 
If it is desired to differentiate the angular displacement of the warp beam 
per weaving cycle between the normal operation and the downtime operation, 
this can be done by the first and second divider circuits. For example, 
the output of the first divider circuit 40 can be set at "four". That is, 
the first divider circuit 40 will output one pulse each time it receives 
four pulses, and the second divider circuit 50 outputs one pulse each time 
it receives five pulses. In this case, the warp beam angular displacement 
per weaving cycle of the downtime operation is reduced by 20% as compared 
with that of the normal operation. Thus, this system can provide a warp 
beam rotation control adapted to the kind of the fabric. 
One example of the stepless speed change transmission 6 is shown in FIGS. 6 
to 11. An input shaft 7 has a plurality of eccentric inner discs 128, 
which are fastened eccentrically around the input shaft 7 and rotatable 
with the input shaft 1. Each of the eccentric inner discs 128 rotates in 
an eccentric outer ring 129. Each of the eccentric outer rings 129 has a 
lobe which is swingably connected by a pin 130 to one end of a control arm 
132 and one end of a connecting arm 133. The other end of each of the 
control arms 132 is swingably connected to a common shaft 131. The other 
end of each of the connecting arms 133 is connected to a lobe of a driven 
ring 135 by a pin 134. When the input shaft 7 rotates in either of the 
forward and reverse directions, the control arms 132 swings on the common 
shaft 131, and the connecting arms 133 move in a reciprocating manner 
irrespective of whether the direction of the rotation of the input shaft 7 
is forward or reverse. Thus, the forward and reverse rotations of the 
input shaft 7 is converted to reciprocating angular movement of the driven 
rings 135. 
The common shaft 131 is rotatably supported on a yoke 137, which is 
connected to a shaft 136. The shaft 136 is rotatably supported on a 
transmission case 140. A speed change lever 138 is fastened to the shaft 
136. The position of the common shaft 131 can be changed by shifting the 
speed change lever 138. In accordance with the position of the common 
shaft 131 on which the control arms 132 swings, the stroke of the 
reciprocating motion of the connecting arms 133 is changed, so that the 
degree of the reciprocating angular movement of the driven rings 135 can 
be changed. 
The speed change lever 138 is connected, through a rod 139 as shown in 
FIGS. 12 and 13, to a tension lever of a warp tension detector (not shown) 
so that the speed change lever 138 is shifted in accordance with warp 
tension. 
As shown in FIG. 7, the output shaft 10 is rotatably supported on side 
walls of the transmission case 140 through bearings 141. Each of the 
driven rings 135 is mounted on the output shaft 10 through a one-way 
clutch, as shown in FIG. 8. 
For each of the driven rings 135, the output shaft 10 is formed with a set 
of recesses 142 which are arranged circumferentially around the periphery 
at regular intervals. Each recess 142 has a roller 143 which is disposed 
between the bottom of the recess 142 and the driven ring 135. There are 
provided arc members 144 each of which is interposed between a neighboring 
pair of the rollers 143. Each of the arc members 144 is disposed slidably 
between the outer surface of the output shaft 10 and the inner surface of 
the driven ring 135. A spring 145 is disposed between each neighboring 
pair of the roller 143 and the arc member 144. Each of the driven rings 
135 is sandwiched between cover rings 146 and 147 which cover the annular 
space formed between the output shaft 10 and the driven ring 135. Each of 
the arc members 144 is rotatable relative to the output shaft 10, and 
integral with one of the cover ring 146 and 147. 
The arc members 144 and the cover rings 146, 147 are integrated into a 
single unit by common shafts 148 which pass through these members. The 
common shafts 148 are supported by a shift ring 149 which is rotatably 
mounted on the output shaft 10. 
The output shaft 10 is formed with a guide hole 150 which extends along the 
axis of the output shaft 10. A shift rod 151 is inserted into and slidable 
in the guide hole 150 of the output shaft 10. A radially extending pin 152 
is fixed to an inner end of the shift rod 151. The output shaft 10 is 
further formed with an axially elongated slot 153 which extends radially 
from the guide hole 150 and opens to the outside. The pin 152 passes 
radially through the slot 153, so that the output shaft 10 and the shift 
rod 151 rotate together. The shift ring 149 is formed with a slant slot 
154 which is elongated obliquely as shown in FIG. 11. The pin 152 passes 
radially through the slant slot 154 of the shift ring 149. Therefore, when 
the shift rod 151 moves axially, the shift ring 149 is compelled to rotate 
relative to the output shaft 10. 
The shift rod 151 projects axially out of the guide hole 150. An outer end 
of the shift rod 151 is integrally formed with a cylindrical rack 155. The 
cylindrical rack 155 is engaged with a pinion 158 fixedly mounted on a 
shaft 157 which is supported on a case 156. The shaft 157 is connected to 
a reversing lever 159. The shift rod 151 can be axially moved by operating 
the reversing lever 159. The shift rod 151 is formed with three recesses 
160, 161 and 162 which are axially aligned. The output shaft 10 is formed 
with a radial hole 163, which contains a spring 164 and a lock ball 165. 
The lock ball 165 can engage with any one of the recesses 160, 161 and 
162. 
When the reversing lever 159 is turned in clockwise direction as viewed in 
FIG. 7, the cylindrical rack 155 and the pinion 158 cooperate to move the 
shift rod 151 rightward in FIG. 7 into a forward position in which 
position the lock ball 65 engages with the recess 160. During this, the 
pin 152 moves rightward as viewed in FIG. 11, and by so doing, causes the 
shift ring 149 to rotate relative to the output shaft 10 with the help of 
the slant slot 154. Consequently, the arc members 144 rotate in clockwise 
direction as shown in FIG. 8 with respect to the output shaft 10, because 
the arc members 144 are integral with the shift ring 149 through the 
common shafts 148. Thus, the rollers 143 are pushed in clockwise direction 
by the arc members 144 as shown in FIG. 8. 
In this state, only the clockwise rotational movement of the driven rings 
135, as viewed in FIG. 8, is transmitted to the output shaft 10 through 
the roller 143, while the driven rings 35 moves back and forth 
rotationally. Therefore, the output shaft 10 rotates intermittently in a 
clockwise direction as viewed in FIG. 8. This direction of the output 
shaft rotation is a forward direction, that is, a warp letting off 
direction. 
When the reversing lever 159 is turned in a counterclockwise direction as 
viewed in FIG. 7, the shift rod 151 moves leftward as viewed in FIG. 7 by 
the action of the cylindrical rack 155 and the pinion 158, and the lock 
ball 165 is received in the recess 162. With this linear movement of the 
shift rod 151, the pin 152 moves leftward as viewed in FIG. 11, and the 
shift ring 149 rotates with respect to the output shaft 10 with the help 
of the slant slot 154. Thus, the arc members 144 rotate integrally with 
the shift ring 149 in a counterclockwise direction as shown in FIG. 9 with 
respect to the output shaft 10, and push the roller 143 in the same 
direction. 
In this state, only the counterclockwise rotation of the driven rings 135 
is transmitted to the output shaft 10 through the rollers 143 while the 
driven rings 135 moves back and fourth rotationally. Thus, the output 
shaft rotates intermittently in a counterclockwise direction as viewed in 
FIG. 9, which is a reverse direction opposite to the forward direction. 
When the reversing lever 159 is in an intermediate position as shown in 
FIG. 7, the shift rod 151 is in an idle position in which position the 
lock ball 165 engages with the recess 161 lying between the recesses 160 
and 162. Thus, the arc members 144 move, through the action of the pin 
152, the shift ring 149 and the common shafts 148, into a position shown 
in FIG. 10, relative to the output shaft 10. In this position, each of the 
rollers is in the middle of the recess 142 and has play. 
In this state, neither of the clockwise and counterclockwise rotations of 
the driven rings 135 is transmitted to the output shaft. Thus, the driven 
rings move back and forth rotationally, but the output shaft 10 does not 
rotate. 
Thus, the stepless speed change transmission has three positions, a forward 
position in which the output shaft rotates in the forward direction 
irrespective of the direction of the input shaft rotation, a reverse 
position in which the output shaft rotates in the reverse direction 
irrespective of the direction of the input shaft rotation, and an idle 
position in which the output shaft is not driven. The ratio of input speed 
to output speed is changed in accordance with the tension of the warp 
threads. 
The reversing lever 159 of the stepless speed change transmission 106 is 
connected to a piston rod 185 of a double acting air cylinder 184. Air 
supply to both chambers of the double acting air cylinder 184 is 
controlled by an electromagnetic valve 186, which is controlled by an 
electric signal in accordance with the position of an operating lever of 
the weaving machine. Thus, the reversing lever 159 is moved in accordance 
with the movement of the operating lever of the loom. There is provided a 
proximity switch 187 for detecting an middle position of the piston of the 
double acting air cylinder 184. The idle position of the stepless speed 
change transmission can be obtained by detecting the piston of the double 
acting air cylinder 184 in the middle position and controlling the 
solenoid valve 186. 
Thus, the stepless speed change transmission may be of a reversible type. 
Another example of the stepless speed change transmission 206 is shown in 
FIG. 14. This transmission is usually called Hunt lef-off motion. An input 
shaft 7 is supported by bearings 250 and 251. A first variable speed 
pulley 252 has a pair of cone members 253 and 254 mounted on the input 
shaft 7. Keys 255 and 256 prevent relative rotation between the cone 
members 253, 254 and the input shaft 7 but allows the cone members 253, 
254 to slide axially. An output shaft 215 is supported by bearings 257 and 
258. A second variable speed pulley 259 has a pair of cone members 260 and 
261 mounted on the output shaft 215. Keys 262 and 263 prevent relative 
rotation between the output shaft 215 and the cone members 260 and 261, 
but allows the cone members 260 and 261 to slide axially. A reference 
numeral 264 denotes a bearing for supporting an output shaft 15. The first 
and second pulleys 252 and 259 are drivingly connected together by a belt 
265. A two-arm lever 268 is centrally pivoted on a fixed shaft 266. One 
arm of the two-arm lever 268 pushes one end of the cone member 254. A 
three-arm lever 270 is pivoted at the center on a fixed shaft 267. A 
weight member 271 is suspended from a first arm 270A of the three-arm 
lever 270. A second arm 270B of the three-arm lever 270 pushes one end of 
the cone member 260 of the second pulley 259. A third arm 270C of the 
three-arm lever 270 is connected by a rod 272 to a second arm of the 
two-arm lever 268. The three-arm lever 270 is pulled through a rope 273 by 
warp tension detecting means in a direction shown by an arrow in FIG. 14. 
That is, the three-arm lever 270 is biased toward such a direction as to 
rotate in a clockwise direction. The three-arm lever 270 is normally in a 
normal equilibrium position in which a moment exerted by the warp tension 
detecting means through the rope 273 counterbalances a moment exerted by 
the weight member 271. In this state, the cone member 254 of the first 
pulley 252 is held in a position determined by the balance between a push 
of the arm of the two-arm lever 268 and the tension of the belt 265. The 
cone member 260 is held in a position determined by the balance between 
the tension of the belt 265 and a push of the second arm 270B of the 
three-arm lever 270. Thus, torque is transmitted at the gear ratio 
determined by the positions of the corn members 254 and 260. 
If the warp tension increases, the rope 273 is pulled by the warp tension 
detecting means. Consequently, the three-arm lever 270 is rotated in the 
clockwise direction and moves the cone member 254 toward the cone member 
253 and the cone member 260 away from the cone member 261 until the 
balance is established again. Thus, the diameter of the first pulley 252 
is increased, and the diameter of the second pulley 259 is decreased. In 
this way, this stepless speed change transmission increases the rotational 
speed of the warp beam by increasing the gear ratio in accordance with an 
increase of the warp tension, and maintains the warp tension at a 
predetermined level. If the warp tension decreases, the stepless speed 
change transmission decreases the diameter of the first pulley 252 and 
increases the diameter of the second pulley 259 so that the rotational 
speed of the warp beam is decreased to maintain the warp tension at the 
predetermined level.