Note: Descriptions are shown in the official language in which they were submitted.
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"ADJUSTABLE LEG FOR SUPPORTING A TABLE"
BACKGROUND OF THE INVENTION
This invention relates to an adjustable leg for
supporting a table top whereby the height of the table
top can be raised or lowered. The expression table top
is intended to include any substantially horizontal
surface which can support objects such as various sorts
of table, television tables, desk tops and other surfaces
for supporting for example typewriters and computer term-
finals.
Tables and desks particular for use with come
putter terminals and other equipment which includes key-
boards or other devices which require close attention and
manual operation need to be adjusted accurately to the
required height of the individual using the equipment.
In view of the large increase in usage of of such equip-
mint there has developed a particular demand for tables
of this type with the need for a rapid and accurate
adjustment of the height particularly of the table itself
which may or may not carry associated equipment attached
to the table.
Various prior arrangements have been proposed
for adjustable table tops generally comprising a single
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leg which has a screw or rack which can be raised or
lowered by operation of a suitable actuating mechanism.
For example US. Patent 944,560 provides a
height adjustment mechanism in the form of an extension
portion carrying a rack which is raised and lowered
relative to a leg by a pinion and a manually rotatable
handle carried on the leg.
US. Patents 1,783,661 and 3,030,073 provide an
externally screw threaded extension portion with a pod-
vestal on which is mounted a hand wheel which surrounds
the screw threaded portion and can be manually turned to
raise the screw threaded portion to raise the table top.
However these arrangements are complex and
therefore expensive to manufacture and are visually
unappealing. Furthermore in view of the large number of
parts involved they tend to be somewhat unstable and
prone to wear between the various parts whereby the
desired smooth action and accurate control can be lost.
SUMMARY OF THE INVENTION
It is one object of the present invention,
therefore, to provide an improved leg of this general
type for raising a table top which is manufactured simply
from a limited number of parts which are stably and
accurately maintained in position and therefore provide
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an accurate and smooth movement.
According to the invention, therefore, there is
provided a leg for supporting a table top the height of
which can be varied comprising a support tube for mount-
in substantially vertically and defining an outer sun-
face of the leg, an externally screw threaded rod mounted
within the support tube for supporting on an upper end
thereof the table top and arranged so as to be axially
movable from a retracted position at least partially
within the tube to an extended position to raise said
table top, an opening in said tube extending over a part
only of the periphery and length thereof, a toothed gear
member having peripherally mounted axially extended teeth
and mounted within said tube so as to surround said rod
such that the teeth thereof over a part of the periphery
thereof are exposed at said opening, said gear member
including an internal screw thread for cooperating with
said externally screw threaded rod, means for driving
said exposed teeth for rotating said gear member and
collar means within the tube surrounding the rod and
including means for preventing rotational movement of
said collar relative to said tube and relative to said
rod while allowing said axial movement and arranged to
retain said gear member against axial movement whereby
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said rotation thereof acts to move said rod axially to
said retracted and extended positions.
According to a particularly preferred arrange-
mint the toothed gear member provides a first portion and
a second portion axially spaced from the first both of
which present teeth at the opening with one of the port
lions being arranged for cooperation with a ratchet drive
device and therefore has generally rectangular teeth and
a second portion is arranged for cooperation with a gear
wheel and therefore has gear type teeth.
In this way a leg Jan be manufactured simply
and yet used either for drive motor actuation or for
manual lever actuation, the latter using a ratchet drive
member.
The ratchet drive member can include a manual
lever which reciprocates around an arc of the tube in a
radial plane with the extent of the arc being defined by
the peripheral extent of the opening.
A paw having a visual portion in the shape of
an arrow can be rotated through 180 so that when moved
by the manually operable lever it drives the gear member
either in a direction to raise or to lower the rod
depending upon the direction of the arrow of the paw.
The leg can be simply formed from a steel or
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aluminum tube with the collars formed of plastics mater-
tats one on either side of the gear member and providing
bearing surfaces for the gear member and for the axial
movement of the rod.
The leg therefore in the form of the tube
presents a pleasing appearance and the opening can be
covered by a housing clamped around the leg at a position
spaced from both ends of the leg, the housing being
shaped and arranged to contain the manually actable
ratchet and lever device or the electric drive motor
depending upon requirements.
With the foregoing in view, and other ad van-
taxes as will become apparent to those skilled in the art
to which this invention relates as this specification
proceeds, the invention is herein described by reference
to the accompanying drawings forming a part hereof, which
includes a description of the best mode known to the
applicant and of the preferred typical embodiment of the
principles of the present invention, in which:
DESCRIPTION OF THE DRAWINGS
Figure 1 is a side elevation Al view portly in
cross-section of an elevating device for a table or
desk.
Figure 2 is a side elevation Al view of the
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lifting portion of the device of Figure 1 with one half
of the housing and the outer surface of the tubular leg
broken away.
Figure 3 is a plan view of the device of Figure
1 with the upper table support device removed.
Figure 4 is a cross-sectional view along the lines 4-4 in
Figure 1 on an enlarged scale showing the details of the
ratchet mechanism.
Figure 5 is an isometric view of an electric
drive motor arrangement for use with the leg of Figure 1
in place of the manual lever device.
Figure 6 is a cross-sectional view along the
lines 6-6 of Figure 5.
In the drawings like characters of reference
indicate corresponding parts in the different figures.
DETAILED DESCRIPTION
The table support including the elevating
device shown in Figure 1 and comprising a steel or
aluminum tubular column or leg 10 with feet 11 arranged
at the bottom extending outwardly from the central column
to provide a support for the central column to retain it
vertically. The feet can include castors if required
with means for braking the castor wheels to retain the
support in a particular chosen position after adjustment
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on the castor wheels. For convenience of illustration,
the castor wheels and braking mechanism are not thus-
treated. Alternatively the leg can be clamped by means
(not shown) to a table or desk for supporting an also-
elated adjustable surface.
In Figure 2, the lower part of the tubular leg
10 is illustrated in side elevation Al view whereas an
upper part is shown broken away and it will be noted that
the tubular column or leg comprises a relatively thin
walled tube 12 for receiving a height adjustment motion-
is generally indicated at 13 within the upper pat of
the tube 12.
The height adjustment mechanism comprises a
first fixed collar 14 which closes the upper open end of
the tube 12 and provides an upper annular face 15 as
shown in Figure 3 with a central hole 16 for receiving a
screw rod 17. The collar 14 is located in the tube 12
and held against rotational and axial movement by pins 18
and 19 which pass through the wall of the tube 12 and
provide a stud on the outer surface thereof. The collar
14 is manufactured from a central cylindrical portion 141
and a plurality of splints extending radially outwardly
from the cylindrical portion and indicated at 142.
A second fixed collar 20 is positioned in the
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upper part of the tube 12 spaced from the collar 14 and
again is of the same construction as the collar 14 and is
locked in position by pins 18 and 19.
The bottom face of the collar 14 is provided by
a plate 143 which provides a planar lower face of annular
shape surrounding the screw 17. The upper face 203 of
the lower collar 20 is of the same construction. The
faces 143 and 203 provide bearing surfaces for rotational
movement of a central gear member 21 which spans the gap
between the collars 14 and 20 and is held against axial
movement by the collars 14 and 20. The member 21 is
however free to rotate about the axis of the tube 12. A
washer 22 is positioned between the upper face 203 and
the bottom surface of the member 21 in order to accommo-
date axial loads communicated between the member 21 and
the collar 20 while allowing the member 21 to rotate
relative to the upper face 203 of the collar 20.
A rectangular opening 23 is provided in the
tube 12 substantially coextensive in height with the
member 21 and extending over a part of the periphery of
the tube 12 as shown in Figure 3 to provide access to the
member 21 from the exterior of the tube 12. The member
21 has formed in the outer surface thereof a plurality of
axially extending teeth 211 which provide a gear arrange-
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mint on the exterior surface thereof by which the member can be rotated. A second gear formed by axially extend-
in teeth 212 is positioned side by side with the first
on the member 21 so the member 21 effectively` is formed
by the two gears which are coupled together for co-rota-
lion about the axis of the tube 12.
The screw 17 which passes through the collars
14 and 20 also passes through the member 21. The screw
17 includes a screw thread on the outer surface thereof.
The screw 17 is arranged in sliding fit with the cylinder
141 of the collar 14 and with a similar cylinder of the
collar 20 so that the screw 17 can move upwardly and
downwardly in an axial direction relative to the collars
14 and 20 but is prevented from radial movement relative
to the axis of the tube 12. The member 21 carries on
inner surface a cooperating screw thread for engaging the
screw thread 17. As shown in Figure 3, the collar 14
provides a pair of axially extending inwardly projecting
guides 144 which are integral with the collar 14 and
hence are held against axial or rotational movement by
the collar 14. The projections 144 cooperate with slots
171 cut axially of the screw thread 17 and having a depth
equal to that of the screw thread whereby the screw is
prevented from rotating relative to the tube 12. Rota-
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lion of the member 21, therefore, which is held against axial movement but allowed to rotate, causes axial move-
mint of the screw 17 which is prevented from rotating but
allowed to move axially.
Rotation of the member 21 is obtained by
engagement of the gear formed by the substantially
rectangular teeth or splints 211 with a ratchet device or
paw 24 which protrudes through the opening 23. The paw
24 is shown in more detail in Figure 4 in cooperation
with the splints 211 of the collar 21. The paw has a
projecting nose 241 which projects into the spaces
between the splints 211. The nose is formed by a side
242 which extends radially outwardly from the axis of the
tube and therefore lies parallel to the edge 213 of the
splint 211. The other face of -the nose 241 is inclined
away from the edge 213 to contact a corner of the next
adjacent splint 211 and extends beyond that to lie on an
arc 244 concentric with the axis of the tube and with the
outer surface of the splints 211. The arc 244 forming
the remainder of the front surface of the paw 24 is
spaced from the outer face 214 of the splints 211. In
this way as the paw moves in the clockwise position as
shown in Figure 4 it merely slides over the splints 211
without causing rotational movement of the collar 21 with
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the paw being pushed away from the splints by the sun-
face 243. However when moved in the anti clockwise
direction as shown, the paw acts to move the collar 21
in the same anti clockwise direction to move the screw 17
axially.
The paw 24 is mounted on a pin 25 which
includes an operating lever 26. The pin 25 is mounted in
a channel 27 formed in a sleeve generally indicated at 28
which channel 27 allows the pin to be rotated through
180 by operation of the lever 26. Thus the paw as
shown in Figure 4 can be turned through 180 so as to
provide a ratchet effect in the opposite direction and to
rotate the collar 21 in the clockwise direction. The
operating lever 26 is offset from the pin 25 as shown
best in Figure 3 and when rotated through 180 is offset
to the other side of the pin 25 as will be apparent. In
order to indicate the direction of movement of the screw
17 in relation to the position of the paw 24, the lever
26 includes an arrow or pointed end 261 which points up
or down depending upon the orientation of the lever.
The sleeve member 28 surrounds the tube 12 and
is basically formed from two half cylinders 281, 282
which can be screwed together through screw holes 283 and
screws 285. The sleeve 28 has on its inner surface a
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number of peripheral channels 284 which act to retain
grease to enable the sleeve to rotate around the tube 12.
In addition the upper and lower channels 284 act as
guides for the sleeve by cooperating with the studs 18
which slide in the channels 284.
The sleeve member 28 also includes a second
radially extending channel 29 parallel to the channel 27
for receiving an operating lever 30 which extends out-
warmly beneath the paw 24 and beyond the paw 24 to a
knob 31 which can be manually grasped. The lever 30
includes an enlargement 32 cooperating with an enlarged
section of the channel 29 to retain the lever in post-
lion. It will be noted that the inner end of the lever
30 projects into the opening 23 and hence delimits the
angular movement of the sleeve 28 around the tube 12. A
similar enlargement in the channel 27 receives a spring
33 which acts to force the paw 24 inwardly against the
splints 211.
The upper end of the screw 17 (Figure 1) is
turned down to a diameter only slightly greater than the
base of the screw thread over a section indicated at 34.
This turned down section receives a metal support member
35 which is slightly dished and is turned down at a
central opening 36 to provide a collar surrounding the
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section 34 of the screw 17. A cooperating supporting member 37 also includes a collar surrounding the section
34 and is riveted to the plate 35 by rivets 28 and
includes lugs 39 which project through openings 40 in the
plate 35. The plate 35 extends outwardly to a rim area
41 which has openings 42 for attaching the plot 35 to the
undersurface of a panel forming a table or desk the upper
surface of the panel thus can support working equipment
such as a computer terminal and the height of it relative
to the ground can be adjusted over very fine limits by
moving the screw 17 upwardly and downwardly as previously
described.
The panel (not shown) forming the surface of
the desk or table can be of any suitable dimension and
can include drawers or compartments as required. In
addition a sliding arrangement positioned beneath the
panel can be provided for receiving a keyboard or other
similar equipment which can be slid forwardly and rear-
warmly so as to be exposed in the forward position for
operation. The sliding arrangement can include a limited
amount of height and/or angle adjustment to accommodate
the individual user. In addition the panel can be tilted
relative to the support Jo move to a position of comfort
for the user.
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In an alternative arrangement (not shown) an
additional gear mechanism can be added to the lifting
mechanism so that vertical actuation of the lever 31
causes rotational movement of the drive collar 21.
Turning now to Figures 5 and 6 there is shown
the leg 10 and screw 17 of Figures 1 through 4 including
an alternative drive arrangement which can be applied to
the leg in place of the housing 28 and the associated
paw 24 and operating lever 30.
The drive arrangement comprises a housing 43
having a lower section 44 for a battery pack and an upper
section 45 for housing a drive motor 46 shown schematic
ally in phantom. The housing 43 is formed in two halves
47 and 48 with an overlapping lip 49 by which the halves
can be screwed together at 50 Jo clamp the housing 43
around the tube 12.
The motor 46 carries a drive gear 50 which
carries conventional gear drive teeth 51 for cooperation
with the teeth 212 of the lower portion of the gear mom-
bier 21. The teeth 212 are also visible in Figure 4 where
it will be noted that there are the same number of teeth
in the section 212 as in the section 211 but the teeth
are shaped with sloped sides as conventional gear drive
teeth for cooperation with the drive gear 50 of the
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electric motor 46.
A toggle switch 51 is mounted on the upper
portion of the housing as shown in Figure 5 and is act-
able to drive the motor to rotate the gear member 21 to
raise or lower the screw 17. The switch 51 is thus a
three position switch providing drive in both directions
and also a stationary condition of the motor.
The battery pack can be optional and can be
replaced by direct coupling to the mains supply.
Since various modifications can be made in my
invention as hereinabove described, and many apparently
widely different embodiments of same made within the
spirit and scope of the claims without departing from
such spirit and scope, it is intended that all matter
contained in the accompanying specification shall be
interpreted as illustrative only and not in a limiting
sense.
