Note: Descriptions are shown in the official language in which they were submitted.
SCISSOR JACK STAND
BACKGROUND OF THE INVENTION
The invention relates to support devices, and more
particularly to adjustable support devices such as jacks or
jack stands.
Jack stands are known in the art. See for example
U.S. Patent No. 4,556,163. Scissor jacks are also known in the
art. A typical scissor jack includes a scissor mechanism which
is extended and contracted by a screw arrangement.
SUMMARY OF THE INVENTION
The invention provides an improved adjustable support
device, preferably a jack stand, for supporting a vehicle above
the ground.
The jack stand comprises a base, an extensible and
contractible scissor mechanism mounted on the base, and means
on the mechanism for supporting a load. The scissor mechanism
includes a plurality of elongated members pivotally connected
in scissor-like fashion by a plurality of horizontally
extending pins. The jack stand also includes means for
releasably securing the scissor mechanism in a fixed position.
Preferably, a ratch means is used which includes a ratch
; pivotally connected to one of the pins, and the ratch includes
a plurality of spaced recesses for
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removably housing another of the pins. The distance
between the pins and thus the amount of extension of
the scissor mechanism can be selectively varied by
changing the recess in which the pin is housed.
The invention also provides a clamping
mechanism adapted to be used on the jack stand or on
a similar device. Preferably, the clamping ~echanism
is mounted on the upper end of the scissor mechanism
for releasably clamping the pinch weld of a vehicle
supported by the jack stand. rn the preferred
embodiment, the clamping mechanism translates the
weight of the vehicle into a clamping force exerted
by the clamping mechanism on the pinch weld. Thus,
the heavier the vehicle, the greater the clamping
force. The clamping mechanism substantially prevents
slippage between the vehicle and the jack stand.
The invention also provides a scissor
jack comprising the above-discussed base and clamping
mechanism.
Other features and advantages of the
invention will become apparent to those skilled in
the art upon review of the following detailed
description, claims and drawings.
DESCRIPTION OF THE DRAWINGS
Fig. 1 is a top view of a collapsed
jack stand embodying the invention.
Fig. 2 is a side view of the collapsed
jack stand.
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Fig. 3 is a side view of the jack stand
extended.
Fig. 4 is an enlarged, partial, side
view of the upper end of the jack stand.
Fig. 5 is a view similar to Fig. ~.
Fig. 5 is a view taken along line 6-6
in Fig. 1.
Fig. 7 is a side view of a scissor jack
which is an alternative embodiment of the invention.
10 Fig. 8 is an enlarged, partial, side
view of the upper end of a jack stand which ls an
alternative embodiment of the invention.
Before one embodiment of the invention
is explained in detail, it is to be understood that
the invention is not limited in its application to
the details of construction and the arrangements of
components set forth in the following description or
illustrated in the drawings. The invention is
capable of other embodiments and of being practiced
or being carried out in various ways. Also, it is to
be understood that the phraseology and terminology
used herein is for the purpose of description and
should not be regarded as limiting.
DESCRIPTION OF THE PREFERRED EMBODIMEN
A jack stand 10 which embodies the
invention is illustrated in Figures 1 through 5.
The jack stand 10 comprises a
conventional base 12 adapted to be supported by the
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ground. The base 12 includes a pair o~ spaced apart,
vertically extending flanges 20. The jack stand 10
also comprises a vertically extensible and
contractible mechanism mounted on the base. While
various suitable mechanisms can be employed, in the
preferred embodiment, the mechanism includes scissor
means 26.
In the illustrated construction, the
scissor means 26 includes a pair of lower left
elongated members 28 having upper and lower ends.
The lower ends of the elongated members 28 are
pivotally mounted on a pin 30 extending between the
flanges Z0 of the base 12. As shown in Figures 2 and
3, the lower ends of the members 28 have thereon a
plurality of spacea teeth 32. The scissor means 26
also includes a pair of lower right elongated members
34 having upper and lower ends. The lower ends of
the elongated members 34 are pivotally mounted on a
pin 36 which extends between the flanges 20 of the
base and which is spaced from the pin 30. Each of
the members 34 has thereon a plurality of spaced
teeth 38 which mesh with the teeth 32 on the lower
end of an associated one of the members 28. The
meshed teeth maintain a relationship between the
lower members 28 and 34 such that the left and right
lower members are always bisected by a vertical plane.
Thus, the lower members 28 and 34 are
connected together for pivotal movement about a
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generally horizontal axis and so that the upper ends
of the lower members 28 and 34 are vertically,
adjustably moveable.
The scissor means 26 also includes a
pair of middle left elongated members 40 having upper
and lower ends. The lower ends of the middle left
members 40 are pivotally connected to the upper ends
of the lower left members 28 by a pin 42. The
scissor means 26 also includes a pair of middle right
elongated members 44 having upper and lower ends.
The lower ends of the middle right members 44 are
pivotally connected to the upper ends of the lower
right members 34 by a pin 46. Also, the middle right
members 44 are pivotally connected to the middle left
members 40 by a pin 48 located at a point
intermediate the ends of each of the members 40 and
44.
Thus, the middle members 40 and 44 are
connected together for pivotal movement about a
generally horizontal axis and so that the upper ends
of the middle members are vertically, adjustably
moveable.
The scissor means 26 also includes a
pair of upper left elongated members 50 having upper
and lower ends. The lower ends of the upper left
members 50 are pivotally connected to the upper ends
of the middle right members 44 by a pin 52. The
upper ends of the upper left members 50 have thereon
a plurality of spaced teeth 53. The scissor means 26
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also includes a pair of upper right elongated members
54 having upper and lower ends. The lower ends of
the upper right members 54 are pivotally connected to
the upper ends of the middle left members 40 by a pin
56. The upper ends of the upper right members 54
have thereon a plurality of spaced teeth 57 which
mesh with the teeth 53 on the upper end of an
associated one of the upper left members 50. The
meshed teeth maintain a relationship between the
members 50 and 54 such that they are always bisected
by a vertical plane.
The jack stand 10 also comprises means
for securing the extensible and contractible
mechanism, i.e., the scissor means, in a fixed
position. While various suitable securing means can
be employed , in the preferred embodiment, the
securing means includes means connected between the
pin 42 and the pin 46 for releasably securing the
pins 42 and 46 in spaced relationship and for
selectively varying the spacing between the pins.
Alternatively stated, because the pin 42 is connected
to the lower left member 28 and the pin 46 is
connected to the lower right member 34, the securing
means includes means connected between a first point
located on the lower left member 28 and a second
point located on the lower right member 34 for
releasably securing the first and second points in
spaced relationship and for selectively varying the
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spacing between the first and second points. Further
alternatively stated, because the pin 42 is connected
to the middle left member 40 and the pin 46 is
connected to the middle right member 44, the securing
means includes means connected between a first point
located on the middle left member 40 and an second
point located on the middle right member 44 for
releasably securing the first and second points in
spaced relationship and for selectively varying the
spacing between the first and second points.
While various suitable connecting means
can be used, in the illustrated construction, the
connecting means includes ratch means. The ratch
means includes the pin 46, and a ratch 58 having a
longitudinal axis and an end pivotally supported by
the pin 42. As shown in Fig. 6, the ratch 58 is
preferably channel-shaped and includes a generally
horizontal portion 60 and a pair of spaced apart
vertical side portions 62. The side portions 62
include a plurality of aligned recesses 64 which are
formed in the lower edges of the side portions 62 and
which are adapted to removably house the pin 46. The
recesses 64 are spaced from the pin 42 and are spaced
along the lower edges of the side portions 62 in the
direction of the longitudinal axis of the ratch 58.
Alternatively stated, because the pin
42 is connected to the lower left members 28 and to
the middle left members 40, and because the pin 46 is
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connected to the lower right members 34 and to the
middle right membecs 44, the ratch means includes
projection means (the pin 46) located on the members
34 and on the members 44, and a ratch 58 connected to
the members 28 and to the members 40.
As is apparent from viewing Figure 3,
location of the pin 46 in an aligned pair of the
recesses 64 secures the pins 42 and 46 in spaced
relationship and thereby secures the scissor means 26
in a fixed position. The spacing between the pins 42
and 46 and thus the amount of extension of the
scissor means 26 can be selectively varied by
changing the recesses 64 in which the pin 46 is
- housed.
lS The jack stand 10 further comprises
means mounted on the extensible mechanism, i.e., on
the scissor means 26, for supporting the load above
the ground. While various suitable supporting means
can be used, in the preferred embodiment, the
supporting means includes means connected to the
upper ends of the upper members S0 and 54 for
supporting the load above the ground.
In order to prevent slippage between
the supporting means and the load, the supporting
means preferably includes means for releasably
clamping the load. In the preferred embodiment, the
jack stand 10 is adapted to support a vehicle, and
the clamping means releasably clamps the pinch weld
66 of the vehicle.
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The clamping means includes means for
translating the weight of the load or o~ the vehicle
into a clamping force exerted by the clamping means
on the load or on the pinch weld 66 of the vehicle.
Preferably, the clamping means includes (see Figs. 4
and 5~ a pair of vertically oriented plates 68 which
are pivotally connected to the upper ends of the
upper left members 50 by a pin 70, and which are
pivotally connected to the upper ends of the upper
right members 54 by a pin 72. As shown in Fig. 4,
each plate 68 has in its upper edge a downwardly
extending slot 74 which is partially defined by a
wall 75. The clamping means also includes a clamping
member 76 which is pivotally mounted on the plates 68
by a pin 77 and which is pivotally movable between an
open position tFig. 4) and a closed position (Fig.
5). The clamping member 76 includes a load
supporting portion 78 extending across the slots 74,
a load clamping portion 79, and a slot 80 which
normally engages the pin 70 and prevents
counter-clockwise (as shown in Fig. 4) rotation of
the clamping member 76 beyond the open position. The
clamping member 76 is weighted so as to be biased to
the open position by the force of gravity.
When the jack stand 10 is extended, the
pinch weld 66 is received in the slot 74, and the
load supporting portion 78 engages the bottom of the
pinch weld 66 so that the clamping member 76 pivots
clockwise and the clamping portion 79 clampingly
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engages the pinch weld 66 between the clamping
portion 79 and the wall 75 of the slot 74.
When the jack stand 10 supports the
vehicle, the clamping member 76, and more
particularly the load supporting portion 78 of the
clamping member 76, supports at least a portion of
the weight of the vehicle. Thus, the vehicle exerts
a force on the load supporting portion 78 of the
clamping member 76. This force causes pivotal
movement of the clamping member 76 so that the
clamping portion 79 exerts a clamping force on the
pinch weld 66. Therefore, the clamping force is
proportional to the force exerted by the vehicle on
the load supporting portion 78. In other words, the
clamping member 76 translates the weight of the
vehicle into a clamping force exerted by the clamping
member 76 on the pinch weld 66 of the vehicle. The
advantage of this arrangement is that a heavier
vehicle results in a greater clamping force.
An alternative construction of the
clamping means is shown in Fig. 8. In the
alternative construction, the clamping means includes
a pair of vertically oriented plates 81 mounted on
the upper ends of the members 50 and 54 by respective
pins 83 and 85. The clamping means also includes a
first clamping member or bellcrank 82 pivotally
mounted on the plates 81 by a pin 84, and a second
clamping member or bellcrank 86 pivotally mounted on
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the plates 81 by a pin 88. Thus, the first clampinq
member 82 is mounted for pivotal movement about a
first axis, and the second clamping member 86 is
mounted for pivotal movement about a second axis
spaced from the first axis.
The first clamping member 82 includes
(see Fig. 8) a middle portion supported by the pin
84, a first lever arm or projection terminating in a
first clamping portion 90, and a second lever arm or
lO projection which terminates in a first load
supporting portion 92 and which extends toward the
second clamping member 86. The second clamping
member 86 includes a middle portion supported by the
pin 88, a first lever arm or projection terminating
15 in a second clamping portion 94 spaced from the first
clamping portion 90, and a second lever arm or
projection which terminates in a second load
supporting portion 96 and which extends toward and
side-by-side with the first load supporting portion
20 92.
In the alternative construction, the
clamping means is biased open. More particularly,
the load clamping portions 90 and 94 are biased
apart. While various suitable biasing means can be
25 used, in the illustrated construction, the biasing
means includes (see Figure 8) torsion springs 98.
As shown in Figure 8, when the jack
stand 10 is extended, the load supporting
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portions 92 and 96 engage the load or the bottom of
the pinch weld 66 so that the clamping member 86
pivots clockwise and the clamping member 82 pivots
counterclockwise. As a result, the clamping portions
90 and 94 move together and clampingly engage the
pinch weld 80.
Like the clamping means of the
preferred embodiment, the clamping members translate
the weight of the vehicle into a clamping force
exerted by the clamping members on the pinch weld of
the vehicle.
A scissor jack 100 which is an
alternative embodiment of the invention is
illustrated in Figure 7. The scissor jack 100 has
many elements in common with the jack stand 10, and
common elements have been given the same reference
numerals.
Specifically, the scissor jack 100 is
substantially identical to the jack stand 10 except
that, instead of ratch means, the scissor jack
includes a conventional screw arrangement 102 for
releasably securing the pins 42 and 46 in spaced
relationship and for selectively varying the spacing
between the pins 42 and 46. This arrangement is
known in the art and will not be described in greater
detail.
Various features and advantages of the
invention are set forth in the following claims.
