Note: Descriptions are shown in the official language in which they were submitted.
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TITLE: SINGLE-WHEEL HYDRAULIC JACK
FIELD OF THE INVENTION
The present invention relates to vehicle jacks and more particularly
it pertains to a single-wheel hydraulic jack having a wheel tray that is
inclinable in a first direction for facilitating the rolling of a wheel
therein,
and in a second direction for preventing a wheel from rolling off the jack
during the lifting of a vehicle with the jack.
BACKGROUND OF THE INVENTION
Vehicle jacks are used in garages and body repair shops for
examples, for lifting one or more wheels of a vehicle off the ground for
carrying out repair or maintenance work on the vehicle. Vehicle jacks are
sometime used by apprentices and inadvertent vehicle owners having more
or less appreciation for the risks associated with the lifting of a vehicle
and
working under it. Conventional bumper jacks, axle jacks and scissors-type
chassis jacks for examples are known to be unstable in certain
circumstances and are generally not recommended for use without
additional safety blocking. In that regard, clear written safety instructions
are normally provided with the purchase of every vehicle j ack. However,
because of the inexperience of some users of vehicle jacks, and for other
various reasons, proper vehicle lifting instructions are not always followed
and users of vehicle jacks continue to be exposed to serious accidents.
In regard to improving the safety of vehicle jacks, a number of
single-wheel jacks have been developed in the past. Some of these single-
wheel jacks have a wheel tray for receiving a vehicle wheel and a broad
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base to prevent tilting of the jack when used on soft or uneven ground for
example. Three models of single-wheel jacks of the prior art are described
and illustrated in the following documents for reference purposes:
US Patent 3,292,902 issued on Dec. 20, 1966 to M.F. Lynch. The
portable tire lift illustrated therein has a broad base, a lifting plate, a
wheel
tray mounted to the lifting plate and a scissors-type lifting mechanism
connected to the broad base and to the lifting plate. A support post is
mounted to the base and is engaged into a portion of the lifting plate. The
post has vertically spaced-apart ridges for supporting the lifting plate and
for preventing accidental collapsing of the lifting plate.
US Patent 3,784,161 issued on Jan. 8, 1974 to R.L. Frese. The
wheel removal safety device illustrated therein is used for assisting in
positioning a flat tire wheel at a certain height such that an axle jack or a
bumper j ack may be installed for removing and replacing the wheel. The
device has a tilting plate forming an inclined surface on which the wheel
is driven. The plate has a fulcrum at its centre point and is adapted to tilt
and form an elevated horizontal surface when a wheel is driven thereon
and moves pass the fulcrum. A conventional jack is then easily introduced
under the elevated axle or bumper.
US Patent 5,503,368 issued on Apr. 2,1996 to Manuel Tones. This
patent describes a scissors-type wheel lift having broad base, a wheel tray
and a scissors-type lifting mechanism connected to the wheel tray and to
the broad base, for lifting the wheel tray. The wheel lift is used in
combination with a ramp having a height corresponding to the height of
the wheel tray when the wheel tray is in a collapsed mode. In use, a wheel
is driven over the ramp and into a wheel tray. A hand crank and a screw
are used to operate the scissors-type lifting mechanism.
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It has been found that a common problem with the lifting of a
vehicle with a jack is that a partial raising of a vehicle, on one corner or
on
one end of the vehicle, causes the whole vehicle to be pulled toward the
jack. Therefore, when the wheel being lifted is not properly retained inside
the wheel tray of a jack, or when one of the supporting wheels is chocked
against the jack, the wheel being lifted tends to roll out of the wheel tray,
thereby causing a hazardous condition.
Another problem with scissors-type lifting mechanisms of single-
wheel jacks of the prior art is that the mechanism has a substantial vertical
thickness. Modern compact vehicle have relatively small diameter wheels,
of 14 and 15 inches for examples. These wheels are often too small to
afford a smooth rolling over the scissors-type lifting mechanism and into
the wheel tray of these vehicle jacks.
It is believed that these problems basically, have contributed to
cause significant obstacles to the commercial success of the wheel-tray
type jacks of the prior art. It is further believed that there continues to be
a need for a better single-wheel jack capable of being used easily and
safely by the experienced tradesmen as well as by the hobby-time auto
mechanics.
SUMMARY OF THE INVENTION
In the present invention, however, there is provided a single-wheel
jack that has a wheel tray that is inclinable in two directions, to facilitate
the entry of a wheel therein when the j ack is in a collapsed mode, and to
positively retain a vehicle wheel when the jack is in a raised mode. The
single-wheel jack of the present invention further has a latching
mechanism to prevent unintentional lowering of the wheel tray.
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Broadly, in accordance with a first feature of the present invention,
there is provided a jack for raising a wheel of a vehicle and comprising a
horizontal base having spaced-apart front end and entry end, spaced-apart
side members extending between the front end and the entry end and
longitudinal and transversal dimensions. A scissors-like lifting mechanism
is connected to the horizontal base and has an upper end movable between
a raised position at a distance above the horizontal base and a collapsed
position against the horizontal base. A force-applying actuator is
connected to the horizontal base and to the scissors-like lifting mechanism
for actuating the scissors-like lifting mechanism. A wheel tray is
connected to the upper end of the scissors-like lifting mechanism for up
and down movements thereof between the raised position and the
collapsed position. The wheel tray has spaced-apart front portion and
entry portion, a bottom surface and a bumper on the front portion.
There is also provided a crossbar mounted in the scissors-like lifting
mechanism for engaging with the wheel tray and for causing the entry
portion of the wheel tray to lean down relative to the front portion when
the upper end of the scissors-like lifting mechanism is in the collapsed
position.
The scissors-like lifting mechanism has connections with the front
and entry portions of the wheel tray and the connections with the front
portion are differing in height and engagement sequence with the
connections with the entry portion for causing the front portion of the
wheel tray to lean down relative to the entry portion when the upper end
of the scissors-like lifting mechanism is in the raised position.
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The principal advantages of the jack of the present invention are
that the wheel tray of the jack is inclinable to lean down toward the entry
end of the horizontal base for facilitating a rolling of a vehicle wheel
therein when the scissors-like lifting mechanism is in a collapsed position,
and the wheel tray is inclinable to lean down toward the front end of the
horizontal base, when the scissors-like lifting mechanism is in a raised
position, for urging a vehicle wheel against the bumper of the wheel tray
and for preventing the vehicle wheel from rolling out of the wheel tray.
According to another feature of the present invention, the scissors-
like lifting mechanism has a pair of spaced-apart drive members and a pair
of spaced-apart driven members joined at their midpoints by a pair of
spaced-apart pivots defining a transversal articulation axis of the scissors-
like lifting mechanism. The scissors-like lifting mechanism is actuated by
an hydraulic cylinder connected to the base and to the spaced-apart drive
members. When the scissors-like lifting mechanism is in a collapsed
position, a longitudinal axis of the hydraulic cylinder is offset from the
transversal articulation axis by a distance of at least 1/8 inch to 3/16 inch.
This offset distance has been found to be advantageous for providing a
substantial moment of force by the hydraulic cylinder on the scissors-like
lifting mechanism for initiating a lift with ease.
In accordance with another feature of the present invention, there
is provided a latching mechanism comprising a latch block affixed to the
horizontal base and a loop member connected to one of the drive members
for engagement with the latch block, when the scissors-like lifting
mechanism is in the raised position. The scissors-like lifting mechanism
is thereby lockable in the raised position for preventing accidental or
unintentional lowering thereof.
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In yet another feature of the present invention, the latching
mechanism comprises a pair of wedge-like latch blocks respectively
connected to one of the side members of the horizontal base and a pair of
loop-shaped hook members respectively connected to one of the lower
ends of the drive members. The loop-shaped hook members have inside
dimensions for engagement with the wedge-like latch blocks as soon as the
scissors-like lifting mechanism reaches a raised position.
The loop-shaped hook members are joined to one another by a
round bar. A pair of cleft tabs are mounted on an actuator rod pivotally
connected to the side members ofthe horizontal hollow base and extending
parallel to and at proximity of the round bar when the hook members are
engaged over the latch blocks, for engagement of the cleft tabs with the
round bar. Each of these cleft tabs has a fork-like end for engagement
thereof with the round bar and for selectively lifting the round bar and the
loop-shaped hook members over the wedge-like anchor blocks. The
actuator rod further has a handle connected thereto and disposed outside
the horizontal hollow base. The scissors-like lifting mechanism is thereby
releasable from a latch condition by actuating the handle on the actuator
rod.
Still other features of the invention are that it is susceptible of a low
cost of manufacture with regard to materials, equipment and labour, and
which accordingly is then susceptible of low price of sale to the industry,
thereby making such single-wheel jack economically available to the
public.
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BRIEF DESCRIPTION OF THE DRAWINGS
One embodiment of the present invention is illustrated in the
accompanying drawings, in which like numerals denote like parts
throughout the several views, and in which:
FIG. 1 is an entry end, right side and top perspective view of the single-
wheel hydraulic jack according to the preferred embodiment of the
present invention, shown with the wheel tray in a raised position;
FIG. 2 is a top plan view of the single-wheel hydraulic jack shown with
a partial view of the handle member usable for operating the
hydraulic cylinder of the jack;
FIG. 3 is a partial transversal cross-section view of the wheel tray of the
single-wheel hydraulic jack, as seen along line 3-3 in FIG. 2, but
with the wheel tray in a raised position;
FIG. 4 is a partial longitudinal cross-section view of the single-wheel
hydraulic jack as seen along line 4-4 in FIG. 2, but with the
scissors-like lifting mechanism in a collapsed position;
FIG. 5 is a side view of the single-wheel hydraulic jack, shown with the
scissors-like lifting mechanism in the collapsed position, with a
partial view of a wheel being driven in the wheel tray;
FIG. 6 is a side view of the single-wheel hydraulic jack shown with the
scissors-like lifting mechanism in the raised position and a partial
view of a wheel being supported in the wheel tray;
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FIG. 7 illustrates a partial top view of the horizontal base of the single-
wheel hydraulic jack according to the preferred embodiment;
FIG. 8 is a first side view of the locking mechanism mounted inside the
horizontal base of the single-wheel hydraulic j ack and shown in a
locked position;
FIG. 9 is a second side view of the locking mechanism shown with the
cleft tabs in an engaged and active mode;
FIG. 10 is a third side view of the locking mechanism shown with the
cleft tabs in an unlatching mode;
FIG. 11 is an entry end and right side perspective view of a wheel chock
usable with the single-wheel hydraulic jack according to the
preferred embodiment;
FIG. 12 is a partial cross-section of the hydraulic cylinder base showing
a partial view of a flow control valve usable to regulate the
lowering speed of the single-wheel hydraulic jack; and
FIG. 13 is a front and right side partial perspective view of a socket and
a handle used to operate the hydraulic cylinder on the single-wheel
hydraulic jack according to the preferred embodiment.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
While this invention is susceptible of embodiments in many various
forms, there is shown in the drawings and will be described in details
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herein a specific embodiment, with the understanding that the present
disclosure is to be considered as an example of the principles of the
invention and is not intended to limit the invention to the embodiment
illustrated.
The preferred embodiment of the present invention is a single-
wheel hydraulic jack 20 usable for lifting a single wheel of a vehicle. The
utility of this jack is well known to auto-mechanics, to body shop
personnel and to all individuals who perform maintenance work on
wheeled vehicles. This single-wheel hydraulic jack 20 is particularly
advantageous for its low profile when it is in a collapsed mode, for its
inclined wheel tray when fully raised, for its locking mechanism, and for
several other features that are described herein below. The single-wheel
hydraulic jack 20 according to the preferred embodiment is also referred
to herein as the vehicle jack.
The vehicle jack 20, several features of which are illustrated in
FIGS. 1-6, comprises broadly, an horizontal hollow base 22, a scissors-
like lifting mechanism 24 mounted to the base, an hydraulic cylinder 26
connected to the base and to the scissors-like lifting mechanism for
actuating the scissors-like lifting mechanism 24, and a wheel tray 28
mounted to the scissors-like lifting mechanism for receiving a wheel 30 to
be raised.
The horizontal hollow base 22 is preferably rectangular in shape
and made of angle iron having a thickness'A' from the ground of about 1-
1/2 inches (38 mm) as shown in FIG. 4. The horizontal rectangular base
22 has a front end and an entry end, a longer side defining a longitudinal
dimension and a shorter side defining a transversal dimension. The front
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end is the portion where the hydraulic cylinder 26 is mounted, and the
entry end is the portion upon which a vehicle wheel rolls over to enter the
wheel tray 28.
A pair of fixed clevises 32 are affixed to the front end of the base
22 for rigidly supporting the pivot end of the hydraulic cylinder 26. There
is also provided a pair of gusset members 34 affixed diagonally across
each corner of the front end of the base for reinforcing that end of the base
22.
A first handle 36 is affixed to the front end of the base 22 for
handling the vehicle jack 20 about a garage or under a vehicle. A second
handle 38 is optionally affixed to the entry end of the base 22 to further
facilitate the handling of the vehicle jack 20. This optional handle 38 is
preferably a retractable one such that the vehicle jack 20 according to the
preferred embodiment can be shipped or stowed in a form which is as
compact as possible.
The scissors-like lifting mechanism 24 comprises a pair of drive
members 40 set inside a pair of driven members 42 and connected to the
driven members 42 by means of a pair of pivots 44 defining a first
transversal articulation axis thereof passing through the midpoint of each
of the members 40 and 42.
The drive members 40 have a respective first upper-driven end
pivotally connected to the entry portion of the wheel tray 28 at pivots 46
on the wheel tray, and a respective lower drive end 48 having a lower
roller 50 affixed thereto. The drive members 40 are mounted and extend
astride the bottom surface of the wheel tray 28.
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Each lower roller 50 is adapted to roll inside the angle iron of the
horizontal base 22. Each lower roller 50 is preferably the type having a
threaded stem extending along an axis thereof and being known in the
industry as a track runner bearing.
There is also provided, and mounted across the drive members 40,
a crossbar 60 which is visible in the perspective view in FIG. 1 and in the
cross section view in FIG. 4. The crossbar 60 is connected to both drive
members 40, near the driven ends of the drive members 40 and has a pair
of driven clevises 62 connected thereto for pivotally receiving the rod end
of the hydraulic cylinder 26 and for transmitting the force of the hydraulic
cylinder 26 to the drive members 40.
The driven members 42 have a respective lower reactive end
pivotally connected to the entry end of the base 22 at pivots 64. The upper
driven end of each driven members 42 has an upper roller 66 which is
adapted to roll inside a channel-like rail member 68 formed in the wheel
tray 28. Hence, when the drive members 40 are pushed by the hydraulic
cylinder 26, the drive and driven members 40, 42 are pivoted about the
transversal articulation axis 44 for lifting the wheel tray 28 in a manner
which is common to scissors-type lifting mechanisms.
The longitudinal axis 70 of the hydraulic cylinder 26 is preferably
set at an angle 'B' of one or few degrees down from a horizontal line 72
such that the force of the hydraulic cylinder 26 causes the lower rollers 50
to remain in contact with the angle iron of the base 22. The alignment of
the axis 70 also contributes to providing a push-force moment about the
transversal articulation axis 44 for initiating a lifting action. For this
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purpose, a minimum distance 'C' of about 1/8 to 3/16 inch (3-5 mm) is
preferably maintained between the longitudinal axis 70 of the hydraulic
cylinder 26 and the transversal articulation axis 44.
The wheel tray 28 is preferably manufactured with pressed metal
sheet . A channel-like rail member 68 is preferably formed on each side
of the wheel tray 28 for laterally enclosing a bottom surface of the wheel
tray. The wheel tray 28 preferably has reinforcing corrugations 74 across
its bottom surface for reinforcing the bottom surface. The wheel tray 28
further has a front bumper 76 across its front end.
Referring now particularly to FIGS. 4-6, there are illustrated
therein some important features of the vehicle j ack 20 according to the
preferred embodiment. A first important feature is that when the vehicle
jack 20 is fully collapsed, the bottom portion of the wheel tray 28 comes
in contact with the crossbar 60 and is raised by the crossbar 60 as
illustrated in FIG. 4. The crossbar 60 causes the wheel tray 28 to tilt about
the pivots 46 an angle 'D' of one or few degrees from a horizontal plane,
such that the front portion of the wheel tray remains above the hydraulic
cylinder 26 and above the driven clevises 62, and such that the entry
portion of the wheel tray 28 is able to at least partly retract into the base
22.
This feature is particularly appreciable for easily driving a wheel 30 into
the wheel tray 28 without requiring a ramp or similar inclined structure at
the entry end of the wheel tray 28, as illustrated in FIG. 5.
The tilting of the tray 28 as just described causes the front portion
of the tray to be raised above the upper rollers 66 on the driven members
42 by a distance 'E' as also illustrated in FIG. 5. Therefore, when the
hydraulic cylinder 26 is extended from a retracted position, the entry
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portion of the wheel tray 28 starts to rise first, and continues to be raised
until the upper rollers 66 are up into the channel-like rail members 68, and
in contact with the inside portion of the rail members 68.
The height of the crossbar 60 relative to the drive members 40 when
these drive members are in the collapsed mode, the engagement sequence
between the driven ends of the drive and driven members and the wheel
tray, and the associated distance 'E' are preferably selected such that when
the upper rollers 66 are in contact with the channel rail members 68, the
wheel tray 28 is lightly inclined downward forwardly.
The thickness of the crossbar 60, the location of the pivots 46, the
distance 'E' and the size of the upper rollers 66 are selected such that when
the wheel tray 28 is in a raising mode and in a raised position, it is
preferably inclined forwardly an angle'F' of one or few degrees below an
horizontal line 78, to urge the wheel 30 being raised against the front
bumper 76.
The preferred inclination 'F' is a difference of about'/2 inch (13
mm) between the height 'G' of the front portion, the front portion being
lower, and the height'H' of the entry portion. This feature is advantageous
for preventing the wheel 30 from rolling off the vehicle jack 20 when the
vehicle jack is in use.
For additional safety, although this is optional, a wheel chock 80
having an anchor pin 82 thereon as illustrated in FIG.11, may be installed
in the wheel tray 28 as illustrated in FIG. 6, with the anchor pin 82
inserted into one of several holes 84 provided for this purpose in the
bottom surface of the wheel tray 28.
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Referring now to FIGS. 7-10, there is illustrated therein another
important feature of the vehicle jack 20 according to the preferred
embodiment. The vehicle jack 20 has a locking mechanism 90 for locking
the scissors-like lifting mechanism 24 in a raised position. The locking
mechanism 90 comprises a pair of elongated loop-shaped hook bars 92
respectively pivotally connected to the lower end 48 of a drive member
40. Each loop-shaped hook bar 92 is adapted to engage onto a wedge-like
anchor block 94 affixed to the lower portion of the side member 96 of the
horizontal base 22, when the drive members 40 reaches an uppermost
position. Both loop-shaped hook bars 92 are connected to each other by
a transversal round bar 98 such that they are movable together.
There is also provided, a pair of cleft tabs 100 rigidly mounted on
an actuator rod 102 extending across the base 22. The actuator rod 102
extends along the transversal round bar 98 when the scissors-like lifting
mechanism reaches a raised position. The actuator rod 102 extends
through the angle iron of the base 22, and has one or two handle-like bent
portions 104 extending outside the base 22.
When the scissors-like lifting mechanism 24 is actuated to raise the
wheel tray 28, the loop-shaped hook bars 92 slide over the inclined
surfaces 106 of both anchor blocks 94, and drop down at the entry end of
the anchor blocks 94 to engage with the anchor blocks 94 as shown in
FIG. 8, and to prevent any unintentional lowering of the jack 20. During
this motion, the transversal round bar 98 slides over the cleft tabs 100, and
rests above the cleft tabs 100 as illustrated in FIG. 8.
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The releasing of the locking mechanism 90 is effected by turning
the bent portion 104 of the actuator rod 102, causing the cleft tabs 100 to
lift the transversal round bar 98 and to cause the loop-shaped hook bars 92
to disengage from the anchor blocks 94. The turning of the cleft tabs 100
in a counterclockwise direction as indicated by arrow 108 in FIG. 9 also
causes the transversal round bar 98 to engage into a hollow 110 in each
cleft tab 100. Each hollow 110 is defined by a forward leg 112 and an
entry side leg 114. The forward leg 112 is longer than an entry side leg 114
such that a turning of the tabs 100 in the counterclockwise direction 108
is partly limited by the engagement of the forward legs 112 against the
transversal round bar 98, as illustrated in FIG. 9. The rotation of the cleft
tabs 100 in a counterclockwise direction 108 is also limited by a stopper
pin 116 protruding from the side of the base 22 and acting against the
handle-like bent portion 104. The stopper pin 116 is illustrated in FIGS.
1 and 5-7.
During the lowering of the vehicle jack 20 according to the
preferred embodiment, the cleft tabs 100 retain the transversal round bar
98 and both loop-shaped hook bars 92 in a raised position above the
anchor blocks 94. The lowering of the wheel tray 24 causes the cleft tabs
100 to rotate in a clockwise direction as indicated by arrow 118 and to
release the transversal round bar 98 when the loop-shaped hook bars 92 are
in a position to slide down over the inclined portion 106 of the anchor
blocks 94, as illustrated in FIG. 10.
The lowering of the vehicle j ack 20 according to the preferred
embodiment is preferably effected in a smooth and controlled condition to
avoid any sudden drop of the vehicle's wheel 30. Therefore, when a
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common hydraulic cylinder 26 is used to operate the scissors-like lifting
mechanism, the release valve in this cylinder is preferably equipped with
a flow regulator such as an elongated needle-type screw 120 in the oil
return path of the valve, such as illustrated in FIG. 12, or any other flow
control devices known in the industry.
Referring now to FIGS. 2 and 13, the pump-handle bar 130 used
to actuate the hydraulic cylinder 26 is preferably bent sideway an angle'J'
of between about 5 degrees and about 45 degrees. This feature is preferred
for preventing a rubbing of the handle bar 130 against a painted surface of
a bumper or a fender of a vehicle for example when the vehicle jack 20 is
used to raise a wheel of a vehicle.
It will be appreciated, however, that the vehicle j ack 20 may be used
under a driver or a passenger side of a vehicle and therefore, the handle bar
130 according to the preferred embodiment is reversible for use on either
sides of a vehicle. For this purpose, the handle bar 130 has a pair of tabs
132, 134 extending in opposite directions from each other and from the
socket-engaging end of the handle, and at right angle with a plane defined
by the angle 'J' . Each tab is mountable into a slot 136 formed under the
pump socket 138 of the hydraulic cylinder 26. The engagement of either
tabs 132, 134 into the slot 136 prevents a rotation of the bar 130 when
pumping the hydraulic jack 26 of the vehicle jack 20. The slot 136 is
defined by a pair of spaced-apart and parallel plates 140, affixed to an
underside of the pump socket 138. Therefore, the handle bar 130 is usable
for examples, on a driver side of a vehicle with the tab 134 engaged into
the slot 136, or on a passenger side of a vehicle with the tab 132 engaged
into the slot 136.
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Each of tabs 132, 134 preferably has a rounded notch 142 therein
for optional engagement with the first handle 36 or with any part of the
vehicle jack, for conveniently moving the vehicle jack 20 on a shop floor
or from under a vehicle.
As to further manner of usage, further structural details and
manufacturing of the vehicle jack according to the present invention, the
same should be apparent from the above description and accompanying
drawings, and accordingly, further discussion relative to these aspects
would be considered repetitious and is not provided.
It will also be appreciated that while the above description provides
a full and complete disclosure of the preferred embodiment of this
invention, various modifications, alternate constructions and equivalents
may be employed and various uses may be devised without departing from
the true spirit and scope of the invention. Such changes might involve
alternate components, structural arrangements, construction features or the
like. Therefore, the above description and the illustrations should not be
construed as limiting the scope of the invention which is defined by the
appended claims.
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