Note: Descriptions are shown in the official language in which they were submitted.
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Title: Raising and Lowering' Columns
This invention relates generally to raising and lowering columns,
ie columns which comprise a relatively fixed base part and an
upper part which can be raised and lowered relative to the base
part. More particularly, the invention concerns apparatus for
raising and lowering the columns, and a method of attaching th.e
apparatus to the columns.
Operation of raising and lowering columns is generally performed
by one or more piston and cylinder devices which is/are secured
to respective attachment points on the two column parts. In
locations where a large number of such columns are fitted, it is
expensive to provide each column with its own individual piston
and cylinder device(s). Instead, a so called counterbalance unit
is employed, which is moved from column to column and on which
the piston and cylinder devices) are mounted for detachable
securement to whichever column needs to be serviced/repaired.
Such securement is often performed by manual lifting of the
piston and cylinder devices) into position on the column. This
can be a hazardous operation, particularly where tall columns are
concerned and the piston and cylinder device ( s ) are large and
therefore heavy.
DE-A-1901659 discloses one example of such a counterbalance unit,
wherein the piston and cylinder device is carried on a wheeled
support. Although the support does assist in the manoeuvring of
the piston and cylinder into position, there is still a danger
that the device will fall during the process of its attachment
to the column, with a resultant risk of injury to the operative
or operatives.
According to one aspect of the present invention, this problem
is obviated or mitigated by proving a disengageable mounting
whereby the or each piston and cylinder device is carried by the
support, the disengageable mounting being operative to permit one
end of the device to be engaged with a respective attachment
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point on the column while the device is still carried by the
support, the mounting also being operative to permit
disengagement -of the device from the support by subsequent
operation of the device to lift it bodily relative to the
support, whereby the device can them be swung to bring its other
end into engagement with another attachment point on the column.
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Preferably, the support is in the form of a wheeled chassis.
Advantageously, the disengageable mounting between the or each
piston and cylinder device and the support is a disengageable
pivotal mounting, and the or each piston and cylinder device is
stored in a predetermined pivotal position relative to the
support.
Desirably, the support includes engagement means which releasably
engages the or each piston and cylinder device ( preferably at one
end of the latter) to hold the device in its stored position.
Conveniently, said one end of the or each piston and cylinder
device includes an aperture, and the engagement means comprises
a slot or opening in the support which is aligned with said
aperture in the stored position of the piston and cylinder
device, and a removable pin which extends through the
slot/opening and the aperture.
Preferably, the disengageable mounting comprises at least one
slot in the support which engages a respective pivot pin on the
or each piston and cylinder device.
Advantageously, said at least one slot is angled so that the
respective pivot pin cannot disengage therefrom when the or each
piston and cylinder device is in its stored position.
According to a second aspect of the present invention, there is
provided a method of attaching a piston and cylinder device to
a raising and lowering column, the method comprising positioning
in close proximity to the column a support on which the piston
and cylinder device is carried by means of a disengageable
mounting, operating the device to bring one end thereof into
engagement with a first attachment point on one of the column
parts, securing said one end of the device to the first
attachment point, operating the device to move the latter bodily
relative to the support and thereby disengage the mounting,
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swinging the device about the first attachment point to bring its
other end into engagement with a second attachment point on the
other column part, and securing said other end of the device to
the second attachment point.
Preferably, the first attachment point is on the upper column
part, and the piston and cylinder device is extended to bring
said one end into engagement with the first attachment point and
is retracted to disengage the mounting.
Advantageously, the disengageable mounting between the piston and
cylinder device and the support is a disengageable pivotal
mounting, the device is stored in a predetermined pivotal
position relative to the support, and is pivoted out of that
predetermined pivotal position before being operated to bring
said one end into engagement with the first attachment point.
The invention will now be further described, by way of example
only, with reference to the accompanying drawings, in which:
Figure 1 is a schematic exploded perspective view of apparatus
(in the form of a counterbalance unit) for operating
a raising and lowering column, according to one aspect
of the present invention;
Figures 2 to 6 are side views showing successive steps in a
method of attaching the apparatus shown in Figure 1 to
a raising and lowering column, according to another
aspect of the present invention; and
Figure 7 is a perspective view of a modified version of the
counterbalance unit.
Referring first to Figure 1, the illustrated counterbalance unit
comprises a support in the form of a wheeled chassis 10 which
carries a pair of hydraulic piston and cylinder devices or rams
11. The chassis 10 is composed of a pair of side frames 12
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linked inter alia by cross-members 13 and 14. The chassis is
open at its rear, and at its forward end has a fitment 15 by
which it can be towed e.g. by a motor vehicle. Also at the
forward end there is provided a swivelling caster 16 which
assists in manoeuvring the chassis into position once it has been
detached from the towing vehicle.
Each of the rams 11 comprises a relatively expandable and
retractable cylinder unit 17 and piston rod 18. The piston rod
18 has at its end a boss 19 with an aperture 20 therein, while
a further aperture 21 is provided in the cylinder unit 17 at the
opposite end of the ram. The cylinder unit 17 also carries on
its sides opposed pivot pins or trunnions 22 and these are
pivotally and detachably received in respective slots 23 in hook-
like mounting members 24 which extend rearwardly from the cross-
member 13. During transportation and storage, the rams 11 occupy
a predetermined pivotal position relative to the chassis 10,
wherein the apertures 20 in the bosses 19 are aligned with holes
25 in members 26 which extend rearwardly from the cross-member
14. The rams are releasably held in those positions by means of
removable retaining pins 27 which extend through each boss 19 and
the slots 25 in the respective adjacent members 26. The slots
23 are angled so as to prevent the pivot pins 22 from disengaging
therefrom when the rams 11 are in their stored positions, for
example when the counterbalance unit is being towed over a bumpy
surface.
The chassis 10 also carries the necessary hydraulic equipment for
operating the rams, such as a reservoir for hydraulic fluid, a
pump and connecting pipework. Although not specifically
illustrated, this equipment is mounted on a forward end of the
chassis in a space generally designated at X.
Referring now briefly to Figure 4, the counterbalance unit is
intended for use with a column 28 comprising a relatively fixed
base part 29 and an upper part 30 which can be pivotally raised
and lowered relative to the base part 29, in order to enable e.g.
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a lighting fitment (not shown) mounted at the top of the part 30
to be brought down to ground level for servicing and/or repair.
The base part 29 has to either side thereof a pair of laterally
spaced gussets 31 for receiving the cylinder unit 17 of a
respective one of the rams 11, while the upper part 30 similarly
has to each side thereof a pair of laterally spaced gussets 32
for engagement with the boss 19 on the piston rod 18 of the
respective ram.
Figure 2 shows the counterbalance unit with the rams 11 in their
stored position. In order to attach the rams to the column 28,
the retaining pins 27 are removed and the rams are pivoted
relative to the chassis 10 to a position where they are slightly
rearwardly inclined, as depicted in Figure 3. The chassis 10 is
then manoeuvred into position so that the rear of the side frames
12 extend respectively on either side of the column 28. The
counterbalance unit is then in the position illustrated in Figure
4.
The rams 11 are then extended to bring the boss 19 on each piston
rod 18 into engagement with the respective gussets 32, with the
aperture 20 in the boss being aligned with holes 34 in the
gussets. The pivotal position of each ram 11 relative to the
chassis 10 can be adjusted at this time to ensure proper
alignment of the boss and the gussets. A retaining pin 35 is
then inserted through each aperture 20 and the associated holes
34. The counterbalance unit now occupies a position as shown in
Figure 5. To facilitate insertion of the pins 35, the
counterbalance unit is provided with a platform P on which the
operative can stand, access to the platform being gained by way
of a ladder L on one side of the unit.
Following this, the piston rods 18 of the rams 11 are retracted
slightly to lift the cylinder units 17 bodily relative to the
chassis 10 and thereby raise the pivot pins 22 out of the slots
23. The forward angling of the slots 23 means that it is not
necessary to swing the rams 11 during this operation to ensure
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that the pins 22 clear the slots 23. Once the pins 22 are clear
of the slots 23, the rams 11 are swung downwardly about the
respective pins 35 to bring the cylinder units 17 into engagement
with the respective gussets 31 on the base part 29. The rams are
also extended or retracted as necessary to align the apertures
21 in the cylinder unit with holes 36 in the gussets 31. A
retaining pin 37 is then inserted through each aperture 21 and
the associated holes 36. The rams 11 are thereby attached to the
column 28 (as depicted in Figure 6) and are ready to assist in
the pivotal lowering and raising of the upper column part 30 in
a conventional manner.
In order to remove the rams 11 from the column, the above-
described sequence of operations is followed in reverse.
The pins 27, 35 and 37 are arranged so as to be of the same size
and design, so they can be interchanged.
Figure 7 illustrates a modified version of the counterbalance
unit which is intended for use with taller (and therefore
heavier) columns, and in which the rams 11 are of heavier duty
construction. In this unit, the members 26 extend rearwardly
from a cross-member 50 which is provided at the front of the
chassis 10, and the rams 11 are depicted in their
transportation/storage position wherein they are near-horizontal
and their bosses 19 are engaged with those members 26 by the
retaining pins 27.
Operation of this version of the counterbalance unit is generally
similar to that described above. In this unit, however, there
is also provided a safety bar 51 which is selectively engageable
with mountings 52 on sloping rear members 53 of the chassis 10
and with mountings 54 on upright intermediate members 55 of the
latter. During transportation and storage, the safety bar 51 is
engaged with the mountings 52 so that it is disposed below the
free ends of the rams 11, to prevent the rams from accidentally
rotating. Prior to operation of the unit, the safety bar 51 is
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removed. Once the rams 11 have been rotated into their near-
vertical positions ( as depicted at 11' ) , the safety bar 51 is re-
engaged with the mountings 54, to prevent the rams from rotating
while they are engaged with the upper column part 30. Once such
engagement has been achieved, the bar 51 is removed once again
to allow the rams to be lifted from their mountings and swung
into engagement with the column base part 29. The safety bar 51
is used in an analogous manner during de-mounting of the rams
from the column.
The counterbalance units described above are particularly (though
not exclusively) applicable for use with columns which are 35
metres or more high, where the rams must be fairly robust in
order to support the weight of the upper column part during its
raising and lowering. This in turn means that the rams
themselves are fairly heavy, and would present considerable
hazards to operatives attempting to attach them to the column by
purely manual means. By utilising the above-described
counterbalance unit and method of attaching the rams to the
column, the whole operation can be conducted safely with no
danger of the operative suffering muscular strains through manual
manipulation of the rams into position, or becoming injured due
to the rams accidentally being dropped.
Although the counterbalance units have been described as
containing two rams, they can alternatively have just one.
