Note: Descriptions are shown in the official language in which they were submitted.
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RIGID B~AM SUSP~NSION ASS~MBLY FOR TRAILERS
BACKGROUND OF TH~ INVENTION
Field_of the Lnven~ion
The present invention ~elates to tractor-trailer
rigs in general, and in particular to semi-trailers and
the like such as over-the-ruad haulers, liquid tank
trailers, and so forth. More particularly still, it
relates to wheel suspensions of the rigid beam type.
Prior Art of the Invention
Rigid beam suspensions are known from Vnited States
Patent 3,332,701 ~ranted July 2S, 1967, to Lloyd D.
Masser and titled "Suspension For Automotive Vehicles."
The patent states that the suspension disclosed is
especially adapted ~or the use of air sprin~s in
commercial vehicles, and continues:
"The inherent lack of lateral stability of an air
~pring, which e6sentially is an air-in~late~ bag9
has necessitated in previous air suspensions the
use of relatively complicated systems of torque
rods, lateral stabi.lizer bars, bolsters, a~d the
like, esPeciallY in tandem structures. Such
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equipment is relatively heavy and reduces the
amount of payload which can be carried by the
vehicle where load restrictions are in force.
Moreover, such equipment is expensive and gives
rise to design problems in the relatively crowded
understructures of commercial vehicles.
The object of this invention is to provide a
simple, light-weight, relatively inexpensive air
spring suspension s-tructure which eliminates the
necessity for torque rods, stabilizer bars,
bolsters, and the like and which can he used in
either sin~le- or multiple-axle arrangements.
In general, the invention contemplates the use of
substantially rigid control arms extending
longitudinally away from pivotal mounts at opposite
sides of the vehicle, the springs being disposed in
load-transmittin~ relation between portions of the
arms and vehicle frame.
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A substantially rigid wheel-carrying axle is
attached to the arms, and each axle attachment
includes two pins which extend generally parallel
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to the axle, the pins being spaced apar~ to provide
a broad base for support a~ainst lateral thrust on
the control arms and against drive or braking
torque on the a~le. Bodies of ruhber or the like
are confined between the pins and adjacent portions
of the axle attachments. The arms and their
pivotal mounts and the axle and axle attachments
are capable of themselves of withstanding the
torsional and lateral forces thereon incidental to
operation of the vehicle."
A generally useful bac~ground discussion of rigid
beam type suspensions is found in United States Patent
4,566,719 g-ranted January 28, 1986 to Ervin K. Van
Denberg. The patent states:
"Rigid beams> while denoted 'rigid', do, of course,
flex during operation of the vehicle. This flexing
is, simply stated, less than tha~ of a
conventional, flexible leaf spring type of beam;
t~us requiring resilient mountings at either or
both of the two aforementioned points. Not only do
such beams flex during operation, but they must be
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allowed to flex or, given reasonable sizes and
thicknesses, they wilL hreak during vehicle
operation, Indeed, early attempts to rigidity
connection~s in the beams either at the frame
connecting member (e.g. a hanger bracket) or at the
axle connection (or at both) without providing
sufficient resiliency at one or both of the
connections proved futile in that frequent beam
breakage was experienced."
The patent continues to state that one early
solution to this problem was to provide a relatively
small resilient pivot bushing at the hanger (connection)
and that while somewhat success~ul, wear-out of the
resilient bushing was a frequent problem.
Both United States Patents 3,332,701 and 4,566,7l9
are incorporated herein by reference.
SUMMARY OF THE INVENTION
T~e present invention provides a rigid beam
suspension system exhibiting improved torsional
2~ stability while being simple in design and construction.
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In a narrower aspect, the present invention
provides a combined main frame and suspension assembly,
which7 in cer-tain embodiments permits a decrease in
trailer height and/or lower center of gravity for
improved stability.
In a preferred embodiment of the pre~ent invention,
the conventional I-beams, running the length of the
trailer, are replaced by a tubular beam, such as a
rectangular tube, which provides additional ~apacity for
carrying fuel or other liquids.
It is expected that the present invention will lead
to the design of multi-wheel vehi~les, especially semi-
trailers, which exhibit improved stability and safety of
operation. It appears that such vehicles may provide
better load weight distribution among the wheels, and
should improve ~he durability of the unit in road use.
In the embodiments incorporating a closed or open
~ubular longitudinal beam additional load may be
accomodated, leading ~o lar~er loads for light
materials, or lower center of gravity for heavy
materials such as liquids, or additional fuel capacity.
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Accordingly, the present i.nvention provides a rigid
beam type wheel suspension for a wheeled vehicle7
comprising, on each side of said vehicle: a transverse
pivot shaft rigidly affixed to a frame of said wheeled
vehicle and proJecting horizontally outwardly therefrom;
a cylindrical bearing rotatably mounted on said pivot
shaft; a ri~id beam memb0r rigidly affixed at a forward
end thereof to said cylindrical bearing at its outer end
and perpendicular thereto, and adapted at a mid portion
to support a wheel axle; and said rigid beam member
havin~ a compression spring means affixed at a rear end
thereof ~o meet said vertical frame.
In one aspect, the present invention provides a
combined main frame and suspension assembly for trailer
lS vehicles and the like, comprising: a main load carrying
frame for said trailer vehicle, a longitudinal tubular
main frame beam extending substantially along the length
of said main frame at a lower part thereof and adapted
~o-r storage of cargo therein; and at least a pair of
wheel suspension assemblies affixed one on either side
of said tubular main beam.
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In a further embodimPnt, the invention prDvides a
combination oE a main frame with suspension assemblies
for a trailer vehicle, or the like, comprising: a main
load carrying frame for a trailer bndy or load, having a
S main tubular beam longitudinally extendin~ along said
main frame providing the vehicle with torsional
stability and with tank capacity Por carryin~ fuel or
other cargo, said main frame further having a number of
pairs of cross beams spaced along the length of said
tube beam, extending from both sides of said tube beam
at its upper portion and forming a base for positioning
the trailer body or loads, a number of pairs of
suspension assemblies corresponding to a number of said
cross beams, each pair of said suspension assemblies
lS linking a pair of split-wheel axles to the two sides of
said tube beam respectively, each suspension assembly
further comprisin& on each side of said tube beam a
cushioning pneumatic spring, a wheel axis support arm
: which extends parallel to said tube beam and is pivoted
at~ its one end on a shaft extending transversely through
said tube beam at its lo~er portion, and attached at its
other end to the spring ~which is secured to said tub~
beam, said shaf~ bein& held at its outer end by a
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bracket depending from said cross beam, said wheel axles
being incorporated into said support arm at its middle
portion.
BRIEF DESCRIPTION OF THE DRAWINGS
The preferred embodiment o~ the present
invention will now be described in detail in corlJunction
with the at~ached drawing fi~ures, in which:
Figure 1 is a side elevation o~ a wheel suspension
and partial view o~ the frarne of a trailer in accordance
with the present invention;
Figure 2 is a view alon~ the line A-A in Figure l;
and
Figure 3 is a top partially exploded view of the
ri-~ht-hand suspension shown in Figure 2 without the
trailer frame.
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Figures 4, 5, and 6 show additional embodiments of
the tubular longitudinal beam~ and of the loading
portion of the vehicle.
DESCRIPTION OF THE. PREFERRED EMBO~IMENT
With reference to Fi~ures 1 and 2 of the drawings
there is illustrated part of a trailer showing one set
of two dual wheels on either side, usually being one of
several sets of such wheels supporting the trailer on
the road surface along the length thereof. The trailer
lQ frame comprises a supportin~ rectangular tubular beam 10
running along the length of the trailer, which is shown
here only in the vicinity of a set of trailer wheels 11.
An axle 12 of the wheels 11 is anchored in a suitable
and conventional manner on a rigid beam 13 having at one
end thereof a conventional air bag spring 14 and welded
; at its other end to a swivelling pivot bearin~ (fulcrum)
15, the bearing 15 surrounding and mounted on a fixed
-shaft 16 with a cylindrical TEFLON (TM) bushing 17
between the swivelling bearing 15 and the fixed shaft
16. The shaft 16 extends on either side of the
.~ rectangular beam lO, piercing throu~h and being welded
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to the latter. Between the outer wall of the
rectangular beam 10 and the acljacent end of the bearing
15 there is a w~sher 18 welded~ to the outer wall o~ the
rectangular beam 10 in order to protect it frorn wear and
friction due to the movement of the cylindrical bearing
15. The outside end of the cylinder 15 i5 prevented
from axial movement by means of a bolt 19 bolted tu a
bracket 20 at the end of which the shaft lh is anchored.
The upper end of the bracket 20 is affixed to cross beam
21, which, together with the rectangular beam 10 to
which it is welded, forms part of the supporting frame
of the trailer. Cross beam 21 also terminates at its
outer end in a vertical stake well 22 for receiving a
stake 23 which forms part of the frame superstructure of
the trailer. A trailer load is shown symbolically as
tree logs 24.
In the above description only the right-hand side
suspens:ion was described, the other (left-hand) side
bein~ a mirror image thereof. As may be seen f rom the
description the simple eonstruction of the rigid beam
suspension exhibits a pivot joint with a long inCerface
between the pivoting cylin~ical bearing 15 and the fixed
pivot shaft 19, thereby improving the stability of the
independent wheel suspension. A shaft 16 thickness of
three inches in diameter is suf`ficient for an eight ~oot
long shaft spanning the width of a conventional heavy
duty hauler.
In the disclosed embodimen-t, the shaft 16 extends
transversely through the main support beam 10 at a level
9.5 inches above its bottom wall, which is itself
approximately 12 inches above ground in operation. In
cross section the main support beam 10 is 24 inches by
30 inches and is made of 3/8 inch thick steel. The
pivo~ cylindrical bearing 15 is made from steel tubing
havin~ 4 inches internal diameter and is 3~ inches long.
Thus the nylon bushing 17 is made from a 1 inch thick
nylon tube having a 3 inches internal diameter and is
also 35 inches long. The washer 18 is a 112 inch thick
steel washer with 4 inches internal diameter.
As may be seen from Figure 2, the fact that the
shaft 16 goes through the main support beam 10, permits
smaller trailer height with the load being closer to the
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ground and thereEore increa~sed stability due to the
lower center of gravity of the entire trailer. This
would be particularly advantageous for liquid tank
trailers9 especially when they are not completely
filled. Figure 5 shows a flalt bed 25 trailer profile,
in which some of the aforementioned advantages would
still be obtained.
A further advantage of using a sealed reetan~ular
or otherwise tubular box or cylindrical for ~he main
frame beam lO is that the enclosed volume may be used
for additional fuel tank capacity, or for any other
purpose. Of course, the advantages of the ri~id beam
suspension itself, as disclosed herein, are independent
of whether the main support beam lO is a volume
enclosing tube or not. For it may be any other type of
sufficiently rigid support beam for anchoring a fixed
pivot shaft on either side thereof.
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measuring 6 inches nn each side with the axle 12
anchored through it a~ a distance of 27 inches from the
center cf the shaft 16. The cen-tral axis of the air bag
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14, which is preferably bolted to a plate welded to the
ri&id beam 13, is at a distance of 23 inches from the
center of the axle 12.
Figures 4 and 6 show such rigid beams 10 which are
S at least partly open at the top to communicate with the
main volume containin~ enclosures 26 (Figure 4) and 27
(Figure 6), and so are adapted to increase directly the
load capacity of the trailer, even for solid or granular
loads; but more importantly for tank trailers, where
given the same capacity the centre of gravity is lowered
as in Figure 6.
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