Tendon pulling

Poultry carcasses suspended from the feet are carried along a straight path through a first zone where the lower legs are broken at a given level, and then through a second zone whereat opposing shearing forces are applied above and below the said level whereby to tear the skin and pull tendons from the upper legs of the carcasses.

This invention relates to an improved method and apparatus for removing the 
feet and tendons of poultry. More specifically the present invention is an 
improved method and apparatus applicable to a straight path continuous 
processing line utilizing shearing forces to break the lower legs of 
poultry carcasses and to separate the feet and pull tendons from the upper 
legs. 
There are a number of devices presently used for breaking the feet and 
pulling tendons from the legs of poultry carcasses. This procedure is 
highly desirable with the larger mature fowls, such as turkeys, since the 
tendons are quite tough and unpleasant to the ultimate consumer. However, 
the procedures and apparatus known heretofore are subject to a number of 
disadvantages. For instance U.S. Pat. No. 2,790,200 to Zebarth describes 
an apparatus comprising a drum or rotor which revolves to carry a 
plurality of hammer-puller members past a fixed anvil, whereby to shear 
poultry legs and pull tendons. However, an operator must position and 
manually hold each successive carcass. This apparatus has the disadvantage 
of requiring manual manipulation of each carcass, and consequently exposes 
the operator to the risk of injury by the moving machine parts. 
Another apparatus is shown in U.S. Pat. No. 2,836,845 to Farchmin et al 
wherein each carcass is individually positioned to one side of a fixed 
anvil and the feet are extended through a second movable anvil which is 
powered to first break the legs and then pull substantially longitudinally 
to separate the leg and pull the tendons. Although the operator appears to 
be exposed to less risk with the latter machine, each carcass must be 
separately handled and removed from a processing line. 
More recently U.S. Pat. No. 3,755,854 to Van Mil describes apparatus which 
is adaptable to continuously operate on a poultry processing line, but is 
limited in application to a point where the processing conveyor is trained 
about a 90.degree.-180.degree. turn and possibly depends on the conveyor 
for its power. According to this apparatus the legs of successive 
carcasses, hanging by the feet from shackles, are received in recesses on 
a first revolving disk located at the conveyor turn. A leg breaking wheel 
is positioned beneath the disk near the point of entry of the carcasses; 
and a second disk with recesses to receive the legs below the feet is 
positioned at a declining angle from about the same point. The two disks 
rotate together, and as the space therebetween increases, after the legs 
are broken, the feet and tendons are pulled substantially longitudinally 
and separated from the legs. The major deficiency of this apparatus is 
that it can only be installed at corners in the conveyor path and is not 
adaptable to straight line processing. 
Accordingly, it is a principal object of the present invention to provide 
an improved method and apparatus for automatically separating the feet 
from poultry carcasses and pulling a substantial number of tendons 
therewith. 
Another object of the present invention is to provide an improved method 
and apparatus for automatically breaking the legs and pulling the tendons 
of poultry carcasses while the carcasses are carried along a straight 
path. 
Briefly, the present invention provides for the carrying of successive 
poultry carcasses suspended by the feet from shackles secured to an 
overhead conveyor, or the like. Each carcass is advanced along a straight 
path into the bight of two counter-rotating cam plates which are 
positioned in two slightly spaced parallel planes with the operative 
peripheries thereof overlapped along said path at a level slightly below 
said poultry feet. The metatarsus bone and surrounding flesh and skin will 
thereby be separated and torn apart, and many of the tendons will remain 
attached to the foot portion and be pulled from the upper legs. It is 
preferred that the metatarsus bones be broken at about said level at a 
point on the path prior to reaching the cam plates; and it is also 
preferred that the cam plates be provided with notches to positively 
receive and advance the carcass legs.

The preferred embodiment of the present method is performed upon turkey 
carcasses 10 as they are carried along a processing line generally 12 (in 
the direction of arrow "A") where they may have previously been 
defeathered, dressed and/or eviscerated. The carcasses (one shown in FIG. 
1) are carried by the feet, with the body freely suspended neck 
downwardly, from shackles 14 which are, in turn, secured at regular 
intervals to a continuously moving overhead conveyor chain 16. It will be 
seen that each of the successive carcasses will be held with the feet at a 
specific vertical height so that the shank or metatarsus bones (the bone 
between the foot and the next joint) of carcasses within a fairly broad 
weight range will fall across a given level or horizontal plane. The 
metatarsus bones are broken at about that level as each carcass moves 
through a first zone, but the breaking is conducted so as to not sever the 
legs. 
Thence, the carcasses are each successively advanced, while holding the 
feet, through a second zone whereat spaced, opposing shearing forces are 
applied to the two broken parts of the metatarsus bones both slightly 
above and slightly below said level. The shearing forces will tear and 
sever the poultry skin and a small amount of flesh at the point where each 
bone was broken. This shearing action will not, however, cut many of the 
tendons extending along the leg as the tendons are tough and flexible and 
the shearing forces are spaced slightly. As a result the tendons are 
pulled with the feet and are caused to break at points within the upper 
leg toward the body and thence pulled from the tendon sheaths. At this 
point in the second zone the bodies of the poultry carcasses fall free and 
are collected beneath the zone while the feet and tendons are carried 
further on the shackles 14. 
The apparatus may be seen in full detail in FIGS. 1 through 3. The 
processing line generally 12 comprises a plurality of poultry shackles 14 
carried at the lower ends of rods 18 which in turn depend from roller 
carriages 20, and are connected to the conveyor chain 16. The roller 
carriages 20 ride on the lower web of an "I" beam overhead rail 22 that is 
suspended by hangers 24 from the ceiling. The foregoing structure is well 
known in the art. 
The present invention adds to the foregoing processing line generally 12 an 
overhead frame 26 from which the operating elements are suspended and 
braced by a plurality of struts 28, and the like. All of the operating 
elements are located just slightly below the lowermost portions of the 
shackles 14. The first operative element is a leg breaker wheel 30 
(preferably in the general form of a sprocket) which is positioned in a 
horizontal plane perpendicular and to one side of the shackles 14 with a 
portion of the wheel periphery extending beyond the opposite side of the 
shackles 14. Along the opposite side and just beneath the shackles are a 
pair of spaced anvil plates 32, 34 positioned to receive the extending 
portion of the breaker wheel 30 therebetween. 
The breaker wheel 30 is mounted directly on a vertical drive shaft 36 
extending from the overhead frame 26 where it is operatively attached to a 
drive motor 38 by a gear reducer 40. An enclosure (not shown) such as a 
hollow pipe or cylinder may be placed around the drive shaft 36 if desired 
for sanitation and/or safety purposes. Such an enclosure may also serve as 
part of the frame. The peripheral speed and direction of motion of the 
breaker wheel 30 should be approximately the same as the linear speed of 
the processing line. The breaker wheel 30 is preferably partly enclosed by 
a shroud 42 held in position by struts 28. It will be understood that the 
carcass legs extending across the anvils 32, 34 will be engaged and broken 
by the breaker wheel 30. 
As the shackles 14 move beyond the breaker wheel 30 they carry carcasses 
into a second zone where a pair of substantially circular shearing cams 
44, 46 are located. The shearing cams 44, 46 are rotatably mounted in 
planes perpendicular to the shackles, on axes to each side of the shackle 
path, and are spaced about 3/8 inch to 7/8 inch from one another and are 
positioned slightly above and below, respectively, the level of the 
breaker wheel 30 so as to engage the metatarsus bones both above and below 
the breaks therein. Each shearing cam 44, 46 is mounted on a shaft 48, 50, 
respectively, and is drivingly connected by gearing 52 to a motor 54 so as 
to rotate opposite to one another, with the peripheral direction of motion 
being the same as the processing line 12 and at a peripheral speed 
slightly exceeding the speed of the processing line. The shearing cams 44, 
46 are of a relatively large diameter (as compared to the breaker wheel 
30) and overlap directly beneath the shackle path. The drive shafts 48, 50 
may also be enclosed (not shown). 
Preferably each shearing cam 44, 46 has a continuous succession of evenly 
spaced fingers 56, 58, and intervening notches, which are angled slightly 
from the radii in the direction of rotation. Such fingers 56, 58 tend to 
positively engage the legs of carcasses suspended from shackles 14 and 
advance same between the cams 44, 46. Also it is preferred to enclose the 
outer portions of the cams 44, 46 with shrouds 60, 62, respectively which 
are also held in place by the struts 28. 
It is further preferred that the shearing cams 44, 46 be overlapped to the 
maximum possible extent, which may approach their radial measure. The 
amount of overlap will affect, to a large degree, the duration and 
magnitude of separation and tension applied to the tendons which may 
stretch before becoming separated from the upper leg portions. Further, it 
is preferred, as may be seen in FIGS. 1 and 2 to extend the lower anvil 
plate 34 directly toward the bight of cams 44, 46 and even under the cam 
44 where it is arcuately relieved so as to not interfere with the lower 
cam 46. The extension of the lower anvil plate assists in stabilizing the 
carcasses and feeding them accurately to the shearing cams 44, 46. 
To further stabilize and guide the poultry carcasses, a pair of horizontal 
spaced guide rods 64, 66 are mounted between the rail 22 and the breaker 
wheel 30 and shearing cams 44, 46. The guide rods 64, 66 are positioned to 
confine the path and orientation of the shackles 14 and thereby cause the 
suspended carcasses to be properly presented to the breaker wheel 30. 
It should also be understood that the apparatus of the invention is to be 
constructed of materials that will wear well and withstand compressive 
forces such as steel. Preferably stainless steel is used, at least for the 
breaker wheel 30 and shearing cams 44, 46, because it is readily sanitized 
and resists corrosion. Furthermore, motors 38, 54 may be of any suitable 
type such as hydraulic or electric although electric motors are preferred 
because of their available power. Other drive means may be provided 
however; and if the processing line is subject to speed variations, then a 
variable speed motor and/or gear drive should be provided. 
Operation of the apparatus will have become apparent from the foregoing 
detailed description. Power requirements for pulling tendons will not 
overload the processing conveyor. The poultry carcasses will automatically 
fall downwardly beneath the shearing cams 44, 46 when the tendons have 
been released, and accordingly appropriate equipment known to the art (not 
shown) is positioned therebelow to receive the carcasses and the carcasses 
may then be further processed. Also poultry feet, with attached tendons, 
will remain hanging from the shackles 14 as they pass beyond the cams 44, 
46, and appropriate equipment (also not shown but known to the art) will 
be positioned downstream thereof to remove the feet from the shackles 14 
and to clean the shackles. 
Obviously many modifications and variations of the invention as 
hereinbefore set forth may be made without departing from the spirit and 
scope thereof, and therefore, only such limitations should be imposed as 
are indicated in the appended claims.