GB2362396A - A fold down column - Google Patents

Abstract

A column, as used for mounting lamps or television cameras, has an upper section (above line 18) which is hingedly connected to a lower section (below line 18) by pivot pins (24) so as to be capable of being folded down to allow access and maintenance of the mounted equipment. The mechanism for lowering the column is contained wholly within the lower section and preferably includes a counterbalance (44, 46) in which a spring (40) is increasingly compressed as the upper section is lowered. Pivoting of the upper section may be brought about by a vertical actuator (50) which is threadedly engaged with a retained element, such as a nut (70) or a bevel gear (Fig 1a), to which a tool, such as a spanner (80) or crank handle may be applied.

Description

2362396 -I- - P650663 - A Fold Down Column This invention concerns a

column, as used, for example, for the mounting at a height of lurninaies, lamps, television cameras, etc. having an upper section which is hingedly connected to a lower section so as to be capable of being folded down to allow access to and maintenance of the mounted equipment.

Such a column is commonly used in any location where it is not possible to reach the equipment at the top of the column by means of a vehicle mounted access platform. This may be because vehicular access to the area where the column is installed is not practical, e.g a railway platform, pedestrian walkway, sports ground etc, or because a raisable platform is not allowed for safety reasons e.g near to overhead electricity lines.

There are several known designs for such a hinged column, each with a corresponding manner of lowering the upper section. Firstly, some small columns (4, 5 or 6 m high) are of particularly simple design and the counterbalancing force, as the upper section is lowered, is provided by an operator applying his weight at the end of a long handle or cable. Other columns are provided with an external pulley arrangement whereby the upper section is counter balanced as it is lowered, and also to enable it to be raised again, in both cases using manual force alone. Yet other columns are designed to enable external attachment of a separate device which incorporates a hydraulic mechanism or a spring loaded mechanism for purposes of counter balance and controlled lowering and raising of the upper section.

An object of the present invention is to provide a hinged column with an inbuilt mechanism for controlled lowering and raising of its upper section, so as to obviate the need for attachment of a separate device for this purpose, thus reducing long term costs in terms of operator time and labour in effecting the attachment and in moving the external device from column to column.

With this object in view, the present invention provides a fold down column comprising an upper section which is pivotably mounted relative to a lower section and means for lowering the upper section which are disposed entirely within the lower section.

Thus the lower section and the upper section are substantially hollow, as is conventional, and the lowering means are located inside the former. This necessitates careffil design as the lower section, which is generally of approximately circular cross-section, and may be tapered, or have a reduced diameter upper portion, is often required to be of less than 20Omm in diameter.

The lowering means preferably includes a spring-operated counter balance mechanism. This may comprise a helical spring which is increasingly compressed as the upper section is lowered.

Another component of the lowering means may comprise a substantially vertical actuator which can push and/or pull part of the upper section and cause it to pivot relative to part of the lower section. In this respect, the aforesaid part of the upper section may be connected by a pivotal linkage to a piston which can act to compress the spring.

In order to move the actuator, a bevel gear may be provided. Alternatively, a nut which threadedly engages the actuator and is also mounted rotatably in a block may be turned by means of a spanner in order to move the actuator.

-3Two practical embodiments of the column of the invention will be described further, by way of example, by reference to the accompanying drawings, in which:

Figures 1 a and 1 b when placed together, 1 a above 1 b, are a partial longitudinal section of a first embodiment of the column showing a region where an upper section is hingedly connected to a lower section and a region therebelow; Figure 2 is a transverse cross-section along line II II in the direction of the arrows shown in Figure 1 a; Figure3' is a similar view along line III-111 in figure 1 a; Figure 4 is a similar view along line IV - IV in Figure I b; Figure 5 is a reduced scale longitudinal section of the column region shown in Figures 1 a and 1 b, from the line II - II downwards, and perpendicular thereto; Figure 6 is a reduced scale longitudinal section of part of a second embodiment of the column of the invention, corresponding to the part shown for the first embodiment in Figs. 1 a and 1 b; Figure 7 is a section taken at right angles to that in Figure 6; and Figure 8 is a sketch of a spanner for use with the second embodiment and shown in its position of use in Figure 6.

With reference to Figs. I a and I b, this embodiment of the column of the invention comprises a base (10) which is substantially cylindrical with a tapering upper portion (12) and which may be about 1 m high, supporting an upper post (14), also substantially cylindrical, which may be anything from about 3 to 7m high. As shown, the lower end of the post (14) is welded to an annular plate (16) secured inside the base (10), near the top of the cylindrical portion. The base (10) is provided with a hinged door (19), which is flush with the remainder of the cylinder walling when closed. An arched sill or doorway element (17) is attached internally of the door opening for reception of the edge of the door ( 19) when closed.

The cylindrical portion of the base (10) is cut through obliquely at (18), starting from near the top of the door (19) and extending downwards (Fig. I a), thereby dividing the column into a lower section (20), which includes that portion of the base below the cut (18), and an upper section (30), which includes that portion of the base (10) above the cut (18) as well as the entire upper post (14).

The lower section (20) has a pair of substantially parallel inverted Lshaped plates (22) which are welded internally to the walling ofthe base (10) in region (23) and extend upwards beyond the cut (18). These plates (22) are also shown clearly in Figs. 2 and 5. At the top they extend right across the interior of the column.

The upper section (3 M has a pair of substantially parallel, pentagonal plates (32) which are welded internally to the walling of the base (10) 1 1 -1 in the regions (33) and (34). These plates (32) are arranged parallel to and between, ie inwardly of, the plates (22), as best shown in Figs. 2 and 5. Al so, each plate (3) 2) is pivotally connected to an upper laterally extending part of its respective -5adjacent plate (22), by a respective pivot pin (24). This constitutes the pivotal or hinge connection between the upper and lower sections (30, 20) of the column.

As shown in Fig. lb, a helical spring (40) is mounted inside a cylindrical housing (42) which is pivot mounted in a region of the base (10) below the plate (22). A shaft (44) extends through the spring (40) and carries at its lower end a piston (46) upon which the spring (40) is supported. At the upper end, of the housing (42) the shaft (44) extends slidably through a fixed bush (48), against which the upper end of the spring (40) abuts and presses.

An electrical gear (35) for operation of a luminaire, or other equipment (not shown) mounted at the top of the column, is shown mounted inside the base (10) adjacent the housing (42).

The upper end of the shaft (44) is screw threaded and is connected by nuts (45) to the bottom of a forked element (36). The respective forks of the element (36) are pivotably connected (at 37) at their upper ends to the respective pentagonal plates (32), as best seen in Fig. 5. The pivotal connection (37) between the forks of the element (36) and the plates (32) are shown in two positions in Fig. 1 b, that marked 3? 7a indicating the position in the fully upright (raised) condition of the upper column section (3 0), and that marked (3 7b) indicating the position when the upper section is partially lowered or folded down. Corresponding positions of the forked element (36) and the attachment nuts (45) are also indicated.

A threaded stainless steel screw (50) is substantially vertically disposed in the interior of the column in the vicinity of the cut (18), and is axially movable by the operation of a double bevel gear (60), which is pivotally mounted by brackets, between the fixed plates (22). The top of the screw (50) carries a block (52) which is pivotally mounted (at 38) between the inner plates (32) attached to the upper section (3) 0) (see Fig. 5). Therefore when the bevel gear (60) is operated to cause the screw shaft (50) to move upwards, it causes the plates (32), and hence the upper section (3 0) to pivot relative to the plates (22), and hence the lower section (20) to which they are fixed.

However, the pivotting of the plates (3) 2), also lifts the forked element (3 6), which is pivotally connected thereon (moving from pivot position (3 7a) to (3 7b) in Fig. I a and beyond). This in turn raises the shaft (44) and the piston (46), thereby increasingly compressing the spring (40) and increasing the counterbalance force as the upper section (-3) 0) is lowered.

Respective positions of the nuts (45) and the forked element (36) corresponding to the pivot position (-')7a),'(-')7b) are also shown in Figs. la and lb, but, as mentioned, the pivot (37) will actually move higher, to the position indicated by the top of the arc in Fig. 1 a, when the upper section (30) is fully lowered.

A hexagonal section end portion (54) (see Fig. la) of a crank handle (not shown) is inserted through an aperture in the walling of the base (10) into engagement with a corresponding socket (64) in a first gear (62) of double bevel gear (60). The crank handle is manually turned to rotate the first bevel gear (62) which will bring about rotation of a second gear (66) and axial movement of the screw shaft (50). The direction of rotation of the crank handle is simply reversed in order to raise the upper section (30) of the column again.

A bolt or pin (56), shown only in Fig. 2, is insertable through apertures in one of the plates (22) and the adjacent plate (332) to lock these together in the raised condition of the upper section. This bolt (56) is accessible via the hinged door (19). Therefore, in order to lower the upper section (30) in the manner described, the door (19) must firstly be unlocked and the bolt (56) removed. This measure prevents unauthorised actuation of the column lowering mechanism by use of a substitute crank handle, A second embodiment of the column of the invention is shown in Figures 6 and 7. This differs from the first embodiment only in the mechanism employed for moving the screw threaded actuator (50) upwards or downwards to lower or raise the upper section respectively. The remaining components are exactly the same as in Figures 1 to 5 and have accordingly been designated by the same reference numerals and a description of same need not be repeated.

A special nut (70) is threadedly engaged with the actuator screw (50) and is rotatable within a housing (72), being retained therein by thrust washers (not shown). The housing (72) is pivotally mounted between plates (74) which are bolted to the fixed plates (22). The external surface of part of the nut (70) projects below its housing (72) and carries splines, for ease of rotatable engagement thereof by a rachet spanner (80), as shown in Figure 8.

In order to turn the nut (70), and thereby move the screw (50) up or down, the spanner (80) is inserted into the interior of the column base (10), via the door (19), and passed over the lower end of the screw (50) from below so as to engage the nut (70) from below. It is retained in this position, shown in Figure 6, by a small spring loaded ball (76) mounted near the bottom of the nut (70).

In this embodiment, additional plates (78) are also shown. These are welded to the inside of the column base (10) to increase strength and allow mounting of the plates (22) thereto by means of bolts.

The foregoing is illustrative not limitative of the scope of the invention. Many variations in design detail are possible. In particular it may be possible to replace the hinged door (19) by an extension of the foldable upper section of the column, the door, or its replacement cover being needed for access to the equipment (3) 5) relating to operation of the device which the column mounts.

Claims (7)

1. Claims

   A fold down column comprising an upper section which is pivotably mounted relative to a lower section and means for lowering the upper section which are disposed entirely within the lower section.
2. 2. A column as claimed in claim 1 wherein the means for lowering the upper section includes a spring operated counterbalance.
3. 3.

   A column as claimed in claim 2 wherein the counterbalance comprises a helical spring which is increasingly compressed as the upper section is lowered.

   Z
4. 4. A column as claimed in claim 1, 2 or 3 wherein the means for lowering the upper section includes a substantially vertically movable actuator.
5. 5.

   A column as claimed in claim 4 wherein the means for lowering the upper section includes a bevel gear which is operable to move the actuator.
6. 6.

   A column as claimed in claim 4 wherein the means for lowering the upper section includes a captive nut, which threadedly engages the actuator and is rotatable to move the actuator.
7. 7. A fold down column substantially as hereinbefore described with reference to and as illustrated in any of the accompanying drawings.