Note: Descriptions are shown in the official language in which they were submitted.
llOOS3S
The invention generally relates to air-ride suspension
systems for vehicles, ana more particularly to a supplemental
air spring assembly adapted to be provided in kit form for
installation in a front end suspension system for a truck or
similar vehicle.
As can readily be appreciated by those familiar with
the trucking industry, shock reduction is particularly signi-
ficant where a truck must ~avel over long stretches of high-
ways and roads in various stages of disrepair. However, any
suspension system employed as a front end suspension system
must be capable of reducing the effects of shock loading
without impairing steering capabilities or of giving an ap-
pearance of being characterized by a low safety factor.
Consequently, even though air springs of one type
known in the prior art have proven to be satisfactory for
their intended use, they have not proven to particularly
attractive for use as a supplemental air spring assembly for
a front end suspension system. This results, at least in
- part, from the fact that the leaf spring assemblies are not
totally captured~ On the other hand, other known systems
tend to be excessively massive, complex and expensive.
It should, at this point, be apparent that the design-
ers of suspension systems for front ends of trucks and the
like are continuously plagued with the problem of overcoming
shock loading without reducing the safety factor of a given
suspension system and without adding substantial weight and
bulk and excessive cost into the design, maintenance and
operation of modified suspension systems.
It is therefore the general purpose of the instant
invention to provide a practical ~olution to the perplexing
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problems aforementioned.
The present invention provides, a supplemental air
spring assembly for use in a front end suspension system for
~ a motorized vehicle of the type~a w~eel-supported axle having
a transversely oriented leaf spring assembly mounted on the
axle and attached at its leading end to a longitudinal frame
member for the vehicle, said supplemental air spring assembly
comprising: a load dissipating arm pivotally connected near
its midportion to the trailing end of the leaf spring assembly,
an air bag seated on one end of the arm and disposed in load
suppor~ing relation with said frame member, and coupling
means including an articulated linkage connecting the opposite
end portion of the arm to said frame member.
In the drawings:
Fig. 1 is a side elev~tion, partially in phantom, de-
picting a use environment for a supplemental air spring
embodying the principles of the instant invention;
Fig. 2 is a partially sectioned end view of the supple-
mental air spring shown in Fig. 1, but on somewhat of an en-
larged scale;
Fig. 3 is a top-plan view of the air spring assembly;
ar,d
Fig. 4 is a fragmentary side elevational view, also
on an enlarged scale, of the air spring assembly shown in
Figs. 1, 2 and 3.
Referring now to the drawings, with more particularity,
wherein like reference characters designate like or correspond-
ing parts throughout the several views, there is shown in
Fig. 1 a supplemental air spring, generally designated 10,
which embodies the principles of the instant invention.
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As depicted in Fig. 1, the air spring assembly 10
is incorporated in a front end suspension system, generally
designated 12, for a truck or similar motorized vehicle, not
designated. It is to be understood, however, that the front
end suspension system 12 includes a pair of leaf spring
assemblies, only one of which is shown, designated 14. The
leaf spring assembly 14 is, in turn, mounted transversely of
a suitable axle, the type of which is dictated by the use
characteristics of the vehicle.
Moreover, it is to be understood that the leaf spring
assembly 14 is ccnnected at its leading end, relative to the
intended direction of normal travel for the vehicle, to a
longitudinal frame member 20 provided for support of the
vehicle. It should, therefore, be appreciated that the vehicle,
leaf spring assembly and supporting axle are of known design.
Therefore, a more complete description of the vehicle and its
leaf spring assembly is omitted in the interest of brevity.
As best illustrated in Fig. 1, the air spring assembly
10 includes a force dissipating arm 22 of an elongated con-
figuration. As a practical matter, the arm 22 is of an inverted
U-shaped configuration and includes a pair of side plates 24,
Fig. 4, between which is extended a bushing received within
an eye 28 of the leaf spring assembly 14. A suitable pin 30
extends through a pair of coaxially aligned apertures formed
in the side plates 24 of the arm 22 and is secured in place
by any suitable means, such as a nut, not designated. It is
to be understood that the force dissipating arm 22 is supported
for pivotal motion relative to the end of the leaf spring
assembly 14, about a pivotal axis established by the pin 30
and coincident with the longitudinal axis thereof.
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The force dissipating arm 22 further includes an ex-
tended end portion 32 which receives an air bag 34 disposed
in a load supporting relationship with the frame 20. The
particular manner in which the air bag is mounted on the force
dissipating arm 22 is a matter of convenience, however, bolts
threaded into blind bores formed in a base plate, designated
36, provided for the air bag 34, serve quite satisfactorily
for this purpose. A similar arrangement is disclosed in
United States Letters Patent No. 3,866,894, aforementioned.
As shown in the drawings, the air bag 34 is a double
convolute air bag which is connected through pneumatic lines
38 to a leveling valve 40, connected in a circuit adapted to
function in the manner generally described in the aforemen-
tioned United States Letters Patent to Sweet et al. Of
course, the particular type of air bag employed is not deemed
to be critical. For example, a single convolute air bag can
be employed equally as well. The purpose of the bag 34 is,
of course, to dissipate as well as to transfer forces between
the frame member and the leaf spring member 14 via the force
dissipating arm 22, as is fully appreciated by those familiar
with air springs for suspension systems.
To the frame member 20 a suitable bracket, not desig-
nated, is bolted or otherwise rigidly secured. This bracket
includes a base web, also not designated, to which is joined
a top plate 44, Fig. 4, for the air bag 34. Consequently, it
should be apparent that the air bag 34 is so disposed as to
be located between the opppsite ends of the leaf spring assem-
bly 14 and is loaded by the frame member 20. Thus a reduc-
tion in the space required in the mounting of the air bag is
achieved.
1~0~S35
In order to stabilize the force dissipating arm 22,
as the air bag 34 is loaded in a reversely varying mode, a
stabilizing linkage, generally designated 46, is proviaed.
This linkage pivotally couples the trailing end portion 48
of the arm 22 to the frame member 20. The linkage 46 is an
articulated linkage and includes a rigid pivotal link 50
which serves to act in opposition to the forces applied to
the air bag 34 for thus restraining the arm 22 against rota-
tion about the pin 30.
As should be apparent from a cursory review of Fig. 4,
due to the moments occurring about the pin 30, the link 50
is placed in compression as the air bag 34 is loaded in com-
pression, and as the air bag 34 is loaded in tension, the
link 50 is similarly loaded. Of course, as the air bag 34
is operatively loaded, the spatial relationship of the pin
30 to the frame member 20 is varied as a consequence of
flexion experienced by the leaf spring assembly 14 in
accordance with the inherent characteristics of leaf spring
design.
In order to accommodate changes in position for the
pivot pin 30, relative to the frame member 20, the link 50
is pivotally connected to a bracket 54 affixed to the frame
member 20. This bracket is located in substantially the
same posi.tion as would have been shackle for coupling the
leaf spring assembly to the frame member, had not the air
spring assembly 10 of the instant invention been incorporated.
As a practical matter, in order to accommodate
pivotal motion, a pin 56 is provided for pivotally inter-
connecting the link 50 with the bracket 54. Similarly, the
link 50 is connected to the end portion 48 o~ the arm 22 by
llO~S3S
a suitable pin 58, as best illustrated in Fig. 2. Thus each
of the pins 56 and 58 serve to accomodate pivotal motion of
the link 50 relative to the bracket 54 and the arm 22. The
pivotal motion thus afforded the link 50 facilitates vertical
and horizontal motion of the force dissipating arm 22, in a
vertical plane, for thus accommodating repositioning of the
arm 22 as load conditions for the bag 34 are varied.
As a practical matter, a leveling linkage, generally
designated 60, is connected between the force dissipating
arm 22 and the leveling valve 40 so that the on-off condition
of the valve 40 is varied as the position of the arm 22 is
varied under changing load conditions for the air bag 34.
The valve 40 forms no specific part of the instant invention.
It should, in view of the foregoing, be apparent
that the arm 22, in effect, remins in a substantially parallel
relationship with the frame member 20 as the air bag 34 is in
operation reversely loaded, due to the fact that the pivotal
axis established by the pin 30 is a flaoting axis and one
end of the force dissipating arm 22 is restrained by the
; 20 articulated linkage 46. Since the arm 22 tends to remain in
a substantially horizontal disppsition, the air bag 34 tends
to be deformed in a substantially uniform manner. Thus the
severity of the localizing of fatigue for the bag 34 tends
to be reduced substantially. This characteristic, along
with the fact that the leaf spring 14 remains captured, tends
to enhance longevity and reduce the liklihood of malfunction
during operation over roads in severe stages of disrepair.
OPERATION
It is believed that in view of the foregoing descrip-
tion the operation of the device embodying the instant
llO~S3S
invention is apparent. However, it will at this point be
reviewed briefly.
With the supplemental air spring assembly 10 inter-
connected, and thus incorporated in a suspension system,
such as a front end suspension system for a selected vehicle,
the suspension system is economically modified. As the
vehicle is operated, reverse loading of the air bag 34 occurs
causing the load applied by the frame member 20 to the force
dissipating arm 22, via the air bag 34 to vary between com
pressive and tensile loads. As the load is varied, the
leaf spring assembly 14 undergoes flexion, whereupon the
axis of the pivot pin 30 changes its position relative to
the frame member 20. The link 50 acts about the pivotal axis,
established by the pin 30, in opposition to the load applied
to the arm 22 by the air bag 34. Since the pin 30 is free to
move vertically, as well as horizontally, flexion of the leaf
spring assembly 14 is accommodated. Of course, as the bag
34 is foreshortened under a compressive load, the leveling
valv e 40 is acti~ated, through the linkage 60 so that addi-
tional air is introduced from the valve 40 to the air bag 34.
Similarly, as the bag 34 is elongated under tensile loads,
the linkage 60 actuates the leveling valve 40 for reducing
pressure within the bag 34. Consequently, pressurization of
the air bag 34 is dictated by the position of the force dis-
sipating arm 22. Thus, a portion of the forces of the loadsapplied by the frame member 20 is dissipated by the air bag
34, while the remaining forces are transmitted to the leaf
spring assembly, while the leaf spring assembly 14 remains
captured. Due to the floating characteristics of ~he pivotal
axis for the arm 22, deformation of the air bag 34 remains
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~IQ~S3S
substantially uniform throughout.
It should, therefore, be apparent that the supple-
mental air spring assembly 10 embodying the principles of the
instant invention provides a satisfactory solution for the
perplexing problem of incorporating a practical and safe
supplemental air spring assembly in the front end suspension
system for motorized vehicles such as trucks, tractor-trailer
rigs and the like.
Although the invention has been herein shown and
described in what is conceived to be the most practical and
preferred embodiment, it is recognized that departures may be
made therefrom within the scope of the invention, which is
not to be limited to the illustrative details disclosed.
