Note: Descriptions are shown in the official language in which they were submitted.
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FIELD OF THE INVENTION
The present invention relates generally to devices
adapted to distribute the weight of a tractor trailer
more efficaciously.
BACKGROUND OF THE INVENTION
It is very well known in the art to provide devices
of the above type. The desired effect o such devices
is to shift weight to the front axle of the tractor away
from the rear axle of the trailer,~in or~er ~ :-
to meet legal load limitations on ~he various axles and toimprove handling of the tractor~ The devices in question
are embodied by pneumatic means exerting upward force~n
the forward end of the trailer. Till now, such devices
have been located forwardly of the fifth wheel of the
tractor.
However, it is not always advantageous to shift
weight away from the driving wheels of the tractor. For
example, a tractor trailer unit travelling on a rough dirt
or sand forest road with insufficient weLght on the driving
wheels of~the tractor~may undergo wheel jumping and/or dif-
ferential breakdown. Poor traction is also produced on
snow- or ice-covered roads, or on forest ro~ds. Poor
traction necessitates the use of~e~ply-grooved tires
which are expenslvej ox~chains which are time-consuming
to Ln~tall and remove.
OBJECTS OF~ ~THE~ INVENTION
~ In view o the above, it is a prime~object of the
present invention to provIde~a weight~transer device which
avoids the~above problems. ~ ~ ~
~It~is another~object of the~present invention to
prov~de a we~ght transfer dev~ce~of the~character described,
whlch ~s~simple~ln~des~gn~and whiah will~fit aLl tractors.
SUMMARY~ OF~THE INVENTION
The~above and other advantages o~ the present
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invention are realized according to a preferred embodiment
comprising an upward ~orce-producing means, preferably a
vertically-expandable air bag which can be quickly exhausted
on rough roads. A frame means is provided to support
the force-producing means and to secure the latter to the
rearward frame members of the tractor. The force-producing
means is located no more than six inches rearwardly of the
rearmost driving wheels of the tractor and behind the
fifth wheel of the tractor. The top of the force-producing
means has secured thereto a rotation plate provided with
an antifriction means to allow lateral pivotal motion of
the trailer about its kingpin relative to the tractor. The
frame means serves also to stabilize the force-producing
means, as will be disclosed below.
Controls for the force-producing means are
preferably located in the tractor cab.
BRIEF DESCRIPTION OF THE DRAWINGS
The above will be more clearly understood by having
referral to the preferred embodiment of the invention, illus-
~0 trated by way of the accompanylng drawings, in which:
Figure 1 is a perspective view of the inventioninstalled on a tractor frame; and
Figure 2 is a~side elevation of the invention,
showing a tractor trailer unit in dashed outline.
Like numerals refer to like elements throughout
the drawings.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
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~ In the~figures, the weight transfer device of the
prèsent inventlon, indicated~at lj is installed at the rear
portion of a~tractor 2. ~The latter includes a pair of rear-
wardly-extending~pa~rallel frame msmbers 3, 4, cab 5, rear
driving wheels~6, 7j and;a fifth wheel 8.
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To the top of both frame members 3 and 4 are
fixed inclined ramps 9, 10 to facilitate hitching of
trailer 11 to tractor 2.
The frame of device 1 consists of a pair of paxallel
transverse mounting bars 12 and 13, each secured at their
opposite ends to fastening members 14 (only one being visible).
Members 14 are bolted at 15, or otherwise rigidly secured
to the adjacent frame members 3 and 4. The middle portions
of mounting bars 12 and 13 have rigidly secured thereto a
supporting plate 16. Seated on the latter is a vertically-
expandable air bag 17, which is fed by a compressed-air
line 18. Controls in the cab (not shown) operate the air
bag.
Secured to the upper end of the air bag 17 is a
rotation plate 19, which has a forward edge 19'. Forward
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edge 19' has rigidly secured thereto~a pair of laterally-
spaced brackets 20. Pivotally secured to each of the latter
at 20a is a rigid stabillzing arm 21. The~middle portions
of arms 21 are reinforced by a brace 22. The forward ends
of arms 21 are pivotally attached~at 24 to lugs or brackets
25, in turn fixed to a transverse~member,23, the latter~
extending between ramps 9,~10 and frame memb~ers 3, 4 and
releasably secured to the latter by lugs 9-i, lO'.~ Elements
20, 21, 22, 23,~24, and~;25~constitute~the~rest of the
frame means.
~ As shown;in figure 2, each upwardly- forwardly--inclined
ramp 9, lO~pre~ferably extends between the;~horizontal;plane=
defined by the~support pl=te~16 and~the~rot=tion~plate l9,~ at
least when the ~expandab~le air bag~l7~ }s inflated~to its ~
operàtive conditian~of figure 2 via,pressurized~air~line 18.
Device l further consists ¢f~a pair of rollers 26 and
27.~These two rollers are each disposed along a respective
radial~line extending from the center of the i~th wheel.
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Thus, as the trailer pivots about its kingpin when
the air bag is operating, the rollers will engage
a rigid wear-plate (not shown) fixed to the underside
of the trailer to provide substantially frictionless
contact between tractor 2 and trailer 11 during a turn.
The rollers embody the antifriction means. Pivotal
connections 20a and 24 are parallel,horizontal and
transverse of the truck. They allow rollers 26 to always
be applied flat against ~he trailer wear-plate, despite
changes in road inclination.
It will be readily apparent that, as the
pressure exerted by the air bag is increased, the load
exerted by the trailer is adjustably and partially trans-
ferred rearwardly from the fifth wheel over the driving
axle~(s~ of the tractor. The air bag is adapted to
exert up to 10,000 pounds of force on the trailer.
It is to be noted that the improved tractor
obtained by the device is not at the expense of~a weakened
tractor frame. The device is easy to install and remove.
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