GB2142110A - Foot-elevatable working platforms - Google Patents

Abstract

A support beam or column arrangement comprises a plurality of sections 2A,2B???2X which are connectable end-to-end by a connecting system 13 which is totally internally cooperable with the sections upon relative expansion of members 26,27 by tunbuckles 36A,37A. The sections are provided with flanges (22,23,24,25 Fig. 4) which are used to provide guide channels (46 Fig. 4) for wheels (45 Fig. 4) provided on user foot support plate assemblies or units 11 which are displaceable lengthwise of the sections. A control system comprising a rack and paw (48,53 Fig. 5) or toothed wheel and rack and braking system (75,87,80 Fig. 9) is used to prevent or allow lengthwise movement of the foot support plates by the user so that by alternately moving each plate the user can climb or descend the beam or column 2. <IMAGE>

Description

SPECIFICATION Elevatable working platforms and like assemblies This invention relates to elevatable working platforms and like assemblies. In particular, the present invention is concerned with an operator support system by which an operator or work person can be supported above ground level with a view to carrying out activities, such as the repair and decoration of the buildings or the like, at elevated positions.

It is extremely well known to use ladders to enable a work person to reach elevated positions and to use them in the manner of a support platform. It is also known to attach tools, and equipment support tables to ladders for facilitating their use.

A basic difficulty with the conventional ladder is the storage thereof when not required for use together the problems of transportation and handling. With a view to dealing with these problems it has been proposed to use extendible forms of ladder whereby a ladder length can be extended as required between a closed length and an open length.

However, even with the extendible forms of ladder they still remain lengthy when closed.

It is also known to provide scaffolding systems in which a scaffolding tower can be constructed from an arrangement of bars and jointing sections.

A further disadvantage arising during the use of a ladder is that the relatively small diameter foot support rungs rapidly became uncomfortable to stand upon after a relatively short period of time.

It is an object of the present invention to provide a working platform or like assembly which avoids or reduces some of the disadvantages associated with a conventional ladder or tower forms of scaffolding.

According to the present invention there is provided a support beam or column arrangement, wherein at least two elongate beam or column sections are adapted for connection in end-to-end relationship by inter-connection means including at least two connection elements adapted to fit internally of the end regions of adjacent beam or column sections to be connected end-to-end and wherein means are provided for enabling selective variation of the inter-relationship between the elements in such manner that the elements can be urged into firm contact with the beam or column end regions so as effectively to attain the inter-connection.

Preferably, each beam or column section incorporates first and second guide track arrangements located at opposite sides of the beam of column sections for mounting first and second units or mechanisms for providing support to a person and for enabling such person to travel lengthwise of the beam or column sections, and wherein each said unit or mechanism includes control means for enabling said person to control the displacement of the unit or mechanism lengthwise of the beam or column sections.

For a better understanding of the invention and to show how to carry the same into effect reference will now be made to the accompanying drawings in which Figure 1 is a schematic perspective view of an elevatable support platform assembly incorporating the features of the invention, the assembly being shown when being used by a work person; Figure 2 is a sectional side view of a detail of the assembly of Figure 1, the detail being shown to an enlarged scale; Figure 3 is a side-view of the detail of Figure 2; this view, in practice, being the side of the assembly when in use; Figure 4 is a sectional view, in part, of the assembly as seen from above, the scale being similar to that of Figure 2; Figure 5 is a perspective view schematically showing the relationship of a work person's feet to the assembly of the invention; Figure 6 is a schematic representation of a support table being provided in addition to the work person foot supports shown in the previous Figures; Figure 7 schematically shows an arrangement in which the assembly can be set into an inverted V form; Figure 8 is a view of a modified form of a detail of the assembly of the invention; Figure 9 is a part sectional side view of a modified assembly of the invention; Figure 10 is a view from above of the assembly of FigureS; Figure 11 is a view of a detail of the assembly of Figure 10; and Figure 12 is a view in part section of the assembly of Figures 8 to 11, the view illustrating the user's feet positions as from the rear.

Referring now to the drawings and more particularly to Figures 1,2,3 and 4 which relate to a construction of an elevatable work person platform assembly including a main beam or column and associated user support mechanism providing a support platform facility for the operator or user of the assembly and incorporating the features of the invention.

The platform assembly 1 includes a main support beam or column 2 which is formed by joining end-to-end two or more similarly constructed sections 2A, 2B; ... 2X, (only the sections 2A and 2B being shown in detail) The lower end of the column 1, that is the lower end of the lowermost section 2A connects with a cross piece 3 provided at each end thereof with level adjusting feet units 4, each including an adjusting screw 3 having a foot pad or the like 6 at its lower end and a user operating head at the upper end.

These adjusting feet units enable the column 1 to be set into an acceptable setting what ever the level of the ground upon which the column may be required to stand.

A second cross piece 8 is located at the upper end of the uppermost section 2this cross piece being provided at each end thereof with wall bearing pads 9, the latter being intended to provide a relatively wide spread of contact between the assembly of the invention and a surface 10 against which the assembly is required to be supported. In the Figure the surface is shown as the wall of a building.

The assembly of the invention includes positionally adjustable foot rest units 11, one for each foot of a person using the assembly. In the Figure 1 a workperson is shown standing upon the foot rests and using a hand tool such as an electric drill.

Each unit 11 is selectively movable lengthwise of the column 1 by the operator or user in either the upwardly or the downwardly direction as required A work tray or table unit 12 is mountable to the column and is selectively positionally adjustable lengthwise of the column.

The column sections 2A,28... 2X are interconnected end to end to form a column of desired length by a jointing system 13 which is used to couple adjacent ends of the sections together, the system 13 being totally internally fitting.

The jointing system is shown in detail in Figures 2,3 and 4. It will be appreciated that the jointing system has to be such as to maintain the requisite rectilinear alignment of the column sections.

As will be noted from Figure 4 the beam sections are each of a hollow generally rectangular crosssection, having side walls 14 and 15 and front and rear walls 16 and 17. The internal profile of the sections is such that each adjacent pair of walls 14,17;17,15; 15,16 and 16,14 meet at an angled pieces 18,19,20 and 21 respectively. As will be seen the extent of the profiled shaping of the beam is such as to provide four similarly shaped profiled flanges 22,23,24, and 25. The function and detail of the latter will be considered hereinafter.

Each beam section connecting system 13 of the invention includes two elongate bars 26, 27 so shaped as to be nestable into the internal shape of the interior of the beam. Thus the bars 26,27 are of a generally rectangular cross-section except for angled corners 28,29,30 and 31 which are respectively complementary to the angled pieces 18,19,20 and 21 of the beam section.

As can be seen from Figure 2 upper and lower through bores 32 and 33 are formed in the bar 26 and blocked bores 34 and 35 in the bar 27. The pitch of the bores in the two bars are identical so that the pairs of bores 32,34 and 33,35 can be aligned with each other. The bores of each pair are provided with opposite hand threads and are intended to receive suitably dimensioned and threaded screw elements, such as studs Allen screws, 36,37. The screw element 36 has threaded sections 36A and 36B of opposite hand and the element 37 threaded sections 37A and 37B of the opposite hand. The Figure essentially represents the screw elements 36,37 in diagrammatic form and should not be regarded as a precise representation of diameters and thread lengths of actual screw elements.The relative diameters and threaded part lengths are such as to enable the engagement of the elements 36,37 as indicated in the Figures.

As can be seen in Figure 2 through bores 40 and 41 are respectively provided in the sections 2A and 28.

The pitch of the bores 40,41 is the same as that of the bores in the bars 26, and 27.

In practice, in orderto achieve the required end to end connection between the column sections the bars need to be pushed firmly into contact with the internal surfaces of the walls of the sections involved. For reasons to be considered hereinafter the bars are slightly tapered in the lengthwise direction thereof.

The bars are locked in place by suitable rotation of the screw elements 36 and 37. In the Figure the elements are shown to be rotated by a suitable key or the like 42.

In practice, the connection of two adjacent sections is effected as follows:- the bars are initially inserted, after having fitted the screw elements 36,37 and after having adjusted them to enable easy introduction, into the end of beam section that is to be the upper section of an adjacent pair i.e., the section 2B in the case of sections 2A and 2B.

After having inserted the pair of bars 26 and 27 into the end of the section 2B to the extent that the bores in the bars align with the bore 41 in the beam or column section 2B the screwed element 36 is rotated in the sense that urges the bars apart and thus force them into firm contact with the walls of the section 2B. At this point the bars will be firmly effectively secured to the section 2B, and with a portion of the bars projecting from the end of the section.

The projecting portions of the bars are now inserted into the upper end of the lower section 2A.

The tapering of the bars 26 and 27 is sufficient to enable the bars to be entered into the end of the section 2A even though they have been spread apart sufficiently to lock them to the end of the upper section 28. It will be found that the screw element 37 will align with the bore 40 so that the element 40 can be turned by the key 42 to press the bars firmly against the internal walls of the section 2A.

It will be understood that the length of the bars 26 and 27 is such as to provide not only the secuirty of connection required for the sections of the beam but also to ensure that the beam is rectilinear, and does not excessively deform under load.

As the jointing system 13 is totally internally fitting the system does not produce any protruding parts whereby the beam presents an undisturbed profile along the length thereof.

It will be understood that a main column or beam can be formed of any required length by coupling the requisite number of sections end to end.

The assembled beam or column is intended to provide the guide track or the like for the selectively positionable foot units 11. A first embodiment of the foot rest units will be considered in relation to Figures 4 and 5. Since the units for the user's feet are of similar construction and operationally the same except, of course, for the need to have a left hand and a right hand fitting only one such unit will be described in detail.

Each unit 11 includes a main mounting plate 43 which is intended to lie, in a generally face-to-face relationship with the associated adjacent wall 14 or 15 of the column. The plate has bearing members 44 which mount wheels 45 which are so profiled as to be engageable with corresponding profiled grooves 46 defined by the profiling of the flanges 22,23,24 and 25 and their relationship to the adjacent walls 14,15,16 and 17 of the beam sections 2A,2B ... 2X.

Each unit includes upper and lower pairs of the wheels 45, the wheel pairs being so positionted that the wheels of each pair can engage with the adjacent pair of flanges, i.e., the left hand side unit with the flanges 22 and 23 and the right hand side unit 11 with the flanges 24 and 25.

The mounting arrangement of the wheels 45 is such that they can be caused to co-operate with the relevant groove 46 by being entered into engagement with the grooves 46 from an end of the associated column section. The flanges 22,23,24 and 25 also effectively define locking bars which ensure that following engagement of the wheels with the grooves the wheels and thus the associated unit 11 cannot disengage from the column other than by the user intentionally moving the unit to an end of the column for the definate purpose of removing the unit from the beam or column.

The position ofthefootplate unit 11 relative to the beam 2 is controllable by the operation by the user of a locking pawl system 47 which is adapted to engage with a rack arrangement 48 extending lengthwise of the beam 2.

The locking pawl system will now be considered in greater detail. The flanges 22 to 25 are additionally provided with lugs 49,50,51 and 52 respectively, these lugs having an L cross section extending away from the grooves 46. The L-shaped lugs 50 and 51 effectively form retaining brackets for the rack arrangement 48, the latter comprising two side by side racks 48A and 48B. The racks extend for the full length of the beam or column sections 2A,2B... 2X.

The profile or form of the teeth of the racks are particularly shown in Figure 2.

The arrangement 47 includes a suitably shaped pawl 53 which is able securely to engage or lock into the rack teeth as shown in Figures 4 and 5. The pawl 53 is mounted from a laterally extending part 54 of an elongate plate 55 which is pivotally connected by a pivot 56 to an extension 57 of the plate 43. A second transversely directed part 58 projects from the plate 55, the part 58 extending in the opposite direction to that of the part 54. This part 58 carries the user foot plate 59, the latter being the plate upon which the user rests his foot when using the arrangement of the invention.

A strap 60 is provided for securing the user's foot in the support position on the plate 59. The free end 61 of the strap is adapted for attachment to a locking part 62 located at the outer edge region of the plate 59.

The construction of the laterally extending part 54 and its relationship with the plate 43 to which it is effectively pivoted is such that the part 54 acts as a limited stop which limits the extent to which the plate 59 can pivot downwards relative to the main plate 43.

In practice, the inter-relationship between the lateral part 54, the pawl 53, and the plate 55 is such that when the plate 55 is in its lowermost position (as shown in Figures 4 and 5) the pawl 53 is firmly locked in engagement with the rack 48A whereby it is not possible for the unit 11 to move along the associated beam 2.

When the plate 59 and thus the plate 55 is inclined slightly upwardly the pawl is automatically disengaged from the rack 48A thereby to allow the unit 11 to be displaceable lengthwise of the beam 2. It will be clear that as the plate 53 is pivoted at its forward end the foot plate tends always to move to the pawl engaged position, and that when a user is resting a foot upon the plate 59 the locking effect is enhanced and maintained.

If desired, as is indicated in Figure 6 a seat unit 64 incorporating a mechanism similar to that discussed in relation to the unit 11 can be mounted to the column 2 the seat unit 64 being connected to the seat ascending and descending unit 65 by way of a support bracket 66.

In the Figure 6the shelf ortable unit 12 is indicated. This unit 12 can include the plate and wheels features of the foot plate units 11 together with a hand operable locking screw or the like (not shown) which can be tightened or released as required, This locking screw can engage in a threaded bore in the side plate of the wheeled unit to be screwable towards the beam side wall for the purposes of locking the unit 12 against movement.

Figure 7 very schematically illustrates an arrangement in which the beam sections can be adapted to provide a hinged structure, in the manner of the inverted Vee steps formation.

In this adaptation two separate beams are formed in that the lower end of one beam section is provided with the cross piece 3 and the lower end of a second beam section is provided with the second cross piece 8, the latter being intended to act as a second floor engaging cross piece. The upper ends of the two sections i.e., 2A and 2B are pivtally interconnected by a hinge including hinge parts 67,68 respectively connected to the upper ends of the beam sections 2A and 2B by any convenient attachment means (not shown) i.e., bolts or the like clamping the hinge parts to the sections. The hinge parts are pivotally connected by a hinge 69. The formation of the hinge parts can be such that they can only open to a certain predetermined angle which ensures the stability of the hinged beam sections.If it is required to form a hinged beam structure having a length greater than that afforded by a single length of beam section additional sections can be added to each beam assembly.

To use the beam or column assembly 1 discussed in relation to the Figures 1 to 6 the following procedures can be used. The requisite number of beam sections necessary for a work person or other user to reach a desired height are connected end-toend by the connecting systems 13 in the manner discussed above. Prior to the connection of the sections 2A,2B... 2X its is important two connect the cross piece 3 to the lower end of the section forming the lowermost section, and the cross piece 8 to the upper end of the section that is to provide the upper most section.

Since, as described, above the foot support units 11 can only be mounted to the beam sections by engagement from the end of a section it will be essential to mount the units 11 to the lowermost section prior to connecting the second section thereto.

In the event that a seat unit is required this will need to be mounted to the lowermost section before connection with other beam sections. The same requirement applies in the case of the support tray or table unit 12. In other words the foot support units 11, the seat unit 64 and the unit 12 have to be mounted in the order given.

Following the connection end-to-end the beam 2 would be lifted so that the pads 9 on the cross piece 8 bear against the wall 10. The levelling of the feet units 4 is effected by suitable rotation of the adjusting screws 3 to ensure that the column 2 is correctly set in a stable condition.

The operator then stands upon the foot plates 59 and clamps his feet to the plates 59 by engaging the free ends of the straps 60 with the locking parts 62.

To ascend the beam the operator inclines one foot i.e., the left foot downwardly by lifting the heel and by taking the weight off this foot. This action will tilt the plate 59 (because of the clamping by the strap 60) and thus disengage the pawl 53 from the rack 48A. The operator then bends his leg and in so doing lifts his foot upwards thereby causing the unit 11 to move upwards along the beam 2. When the operator has lifted his foot to a suitable height he lowers his heel thereby returning the plate 53 to the lowered position in which the pawl 53 is caused to lock with the rack 48A.

The operator then repeats the sequence for the other foot. At the end of the two foot movements upwards the operator will have ascended a short distance up the beam. By alternately moving his feet to release, lift and lock the assoicated units 11 the operator progressively moves up the beam to a required height.

To descend, the operator effectively repeats the sequence of operations except that during the pawl release stage the foot is lowered, in a controlled manner.

With a view to preventing the lowering of a unit 11 by an excessive amount of downward movement of a unit when in the pawl released position a chain or the like is used to interconnect the two units 11, thereby limiting the extent of downward movement of one foot relative to the other. It will be realised that the provision of the chain also acts as a safety device in that if the foot should lower unexpectedly the chain will arrest the downward movement at the limit distance.

When it is required to dismantle the beam assembly the various beams sections are separated by releasing the connecting systems 13, in turn, and then removing the units 11 and the cross pieces 3 and 8.

It will be understood that when the seat unit and/or table unit 12 are being used these will be moved up or down the beam in step with the upward and downward movement of the operator.

A second embodiment of the ascending and descending mechanism is illustrated in Figures 8 to 12.

Also in this embodiment the profile of the beam 2 is changed in that the flanges that provide the wheel guides are differently shaped and arranged.

In this embodiment the beam sections 2A,2B ... 2X each have a generally rectangular cross section including sides 14,15,16, and 17 and the angle pieces 18,19,20 and 21. as in the previous embodiment. It should be noted that those components of Figures 8 to 12 that are similar to those of Figures 1 to 7 will be identified by the same reference numerals.

in the modified construction two of the flanges 70 and 71 are so shaped as to provide locating grooves 72 and 73 for receiving individual racks 75. Two further flanges 76 and 77 provide grooves 78 for receiving the guide and running wheels 79 of the operator or user actuatable ascending/descending mechanism 80 for the user foot support unit 81.

Each user foot operated mechanism 80 of this embodiment includes a generally trapezoidally shaped plate 83 having an extension piece 84 projecting from one of the sides of the trapezoidal plate 83. Upper and lower guide wheels 79 are mounted on upper and lower shafts 85 projecting from that side of the plate that is remote from the extension piece 84. The working or rolling surfaces 86 of the wheels 79 are profiled so as to be co-operable with the internal form of the channels or grooves 78. Upper and lower toothed wheels 87 are rotatably mounted on upper and lower shafts 88 journalled in the plate 83. The wheels 87 are engageable with the teeth 89 of the adjacent rack member 75.

As will be seen the shaping of the flanges 70 and 71 is such as to provide side plates which prevent the assembly 80 as so far considered from detaching itself from the beam 2. In practice, it is necessary to engage the mechanism 80 from the upper end of a beam section in order to mount the mechanism to the section guide track and rack.

A face plate 90 is pivotally mounted to the extension piece 84. In Figure 10 only one of the plates 90 is shown. The plate 90 carries a support bracket 92 which in turn supports a foot plate 93. A resiliently loaded foot or toe clip unit 94 is connected to the forward end of the foot plate 93. The clip unit 94 includes two part-circular parts 95 and 96 secured at one end to the plate 93 and at the adjacent ends by an interconnection 97 this interconnection being loaded by a spring 98. The clip unit 94 is shaped so as to be engaged by the foot 99 of a person placing his foot upon the foot plate 93.

A braking assembly 100 is provided for controlling the movement of the mechanism 80 relative to the beam 2.

The braking assembly includes a brake wheel 101 journalled on an extension to the shaft 88 carrying the toothed wheel 87. The mounting of the brake wheel 101 is such that the brake wheel 101 rotates with the toothed wheel 87. Thus by preventing the wheel 101 from rotation the toothed wheel 87 is prevented from rotation whereby movement of the mechanism 80 relative to the beam rack 75 is prevented. The brake wheel 101 is provided with a working surface which enhances braking effect for example, a brake liner type of material shown at 104.

A brake shoe element 102 is mounted from the underside of the bracket 92. The shoe presents a curved profile braking surface 103 which is complementary to the curvature of the working surface 104 of the brake wheel 101. The shoe has a non-slip liner 105 providing the brake shoe working surface.

Since the foot plate 93 is pivoted at 91 in advance of the line joining the axes of rotation of the toothed wheels 87 the weight of the plate 93 serves to press the brake shoe 102 against the brake wheel 101 so that the brake can be regarded as a normally ON brake system.

The brake assembly is released by the user tilting the foot plate 93 upwardly to remove contact between the brake shoe and brake wheel.

A stop pin 106 is provided on the side plate 83 to limit the extent of the upward movement of the plate 93 relative to the plate 83.

In order to move the mechanism 80 and thus the foot plate 93 lengthwise of the beam 2 the user releases the brake as above described and the lifts the whole foot upwards if he should wish to ascend or lowers the whole foot if he wishes to descend.

As soon as the displacement movement has been completed, the extent of displcement being related to the leg movement range of the user, the user lowers his heel thereby allowing the plate 93 to return to its initial position thereby the re-set the brake assembly 100 to its ON setting.

It will be appreciated that the riser mechanism for both of the users feet will be of the same construction. Figure 12 is a view of a beam having the two foot support plates and associated riser mechanisms 80.

Since the mode of use of this second embodiment of the invention is essentially similar to that discussed in relation to the previous embodiment it is not thought necessary to provide a detailed description of how a user progresses the second embodiment arrangements lengthwise of the beam 2.

The above described beams can be used as permanent fixtures and can thus be secured to a wall chimney or other high structure. In this case the riser mechanisms provide a means of climbing first beam arrangements Figure 10 illustrates a wall support bracket unit 107 which is connected by bolts 108 to the beam side 17. the wall connected bolts or the like are indicated at 109.

In practice the above discussed beam and ascend/ mechanisms can be conveniently contained within a container of dimensions 1 metre x 0,20metre x 0,30 metre.

Claims (12)

1. A support beam or column arrangement, wherein at least two elongate beam or column sections are adapted for connection in end-to-end relationship by inter-connection means including at least two connection elements adapted to fit inter nally of the end regions of adjacent beam or column sections to be connected end-to-end and wherein means are provided for enabling selective variation of the inter-relationship between the elements in such manner that the elements can be urged into firm contact with the beam or column end regions so as effectively to attain the inter-connection.

2. A support beam or column arrangement as claimed in claim 1, wherein the means for varying the inter-relationship between the elements includes screw threaded means, and wherein the ends of the beam or column sections are suitably apertured to provide for operational access to the screw threaded means.

3. A support beam or column arrangement as claimed in claim 1, wherein the inter-connection means includes two elongate elements having exter nal surface regions complementary to the interior surfaces of the end regions of the beam or column sections, and screw threaded means interconnecting the two elements in such manner that a screw threaded element is associated with opposed end portions of the elements, and wherein the screw threaded elements are such that on rotation thereof the elongate elements are either displaced away from each other to effect said firm connection or towards each other to release said firm connection to enable dismantling of the beam or column sections from each other.

4. A support beam or column arrangement as claimed in claim 3, wherein the elongate elements are so tapered that the elements can be effectively secured to the end region of one of the beam or column sections to be joined prior to the insertion of the elements into the end region of the other beam or column section to be joined by the same elongate elements.

5. A support beam or column arrangement as claimed in claim 1,2,3 or 4, wherein each beam or column section incorporates first and second guide track arrangements located at opposed sides of the beam or column sections for mounting first and second units or mechanisms for providing support to a person and for enabling such person to travel lengthwise of the beam or column sections, and wherein each said unit or mechanism includes control means for enabling said person to control the displacement ofthe unit or mechanism lengthwise of the beam or column sections.

6. A support beam or column arrangement as claimed in claim 5, wherein each of said units or mechanisms incorporates guide wheels mounted such as to be operationally engageable with the guide track arrangements, and wherein the guide track arrangements comprise grooves, channels or the like defined by the provision on the beam or column sections of opposed pairs of flanges extending lengthwise of the beam or column sections.

7. A support beam or column arrangement as claimed in claim 5 or 6, wherein the first and second units or mechanisms each include a foot rest assembly upon which said person is intended to place an appropriate foot, and wherein the lengthwise displacement control means is arranged to be foot operable.

8. A support beam or column arrangement as claimed in claim 5,6, or 7, wherein each displacement controls means includes a rack means extending lengthwise of the beam or column section, a pawl member bodily movable with the associated unit or mechanism, and mounted for movement between a position in which the pawl member is engageable with the rack means to prevent the lengthwise displacement and a position in which the pawl member is prevented from engagement with the rack means thereby to allow the lengthwise displacement, and a foot operable means for changing the operational position ofthe pawl member.

9. A support beam or column arrangement as claimed in claim 8, wherein the rack arrangement is held in its operational position lengthwise of the beam or column section byfurtherpairofflanges extending lengthwise of the beam or column sections.

10. Asupport beam or column arrangement as claimed in claim 5, wherein each of said units or mechanisms incorporates guide wheels for cooperation with the guide track arrangement associated therewith and toothed wheels adapted for engagement with a rack means forming part of the guide track arrangement.

11. A support beam or column arrangement as claimed in claim 10, wherein the means for enabling said person to control the displacement of a unit or mechanism lengthwise of the beam or column sections includes a foot operable braking system adapted to control the rotation of a said toothed wheel of the associated unit or mechanism.

12. A support beam or column arrangement as claimed in claim 11, each unit or mechanism includes a foot support plate pivotally connected to a main body part of the unit or mechanism provided with said wheels, and wherein said foot support plate supports a brake member for coperation with a brake surface connected to rotate with the said toothed wheel, the arrangement being such that pivotal movement of the foot support plate by the foot of said person serves to control operation of the braking system.