U.S. patent application number 12/261918 was filed with the patent office on 2009-06-04 for articulating support mechanism with pivotal brake shoe.
This patent application is currently assigned to CompX International Inc.. Invention is credited to NICHOLAS L. BLACKBURN.
Application Number | 20090140114 12/261918 |
Document ID | / |
Family ID | 40589940 |
Filed Date | 2009-06-04 |
United States Patent
Application |
20090140114 |
Kind Code |
A1 |
BLACKBURN; NICHOLAS L. |
June 4, 2009 |
ARTICULATING SUPPORT MECHANISM WITH PIVOTAL BRAKE SHOE
Abstract
A four bar articulating support mechanism has four pivot axes
with one of the pivot axes being movable relative to a linkage of
the support arm. The linkage has at least two arcuate slots therein
that receive a pin. As the linkage is moved vertically relative to
a mounting member, the pin slides in the at least two arcuate slots
which pivot about a theoretical third pivot axis. The support arm
has two brake shoes that are pivotally mounted on a mounting
member, the brake shoes having a locking surface that corresponds
to a locking surface on the linkage. The mechanism operates on a
parallelogram linkage.
Inventors: |
BLACKBURN; NICHOLAS L.;
(Wellesley, CA) |
Correspondence
Address: |
DARYL W SCHNURR;MILLER THOMSON LLP
ACCELERATOR BUILDING, 295 HAGEY BLVD., SUITE 300
WATERLOO
ON
N2L 6R5
CA
|
Assignee: |
CompX International Inc.
|
Family ID: |
40589940 |
Appl. No.: |
12/261918 |
Filed: |
October 30, 2008 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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60983703 |
Oct 30, 2007 |
|
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Current U.S.
Class: |
248/282.1 |
Current CPC
Class: |
A47B 21/0314
20130101 |
Class at
Publication: |
248/282.1 |
International
Class: |
A47B 96/06 20060101
A47B096/06 |
Claims
1. An articulating support mechanism for use in supporting one or
more objects on a platform, said mechanism being usable with a
base, said mechanism comprising a linkage having a first end and a
second end with a mounting member being pivotally connected to said
linkage at said first end and said platform being pivotally
connected to said linkage at said second end, said linkage having
an upper arm and a lower arm, said upper arm being pivotally
connected to said mounting member at a first pivot axis and being
pivotally connected to said platform at a second pivot axis, said
lower arm having at least one arcuate slot that is connected to
said mounting member to enable said lower arm to pivot about a
third pivot axis, said lower arm being pivotally connected to said
platform at a fourth pivot axis, said pivot axes being parallel to
one another, said mounting member being sized and shaped to be
mounted on said base and to receive said first end of said linkage,
said mounting member and said upper arm being constructed to pivot
relative to one another about said first pivot axis, a pin
extending through said mounting member and through said at least
one arcuate slot in said lower arm, said third pivot axis being
located along an imaginary line about which said at least one
arcuate slot pivots when said linkage moves vertically relative to
said mounting member, said pin being slidable in said at least one
arcuate slot, said first, second, third and fourth pivot axes being
in a parallelogram configuration at all times, a brake shoe being
pivotally mounted on said mounting member about a fifth pivot axis,
said brake shoe and said linkage having locking surfaces thereon
that removably lock with one another in infinite positions of said
linkage relative to said mounting member, said linkage locking by
gravitational forces and being releasable by an upward force on
said linkage or on said platform or by manually tilting said
platform upward, said platform being pivotable relative to said
linkage independently of said platform and said linkage pivoting
relative to said mounting member.
2 A support mechanism as claimed in claim 1 wherein said pin in
said at least one arcuate slot being in a non-parallelogram
configuration with said first, second, and fourth pivot axes.
3. A support mechanism as claimed in claim 2 wherein said mounting
member, upper arm, and lower arm, each have two sides and said at
least one arcuate slot in said lower arm, being two arcuate slots,
one arcuate slot being located on each side of said lower arm.
4. A support mechanism as claimed in claim 3 wherein said arcuate
slots of said lower arm are first arcuate slots, said first arcuate
slots being equidistant from said third pivot axis.
5. A support mechanism as claimed in claim 4 wherein said third
pivot axis is theoretical, there being no pin located at said third
pivot axis.
6. A support mechanism as claimed in claim 4 wherein said upper arm
has two second arcuate slots, there being one second arcuate slot
in each side of said upper arm, said second arcuate slots being
oriented about said first pivot axis.
7. A support mechanism as claimed in claim 4 wherein said arcuate
slots in said lower arm have a heat tempered insert lining said
slot on each side of said lower arm, there being two inserts.
8. A support mechanism as claimed in claim 3 wherein said arcuate
slots in said lower arm are oriented about said third pivot axis,
said third pivot axis being a theoretical pivot axis for said
mounting member and said lower arm.
9. A support mechanism as claimed in claim 3 wherein said first
pivot axis is further from an outer end of said linkage than said
third pivot axis.
10. A support mechanism as claimed in claim 1 wherein said brake
shoe has a curved locking surface that is oriented to correspond to
a locking surface of said upper arm.
11. A support mechanism as claimed in claim 10 wherein said locking
surface of said brake shoe frictionally engages with said locking
surface of said upper arm to lock said mounting member relative to
said linkage.
12. A support mechanism as claimed in claim 11 wherein said locking
surface on said brake shoe is curved inward and a locking surface
on said upper arm is curved outward.
13. A support mechanism as claimed in claim 12 wherein said brake
shoe is heat tempered.
14. A support mechanism as claimed in claim 13 wherein said brake
shoe is a first brake shoe that is pivotally mounted on one side of
said bracket and there is a second brake shoe pivotally mounted on
an opposite side of said bracket.
15. A support mechanism as claimed in claim 7 wherein said platform
can be pivoted relative to said linkage independently of said
linkage pivoting relative to said mounting member.
16. A support mechanism as claimed in claim 14 wherein said second
brake shoe is a mirror image of said first brake shoe.
17. A support mechanism as claimed in claim 1 wherein said brake
shoe has an orientation interface that interacts with a surface of
said lower arm to cause said brake shoe to lock with said upper
arm.
18. A support mechanism as claimed in claim 14 wherein said brake
shoes each have an activation surface that abuts a corresponding
activation surface on said lower arm to pivot said brake shoes to
maintain said locking surfaces in alignment.
19. An articulating support mechanism for use in supporting one or
more objects on a platform, said mechanism being usable with a
base, said mechanism comprising a linkage having a first end and a
second end, with a mounting member being pivotally connected to
said linkage at said first end and said platform being pivotally
connected to said linkage at said second end, said linkage having
an upper arm and a lower arm, said upper arm being pivotally
connected to said mounting member at a first pivot axis and being
pivotally connected to said platform at a second pivot axis, said
lower arm being slidably connected to a pin extending through said
mounting member and into at least one arcuate slot in said lower
arm to enable said lower arm to pivot about a third pivot axis,
said lower arm being pivotally connected to said platform at a
fourth pivot axis, said pivot axes being parallel to one another,
and said mounting member being sized and shaped to be mounted on
said base, said first and second and fourth pivot axes and said pin
having a non-parallelogram configuration, said first, second, third
and fourth pivot axes having a parallelogram configuration at all
times, said third pivot axis being imaginary, a brake shoe being
pivotally mounted on said mounting member about a fifth pivot axis,
said brake shoe and said linkage having locking surfaces thereon
that removably lock with one another in infinite positions of said
linkage relative to said mounting member, said linkage locking by
gravitational forces and being releasable by an upward force on
said linkage or on said platform or by manually tilting said
platform upward, said platform being pivotable relative to said
linkage independently of said platform and said linkage pivoting
relative to said mounting member.
20. A support mechanism as claimed in claim 19 wherein said
mounting member, upper arm, and lower arm each have two sides and
said at least one arcuate slot in said lower arm, being two arcuate
slots, one arcuate slot being located on each side of said lower
arm.
21. A support mechanism as claimed in claim 20 wherein said arcuate
slots of said lower arm are first arcuate slots, said first arcuate
slots being oriented about said third pivot axis, there being no
pin located at said third pivot axis.
22. A support mechanism as claimed in claim 21 wherein said upper
arm has two second arcuate slots, there being one second arcuate
slot in each side of said upper arm, said second arcuate slots
being oriented about said first pivot axis.
23. A support mechanism as claimed in claim 21 wherein said arcuate
slots in said lower arm each have a heat tempered insert lining
said slot, there being two inserts.
24. An articulating support mechanism for use in supporting one or
more objects on a platform, said mechanism being usable with a base
and comprising a linkage having two ends with a mounting member at
one end and a platform at an opposite end, with two pivot axes at
each end, said pivot axes being parallel to one another, said
mounting member being sized and shaped to be mounted on said base,
said linkage having an upper arm and a lower arm, said upper arm
having a first pivot axis with said mounting member and a second
pivot axis with said platform, said lower arm having a third pivot
axis with said mounting member and a fourth pivot axis with said
platform, said mechanism having a pin extending through said
mounting member and through at least one arcuate slot, said at
least one arcuate slot being located on said lower arm, said at
least one arcuate slot in said lower arm pivoting about said third
pivot axis and said pin sliding in said at least one arcuate slot
as said linkage moves vertically relative to said mounting member,
said third pivot axis being located along an imaginary line, a
brake shoe being pivotally mounted on said mounting member about a
fifth pivot axis, said brake shoe and said linkage having locking
surfaces thereon that removably lock with one another in infinite
positions of said linkage relative to said mounting member.
25. A support mechanism as claimed in claim 24 wherein said
mounting member, upper arm, and lower arm, each have two sides and
said at least one arcuate slot in said lower arm, being two arcuate
slots, one arcuate slot being located on each side of said lower
arm.
Description
[0001] Applicant claims the benefit of U.S. Provisional Application
Ser. No. 60/983,703 filed on Oct. 30, 2007.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] This invention relates to an articulating support mechanism
that is used to support articles on a platform, the mechanism being
used with a base and the platform moving up or down or pivoting
relative to the base.
[0004] 2. Description of the Prior Art
[0005] Keyboard support mechanisms are known and Wisniewski et al
U.S. Pat. No. 6,134,404 issued Oct. 24, 2000 describes a four bar
linkage having a keyboard support that can swing vertically
relative to a base such as a desk or table top. A central elongated
member has a first link and a second link that are pivotally
connected to a mounting member at the same pivot point. The support
mechanism has a locking system.
SUMMARY OF THE INVENTION
[0006] It is an object of the present invention to provide an
articulating support mechanism having four pivot axes between a
linkage with a mounting member at one end and a platform at another
end. It is a further object of the present invention to provide an
articulating support mechanism that locks precisely and securely
when the mechanism is in the locked position and unlocks easily to
permit further movement.
[0007] An articulating support mechanism is used to support one or
more objects on a platform, the mechanism being used with a base.
The mechanism comprises a linkage having a first end and a second
end with a mounting member being pivotally connected with the
linkage at the first end and the platform is pivotally connected to
the linkage at the second end. The linkage has an upper arm and a
lower arm, the upper arm being pivotally connected to the mounting
member at a first pivot axis and being pivotally connected to the
platform at a second pivot axis. The lower arm has at least one
arcuate slot that is connected to the mounting member to enable the
lower arm to pivot about a third pivot axis. The lower arm is
pivotally connected to the platform at a fourth pivot axis. The
pivot axes are parallel to one another and the mounting member is
sized and shaped to be mounted on the base and to receive the first
end of the linkage. The mounting member and the upper arm are
constructed to pivot relative to one another about the first pivot
axis. A pin extends through the mounting member and through at
least one arcuate slot in the lower arm. The third pivot axis is
located along an imaginary line about which the at least one
arcuate slot pivots when the linkage moves vertically relative to
the mounting member, the pin being slidable in the at least one
arcuate slot. A brake shoe is pivotally mounted on the mounting
member about a fifth pivot axis. The brake shoe and the linkage
have locking surfaces thereon that removably lock with one another
in infinite positions of the linkage relative to the mounting
member. The linkage is locked by gravitational forces and is
releasable by an upward force on the linkage or on the platform or
by manually tilting the platform upward. The platform is pivotable
relative to the linkage independently of the platform and linkage
pivoting relative to the mounting member.
[0008] An articulating support mechanism is used to support one or
more objects on a platform. The mechanism is usable with a base and
comprises a linkage having two ends with a mounting member at one
end, and a platform at an opposite end. There are two pivot axes at
each end, the pivot axes being parallel to one another. The
mounting member is sized and shaped to be mounted on the base, the
linkage having an upper arm and a lower arm. The upper arm has a
first pivot axis with the mounting member, and a second pivot axis
with the platform. The lower arm has a third pivot axis with the
mounting member, and a fourth pivot axis with the platform. The
mechanism has a pin extending through the mounting member, and
through at least one arcuate slot. The at least one arcuate slot is
located on the lower arm, the at least one arcuate slot on the
lower arm pivoting about the third pivot axis and the pin sliding
in the at least one arcuate slot as the linkage moves vertically
relative to the mounting member. The third pivot axis is located
along an imaginary line. A brake shoe is pivotally mounted on the
mounting member about a fifth pivot axis, the brake shoe and the
linkage having locking surfaces thereon that removably lock with
one another in infinite positions at the linkage relative to the
mounting member.
[0009] An articulating support mechanism is used in supporting one
or more objects on a platform, the mechanism being usable with a
base. The mechanism comprises a linkage having two ends with a
mounting member at one end and a platform at an opposite end, with
two pivot axes at each end. The pivot axes are parallel to one
another and the mounting member is sized and shaped to be mounted
on the base. The linkage has an upper arm and a lower arm, the
upper arm having a first pivot axis with the mounting member and a
second pivot axis with the platform. The lower arm has a third
pivot axis with the mounting member and the fourth pivot axis with
the platform. The mechanism has a pin extending through the
mounting member and through at least one arcuate slot, the at least
one arcuate slot being located on the lower arm. The at least one
arcuate slot in the lower arm pivoting about the third pivot axis,
and the pin sliding in the at least one arcuate slot as the linkage
moves vertically relative to the mounting member. The third pivot
axis is located along an imaginary line. A brake shoe is pivotally
mounted on the mounting member by a fifth pivot axis. The brake
shoe and the linkage have locking surfaces thereon that removably
lock with one another in infinite positions of the linkage relative
to the mounting member.
BRIEF SUMMARY OF THE DRAWINGS
[0010] FIG. 1 is a sectional side view of an articulating support
mechanism with a platform in a low position relative to a mounting
member;
[0011] FIG. 2 is an enlarged sectional side view of that part of
FIG. 1 contained in a dotted circle;
[0012] FIG. 3 is an exploded view of the articulating support
arm;
[0013] FIG. 4 is a sectional side view of the articulating support
arm with the platform in a high position:
[0014] FIG. 5 is a sectional side view of that part of the support
mechanism contained within a dotted circle of FIG. 4;
[0015] FIG. 6 is a perspective view of an outside of a brake
shoe;
[0016] FIG. 7 is a perspective view of an inside of the brake
shoe;
[0017] FIG. 8 is a side view of an inside of the brake shoe;
[0018] FIG. 9 is a perspective view of an upper arm;
[0019] FIG. 10 is a sectional side view of the upper arm;
[0020] FIG. 11 is a sectional side view of a lower arm;
[0021] FIG. 12 is a perspective view of the lower arm;
[0022] FIG. 13 is a perspective view of a mounting member;
[0023] FIG. 14 is a sectional side view of the mounting member;
[0024] FIG. 15 is an end view of the mounting member.;
[0025] FIG. 16 is a sectional side view of the articulating support
mechanism as shown in FIG. 4 with a spring added;
[0026] FIG. 17 is an enlarged view of that part of FIG. 16
contained within the dotted circle;
[0027] FIG. 18 is a top view of a platform;
[0028] FIG. 19 is an end view of the platform;
[0029] FIG. 20 is a side view of the platform;
[0030] FIG. 21 is a top view of the support arm;
[0031] FIG. 22 is a top view of that part of the support arm
enclosed within the circle of FIG. 21.
DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT
[0032] In FIGS. 1 and 2, an articulating support arm 2 has a
linkage 4 with an upper arm 6 and a lower arm 8. The linkage 4 has
a first end 10 with a mounting member 12 pivotally connected
thereto and a second end 14 with a platform 16 pivotally connected
thereto. The upper arm 6 is pivotally connected to a bracket 18 of
the mounting member 12 at a first pivot axis 20 and is pivotally
connected to the platform 16 at a second pivot axis 22. The lower
arm 8 has an arcuate slot 26 that is connected to the bracket 18 of
the mounting member 12 to enable the lower arm to pivot about a
third pivot axis 30. The lower arm 8 is pivotally connected to the
platform 16 at a fourth pivot axis 29. A pin 24 extends through the
bracket 18, through an arcuate slot 32 in the upper arm 6 and
through the arcuate slot 26 in the lower arm 8, all at the first
end 10 of the linkage 4. A point of contact 28 is located between
the pin 24 and an edge of the arcuate slot 26 on each side of the
support arm 2. The point of contact 28 is movable along the outer
edge of the slot 26 as the linkage 4 moves up or down relative to
the mounting member 12. The third pivot axis 30 is the pivot axis
for the arcuate slot 26 and the lower arm 8. The slot 26 in the
lower pivot arm 8 and the slot 32 in the upper pivot arm 6 are
oriented to be approximately 180.degree. apart from one another as
the slot 32 rotates about the first pivot axis 20 and the slot 26
rotates about the third pivot axis 30. The third pivot axis 30 is
imaginary in that there is no pin located at the third pivot axis
30. The pivot axes one through four are configured to form a
parallelogram at all times. The first, second and fourth pivot axes
and the pin 24 in the slot 26 do not form a parallelogram. The slot
26 is equidistant from the third pivot axis 30. Preferably, there
are two slots 26 (only one of which is shown), one located in each
side of the bracket 18.
[0033] A brake shoe 34 is pivotally mounted about a fifth pivot
axis 36 to the bracket 18. The brake shoe 34 has a locking surface
38 that corresponds to a locking surface 40 on the upper arm 6,
both of which are shown by a single dotted line. The locking
surface 38 curves inward on the brake shoe 34 and the locking
surface 40 curves outward at the first end 10 of the linkage 4. The
brake shoe has an actuation surface 42 that corresponds to an
actuation surface 43 on the lower arm 8. There is one brake shoe 34
on each side of the support mechanism. The actuation surfaces 42,
43 pivot the brake shoes 34 (only one of which is shown) about the
pivot axis 36 as the linkage 4 moves upward and downward relative
to the mounting member 12. Preferably, the slot 26 is sized to
receive an insert 46 that is heat tempered and the pin 24 moves
along an inner edge of the insert 46 which defines the slot 26.
Alternatively, the slot 26 can be appropriately sized to receive
the pin 24 without the insert 46 and the slot 26 can then be heat
tempered. The brake shoes 34 (only one of which is shown in FIGS. 1
and 2) are also preferably heat tempered as is the locking surface
of the upper arm 6. The mounting bracket 12 has an upper end 44
that is shaped to be slidably mounted into a base (not shown). The
upper end 44 of the mounting bracket 12 is conventional.
[0034] In FIG. 3, the reference numerals are the same as those used
in FIGS. 1 and 2 for those components that are identical. A
universal screw 48 extends through the platform 16 to form the
second pivot axis 22 as shown in FIG. 1. A handle 52, washer 54 and
nut 56 fit onto the universal screw 48 and allow the handle 52 to
be connected thereto. When the handle 52 is rotated in one
direction, the angle of the platform 16 relative to the linkage 4
is increased and, when the handle is rotated in the opposite
direction, the angle is decreased.
[0035] As an alternative to the universal screw 48, a sleeve 58
fits over a pin 60 (also shown in FIG. 3), which is held in place
by a washer 62 and a nut 63 to form the second pivot axis 22 as
shown in FIG. 1. The handle 52 is used with the pin 60 and the
angle of the platform 16 relative to the linkage 4 is varied by
turning the handle in one direction to loosen the pressure of the
platform on the ends of the sleeve 58, thereby allowing the
platform to be tilted relative to the linkage 4. When the handle 52
is turned in an opposite direction, the handle is tightened and
exerts pressure on the sides of the platform 16, which in turn
contact the ends of the sleeve 58 to prevent the platform from
tilting relative to the linkage 4 simply by the friction of the
sides of the platform 16 and the sleeve 58. The operation of both
the universal screw 48 or the pin 60 with handle 52 are
conventional. The universal screw 48 extends through a threaded
cylinder 64 in a drive tilt 65. As the universal screw 48 is
rotated by turning the handle 52, the drive tilt 65 moves closer to
or further from the handle 52 depending on the direction in which
the handle is turned. A pin 66 extends through an upper cylinder 68
of the drive tilt 65. A nut 67 holds the pin 66 in position. The
pin 66 and an inside of the upper cylinder 68 are not threaded. The
pin 66 extends through suitable openings in an end of the upper arm
6 and the universal screw or pin 60 extend through suitable
openings in an end of the lower arm 8. The ends of the upper arm
and lower arm referred to are the ends that are pivotally connected
to the platform 16. The drive tilt 65 has an abutment 70 that abuts
an angled wall, (not shown in FIG. 3) of the platform 16. A height
indicator 72 is installed to pivot at the theoretical pivot axis 30
(see FIG. 2) of the lower arm 8. While only one brake shoe 34 is
shown, there are preferably two brake shoes 34, one on each side of
the support arm 2. Two openings 74, one on each side of the bracket
18, are sized to receive the pin 24. Nodules 76 (only one of which
is shown) extend inward on either side of the bracket 18 of the
mounting member 12 to receive openings 78 in the upper arm 6 that
form the first pivot axis 20.
[0036] Two nodules 80 (only one of which is shown in FIG. 3),
extend inward from the bracket 18 to receive openings 82 in each of
the brake shoes 34 to form the fifth pivot axis 36 shown in FIG.
2.
[0037] In FIG. 4, there is shown the support mechanism 2 with the
linkage 4 and platform 16 raised upward relative to the mounting
member 12 from the position shown in FIG. 1. FIG. 5 is an enlarged
side view of that part of the support mechanism 2 that is located
within the dotted circle of FIG. 4. The same reference numerals are
used in FIGS. 4 and 5 as those used in FIGS. 1 to 3 for those
components that are identical. The brake shoe 34 is in the locked
position relative to the linkage 4 and, particularly, the upper arm
6. From FIG. 5, it can be seen that the point of contact 28 has
moved almost to opposite ends of the slots 26, 32 compared to the
location of the point of contact 28 shown in FIGS. 1 and 2.
[0038] In FIGS. 6, 7 and 8, there are shown perspective views of an
outside and inside of the brake shoe 34 as well as a side view
respectively. The same reference numerals in FIGS. 6, 7 and 8 as
those used in FIGS. 1 to 5 for those components that are identical.
Only one of the locking surfaces 40 is shown on the brake shoe 34.
The brake shoe has an opening 82 to receive the pin 36 (not shown
in FIGS. 6, 7 and 8).
[0039] In FIGS. 9 and 10 there is shown a sectional side view and a
perspective view of the upper arm 6. The upper arm 6 has an
elongated opening 84 in an upper surface thereof to receive the
height indicator (not shown in FIGS. 9 and 10). The same reference
numerals are used in FIGS. 9 and 10 as those used in FIGS. 1 to 6
for those components that are identical.
[0040] In FIGS. 11 and 12, there is shown a sectional side view and
a perspective view respectively of the lower arm 8. The same
reference numerals are used in FIGS. 11 and 12 as those used in
FIGS. 1 to 5 for those components that are identical. A T-shaped
slot 86 in an end that is closer to the mounting member 12 (not
shown in FIGS. 11 and 12) is used to receive one end of a spring
(not shown in FIGS. 11 and 12).
[0041] In FIGS. 13, 14 and 15, there is shown a perspective view, a
sectional side view and a sectional end view of the mounting member
12. The same reference numerals are used in FIGS. 13, 14 and 15 as
those used in FIGS. 1 to 5 to describe those components that are
identical. The upper end 44 of the mounting member 12 has been
omitted from the mounting member shown in FIGS. 13, 14 and 15.
[0042] In FIGS. 16 and 17, the same reference numerals are used as
those used in FIGS. 1-15 for those components that are identical. A
spring 88 is coiled around the pin 24 with one end 90 located in
the T-shaped slot 86 of the lower arm 8 and in opposite end 92 is
located against the upper arm 6. The spring 88 was omitted from the
previous drawings so as not to obscure the pivot axis 28 (not shown
in FIGS. 16 and 17) on the pin 24. The spring 88 assists in raising
the linkage for platform 16 relative to the mounting member 12. The
brake shoe(s) and the insert(s) are omitted from FIGS. 16 and
17.
[0043] In FIGS. 18 to 20, there is shown a top view, end view and
side view of the platform 16. In FIG. 18, it can be seen that the
platform has an angled wall 94 therein. In FIG. 20, the platform 16
has an arcuate opening 96 and a second opening 98 in each side
thereof (only one of which is shown).
[0044] In FIGS. 21 and 22, the same reference numerals are used as
those used in FIGS. 1 to 20 for those components that are
identical. The universal screw 48 extends through the arcuate
openings 96 (not shown in FIGS. 21 and 22) on each side of the
platform 16 and also through the threaded cylinder 64 in the drive
tilt 65. The pin 66 extends through the upper cylinder 68 of the
drive tilt 65. As the handle 52 is turned in either direction to
rotate the universal screw 48, the drive tilt 65 moves from
side-to-side across the platform 16. The drive tilt has an angled
projection 100 that is in contact with the angled wall 94. As the
angled projection 100 of the drive tilt 65 moves toward the right
in the orientation shown in FIG. 22, an angle between the platform
16 and the linkage 4 decreases and as the drive tilt 65 moves
towards the left in the orientation shown in FIG. 22, the angle
between the platform and the linkage for it decreases.
[0045] The support mechanism 2 operates as a four bar parallelogram
linkage even though the third pivot axis is imaginary.
* * * * *