Warp yarn stop motion

The warp yarn stop motion is provided with a locating rail which is sub-divided into electrically insulated sections from the U-shaped rail. Each of these sections is electrically connected with pilot lights at the ends of each section. Should a drop wire fall on to a rail section, the pilot lights at the ends of the section are also illuminated so as to define the segment of the weaving width within which a broken warp yarn is located.

This invention relates to a warp yarn stop motion and, more particularly, 
to a warp yarn stop motion for a weaving machine. 
As is known, various types of warp yarn stop motions have been used in 
weaving machines in order to detect warp yarn breaks during weaving. Stop 
motions of this type are described in U.S. Pat. Nos. 3,584,659 and 
3,907,006. Generally, these stop motions have two metal elements in the 
form of rails connected to a power supply and extending in the direction 
of a weft yarn over the warp yarns being processed in the weaving machine. 
In addition, drop wires are threaded over the rails and are supported on 
the warp yarns. Should a warp yarn break, the respective drop wire falls 
under gravity onto the rails so as to short-circuit the rails, and, thus, 
complete an electrical connection for stopping the weaving machine. 
Generally, one rail of the stop motion is of U-shaped cross section while 
the other rail is located within the U-shaped rail in an electrically 
insulated manner and projects from the U-shaped rail with a serration 
along the top edge. In addition, both rails extend continuously over the 
entire cloth width of the weaving machine. Consequently, during actuation 
of the stop motion by a yarn break, it becomes difficult to determine 
which of the numerous warp yarns has broken. For example, in order to 
detect which of the drop wires has dropped as a result of the yarn 
breakage, an operator has to run his hand over all the drop wires. After 
some experimentation, it is possible to determine which one of the 
numerous drop wires cannot be pushed aside in the same way as the 
remainder of the wires. This wire is the wire belonging to the broken warp 
yarn. However, it is especially difficult for an inexperienced operator to 
carry out this locating process. 
Accordingly, it is an object of the invention to reduce the time required 
to locate a broken warp yarn in a weaving machine. 
It is another object of the invention to provide a stop motion of 
relatively simple construction for locating warp yarn breaks. 
Briefly, the invention provides a warp yarn stop motion which is comprised 
of a pair of metal rails at least one of which is subdivided into at least 
two electrically insulated sections, a power supply connected to the rails 
and a plurality of signalling means each of which is electrically 
connected to a respective insulated section. The stop motion also has a 
plurality of drop wires mounted over the rails with each drop wire having 
at least a pair of surfaces for contacting the respective rails to 
complete an electrical circuit therewith. 
The signalling means are disposed so as to emit a visual signal in response 
to a drop wire contacting the rails associated with a respective insulated 
section. For example, with each signalling means in the form of a pilot 
light mounted on the respective end of a respective insulated section, 
completion of a circuit across an insulated section and associated rail 
causes the pilot lights at the ends of the insulated section to 
illuminate. Thus, the lights determine the section within which a drop 
wire has descended. An operator can then more readily determine the actual 
position of the drop wire and the broken yarn and can re-tie the broken 
warp yarn.

Referring to FIG. 1, the warp yarn stop motion includes a contact rail 6 
which is mounted in a pair of holders 7, 8, on a weaving machine. As 
indicated, the holders 7, 8, are situated near the two sides 9, 10, of the 
weaving machine. 
Each contact rail 6 is comprised of a pair of metal rails 2, 4, which 
extend in the direction of the weft, as indicated by the arrow 1, 
transversely above the warp yarns (not shown) being processed in the 
weaving machine. 
Referring to FIG. 2, the contact rail 6 includes a substantially 
rectilinear supporting rail 2 of U-shaped cross section and a second 
locating rail 4 which is subdivided into sections 4a, 4b, 4c, 4d. This 
locating rail 4 is longitudinally inserted into the U-shaped rail 2 and 
electrical insulation 5 is provided between the two rails 2, 4. Further 
the locating rail 4 has a serration 3 along the top edge. The respective 
electrically insulated sections 4a-4d are separated by gaps 11, 12, 13, 
whereas the rail 2 and insulation 5 extend continuously between the 
holders 7, 8. 
Referring to FIG. 1, the warp yarn stop motion also has an electrical 
circuit connected with the rails 2, 4. This circuit includes a power 
supply 20, a line 21 connected to the negative terminal (earth) of the 
power supply 20 and to the sub-divided sections 4a-4d in parallel, and a 
second line 22 which is connected to the power supply and a plurality of 
distribution points 23a, 23b, 23c, 23d in parallel. Each distribution 
point 23a-23d is electrically connected to a respective insulated section 
4a-4d and to a pair of signalling means 31, 32, 33, 34, 35. As shown, each 
of the signalling means is disposed at one end of a respective insulated 
section 4a-4d and is in the form of a pilot light for emitting a visual 
signal. The pilot lights 31-35 are actuated in pairs in response to a 
respective insulated section 4a-4d adjacent a respective light 31-35 
becoming electrically connected to the rail 2. 
Referring to FIG. 2, a plurality of drop wires 25 are mounted over the 
contact rail 6 in conventional fashion. To this end, each drop wire 25 has 
at least a pair of surfaces for contacting the respective rails 2, 4 to 
complete an electrical circuit therewith. As indicated, each drop wire 25 
has an aperture with a pair of parallel side walls and a sloped upper 
wall. The aperture serves to permit threading of the drop wire 25 over the 
contact rail 6. Each drop wire 25 also has a suitable surface (not shown) 
to be supported on a warp yarn (not shown). In this regard, the drop wire 
25 is supported so that the sloped upper wall surface is disposed above 
the contact rail 6. 
During operation, should a warp yarn break, the associated drop wire 25 
will fall under gravity onto the serrated edge 3 of the contact rail 6. 
For example, in the position 25a shown in FIG. 2, should the drop wire 25 
fall onto the insulated section 4d, the drop wire 25 tilts due to the 
sloped wall surface coming into contact with the rail section 4d to form 
an electrical connection between the section 4d and the rail 2 via the 
points 26, 27, 28. Thus, the two pilot lights 34, 35 associated with the 
rail section 4d become illuminated via the distribution point 23d. In 
similar manner, if a wire 25 drops in section 4a, the two associated pilot 
lights 31, 32 become illuminated. If a drop wire drops in the section 4b, 
the lights 32, 33 are illuminated and in section 4c, the lights 33, 34 
become illuminated. 
Whichever pair of lights 31-35 become illuminated, the associated warp yarn 
breakage is indicated in the associated section 4a-4d so that the broken 
yarn can readily be detected and repaired. 
It is to be noted that U-shaped rail 2 may also be sub-divided into a 
plurality of electrically insulated sections in addition to the locating 
rail 4. Further, the rails 2, 4 may be divided into any number of 
sections, for example 4 or 5 sections depending upon the cloth width of 
the weaving machine. In this case, a corresponding number of pilot lights 
would also be associated with the sub-divided rails. 
It is also noted that when a drop wire 25 falls onto the contact rail 6, an 
electrical signal is also generated for stopping the weaving machine. This 
is well known and need not be further described.