Tractor scraper hitch steering and suspension system

A tractor scraper hitch steering and suspension system wherein a tractor drive wheel axle frame is pivotally connected to a tractor main frame to permit vertical movement of the tractor drive wheels relative to the tractor. Two hydraulic cylinders are pivotally connected between the tractor drive wheel axle frame and a cross arm forming a part of a hitch assembly that secures the tractor to the scraper. The hydraulic cylinders dampen vertical bounce movement that occurs during operation and control tilting or rolling motion between the tractor portion and the scraper portion that occur about their common longitudinally extending axis. A locking brake is provided to resist vertical motion of the tractor drive wheel axle frame to stabilize the depth of a cutting edge of the scraper during operation and obtain a steady depth of cut. A pressurized hydraulic system including an accumulator, a source of fluid pressure, fluid control valves, restrictor orifices and a sensor system are effective to maintain a range of predetermined vertical positions of portions of the articulately connected vehicle regardless of the weight of the load being received, carried by, or discharged from the scraper bowl to thereby control riding characteristics when encountering bounce, pitch or rolling conditions.

BACKGROUND OF THE INVENTION 
This invention relates in general to vehicle steering and suspension 
systems and, in particular, to a hitch steering suspension system and 
control circuit especially useful for a four-wheel, two-axle articulately 
connected tractor-scraper combination. 
More specifically, but without restriction to the particular use which is 
shown and described, this invention relates to a hitch steering, vehicle 
suspension system for use with a four-wheel, two-axle earthmoving 
tractor-scraper for steering and controlling bouncing, pitching and 
rolling motions encountered during operation. In addition, this invention 
relates to a control system for the vehicle suspension system used on an 
articulated earthmoving scraper to minimize the bouncing, pitching and 
rolling motions that occur during operation of a vehicle. 
Articulated wheel or tractor scrapers are used for many applications in the 
construction industry wherein it is necessary to transport heavy loads of 
material such as dirt and rock over terrain from one location to another, 
such as in levelling or filling construction or highway sites. Such wheel 
or tractor scrapers comprise two or four-wheel tractor portions and a 
two-wheel trailer portion which are articulated about a combined draft and 
steering coupling, or hitch, formed between the tractor and trailer. The 
two units are interconnected by a draft frame attached to the trailer 
which is pivotally mounted on an A-frame, gooseneck coupling of the 
tractor. The tractor scraper is steered through the manipulation of 
hydraulic jacks connected between the two portions of the vehicle by 
turning the tractor portion with respect to the trailer portion about a 
vertically disposed articulation pivot axis formed by the interconnection 
between the front and rear portions of the vehicle. 
In operating articulated vehicles such as tractor scrapers, it is 
frequently necessary to allow the tractor and trailer portions of the 
vehicle to tilt relative to each other about a longitudinal axis extending 
through the vehicle. Such tilting or rolling is necessary to keep all of 
the vehicle wheels in contact with the operational surface when travelling 
over uneven terrain to prevent the loss of tractive power. However, the 
amount of tilting or rolling movement between the tractor and trailer 
portions of the vehicle must be controlled in order to maintain vehicle 
stability. While a limited amount of rolling or tilting of the two 
portions of the vehicle relative to each other is desirable within 
predetermined limits, such roll or tilt must be controlled. 
In addition to roll or tilt between the tractor portion and the trailer 
portion of the tractor scraper, bouncing or pitching movement is 
frequently encountered. Such movement is believed to result from the 
resiliency of the tires and the weight of the scraper trailer which is 
suspended between the front and rear wheels of the combination and 
frequently occurs during hauls at relatively high vehicle speeds. Due to 
the large size and weight of the tractor scraper, and of the loads 
transported by it, ordinary shock absorbers or vibration isolators are 
impractical to resolve the problems created by such bouncing or pitching 
movement. Such bouncing or pitching movement is uncomfortable and 
potentially dangerous to the machine operator and, due to the large shock 
loads imparted by the bouncing trailer portion, can result in damage or 
failure of structural parts of the vehicle, particularly those closely 
associated with the load carrying body. 
A number of attempts have been made to resolve or control the rolling, 
bouncing and pitching conditions encountered in tractor-trailer 
combinations. One such control system has been illustrated in the 
inventor's U.S. Pat. No. 4,279,319, the disclosure of which is 
incorporated herein by reference. For example, in U.S. Pat. No. 4,279,319 
there is utilized an arrangement for controlling a vehicle axle suspension 
system wherein a plurality of pitch damping and roll or tilt damping 
hydraulic cylinders are operatively connected to portions of the vehicle 
for dampening undesirable movement. 
Another control system is illustrated in the inventor's U.S. Pat. No. 
4,201,273, the disclosure of which is also incorporated herein by 
reference. In U.S. Pat. No. 4,201,273, there is utilized a first pair of 
hydraulic cylinders to control and dampen vertical bounce movement and a 
second pair of hydraulic cylinders for supplementing the first pair of 
cylinders to control vertical movement between the tractor drive wheels 
and to dampen tilting and rolling motion between tractor and trailer about 
their common longitudinally extending axis. 
Other attempts have been made to resolve the bouncing and pitching problems 
associated with tractor-trailer units. For example, attempts have been 
made to utilize a separate tractor drive wheel axle A-frame pivotally 
connected to the tractor main frame to allow for vertical movement of the 
tractor drive wheels relative to the frame. In U.S. Pat. No. 3,865,205, 
there is disclosed such a separate drive wheel axle frame which is 
pivotally connected to the front portion of the tractor main frame to 
extend rearwardly to a position beneath the hitch assembly. It is the 
object of such a coupling arrangement to obtain better weight distribution 
by permitting the vehicle engine to be mounted on the rear portion of the 
tractor unit and to allow the vehicle operator to be positioned forwardly 
of the engine for increased visibility. 
Other examples of steering and suspension systems are described in U.S. 
Pat. Nos. 2,638,998, 3,032,135 and 3,828,882. These references show 
various arrangements of swing arms pivotally connected to intermediate 
members for movement about a vertical articulation pivot point and 
including steering cylinders to move the swing arms and intermediate 
members for steering the vehicle. 
While each of these patents discloses apparatus that attempt to resolve the 
problems associated with steering tractor trailer units and the 
controlling bouncing and pitching movement thereof have been somewhat 
successful, such disclosures do not provide for completely controlling the 
rolling or tilting conditions between the tractor and trailer portions of 
the articulated vehicle. 
SUMMARY OF THE INVENTION 
It is, therefore, an objective of this invention to improve steering and 
suspension systems of vehicles. 
Another object of this invention is to improve steering and suspension 
systems for off-highway articulated earthmoving equipment. 
A further object of this invention is to dampen or control the bouncing, 
pitching and rolling movement encountered during operation of articulated 
vehicles. 
These and other objects are attained in accordance with the present 
invention wherein there is provided a tractor scraper suspension system 
having a tractor drive wheel axle frame pivotally connected to a tractor 
main frame to permit vertical movement of the tractor drive wheels 
relative to the tractor.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
Referring now to FIG. 1 there is shown a construction machine or 
earthmoving vehicle commonly referred to as a wheeled tractor scraper. 
Although the vehicle hitch and suspension system disclosed herein may be 
used with various vehicles, for convenience of illustration, the preferred 
embodiment is illustrated with reference to its use with a fourwheel 
vehicle comprising a single axle tractor and a two-wheel scraper. 
Generally, such a tractor scraper includes a draft or tractor unit 10 and a 
drawn or trailer portion 11. The trailer portion 11 includes an open 
scraper bowl 12 supported at its rear end by a pair of wheels 13 and at 
its front end by the tractor portion through a draft frame 14 having a 
pair of draft arms 15 pivotally connected to outboard ends of a transverse 
support beam 16 of the draft frame that extend rearwardly to connect with 
the vertical sidewalls of the scraper bowl. The draft frame 14 further 
includes a gooseneck 17 having a forward end or pedestal 18 pivotally 
connected to a coupling hitch 19 secured to supporting main frame 
structure 20 of the tractor 10 in a manner hereinafter described. 
The scraper bowl includes a cutting edge 21 disposed at its bottom front 
end which during operation acts to excavate a predetermined amount of 
earth or other material as the tractor scraper moves along an operation 
surface. The volume or amount of material removed as the scraper passes 
along the surface is controlled by raising or lowering the cutting edge 21 
carried at the front end of the scraper bowl. Raising or lowering of the 
cutting edge to a desired position is accomplished by the action of fluid 
operated motors in a well known manner and not shown herein. 
The tractor 10 of the scraper is supported by a pair of drive wheels 22 and 
includes an operator cab 23 having an instrument and control panel 
conveniently located within the reach of the machine operator for 
controlling the vehicle as well as to monitor or adjust various accessory 
or auxiliary equipment of the tractor scraper for effecting desired 
operations. As shown in FIG. 1, the trailer 11 is joined mechanically to 
the tractor portion 10 by means of a pivotal connection between the 
coupling hitch 19 and the pedestal 18 of gooseneck 17. 
Referring to FIGS. 2 and 3, the coupling hitch 19 comprises a generally 
rectangularly shaped base frame 24 having a forward pair of plates 25 and 
a rearward pair of plates 26 extending downwardly to form first 27 and 
second 28 bracket members, the bracket members having formed therethrough 
apertures 29 with axes that lie along a longitudinal axis coincident with 
a vertical plane of the centerline of the machine. The first bracket 27 is 
adapted to span an intermediate portion of a front crossbeam 30 secured 
between a pair of parallel sides 31 of the main frame 20 of the tractor. 
The front crossbeam 30 has a bore 32 formed therethrough wherein is 
journaled a forward hitch pin 33 that extends through the apertures 29 of 
first bracket 27 in order to effect a pivotal relationship between the 
tractor 10 and the scraper 11. Similarly, the second bracket 28 is adapted 
to span an intermediate portion of a rearward crossbeam 34 secured between 
the pair of parallel sides 31 and main frame 20 of the tractor. The rear 
crossbeam 34 has a bore 35 formed therethrough wherein is journaled a 
rearward hitch pin 36 that extends through the apertures 29 of second 
bracket 28 in order to effect a pivotal relationship between the tractor 
10 and the scraper 11. The pivotal relationship between tractor and 
scraper permits tilting and rolling relative to each other about a 
horizontal axis 37 extending longitudinally of the machine center line. 
Continuing to refer to FIGS. 2 and 3 and also referring to FIG. 8, the 
hitch base frame 24 of coupling hitch 19 extending generally 
longitudinally of the vehicle is connected to the tractor frame 20 at a 
forward horizontal pivot point 38 and a rearward horizontal pivot point 
39. The hitch frame 24 is free to rotate about the longitudinal pivot axis 
37 to permit relative motion between the tractor and scraper that is 
controlled as desired in a manner as hereinafter described. The hitch 
frame 24 has formed thereon a boss 40 having formed therethrough an 
aperture 41, the center of which defines a vertical articulation axis 42 
about which the tractor is free to pivot relative to the scraper. The 
pedestal 18 forming a part of the scraper draft frame 14 has a U-shaped 
forward portion with a lower bracket 43 and an upper bracket 44 formed 
with apertures therethrough and aligned coincidentally with the 
articulation axis 42. A pin 45 is secured in the aperture 41 of boss 40, 
extends into an aperture 46 of lower bracket 43 of the pedestal 18 and 
serves to effect a lower pivotal connection between the hitch frame 24 and 
the pedestal 18. 
An "A"-frame superstructure portion 47 of hitch frame 24 extends vertically 
therefrom and includes a lower boss 48 having an aperture 49, the center 
of which defines a vertically extending common axis 50. The A-frame 47 has 
a horizontally disposed extension 51 located substantially intermediate 
the upper and lower ends of superstructure portion 47. The extension 51 
has an aperture 52 formed therethrough having a vertical axis oriented to 
be coincident with common axis 50. A-frame 47 has an upper, generally 
horizontal portion 53, an extremity of which has formed therethrough an 
aperture 54. The axis of aperture 54 is oriented to be coincident with 
articulation axis 42 and is disposed so that a pin 55 connects the upper 
portion 53 of the A-frame with the upper bracket 44 of pedestal 18 for 
relative rotation therebetween. 
A steering linkage assembly as best seen in FIGS. 3, 4 and 5, generally 
identified by reference numeral 56 is mounted on a portion of the base 
frame 24 and interconnects for articulative control the coupling hitch 19 
and the draft frame 14. The linkage assembly comprises a first group of 
associative members including a first crescent-shaped swing arm 57, a 
first connecting link 58 and a first steering jack 59; and a second group 
of associative members including a second crescent-shaped swing arm 60, a 
second connecting link 61 and a second steering jack 62. 
Each swing arm 57, 60 has located at its inner end a bifurcated yoke with 
upper 64 and lower 65 fingers having formed therethrough apertures 
disposed about a common axis pin 66 connecting the lower boss 48 with 
extension 51 of the hitch frame superstructure 47 along common axis 50. 
Each swing arm 57, 60 extends laterally outwardly from vertical common 
axis 50 of superstructure 47 and has formed at its outer end a respective 
curved portion 67, 68. The first 58 and second 61 connecting links have a 
respective one end pivotally connected to a respective outer curved 
portion 67, 68 by first 69 and second 70 outer pins and have a respective 
other end pivotally connected to the lower bracket 43 of pedestal 18 by 
first 71 and second 72 inner pins. The first and second inner pins are 
vertically oriented and located on the lower bracket 43 of pedestal 18 at 
points rearwardly of articulation axis 42 and outboard from longitudinal 
axis 37. 
The first steering jack 69 includes a rod end 73 pivotally connected to a 
substantially intermediate portion of swing arm 57 as by a pin 74 and a 
head end 75 pivotally connected to a lateral extension 76 of hitch frame 
24 by a pin 77. Similarly, the second steering jack 62 has a rod end 78 
pivotally connected to a substantially intermediate portion of swing arm 
60 by a pin 79 and a head end 80 pivotally connected to the lateral 
extension 76 of hitch frame 24 by a pin 81. It can be noted that extension 
of the steering jack 59 and retraction of steering jack 62 causes swing 
arms 57 and 60 to rotate about common axis 50, and cause the tractor to 
rotate about articulation axis 42 and turn the tractor in a counter 
clockwise direction. Similarly, extension of steering jack 62 and 
retraction of steering jack 59 causes the tractor to turn in an opposite 
direction. Referring to FIG. 4, it can be noted that the steering system 
of the present invention is effective to rotate the tractor ninety degrees 
in either direction left or right about the scraper or a total of 180 
degrees. 
Referring to FIGS. 1, 2, 6, 7 and 8, the vehicle suspension system includes 
a tractor drive wheel axle support, shown generally by the numeral 82, 
which is pivotally connected to a rear portion of the tractor main frame 
to allow the tractor drive wheels 22 to move vertically relative to the 
tractor frame 20. The tractor drive wheel axle support 82 includes a pair 
of suspension support arms 83, the forward portions of which are secured 
to a tractor drive wheel axle 8 which carries and is operatively connected 
to the tractor drive wheels 22 providing rotary driving power thereto. The 
power train from a vehicle engine through a torque converter, transmission 
and differential system are well known to those skilled in the art and 
portions of this power train are shown in phantom in the drawings. The 
opposite ends of the suspension support arms 83 are connected to the 
tractor main frame 20 by means of pivot connections 84 which connect the 
suspension support arms 83 to the tractor main frame 20 to allow the 
tractor drive wheel axle support 82 to move in a vertical direction 
relative to the tractor frame 20. In this manner the tractor drive wheels 
22 are free to move vertically relative to the tractor main frame 20 about 
the pivotal connections 84. 
It is also desirable to dampen and limit the amount of roll or tilt between 
the tractor portion 10 and the trailer portion 11 of the scraper. To this 
end the hitch frame 24 has a cross arm 85 secured thereto intermediate its 
ends, the arm ends extending laterally outwardly transverse to the pivot 
axis 37 that extends longitudinally through the hitch frame. At each outer 
end of the cross arm 85, there is disposed an axle suspension, roll or 
tilt dampening hydraulic cylinder 86 having its rod end 87 pivotally 
connected to the distal ends of the cross arm and a head end 88 pivotally 
connected to a forwardly extending ear 89 secured to a housing 90 of the 
axle 8. In this manner, as the tractor portion 10 and the trailer portion 
11 roll or tilt relative to each other about the longitudinally extending 
hitch pin axis, the movement will be dampened through the action of the 
roll or tilt damping cylinders 86. Roll oscillation between tractor and 
scraper induces or sets up opposite movements therebetween causing fluid 
to flow in cylinders 86 that results in damping the oscillatory movement. 
In addition, the suspension cylinders 86 serve to cushion vertical axle 
movement and thereby perform the dual functions of cushioning vertical 
movement and dampening roll oscillation. 
In order to stabilize lateral motion imposed stresses in the rear portion 
of the tractor main frame 20, there is provided a stabilizer link 91. The 
stabilizer link 91 is pivotally connected at one end 92 to a portion of 
the tractor drive wheel axle support frame 82, for example a differential 
housing 93. The stabilizer link has its other end 94 pivotally connected 
to a portion of the forward cross beam 30 that assists in supporting the 
hitch coupling 19 so that lateral stability is provided for the tractor 10 
and the entire suspension system. 
Referring now to FIG. 9, there is shown in cooperation with the hitch 
steering and suspension system of the present invention, an arrangement to 
provide braking action to resist vertical motion of axle 8 in order to 
stabilize the depth of the cutting blade of the scraper bowl during 
operation of the tractor and trailer vehicle. A disc brake type caliper 
head identified generally by reference numeral 101 is secured to a part of 
the tractor main frame 20 and positioned to engage a plate 102 flexibly 
pinned to the axle housing 90. A conduit 103 supplies pressurized brake 
fluid to the brake from a pressure converter 104. A conduit 105 provides 
make up fluid to the pressure converter from an oil reservoir 106. An air 
compressor 107 and an air reservoir 108 are connected in series to the 
pressure converter 104 through a solenoid operated or other suitable 
control valve 109 by means of conduits 110 and 111. Control valve 109 is 
caused to operate by closing a switch 112. Upon energizing valve 109, the 
normally open position to atmosphere is changed to connect the system to 
the air reservoir which causes pressure in the system to actuate the disc 
brake and hold the axle in a static position at whatever level it is 
currently disposed. The axle being held in this position is effective to 
stabilize or maintain the cutting edge of the scraper bowl in a desired 
position and obtain a steady depth of cut of earth. Thus, the brake will 
maintain a rigid axle mode or locked position for loading earth or other 
material, but will also provide for controlled "slippage" to occur within 
the system to alleviate unusual shock loads in the event the vehicle hits 
an obstacle that causes a sudden bump or extraordinary vertical motion of 
the vehicle. 
The quality of the cut made by the scraper in the locked position is 
therefore improved because fluctuations in the position of the cutting 
edge and bowl with respect to the vehicle supporting surface are 
eliminated. 
Referring now to FIG. 10 there is illustrated a fluid schematic diagram of 
the suspension system and associated control circuit for controlling the 
bounce damping, tilt or roll damping, and automatic load leveling of the 
vehicle and the system lockout. A pump 97 delivers hydraulic fluid from a 
reservoir or sump 98 via an input conduit 113. The fluid is supplied at 
high pressure via an output conduit 114 to a valve group or system shown 
generally by the numeral 115. A pressure relief valve 116 is coupled 
between the output conduit 114 and the sump 112 to protect the hydraulic 
circuit from excess pressure and to prevent overloading the pump 97. The 
valve group 115 includes a pair of two-position valves 117, 118 each 
actuated by a solenoid 119 and 120, respectively. A spring 121 biases the 
valve 117 to a position in which it is in fluid communication with a 
return conduit 122 which in turn is in fluid communication with the 
reservoir or sump 98. Similarly, a spring 123 biases the valve 118 to a 
position which communicates hydraulic fluid from the conduit 114 and 
through a check valve 124 via a conduit 125. 
Conduit 125 communicates high pressure hydraulic fluid to a conduit 126, 
which in turn communicates high pressure fluid to a precharged accumulator 
127. 
The high pressure hydraulic fluid from the pump 97 and the accumulator 127 
is communicated to the head ends of the axle suspension cylinders 86 by a 
conduit 128 via a pair of branch conduits 129, 130. The cylinders 86 
assist in supporting the vehicle and the load, and dampen and limit the 
relative roll motion between the tractor and trailer portions of the 
scraper. A plurality of line restrictors 131, 132 disposed in the lines 
129, 130, respectively, cooperate to control the spring and damping rates 
in the roll damping portion of the circuit by restricting the flow of 
hydraulic fluid as it is forced from either one of the respective ends of 
the cylinders 86 by relative motion between the tractor 10 and trailer 11 
portions of the vehicle. The rod ends of cylinders 86 are connected by 
branch conduits 133 and 134 to a return conduit 135 that is connected to 
the sump 98. 
A sensor, shown generally by the numeral 140, is used for maintaining oil 
pressure to support the tractor with the drive axle in a mid position or 
within a predetermined range of positions relative to the tractor 
regardless of the weight of the load being received, carried, or 
discharged from the scraper bowl. The sensor 140 includes a sensor switch 
141 having a portion affixed to, for example, the tractor frame 20 and a 
movable portion pivotally connected to the axle portion of the tractor. 
The switch 141 has a pair of contacts 142 and 143, located at the extremes 
of the desired range of vertical movement of the drive axle relative to 
the tractor frame. When the circuit is closed by either of the two extreme 
positions being attained, due, for example, to a change in the weight of 
the material in the bowl, an electrical current is established between a 
battery 144 and ground 145 which selectively energizes one or the other of 
the solenoids 119 or 120. For example, if the vehicle drops too low with 
respect to the drive axle 8, the switch 141 completes the circuit when 
closing into contact 142. The solenoid 119 is activated which overrides 
the force of the spring 121, and the valve 117 shifts to its second 
position closing off fluid flow to the reservoir 98. The entire volume of 
fluid provided by the pump 97 is directed to the head ends of the axle 
suspension cylinders 86 and accumulator 127 which lifts the vehicle frame, 
including the bowl and load, until electrical connection through contact 
142 is broken. The system then returns to the equilibrium configuration as 
shown in FIG. 10. 
Similarly, if the vehicle is riding too high with respect to the drive axle 
8, an electrical circuit is established through contact 143. Solenoid 120 
is activated which overrides the force of the spring 123, and the valve 
118 shifts to its second position. Hydraulic fluid from the head ends of 
the cylinders 86 is permitted free return to the reservoir 98, and the 
vehicle frame and bowl are lowered until contact at point 143 is broken. 
The system then returns to the equilibrium configuration as shown in FIG. 
10. A pair of springs 146 and 147 cooperate with a pair of dashpots 148 
and 149, respectively, to filter out minor bounce motion of the drive axle 
8 to the sensor 140 thereby insuring smooth operation of the system. 
While the operation of the present invention is believed clearly apparent 
from the foregoing description, its operation is briefly summarized as 
follows. Referring again to FIG. 10, with the leveling sensor 140 in an 
intermediate or off position, the pump 97 receives hydraulic fluid from 
the reservoir 98 via the input circuit 113. The pump communicates the 
pressurized hydraulic fluid through the output conduit 114 to each of the 
two position valves 117 and 118 of the valve group 115. In an intermediate 
or off position the valve 117 returns hydraulic fluid to reservoir 98 via 
conduit 122. In an operative or on position, valve 117 blocks flow to the 
reservoir 98, and the valve 118 directs hydraulic fluid to conduit 125, 
from which it flows through conduit 128 to the head ends of the cylinders 
86 wherein pressure is maintained by the action of the accumulator 127. 
The conduit 126 communicates high pressure fluid to the accumulator 127 
which cooperates with the line restrictors 131 and 132 in providing the 
spring and viscous damping characteristics of the suspension system. The 
accumulator 127 and the pump 97 maintain the desired pressure in the head 
ends of the cylinders 86 required to maintain the vehicle frame 20 within 
the desired range of preselected positions with respect to the drive axle 
8. 
Similarly, low pressure from the sump 98 or atmosphere is communicated to 
the rod ends of the cylinders 86 via the conduit 135 and branch conduits 
133 and 134, respectively. The line restrictors 131 and 132 on the head 
ends of the cylinders 86 provide the viscous damping characteristics to 
this portion of the circuit during both bounce and roll motions and permit 
controlled flow of fluid back and forth from one cylinder to the other. 
In this manner, the pressure differentials between the head (system 
pressures) and the rod ends (atmospheric pressure) due to bounce damping 
assist the cylinders 86 in supporting the vehicle weight and the weight of 
any load being carried by it. The cushioning required to maintain the 
desired ride characteristics and operator comfort whenever the vehicle 
encounters a bump, is provided by the precharged accumulator 127. 
While the invention has been described with reference to the preferred 
embodiment, it will be understood by those skilled in the art that various 
changes may be made and equivalents may be substituted for elements 
thereof without departing from the scope of the invention. In addition, 
many modifications may be made to adapt a particular situation or material 
to the teachings of the invention without departing from the essential 
scope thereof. Therefore, it is intended that the invention not be limited 
to the particular embodiment disclosed as the best mode contemplated for 
carrying out this invention, but that the invention will include all 
embodiments falling within the scope of the appended claims.