U.S. patent number 3,685,177 [Application Number 05/063,450] was granted by the patent office on 1972-08-22 for two piece cutting edge.
This patent grant is currently assigned to Esco Corporation. Invention is credited to Frederick C. Hahn, Ronald R. Miller.
United States Patent |
3,685,177 |
Hahn , et al. |
August 22, 1972 |
**Please see images for:
( Certificate of Correction ) ** |
TWO PIECE CUTTING EDGE
Abstract
A two part cutting edge structure for an earth moving unit
includes a first or adapter part which is adapted to be removably
secured to the earth moving unit and a second or cutting edge part
which is adapted to be removably secured to the first part. Each of
the parts is generally elongated and includes a longitudinally
extending, generally flat bearing surface arranged in side-by-side
relation, and the other longitudinal edge of the second part
provides a cutting edge. The adapter part is provided with two or
more spaced-apart sockets having upper and lower walls, and the
cutting edge part includes rearwardly extending tab arms which are
received in the socket and are engageable with the upper and lower
socket walls to prevent rotation of the cutting edge part about the
adapter part. The abutting bearing surfaces of the two parts
provide resistance against thrust loading on the cutting edge part,
and the tab arms and sockets provide resistance against beam
loading on the cutting edge part.
Inventors: |
Hahn; Frederick C. (Beaverton,
OR), Miller; Ronald R. (Portland, OR) |
Assignee: |
Esco Corporation (Portland,
OR)
|
Family
ID: |
22049265 |
Appl.
No.: |
05/063,450 |
Filed: |
August 13, 1970 |
Current U.S.
Class: |
37/446 |
Current CPC
Class: |
E02F
9/2833 (20130101); E02F 9/2816 (20130101) |
Current International
Class: |
E02F
9/28 (20060101); E02f 009/28 () |
Field of
Search: |
;37/141R,141T,142R,142A |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Burr; Edgar S.
Claims
We claim:
1. A two part cutting edge structure comprising an adaptor part
adapted to be secured to an earth moving unit and a cutting edge
part adapted to be releasably secured to the adaptor part and
having a front cutting edge and a C-shaped rear edge provided by a
first flat wall and spaced-apart upper and lower flat walls which
extend rearwardly from the first wall, the adaptor part having a
flat front wall abutting the first flat wall of the cutting edge
part and spaced-apart upper and lower walls extending rearwardly
from the front wall and extending parallel to, respectively, the
upper and lower flat walls of the cutting edge part, the adaptor
part being provided with a socket spaced rearwardly of the front
wall of the adaptor part and having upper and lower socket walls,
the cutting edge part including tab means extending rearwardly
beyond the C-shaped rear edge thereof and being received in the
socket of the adaptor part between the upper and lower socket walls
thereof to prevent relative rotation between the cutting edge part
and the adaptor part, and locking means releasably securing the
adaptor part and the cutting edge part together.
2. The structure of claim 1 in which the adaptor part includes
spaced-apart upper and lower surfaces and the socket is provided
through the upper surface of the adaptor part rearwardly of the
flat front wall thereof and extends rearwardly between the upper
and lower surfaces of the adaptor part to provide the upper and
lower socket walls, the tab means including a first portion
extending rearwardly from the cutting edge part above the flat
front wall of the adaptor part and a second portion extending
downwardly and rearwardly into the socket.
3. The structure of claim 2 in which the second portion of the tab
means includes upper and lower surfaces extending adjacent,
respectively, the upper and lower socket walls.
4. A two part cutting edge structure comprising an adaptor part
adapted to be secured to an earth moving unit and a cutting edge
part adapted to be releasably secured to the adaptor part, the
adaptor part having a C-shaped front edge provided by a first flat
wall and spaced-apart upper and lower flat walls which extend
forwardly from the first flat wall, the adaptor part being provided
with a socket spaced rearwardly of the front edge thereof and
having upper and lower socket walls, the cutting edge part having a
front cutting edge and a rear flat wall which abuts the first flat
wall of the adaptor part and spaced-apart upper and lower flat
walls which extend forwardly from the rear flat wall and which
extend parallel to, respectively, the upper and lower flat walls of
the adaptor part, the cutting edge part including tab means
extending rearwardly beyond the rear wall thereof and being
received in the socket of the adaptor part between the upper and
lower socket walls thereof to prevent relative rotation between the
cutting edge part and the adaptor part, and locking means
releasably securing the adaptor part and the cutting edge part
together.
5. The structure of claim 4 in which the adaptor part includes
spaced-apart upper and lower surfaces and the socket is provided
through the upper surface of the adaptor part rearwardly of the
flat front wall thereof and extends rearwardly between the upper
and lower surfaces of the adaptor part to provide the upper and
lower socket walls, the tab means including a first portion
extending rearwardly from the cutting edge part above the flat
front wall of the adaptor part and a second portion extending
downwardly and rearwardly into the socket.
6. A two part cutting edge structure comprising an adaptor part
adapted to be secured to an earth moving unit and a cutting edge
part adapted to be releasably secured to the adaptor part and
having a front cutting edge and a rear flat wall, the adaptor part
having upper and lower surfaces and a flat front wall abutting the
flat rear wall of the cutting edge part, the adaptor being provided
with a socket spaced rearwardly of the flat front wall thereof, the
socket extending downwardly through the upper surface of the
adaptor part and rearwardly between the upper and lower surfaces to
provide spaced-apart upper and lower socket walls between the upper
and lower surfaces, the cutting edge part including a tab arm
having a first portion extending rearwardly above the abutting flat
walls of the adaptor and cutting edge parts and a second portion
extending downwardly and rearwardly into the socket between the
upper and lower socket walls to prevent relative rotation between
the cutting edge part and the adaptor part, and locking means
releasably securing the adaptor part and the cutting edge part
together.
7. The structure of claim 6 in which the second portion of the tab
arm includes upper and lower surfaces extending adjacent,
respectively, the upper and lower socket walls.
8. The structure of claim 6 in which each of the abutting flat
walls includes a first portion which extends below the tab arm and
end portions, the first portion of each flat wall being spaced
forwardly of the end portions thereof.
9. A cutting edge part adapted to be secured to an earth moving
unit comprising a body having a front cutting edge and a flat rear
wall adapted to abut a mounting member for the cutting edge part,
upper and lower surfaces extending between the cutting edge and the
rear wall, a pair of transversely extending end walls, and a tab
arm having a first portion extending rearwardly from the body above
the rear wall, a second portion extending downwardly from the first
portion, and a third portion extending rearwardly from the second
portion and being offset downwardly from the first portion by the
second portion and being adapted to be received in a socket
provided in a mounting member for the cutting edge part.
10. The cutting edge part of claim 7 including spaced-apart upper
and lower flat walls extending rearwardly from the flat rear
wall.
11. A mounting member adapted to mount a cutting edge part to an
earth moving unit comprising an elongated body having upper and
lower surfaces and a front edge portion, the edge portion having a
flat front wall adapted to abut the cutting edge member, the
mounting member being provided with a socket rearwardly of the flat
front wall thereof, the socket extending downwardly and through the
upper surface of the mounting member and rearwardly between the
upper and lower surfaces to provide spaced-apart upper and lower
socket walls between the upper and lower surfaces, the socket being
adapted to receive an arm member of the cutting edge part.
Description
BACKGROUND
This invention relates to a cutting edge for an earth moving unit,
and, more particularly, to a two piece cutting edge assembly in
which the cutting edge is securely mounted yet readily
replaceable.
Earth moving equipment such as scrapers, bulldozers, dragline
buckets, backhoes, shovel dippers, and the like are generally
provided with a cutting edge which is adapted to engage and
displace earth. Because the main digging unit, for example the
bucket of a dragline, is relatively expensive, it is desirable to
provide a replaceable cutting edge structure so that the cutting
edge can be maintained relatively sharp without having to rework
the entire bucket. The cutting edge must be securely mounted,
however, to withstand the considerable forces which are exerted
thereon during digging or scraping, and suitable securement is
generally obtained only by sacrificing some degree of removability.
Further, many so-called replaceable cutting edge parts become
distorted under the extreme stresses encountered during digging,
and replacement of the cutting edge is thereby rendered extremely
difficult, resulting in considerable down time for the earth moving
unit.
SUMMARY
The invention provides a two piece cutting edge structure which
permits the cutting edge to be quickly replaced through mechanical
locks, thereby eliminating excessive down time of the equipment
which generally results when the cutting edge is attached by bolts
or by welding. One part of the cutting edge structure is boltably
secured to the digging unit, but this part seldom requires
replacing. The second part of the structure provides the cutting
edge, and this part is removably secured to the first part by a
locking pin. Although the cutting edge part is readily removable
from the first part, the parts cooperate in a unique manner to
provide resistance against any type of force that is likely to be
encountered during the digging operation.
DESCRIPTION OF THE DRAWING
The invention will be explained in conjunction with an illustrative
embodiment shown in the accompanying drawing, in which
FIG. 1 is a fragmentary perspective view of an earth moving unit
equipped with a two piece cutting edge formed in accordance with
the invention;
FIG. 2 is an enlarged fragmentary perspective view of a portion of
the cutting edge of FIG. 1;
FIG. 3 is a fragmentary top plan view of one part of the two piece
cutting edge;
FIG. 4 is a top plan view of the other part of the two piece
cutting edge;
FIG. 5 is a sectional view taken along the line 5--5 of FIG. 4 with
the arrows representing the external forces that could exist during
operation;
FIG. 6 is a sectional view taken along the line 6--6 of FIG. 3;
FIG. 7 is a view taken along the line 7--7 of FIG. 4 with the
arrows representing the external forces that could exist during
operation;
FIG. 8 is a sectional view taken along the line 8--8 of FIG. 3;
FIG. 9 is a sectional view showing the interrelationship of the two
parts of the cutting edge structure that would be seen along the
lines 5--5 and 6--6 if the parts illustrated in FIGS. 3 and 4 were
assembled;
FIG. 10 is a view showing the interrelationship of the assembled
parts of FIG. 3 and FIG. 4 that would be seen along the lines 7--7
and 8--8;
FIG. 10A is a view similar to FIG. 10 of a modified form of the
invention;
FIG. 11 is an enlarged elevational view of the locking pin shown in
FIG. 9;
FIG. 12 is a top plan view of the locking pin taken along the line
12--12 of FIG. 11;
FIG. 13 is an enlarged elevational view of the pin lock member
shown in FIG. 9; and
FIG. 14 is a top plan view of the lock member taken along the line
14--14 of FIG. 13.
DESCRIPTION OF SPECIFIC EMBODIMENT
The invention will be explained in conjunction with a scraper blade
designated generally by the numeral 20 in FIG. 1 which is provided
as part of an earth moving vehicle 21 commonly used, for example,
in the construction of roads. The invention is not limited to the
cutting edge of scraper blades, however, and is applicable to
almost any earth moving or digging equipment for which a
replaceable cutting edge is desired. For example, the inventive
two-piece cutting edge can be used as the router bit of a scraper,
as the cutting edge of a bulldozer, as an adjustable side cutter on
dragline buckets, backhoes and shovel dippers, as a replaceable lip
for backhoes, draglines, shovel dippers, clamshell buckets, and on
many other types of equipment where structural and wearlife
capabilities are required in a digging tool comprising a lip and
cutting edge assembly.
The scraper blade 20 includes a conventional moldboard 21, and a
replaceable two-piece cutting edge assembly designated generally by
the numeral 22. The cutting edge 22 is seen to include four cutting
edge combinations 22a, 22b, 22c and 22d arranged end-to-end along
the lip of the moldboard 21, and one of the cutting edge
combinations is shown in FIG. 2. Each of the cutting edge
combinations includes a first or adapter part 23 which is removably
secured to the moldboard 21 by bolts 24 and one or more edge parts
25. The adapter part 23 is seen to have a generally elongated
rectangular shape and includes longitudinal edges 26 and 27 and
transverse side or end edges 28 and 29. Each edge part 25 also
includes a pair of longitudinally extending edges 30 and 31 and a
pair of transverse side or end edges or walls 32 and 33. In the
particular embodiment illustrated, the edge parts 25 extend for
about half the length of the adapter part 23 and are arranged in
end-to-end relation on the front longitudinal edge 26 of the
adapter part. The relative sizes of the parts 23 and 25 may be
such, however, that the adapter part may receive one cutting edge
part or three or more cutting edge parts.
Referring to FIG. 6, the adapter part 23 includes a flat bottom
surface 34 which is bolted against the flat moldboard 21 by the
bolts 24 and a contoured upper surface 35. The upper surface 35
extends generally parallel to the bottom surface 34 rearwardly to
bolt holes 36 (FIG. 3) and then tapers downwardly toward the rear
edge 27 to form a trailing edge portion of reduced thickness. The
bolt holes 36 are preferably square for cooperation with a
correspondingly shaped shank on the bolts 24, and the bolt openings
may be countersunk as at 37 to receive the bolt heads.
The front of the adapter part 23 includes nose portion 38 of
reduced thickness provided by downwardly and upwardly extending
shoulders 39 and 40, respectively (FIG. 8), and upper and lower,
generally parallel walls 41 and 42. The nose portion 38 terminates
in a flat front surface 43. The shoulder 39 is interrupted at
spaced-apart locations by recesses 44 which extend downwardly and
rearwardly from the upper surface 35 of the adapter and terminate
in socket portions 45 (FIG. 6) having upper and lower socket walls
46 and 47. Each recess also includes rearwardly extending side
walls 48, downwardly and rearwardly sloping bottom wall 49, and
rear wall 49a. The forward nose portion 38 of the adapter extends
forwardly as at 38a between each pair of adjacent recesses 44 and
is provided with a locking opening 50 aligned centrally with each
recess 44.
Each cutting edge part 25 includes a pair of rearwardly extending
tab portions 51 adapted to be received in a pair of associated
recesses 44, and the rearward longitudinal edge 31 of the cutting
edge part is generally C-shaped as shown in FIGS. 7 and 10 for
cooperative engagement with the nose 38 of the adapter. Referring
to FIG. 7, each cutting edge part 25 includes a generally
rectangular body portion 25a having generally parallel top and
bottom surfaces 52 and 53, respectively, and a reinforced or
enthickened rear edge portion 54. The C-shaped rear edge of the
cutting edge part is provided by inwardly extending upper and lower
walls 55 and 56 and a generally flat wall 57 which extends
forwardly at 57a to follow a contour generally the same as the
forwardly extending nose portion 38a of the adapter part.
Referring to FIG. 5, each of the tab arms 51 includes a rearwardly
extending major portion 58 having a flat bottom surface 58a and
terminates in a tongue portion 59 which is spaced below the major
portion 58 by offset connecting portion 60. The tongue portion lies
generally on the transverse central axis x-- x of the cutting edge
part and includes upper and lower surfaces 61 and 61a spaced
equally from this centerline.
A locking opening 62 extends through each tab 51, and the opening
is aligned with a lower opening 63 through the bottom portion of
the C-shaped rear wall 31 of the cutting edge part. The bottom wall
56 of the rear edge includes a reinforcing rearward projection 64
adjacent the opening 63.
The two piece cutting edge structure is assembled by sliding the
tabs 51 of each cutting edge part 25 into the recesses 44 in the
adapter part 23. As the tabs are inserted into the recesses, the
front nose portion 38 of the adapter is received in the C-shaped
rear edge of the cutting edge part and the bearing surface 43 butts
against the bearing surface 57 (FIG. 10). In this position, the
tongue portion 59 of each tab is received in the correspondingly
shaped socket portion 45 of the associated recess, and the openings
62 and 63 in the cutting edge part are aligned with the openings 50
in the adapter part. The rearward projections 64 of the cutting
edge part are received in a correspondingly shaped recess 65 (FIGS.
3 and 6) in the shoulder 40 of the adapter part.
In the particular embodiment illustrated, the two parts are
releasably locked together by a pin 67 and lock member 68 (FIG. 9).
The pin and lock member are constructed in accordance with U.S.
Pat. No. 3,126,654, issued Mar. 31, 1964, to which reference may be
had for details. Referring to FIGS. 11 and 12, the pin 67 includes
a corrugated front surface 69 provided with recesses or notches 70,
and a straight rear surface 71 provided with a central recess 72
which engages a correspondingly shaped projection 73 (FIG. 6) on
the rear wall of the opening 50 in the adapter part. The lock
member 68 includes a rubber body 74 which encases a pair of metal
cylindrical inserts 75 which are adapted to be received in the
recesses 70 of the corrugated face of the locking pin.
Before the cutting edge and adapter parts are assembled, the
locking member 68 is inserted in the opening 50 of the forward nose
portion of the adapter part, and when the openings 62 and 63 in the
cutting edge part are aligned with the openings 50 in the adapter
part, the locking pin is driven through these openings into
engagement with the metal inserts 75 of the locking member. The
locking pin can be inserted from either the top or the bottom of
the cutting edge, and the resilient rubber body 74 of the locking
member urges the recess 71 of the locking pin against the
projection 72 on the adapter part and the rear wall 71 against the
flat rear walls 62a and 64a of the openings 62 and 64,
respectively, of the cutting edge part.
FIGS. 5 and 7 show the external forces that could exist on the
cutting edge part 25 during the operation of the earth moving unit
on which the cutting edge assembly is mounted. These forces could
be concentrated or distributed equally or non-uniformly along the
front, top, and bottom of the cutting edge part, depending upon the
material resistance to penetration in excavation and/or removal.
For example, force A could exist at any angle in the upper left
quadrant when the unit is in the normal digging and loading cycle.
Force B of varying magnitude and angle could exist in the lower
left quadrant when the unit is being dropped or initially
penetrates the material to be excavated. Force C of varying
magnitude and angle could be encountered when the unit is being
removed or backed out of the material, and force D of varying
magnitude and angle in the upper right quadrant could exist when
the material is being removed from the rear containment area, such
as when a bucket is dumped or material is pushed out of a scraper.
The combination of two or more of these forces could occur,
depending upon variables during the operating cycle. For example,
forces A and B could exist in the event the cutting edge was
penetrating shale and a rock was encountered across the width or at
some point on the cutting edge, thereby creating force B.
Using the laws of resolution of forces, either or any of these
exterior loads can be broken down into horizontal and vertical
components, which, in turn, are resisted by equal and opposite
forces developed by the internal resistance of the assembly, and
the two piece cutting edge structure has unique bearing and
structural shapes which produce these internal reactions. Thus,
force A can be broken into a horizontal component A.sub.h and a
vertical component A.sub.v ; force B resolves into a horizontal
component B.sub.h and a vertical component B.sub.v ; force C
provides a horizontal component C.sub.h and a vertical component
C.sub.v ; and force D provides a horizontal component D.sub.h and a
vertical component D.sub.v.
Referring to FIG. 10, the horizontal or thrust forces A.sub.h
and/or B.sub.h are resisted by like thrust forces in the opposite
direction which are exerted by the flat load-bearing surface 43 of
the adapter part on the flat bearing surface 57 of the cutting edge
part. The flat surfaces 43 and 57 provide a butt contact or a
substantially butt contact within the limits of economical
manufacturing capability, and the thrust resisting force is
normally distributed along the entire leading edge 38 of the
adapter part outside of the forwardly extending portion 38a. Even
if there is some initial clearance between the two load-bearing
surfaces, the part will generally move by load force action or wear
within a relatively short period of time into a butt contact.
The horizontal components of forces C and D are reacted by the
resistance of the locking pin 67 (FIG. 9) to single or double shear
at the points between the adapter part and the cutting edge part.
Forces C and D are not likely to be as high in magnitude as forces
A and B, since these forces are generally created by the backing up
of the cutting edge from the material being penetrated, or by loose
material which is being dumped. Accordingly, the resistance of the
locking pin to shear usually will provide ample resistance to these
forces.
The vertical force components A.sub.v and D.sub.v, or the beam
loading, are resisted by the upper surface 41 of the leading edge
of the adapter part which bears against the upper surface 55 of the
C-shaped rear edge of the cutting edge. Again, even if initial
bearing does not occur between these surfaces, external forces will
cause movement or preferential wear to occur to provide the bearing
surfaces. Similarly, the vertical forces B.sub.v and C.sub.v are
resisted by the surface 42 which bears against the surface 56.
In the event that the forces A.sub.v and/or D.sub.v are relatively
large, translation or rotation of the cutting edge part will occur
to a point where the ends of the tab arms 51 engage the socket
walls of the recesses 44. Referring to FIG. 9, counterclockwise
rotation of the cutting edge part is resisted by the engagement of
the socket wall 46 with the upper surface 61 of the rear end of the
tab arm, and clockwise rotation of the cutting edge part is
resisted by engagement of the bottom wall 47 of the socket with the
bottom wall 62 of the tab arm. It will be appreciated that the tab
acts as a lever arm, thereby providing good capability to resist
and dissipate these forces because of the mechanical advantage
provided. A combination of forces A and B, or a combination of
forces C and D, generally does not occur at the same time. However,
in this event, the algebraic difference between the upward and
downward external forces will be absorbed and resisted at the
appropriate bearing surfaces between the tab arms and the
sockets.
In the particular embodiment illustrated, the end portions of the
leading edge 38 of the adapter part 23 are spaced rearwardly from
the forwardly extending portions 38a adjacent the recesses, and the
vertical surface 57 of the trailing edge of the cutting edge part
is similarly contoured. This provides more wear material in the
cutting edge part to account for typical wear patterns, which are
generally higher at the joints of cutting edges due to the wearing
tendencies of the material being dug and loaded. This higher force
has a tendency to round the corners at these joints, and the
additional wear material provides longer operating life. However,
the thrust-resisting surfaces of the adapter and cutting edge parts
could be straight if desired.
The beam load resisting faces 41 and 42 and 55 and 56 of the
adapter and cutting edge parts, respectively, are generally
parallel to the center line x-- x of the cutting edge part, and
opposite faces are spaced about equidistant therefrom. In one
embodiment the faces 55 and 56 diverged outwardly slightly, being
spaced apart about 1.00 inch at the face 57 and about 1.06 inch at
the rear edge 31 of the cutting edge part. The length of the faces
between these points was about 0.69 inch. Similarly, the faces 41
and 42 were spaced apart about 1.00 inch adjacent the shoulders 39
and 40 and about 0.94 inch at the forward edge of the adapter.
The distance from the cutting edge to the thrust resisting face 57
was about 3.88 inch, and the distance from this face to the end of
the tab arms was about 3.81 inch. The thickness of the tongue
portion 59 of the tab arm was about 0.50 inch and the rear end was
rounded on a radius of about 0.25 inch. The upper and lower socket
walls 46 and 47 were spaced apart about 0.56 inch and the curved
rear end of the socket had a radius of about 0.28 inch.
The cutting edge assembly can be provided in a variety of shapes to
handle variable materials that are encountered in earth moving
applications. For example, the invention can be applied to a clam
shell lip where a tooth type or straight edge could be utilized to
meet the digging and loading requirements while retaining the
capability of quick changing the worn areas without the necessity
of additional downtime for burning out lips and replacing them or
for replacing bolted or welded adapters.
Also, by utilizing different lengths of replaceable cutting edge
parts, it is possible to provide a wide variety of complete
assemblies to suit the variations in scraper design and width with
a relatively small number of parts. The particular adapter parts 23
illustrated in FIGS. 1 and 2 have a length approximately twice as
great as the length of the individual cutting edge parts, and the
bolt holes 36 are spaced about 6 inches apart, with the bolt hole
adjacent each side spaced about 2.88 inches from the side. A
typical gap of about 0.25 inch occurs between adjacent adapter
parts, so that the end bolt holes of adjacent adapter parts are
also spaced about 6 inches apart. Accordingly, the length of the
adapter part can be increased to receive three or even more cutting
edge parts, or the length of the cutting edge part can be increased
to the same length as that of the adapter part. For example, a
typical adapter part for receiving two cutting edge parts may be
35.75 inches long with six bolt holes spaced 6 inches apart; a
typical adapter part for receiving three cutting edge parts may be
53.75 inches long with nine bolt holes spaced 6 inches apart, and a
typical adapter part for receiving one cutting edge part may be
29.75 inches long with five bolt holes spaced 6 inches apart. The
length of the cutting edge parts would, of course, vary depending
upon the lengths of the adapter parts. By varying the sizes of the
adapter parts, a cutting edge assembly can be provided for a
variety of different lengths of scraper blades.
While we have described the generally C-shaped bearing surface as
being located on the rear of the cutting edge part, this could be
located on the adapter part and the nose portion which is received
by the C-shaped edge could be on the cutting edge part. This can be
seen in FIG. 10A in which the adapter part 23' is provided with a
C-shaped forward edge, and the cutting edge part 25' is provided
with a rear nose portion 38'. Further the tab arms and the sockets
on the cutting edge and adapter parts, respectively, could be
reversed so that the tab arms would be located on the adapter and
received by recesses in the cutting edge part.
While in the foregoing specification, a detailed description of
specific embodiments of our invention was set forth for the purpose
of illustration, it is to be understood that many of the details
hereingiven may be varied considerably by those skilled in the art
without departing from the spirit and scope of our invention.
* * * * *