Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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Background of the Invention
The present invention generally relates to
- trailers whlch are adapted to be hooked to and pulled
by tractors. More particularly, the present invention
relates to trailers which are suited for containerized
shipments, such as those commonly handled by air cargo
and/or sea transporters.
Commercially available trailers have changed
only slightly over the last thirty years. These trailers
comprise a load bed, a kingpin assembly adapted to be
engaged by a tractor, one or more sets of wheels, and
various peripheral equipment such as lights, bumpers,
etc., particularly as required by the Interstate Commerce
Commission. Generally, the load bed of a trailer is designed
to facilitate the particular load type to be handled,
as for example, a load bed or undercarriage adapted to
carry a tank for hauling liquids, a flat bed configuration
for hauling items secured thereto, or a van configuration
for confining loose loads.
Any commercially acceptable trailer or trailering
system must be compatible with standard tractors which
have devices known to the industry as "fifth wheels",
mounted thereon wich are adapted to grip and pivot with
respect to the kingpins of the trailers to which they
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are attached. The coupling operation of a fifth wheel
to a kingpin merely involves moving the tractor so that
the kingpin is guided through a tapered slot in the fifth
wheel to an appropriate position, after wh~ch a handle
on the side of the fifth wheel is pulled to close jaws
: around the kingpin to complete the tractor-trailer engagement.
Over the last thirty years, the trend in trailer
construction has been to lighten the weight of the trailer
while maintaining suitable strength characteristics so
that heavier payloads could be accommodated while meeting
the various weight requirements imposed by each state,
particularly concerning the weight carried by each axle
and the bridging distance permitted between axles. Accordingly,
most trailers which have been constructed in recent years
have been built with abbreviated understructures disposed
in the vicinity of the rear axles, thereby substantially
reducing the weight of the understructure while providing
sufficient support in the axle region to handle most
loads. Similarly, the use of "sliders" in connection
with these abbreviated understructures has gained wide-
spread acceptance in the industry. These ~liders generally
allow a double axle assembly supporting the rear of the
trailer to be moved relative to the underside of the
trailer for a distance of approximately nine feet (for
a forty foot trailer), so that, depending upon the particular
load and state weight requirements, a load may be appropriately
balanced between the tractor and trailer. In order to
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reduce tread wear and increase the efficiency of a given
trailer when that trailer is being pulled in an empty
or partially loaded condition, the industry has also,
when appropriate, utilized axles which may be selectively
retracted vertically away from the raod surface to reduce
the number of tires in contact with that surface when
that axle is not needed.
In spite of the approaches discussed above,
most trailers presently in use are subject to certain
drawbacks which result in less efficient load transpor-
tation and higher maintenance and service costs. In
particular, virtually all trailers now in use are equipped
with landing gears which, during the hauling thereof,
are folded under the trailer body. These may be lowered
to support the front end of the trailer when that end
of the trailer i8 not supported by a tractor. Since the
trailers themselves are quite heavy, landing gears are
normally powered by variable speed winches which move
the landing gears into position. Although vital when
needed, landing gears are basically superfluous to the
operation of each trailer during hauling. It has not
been economic, therefore, to construct landing gears
which are so rugged and durable as to adequately support
certain trailers in the fully loaded condition. Further,
these landing gears are particularly prone to failure
or damage during the hook-up operation when a tractor
backing into the trailer to grab the kingpin may exert
substantial torques on the landing gear.
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Very recently, the above described problems
of cargo shipment have been complicated by the increasing
use of containerized shipments, and particularly shipments
of containers having dimensions approximately ten or
twenty feet long and the full width of a trailer body.
While these relatively large containers have gained widespread
acceptance in the air and sea transport industries, they
have created considerable difficulties for truckers who
7 normally deliver the contents of such containers locally,
as for example, to standard loading docks where final
unloading of the transported materials is to take place
Conventionally, twnnty foot containers are provided with
a single set of cargo doors disposed at one end thereof.
Accordingly, as a standard procedure, many haulers have
adapted twenty foot cargo beds to receive such containers,
to buckle those containers to those beds and to transport
each container individually to its destination.
While it may appear that a conventional flat
bed, forty foot long trailer cou7d be adapted to handle
two twenty foot trailers, in reality this configuration
is not feasible if it is desired that the contents of
each of the containers are to be unloaded while the containers
are on the bed, as i8 normally the case. This is because
cargo access at the end of at least one of the two containers
is restricted by door placement. To attempt to unload
a twenty foot container from the side i8 not economical
since almost all loading docks are adapted for end loading
trailers.
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Very recently, one approach which has been
taken by Seaboard World Airlines is the provision of
two coupleable chassis, each of which is intended to
receive a single twenty foot cargo container. Essentially,
each chassis is a twenty foot trailer comprising a load
bed, landing gear, and axle assembly which is mounted
on a sliding sub-chassis. Each of these trailers may
be coupled together to be pulled by a single tractor
according to the following procedure a first of the trailers
having the container positioned thereon is appropriately
located with the landing gears and struts in the down
position while the second trailer is coupled to a trailer
and the landing gear put in the up position. The wheels
on the second trailer are then locked and the cab moved
forward so that the sub-chassis and wheels of the second
trailer extend backward beyond the end of the second
container. The chassis may be operated in this position
or alternatively may be backed into the first trailer
so that the kingpin of the first trailer will engage
with the locking guides in the extended sub-chassis of
the second trailer. The landing gear of the first trailer
may then be moved to the up position after which the
slider on the second trailer is again released and the
entire unit moved forward until the wheels of the second
trailer have extended even further into a correct position
for a one hundred and twenty inch tandem setting, whereupon
the slider of the second trailer is again locked and
the slider of the first trailer released and brake set.
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The entire unit may then move backwards relative to the
wheels of the first trailer until the two suspensions
automatical~y unite into a load equalizing tandem wherein
the axles of the first and second chassis are adjacent
to each other.
As seen from the above description, while the
coupleable trailer approach will facilitate the transport
of two twenty foot containers by a single tractor, this
benefit is achieved at the expense of a relatively elaborate
coupling procedure which requires the tractor operator
to leave the cab five times to couple or un-couple one
trailer from the other. Additionally, in order to effect
delivery of the contents of the containers, it is necessary
to go through the coupling and uncoupling procedure many
times in order to facilitate access to each of the containers.
Accordingly, although this system has achieved some success,
the complexity of this system and its susceptibility
to damage, particularly landing gear damage, during the
coupling and uncoupling operation, has limited its widespread
application in the industry.
When i* is desired to haul greater loads than
may be easily accommodated on a single trailer, the industry
has occasionally resorted to the use of "dogs", which
are additional trailers, usually with pivotal front axles,
attached in tandem to the preceding trailer, usually
through a hook-and-eye or ball hitch arrangement. While
this type of transport has achieved some success, its
use has been severely limited by safety problems as well
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as by difficulties in distributing loads between the front
and rear trailers and in handling the rear trailer, as for
example, during unloading and tight-quarter maneuvering.
SUMMARY OF THE INVENTION
To provide improvements in respect of the foregoing
problems, I have invented an apparatus for transporting a
plurality of cargo containers, said apparatus being selectively
coupleable to the fifth wheel of a tractor, comprising: (a)
a first elongate trailer comprising at least two coupling
means, at least one disposed at each end thereof, for
selective pivotally coupling with a tractor's fifth wheel;
(b) a second elongate trailer comprising at least one coupling
means for selective pivotally coupling with said tractor's
fifth wheel; and (c) a dolly means comprising at least two
fifth wheels positioned for coupling with said coupling
means of said first and said second trailers to tandem link
said trailers, said dolly means further comprising a sub-
stantially elongate frame having at least two fifth wheels
mounted at the opposing ends thereof, and further comprising
at least one axle means for supporting said elongate frame,
said axle means being slidable along substantially the entire
length of said frame for positioning at any of a plurality of
preselected positions along said frame, said dolly frame
further comprising at least two parallel tracking members
engaging each of said axle means.
The invention also consists of an apparatus for
transporting a plurality of cargo containers, said apparatus
being selectively coupleable to the fifth wheel of a tractor,
comprising: (a) a first elongate trailer comprising at least
two coupling means, at least one disposed at each end thereof,
for selective pivotal coupling with a tractor's fifth wheel;
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(b) a second elongate trailer comprising at least one
coupling means for selective pivotal coupling with said
tractor's fifth wheel;~c) a dolly means comprising at least
two fifth wheels positioned for coupling with said coupling
means of said first and said second trailers to tandem link
said trailers; and (d) means for selectively preventing
pivotal movement of said dolly means with respect to at
least one of said trailers to said dolly means has been
coupled, said means comprising at least one retractable pin
which is journalled within a bore formed through at least
one of said dolly fifth wheels, which pin is generally biased
away from said trailer, said means for preventing pivotal
displacement further comprising an eccentric cam means for
selectively extending and retracting said pin.
Finally the invention also relates to a method of
receiving, transporting and presenting to a loading dock, x
number (where x is an integer greater than 2) of end-access
door cargo containers, said method comprising the steps of:
(a) providing y number (y being the nearest whole integer,
rounded down, of the value of x divided by 2) elongate
trailers of sufficient length to receive at least two of
said end access cargo containers, each of said trailers having
at least two coupling portions disposed at generally opposing
ends thereof for alternative coupling to a tractor's fifth
wheel; (b) loading at least x - 1 number of said end-access
door cargo containers onto said trailers with their access
doors located at said generally opposing ends of said
trailer; (c) providing, when the value of x divided by 2 is
not a whole integer: ~i) at least one additional elongate
trailer having at least one coupling portion at one end
thereof for selectively coupling to said trailer's fifth
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wheel; and (ii) loading at least one of said end-access door
cargo containers onto said additional elongate trailer with
its access doors located at the opposite end of said
additional trailer from said coupling portion; (d) tandem
coupling said y number of trailers between adjacent coupling
portions of said trailers utilizing y - 1 number of dollies,
each having a plurality of fifth wheels mounted on a frame
spanning therebetween, said fifth wheels engaging said
coupling portions, to thereby form a cargo train; (e) hauling
said train through a tractor's fifth wheel coupled to a
coupling means of one of said y number of tractors; ~f)
uncoupling said trailers from said dollies; and (g) coupling
said tractor successively to alternate ends of each of said
y numbers of trailers to thereby maneuver said x number of
containers into said loading docks to successively present
each end axis door of each cargo container to said loading
docks, to thereby facilitate access to each of said
containers.
These and other features of the present invention
will become apparent from the following more detailed
description of embodiments thereof.
Brief Description of the Drawings
Fig. 1 is a side elevation of the preferred embodi-
ment trailers and trailer dolly showing cargo containers
loaded thereon wherein the various hook-up steps for trailer
hitching and load balancing are illustrated;
Fig. 2 is a greatly enlarged perspective view
of the preferred embodiment dolly having three axle
: assemblies mounted thereon;
Fig. 3 is a greatly enlarged end view of the pre-
ferred embodiment dolly illustrated in Fig. 2, taken as
indicated by the lines and arrows 3-3 in Fig. 2;
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Fig. 4 is a cross-section of a portion of the dolly
~ fifth wheel shown in Fig. 3, taken as indicated by the
lines and arrows 4-4 in Fig. 3.
Description of the Preferred Embodiment
Although specific forms of the invention have been
selected for illustration in the drawings, and the following
description is drawn in specific terms for the purpose of
describing these forms of the invention, this description is
not intended to limit the scope of the invention which is
defined in the appended claims.
The present invention relates to a cargo trailer
system comprising at least two cargo trailers and a dolly
means for selectively hitching those trailers in tandem.
Unless otherwise specified in the present specification,
the preferred trailers for use with the dolly means and in
the trailer system herein described are those trailers
which are more fully described in my U.S. Patent 4,132,326
issued January 2, 1979 and entitled "Multiple Hook-Up,
Movable Axle, Container Cargo Trailer".
Referring to Fig. 1, a tractor designated generally 100
is shown hitched to a trailer 200 constructed in accordance
with my aforementioned patent application, which trailer has
loaded thereon cargo containers 202, 204 and 206. Referring
to view A, the coupling operation is illustrated between
trailer 200, wherein the pivotal bumper
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208 has been moved to the upper position, and a preferred
embodiment dolly 400. In view A the tractor 100 and trailer
200 are moved towards the dolly designated generally
400, as shown. In Figure 1, a dolly having two axles
is illustrated, the brakes of the axle means of which
dolly have been locked to facilitate easy coupling between
trailer kingpin 210 and front dolly fifth wheel 402.
In view B of Fig. 1, the attachment between
the dolly fifth wheel 402 and kingpin 210 has been completed.
In view B, the previous trailer position is shown in
phantom. As will be described more fully hereinafter,
the dolly may now be interlocked with respect to trailer
200 to prevent pivotal movement of the dolly 400 with
respect to trailer 200 to facilitate the next backing
meneuver, which is linkage with trailer 300, which is
to be pulled as the "dog". The rear trailer 300 is illustrated
loaded with two containers 302 and 304, each of which
has end cargo doors 303 and 305, respectively.
At the present time, commercial cargo container
generally are made in ten, twenty, and forty foot lengths.
Almost all of these cargo containers have end mounted
doors (as illustrated) and must be unloaded from the
end, as for example, to a loading dock. Depending upon
the desired length of the trailer, for trailer 200, for
example, cargo container 202 and 204 may be 10 foot containers,
while cargo container 20~ may be a 20 foot container.
Similarly, for cargo trailer 300, cargo containers 302
and 304 may represent either 10 or 20 foot containers,
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depending upon the length of the cargo bed. In any case,
it may be seen that the trailering system of the present
invention may conveniently present twice the number of
cargo containers as trailers utilized to haul the same,
and at least four times the number of such containers
as tractors needed to make a given run.
As shown by the arrow in view B of Fig. 1,
the preferably interlocked dolly 400-trailer 200 unit
is backed towards trailer 300 in order to interconnect
j 10 dolly fifth wheel 404 with kingpin 310. For this interconnection
process it will be noted that axle assemblies 314 and
316 of trailer 300 have been moved to relatively opposing
ends of track 318, which is the trailer storage position.
- Similarly, the do'ly 400 has had its a~le assemblies
406 and 408 moved to opposing ends of its frame track
, 410, whereupon the proper coupling heights between fifth
wheel 404 and kingpin 310 have been established.
In view C of Fig. ls the interconnection between
dolly 400 and trailer 300 has been completed. As will
be described more fully hereinafter, means are provided
for similarly interconnecting trailer 300 with dolly
400 to prevent relative pivotal movement therebetween.
Accordingly, in the fully linked mode, the entire trailer
system will remain rigid, and therefore may be backed
and otherwise manuevered, within limits, by the tractor
as if a sin~le long trailer unit.
In most instances hauling and maneuvering in
the forward direction will be accomplished by allowing
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each trailer and the dolly to pivot with respect to each
other. After linkage has been completed, as shown in
view C of Fig. 1, appropriate repositioning of the axles
may be accomplished in order to optimize weight distribution
and maneuvering capability. One such reorientation of
axle positions has been accomplished in step D of Fig.
1. In this view, axle assemblies 214 snd 216 have not
been moved from their rearmost running position, as originally
illustrated. It may be seen, however, that the relative
positions of these axles along track 218 of trailer 200
may be varied to affect the weight distribution of the
cargo load, as well as, the relative pivot point of the
cargo bed with respect to rear kingpin 210. These axle
positions may therefore be modified to adjust the tracking
behavior of both dolly 400 and indirectly trailer 300.
In view D, dolly axle assembly 408 and trailer
axle assembly 316 have been relatively shifted to their
rearmost positions adjacent axle assemblies 406 and 314
respectively. This axle assembly movement has been accomplished
by selectively releasing the means otherwise locking
axle assemblies 408 and 316 to tracks 410 and 318 respectively,
by fixing the brakes on wheels 408 and 316, and by moving
the remainder of the apparatus relatively forward as
illustrated by the arrow in view D, first to move axle
assembly 408 into the position shown, and then after
releasing the brakes on axle assembly 408 and locking
that axle assembly with respect to frame 410, by continuing
in the forward direction until axle assembly 316 assumes
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the position shown in view D. The relative positioning
of the dolly axle assemblies 406 and 408 relative to
dolly track 410, as well as the relative positioning
of axle assemblies 314 and 316 along trailer track 318
will, as discussed above, establish the relative pivot
points, load distribution and overall behavior of these
components within the system.
As seen from the above description, it is contemplated
that the novel dolly-and-trailer apparatus of the present
invention will facilitate the transport of a large number
of containers, each of which may be loaded on a trailer
in a position presenting the end loading doors so that,
with a minimum amount of effort, each of the containers
may be end loaded or unloaded to a conventional loading
dock.
In addition to the features of the trailer
described in my aforementioned patent application, both
the trailers and the dolly of the present invention are
also ~itted with removable service brackets 220 and 222
for trailer track 218, 420 and 422 for dolly track 410,
and 320 and 322 for trailer track 318. These service
brackets, the structure of which will be described more
fully hereinafter, prevent the axle assemblies from sliding
off the ends of their respective tracks during the normal
operation of the trailer, but may be easily removed when
it is desired to remove, substitute, or add axle assemblies
to the trailer. In this manner, depending upon the load
which is to be transported, it is on~y necessary to select
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the proper cargo bed and fit that bed with the required
number of axle assemblies needed in order to adequately
transport the load. Accordingly, where light loads are
to be hauled and only one or two axle assemblies necessary,
additional axles may be removed from a given trail~r
so that extra axle-assembly weight need not be transported.
Conversely,~for extremely heavy loads a conventional
trailer may simply be modified by removing the service
brackets from one end of the track and by sliding additional
axle assemblies thereon until the load may be accommodated.
The service brackets function in a similar
manner when incorporated on the preferred embodiment
dolly, and are shown with clarity in Figs. 2 and 3 of
the present application. Referring now to Fig. ~, an
embodiment of the dolly designated generally 500 is illustrated
in an isometric view having three axle assemblies designated
generally 502, 503 and 504 mounted for selective sliding
movement along dolly track 510 thereof. As seen in Fig.
2, in addition to the axle assemblies, the dolly comprises
a substantially elongate frame designated generally 520,
the lower portion of which forms the dolly tracks designated
generally 510 and 512 respectively. On the upper surface
of opposite ends of the elongate frame 510 are mounted
two fifth wheels desiganted generally 530 and 540, each
of which fifth wheels is mounted in a conventional manner
on the frame and comprises a conventional slot and the
standard gripping assembly used by the industry for receiving
and pivotally engaging a kingpin introduced therein
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(the kingpin engagement assembly is not shown in the
drawings, but is generally manually activated by a lever
mounted on the side of the fifth wheel). Fifth wheel
530 is shown having an additional locking mechanism which
may be activated by rotating lever 550 to cause a pin
552 to protrude from the locking aperture 553. Alternatively,
where it is desired to provide the active portion of
the locking means on the trailer, rather than the dolly,
the fifth wheel may be merely provided with an aperture
as for example 554 shown on fifth wheel 540 in Fig. 2,
which aperture is oriented to mate with the piston rod
of a pneumatic cylinder mounted to the undercarriage
: of the trailer assembly so that the dolly may be axially
; aligned with respect to the trailer, and then locked
; in that position by either of the aforementioned locking
means.
As seen from Figs. 2 and 3, the structure of
the dolly assembly i9 relatively simple. Main transverse
"I"-beam 560 and 562 run the length of the dolly and
form in combination with transverse "I"-beam 564, 566,
568, and 570 and integrally welded frame assembly comprising
a suitable upper fifth wheel mounting surface. The lower
portions of the main "I"-beams 562 and 560 form dolly
track means 512 and 510 respectively, which track means
may be seen to comprise a plurality of periodically spaced
apertures formed in the lower central portion of the
main "I"-beams for receiving the locking pins of the
wheel assemblies when those wheel assemblies are to be
fixed with respect to the dolly. As seen particularly
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in Fig. 3, the structure of the axle assemblies (502
in Fig. 3), and particularly the sliding interengagement
between the axle assemblies and the tracking portions
510 and 512 of main "I"-beams 560 and 562, are identical
to those disclosed for the preferred embodiment in my
aforementioned copending patent application. The service
brackets 580 and 582 comprise substantially box-shaped
members having a t-shaped channel formed therethrough
adapted to matingly receive the lower terminal ends of
the tracking 510 and 512 of the main longitudinal "I"-
beams of the dolly. These service brackets 580 and 582
are removably attached to the ends of the tracking portions
by means of bolts 584 and 586 or other similar fastening
means which may be easily attached to the service bracket
to the "I"-beam through an existing axle interlock aperture
in the "I"-beam. Thus, it may be seen that in those instances
where the maximum bridging distance must be attained,
and the safety advantages of the service brackets not
desired, the service brackets may be removed and the
apertures otherwise utilized by the locking pins associated
with the axle assemblies, to thereby facilitate the endmost
positioning of those assemblies with respect to the dolly.
Referring now in particular to Fig. 4, which
is a cross-section of a portion of the fifth wheel illustrated
in Fig. 3 shown hitched to a phantom-illustrated trailer
coupling portion, the structure of the fifth wheel locking
pin assembly for preventing pivotal displacement of the
dolly with respect to the trailer is illustrated. Handle
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550, the shaft of which is shown in cross-section in
Fig. ~, is seen to be pivotally mounted on a plurality
of bearing block brackets 590. An eccentric cam 592 is
attached to shaft 550 and is oriented under a spring-
biased pin 552 wich is journalled within a bore formed
in the fifth wheel plate 531 by utilizing spring 591
to bias the pin 552 away from the trailer. An additional
margin of safety is therefore provided during transit
by preventing the inadvertent interlocking of the fifth
wheel with respect to the trailer. Rotation of the shaft
550 in the directions shown by arrow R in Fig. 4, alternately
withdraws or inserts pin 552 into an appropriate pivot
interlock bore 593 formed in the undersurface of the
trailer axially adjacent railer kingpin 595. Accordingly,
as illustrated in Fig. 4, pivotal movement of the dolly
with respect to the trailer is effectively restrained
for maneuvering purposes.
From the foregoing description, it may be seen
that the trailer system of the present invention is simple,
inexpensive, flexible, and provides superior advantages
~o those tandem trailer hauling systems heretofore known
to the art. In particular, each trailer, and the dolly
to be utilized therebetween, may be tailored to handle
the particular load to be carried, utilizing one or more
standard axle assemblies which may simply be slid onto
or from either the trailers or dolly desired for a given
haul. By relying upon the best known methods of facilitating
an interconnection between trailers, namely that of a
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standard fifth wheel-kingpin couple, the trailer system of
- the present invention provides superior safety. The
maneuverability for a tandem trailer system is also maximized
not only by utilizing a plurality of variously sized trailers
and/or dollies, but also by positioning the wheels of each
trailer and dolly with respect to each other and with
respect to their respective associated trailers or dollies,
such that the pivotal action of those trailers maximizes the
maneuverability of the unit. For example, a wheel positioning
heretofore unacceptable for highway speeds due to "whipping"
or"jack-knife" problems may now be utilized at low speeds in
densely populated areas for increased maneuverability in
tight quarters. Conversely, after leaving metropolitan areas,
the axle assembly positioning may be re-adjusted to achieve
maximum safety at highway speeds.
It will be understood that various changes in the de-
tails, materials and arrangement of parts which have been
herein described and illustrated in order to explain the
nature of this invention may be made by those skilled in the
art within the principle and scope of the invention as ex-
pressed in the following claims.
It will further be understood that the "Abstract of
the Disclosure" set forth above is intended to provide a
non-legal technical statement of the contents of the
disclosure and is not intended to limit the scope of the
invention described and claimed herein.
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