Note: Descriptions are shown in the official language in which they were submitted.
1073893
Background of the Invention
1 . F ield of the Invention
. . .
This invention relates to a resiliently tiltable
load supporting base for vehicle jacks.
2. Description of the Prior Art
.
The mechanical advantage of the vehicle jacks is
usually obtained by screw, lever or hydraulic action. Thus,
the screw jack has a threaded screw fitted to a gear wheel
which is a part of the base of the jack. This gear whe~l
engages a pinion gear which is manually turned by means of
a handle or crank. The screw jack is widely used as a light-
weight vehicle jack. Another form of jack widely used for
this purpose is the scissors jack.
The jack is usually mounted on a flat floor or
ground engaging base with the post of the jack mounted
perpendicularly to this base. One difficulty that has been
encountered with the usual jack of the above type is that
the support surface is not always level and this may result
in jamming of the elevating portion of the jack within the
encasing elevator tube.
One prior system for solving the above problem is
described in Larson et al, U.S. Patent 1,810,667 which
describes a ball and socket joint between base members with
fastening bolts and springs positioned at the corners of -
; the base. These springs and bolts permitted a tilting
movement about the ball and socket joint.
Another tilting system for vehicle jacks is described
in British Patent 817,338 , published July 29, 1959. That
patent shows the use of rubber blocks as resilient means
but the jack is designed for tilting only about one lateral
axis.
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It is the object of the present invention to
provide an improved design of vehicle jack which i9 re-
siliently tiltable in at least four (4) ways..
Summary of the Invention
Thus, according to the present invention there is
provided a resiliently tiltable load supporting base for
vehicle jacks, comprising
(a) a rectangular metallic base member having
a substantially flat bottom with an upwardly extending.
convex dome formed at the center thereof, said base member
having a peripheral stiffening rim including a vertically
upward extending peripheral wall merging to an outwardly and
downwardly flared skirt;
(b) a rectangular metallic load receiving plate having
a substantially flat top with downturned peripheral edges posi-
tioned in close priximity to and freely tiltable within said
; base member vertical peripheral wall and having a socket ex-
~ tending downwardly in a central region of the top, this socket
being adapted to receive a vehicle jack and having a bottom wall
with a concave depression pressed upwardly from the bottom face
ther~of, said concave depression resting on said base member;
(c) a retainer pin member connecting said dome
and said concave recess for swinging movement therebetween
and
(d) elastomeric slab means mounted between said
base member and load receiving plate at least beneath the
four corners of the flat top portion of the load receiving
plate between the socket and the downturned peripheral
edges, whereby the.load receiving plate is resiliently
tiltable with respect to the base member.
The elastomeric slab means is preferably in the
form of a hard synthetic or natural rubber block or blocks,
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e.g. of 60 - 7~ durometer hardness. For convience, four
such blocks can be used, these being positioned adjacent
the four corners of the load receiving plate. Of course,
it can also be in the form of a rectangular ring.
The base according to this invention can be adapted
for use with any kind of vehicle jack, such as screw jacks,
scissors jacks, hydraulic jacks, etc. It is particularly
well adapted for use with the usual screw jack having an
elevator screw engaging a gear wheel mounted on a vertical
axis on the lower end of the jack elevator tube. With this
arrangement a bearing support for the gear wheel is mounted
in the socket of the load receiving plate.
Constructional forms of the invention will now be
described, by way of example only, with reference to the
accompanying drawings in which;
Fig. 1 is a side elevation in partial section
showing details of the jack base of the invention;
Fig. 2 is a plan view of the jack shown in Fig. l;
Fig. 3 is a plan view of the base only.
Referring now particularly to Fig. 1, it will be
seen that the jack portion has a tuhular outer casing or
column 10 in the form of two semi-cylindrical halves joined
by flanges 11. These flanges 11 can be spot welded or joined
- in any other means.
Within the column 10 is a telescopic tube 18 which
can be typically cold drawn seamless mechanical steel with
Q cap on which is mounted a load bearing support 17.
The internal mechanism of the jack has not been
shown in detail because it is a well known design. Thus,
it includes the usual components of a typical screw jack
assembly including a threaded elevating shaft 19 rotated
by means of gear memb~r 20 supported within a bearing member
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31. The gear member 20 is driven by a pinion gear 21.
This pinion gear has a cylindrical shank portion 22 with
gear teeth 21 at one end and a slot 24 at the other end
for receiving a crank handle. The pinion gear is mounted
within a friction bearing 23 which can conviently be of
material such as that available under the trademark "Derlin".
Looking now at the base of the jack, it will be
seen that this includes an outer member 16 and an inner
member 15. The outer member 16 has a ground engaging flat -
bottom portion with upturned peripheral side edges 25.
These upturned peripheral side edges include an inner vertical
wall 26 defining the perimeter of a rectangular cavity.
The inner tiltable base member 15 has a flat
top face portion 37 which peripherally merges into down-
wardly inclined edge portions 36. It also includes a
central downwardly pressed cylindrical socket 30. This
` socket 30 has in the bottom face thereof a rounded dome -
portion 32 formed therein which tiltably rests on a rounded
dome portion 28 formed in the bottom of outer support
base 16. The bottom face of the outer base 16 may also
include a stiffening ridge 27.
- A hole 29 is provided in the center of dome 32
and a corresponding hole is provided in dome 28. A bolt
33 is then passed through these holes and a nut 34 is
applied to join together the inner rocking base and the
outer support base. Also positioned between the inner and
outer bases are rubber blocks 35 and these are positioned
at least in the four corners as illustrated in Figure 3.
Holes 38 are provided in the inner base 15 and
;~ 30 the jack portion is rigidly fixed thereto by way of rivets
~ 14 extending through base flange l3 of the jack
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column and through the inner rocking support base 15.
With the jack portion firmly attached in this manner,
the device is operational.
The rubber blocks 35 completely fill the vertical
space between the support bases 15 and 16 as can be seen
from Figure l so that the rubber blocks tend to hold these
plates in parallel relationship. However, when the jack is
mounted on an irregular floor or uneven ground, the jack
column portion can tilt with respect to the base by com-
pressing one or more of the rubber blocks 34. Of course,since these rubber blocks are quite hard, e.g. 60 - 70
durometer hardness, it will be seen that a considerable load
is necessary before this tilting occurs. When the load on
the jack is released, the resiliency of the rubber blocks
causes the bases 15 and 16 to return to their parallel
positions as shown in Figure l.
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