Note: Descriptions are shown in the official language in which they were submitted.
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TITLE OF THE INVENTION:
Lift Axle Suspension
FIE7~D OF THE INVENTION
The present invention relates to a lift axle suspension.
BACKGROUND OF THE INVENTION
There are numerous examples of lift axle suspensions in
the patent literature, including: United States Patents
3,201,141 (Bernstein (1965); 4,000,913 (Gibson 1977);
4,256,326 (Cantrell et al 1981); 5,403,031 (Gottschalk et al
1995); 5,549,322 (Hauri 1996); 5,655,788 (Peaker 1997) and
6,416,069 (Ramsey 2002).
The use of a lift axle suspension enables a driver of a
vehicle to lift one or more axles in order to selectively
transfer more weight to the tires that remain on the ground.
This may be done when the vehicle is loaded in order to
increase traction or provide more controlled braking. This
may be done when the vehicle is not loaded in order to save
tire wear.
SU1~1ARY OF THE INVENTION
The present invention is an alternative lift axle
suspension that is believed to provide advantages by virtue of
its relative simplicity.
According to the present invention there is provided a
lift axle suspension that includes a pivoting arm, an axle and
a first suspension air bag acting one of directly or
indirectly in a downward direction upon the axle. A lever is
provided having a first end, a second end, and a fulcrum
positioned between the first end and the second end. The
first end is linked to the axle. A second lift air bag acts
in a downward direction upon the second end of the lever.
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This causes the lever to pivot about the fulcrum such that the
first end of the lever, which is linked to the axle, is
raised. Means is provided for selectively supplying air to
either the first suspension air bag to lower the axle or the
second lift air bag to raise the axle.
The above described lift axle suspension is characterized
by the use of a second air bag to exert a force upon a lever
causing the lever to pivot about its fulcrum and lift the
axle. It provides a distinct advantage over spring biased
systems which have an inherent imbalance in weight
distribution as a result of the action of the biasing spring.
BRIEF DESCRIPTION OF THE DRAWINGS
These and other features of the invention will become
more apparent from the following description in which
reference is made to the appended drawings, the drawings are
for the purpose of illustration only and are not intended to
in any way limit the scope of the invention to the particular
embodiment or embodiments shown, wherein:
FIGURE 1 is a side elevation view of a lift axle assembly
constructed in accordance with the teachings of the present
invention, with the axle in a lowered position.
FIGURE 2 is a detail, partial side elevation view of the
fulcrum and first end of a lever as illustrated in FIGURE 1.
FIGURE 3 is a side elevation view of the lift axle
assembly illustrated in FIGURE 1, with the axle in a raised
position.
DETAILED DESCRIPTION OF THE PREFERRED F~ODIMENT
The preferred embodiment, a lift axle suspension
generally identified by reference numeral 10, will now be
described with reference to FIGURES 1 through 3.
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Structure and Relationship of Parts:
Referring to FIGURE 1. pivot arm 12 having pivotal end 14
that is pivotally attached to vehicle frame 16 by pivot
arm bracket 18. Remote end with adapter 20 is attached to axle
with wheels 22 and is actuated by first suspension air bag 24
shown in extended mode. All elements 12 through 24 are shown
as basic lift axle suspension 26. Preferred embodiment 10
comprises lever 28 having a first end 30 and second end 32
which rotates about fulcrum 34 which is attached to frame 16
by lever bracket 36. An adjustable sling 38 adapts first end
30 to axle with wheel 22. Referring to FIGURE 2, lever 28 is
further adapted with a plurality of adjustably positioned
fulcrum points 40 and a sling adjusting mechanism 42.
Referring to FIGURE 1, second end 32 is actuated by second
lift air bag 44 shown in deflation mode. Air supply 46
provides pressure through connection hoses 48. Pressurized air
is channelled through load leveller valve 50 to air diverter
52 and regulator 54.
Referring to FIGURE 3, axle with wheels 22 is shown in
the elevated position relative to any other axle with wheels
at ground level 56. Second lift air bag 44 is now shown in
extension mode and first suspension air bag 24 is now shown in
deflation mode.
Operation:
The use and operation of a lift axle suspension generally
identified by reference numeral 10, will now be described with
reference to FIGURES 1 through 3. The weight and contact
height of select axles with wheels 22 in multiple, tandem-axle
type vehicles may be changed by changing the settings of load
leveller valve 50, air diverter 52 and regulator 54.
Depending upon the need, air will be diverted to second lift
air bag 44 which in turn actuates second end 32 of lever 28
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causing lever 28 to rotate about the fulcrum 34 and, in turn,
lift first end 30. First end 30 then exerts upward pressure
on adjustable sling 38, lifting axle with wheel 22 which, in
turn, lifts remote end with adapter 20 which is now able to
place first suspension air bag 24 in deflation mode due to the
release of pressure allowed by regulator 54. The result is an
elevated wheel position relative to ground level 56 such that
the tires on axles with wheels 22 that are part of lift axle
suspensions 10 are conserved. Further, should the need
to adapt the lift axle suspension 10 to a different vehicle,
an operator may select one of adjustably positioned fulcrum
points 40 and adjust the sling by operating sling adjustment
mechanism 42.
The operation of the above described lift axle suspension
can be manual or automatic. Some jurisdictions do not allow
operators of multiple, tandem-axle type vehicles to manually
operate a lift axle suspension at his or her own discretion.
The reason that laws were passed in such jurisdictions is due
to abuses in the past, where operators were exceeding legal
load limits. The lift axle suspension, as illustrated in
FIGURES 1 through 3, may be actuated by means of an automatic
system having predetermined settings. This is accomplished by
having the diverter automatically make a selected diversion in
response to air pressure. When air pressure is below a preset
level, the axle is lifted. When air pressure is above a
preset level, the axle is lowered.
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With the lift axle arrangement described above, the air
bag suspension will not operate properly if the axle is lifted
when the suspension system is under load. The reason for this
5 is that air pressure provided to the air bags is limited by
regulator 54 to a pre-selected setting within a range of 15
p.s.i. to 30 p.s.i. The preset pressure level is sufficient
for the air suspension system to operate when the trailer is
travelling down the highway without a load. When the trailer
is under load, greater air pressure than 15 p.s.i. to 30
p.s.i. is required in the air bags in order for the air
suspension system to provide operating clearance. This greater
air pressure is never achieved as regulator 54 will keep
exhausting air to maintain its preset pressure level.
In this patent document, the word "comprising" is used in
its non-limiting sense to mean that items following the word
are included, but items not specifically mentioned are not
excluded. A reference to an element by the indefinite article
"a" does not exclude the possibility that more than one of the
element is present, unless the context clearly requires that
there be one and only one of the elements.
It will be apparent to one skilled in the art that
modifications may be made to the illustrated embodiment
without departing from the spirit and scope of the invention
as hereinafter defined in the Claims.
