Ashley, Michael (39 Blundell Road Hightown Merseyside L38 9EF, GB)
| 1. | A retractable tower comprising a housing (10) and a telescopic mast (12) which is extensible out of, and retractable into, the housing (10). |
| 2. | A retractable tower as claimed in claim 1, wherein the mast (12) is retractable substantially completely into the housing (10). |
| 3. | A retractable tower as claimed in claim 2, further comprising illumination means (13) located on one end of the telescopic mast (12). |
| 4. | A retractable tower as claimed in claim 3, wherein the illumination means (13) is retractable into the housing (10). |
| 5. | A retractable tower as claimed in claim 4, wherein the illumination means (13) is retractable substantially completely into the housing (10). |
| 6. | A retractable tower as claimed in any of claims 3 to 5, wherein the housing (10) comprises a recessed member (18) which is shaped to receive the illumination means (13). |
| 7. | A retractable tower as claimed in claim 6, wherein the recessed member (18) comprises a cupor bucketshaped member for receipt of the illumination means (13) and through the base (62) of which the mast (12) is extensible and retractable. |
| 8. | A rectractable tower as claimed in any of the preceding claims, wherein the housing (10) is elongate. |
| 9. | A retractable tower as claimed in claim 8, wherein the axis of the mast (12) is parallel with the longitudinal axis of the housing (10). |
| 10. | A retractable tower as claimed in claim 9, wherein the axis of the mast (12) is coaxial with the longitudinal axis of the housing (10). |
| 11. | A retractable tower as claimed in any of claims 8 to 10, wherein the outer surface of the housing (10) is generally cylindrical in shape. |
| 12. | A retractable tower as claimed in any of claims 8 to 11, wherein the housing (10) comprises a plurality of elongate frame members (16) and a panel (20a, 20b, 20c) between adjacent elongate frame members (16). |
| 13. | A retractable tower as claimed in any of claims 8 to 12, wherein one or both ends of the housing (10) is provided with one or more wheels (52,58). |
| 14. | A retractable tower as claimed in any of the preceding claims, wherein the housing (10) comprises one or more handles (48,54). |
| 15. | A retractable tower as claimed in claim 14, comprising a handle (48,54) at one or both ends of the housing (10). |
| 16. | A retractable tower as claimed in any of the preceding claims, further comprising a plurality of legs or stabilizers (36) to help support the tower in an operative position. |
| 17. | A retractable tower as claimed in claim 16, wherein the legs or stabilizers (36) are pivotally mounted. |
| 18. | A retractable tower as claimed in claim 17, wherein the legs or stabilizers (36) are pivotable between an operative position in which they extend from the tower towards the ground and a stowage position. |
| 19. | A retractable tower as claimed in claim 18, wherein the legs or stabilizers (36) lie adjacent to or against the housing (10) in the stowage position. |
| 20. | A retractable tower as claimed in claim 19, wherein the housing (10) is recessed to receive the legs or stabilizers (36) in the stowage position. |
| 21. | A retractable tower as claimed in any of claims 16 to 20, in which each of the legs or stabilizers (36) is provided with illumination means (44). |
| 22. | A retractable tower as claimed in claim 21, wherein each illumination means (44) is located at the end of a respective leg or stabilizer (36). |
| 23. | A retractable tower as claimed in any of claims 16 to 22, wherein each of the legs or stabilizers (36) is extensible by means of a gasfilled strut (40). |
| 24. | A retractable tower as claimed in claim 23, wherein the struts (40) are lockable in, and releasable from, a desired extension operation of a catch or handle (42). |
| 25. | A retractable tower as claimed in any of claims 16 to 24, comprising three legs or stabilizers (36). |
| 26. | A retractable tower as claimed in any of the preceding claims, further comprising means (30) for indicating the orientation of the housing (10). |
| 27. | A retractable tower as claimed in claim 26, wherein the indication means comprises a spirit level (30) secured to, or connected to, the housing (10). |
| 28. | A retractable tower as claimed in any of the preceding claims, further comprising connection means for supplying electricity to and/or from the tower. |
| 29. | A lighting tower comprising a telescopic mast (12), illumination means (13) connected to one end of the mast and a plurality of legs or stabilizers (36) for supporting the tower in an operative position. |
| 30. | A lighting tower as claimed in claim 29, wherein the legs or stabilizers (36) are pivotally mounted. |
| 31. | A lighting tower as claimed in claim 30, wherein the legs or stabilizers (36) are pivotable between an operative position in which they extend towards the ground and a stowage position. |
| 32. | A lighting tower as claimed in claim 31, further comprising a housing (10) for the telescopic mast and wherein the legs or stabilizers (36) lie adjacent to or against the housing (10) in the stowage position. |
| 33. | A lighting tower as claimed in claim 32, wherein the housing (10) is recessed to receive the legs in the stowage position. |
| 34. | A lighting tower as claimed in any of claims 29 to 33, wherein each of the legs or stabilizers (36) is provided with a illuminated means (44). |
| 35. | A lighting tower as claimed in claim 34, wherein the illumination means (44) is located at an end of the leg or stabilizer (36). |
| 36. | A lighting tower as claimed in any of claims 29 to 35, wherein each or the legs or stabilizers (36) is extensible by means of a gasfilled strut (40). |
| 37. | A lighting tower as claimed in claim 36, wherein the struts (40) are lockable in, and releasable from, a desired extension by operation of a catch or handle (42). |
| 38. | A lighting tower as claimed in any of claims 29 to 37, comprising three legs or stabilizers (36). |
| 39. | A lighting tower as claimed in any of claims 29 to 38, further comprising means (30) for indicating the orientation of the tower (10). |
| 40. | A lighting tower as claimed in claim 39, wherein the indicating means comprises a spirit level (30). |
| 41. | A lighting tower comprising an extensible mast (12) and illumination means (13) at one end of the mast, wherein the illumination means comprises first (100) and second (102) sources which are movable relative to one another. |
| 42. | A lighting tower as claimed in claim 41, wherein the first (100) and second (102) sources each comprise a housing which encloses an illumination source and wherein the two housings are movable relative to another. |
| 43. | A lighting tower as claimed in claim 42, wherein the two housings are pivotable relative to each other. |
| 44. | A lighting tower as claimed in claim 43, wherein one of the housings is pivotable relative to the mast (12). |
| 45. | A lighting tower as claimed in claim 44, wherein the pivotable housing is pivotable between a first position in which it shines in a direction generally opposite to the other housing and a second position in which it shines in generally the same direction as the other housing. |
| 46. | A lighting tower as claimed in any of claims 43 to 45, wherein the two housings are relatively pivotable about a generally horizontal axis between a first relative orientation in which the light outlets of the housings face away from each other and the housings lie generally backtoback with one another and a second relative orientation in which one housing is positioned above the other. |
| 47. | A lighting tower as claimed in any of claims 42 to 46, wherein the two housings are generally semicylindrical. |
| 48. | A lighting tower as claimed in claim 47, wherein one of the housings is fixed to the mast (12) and the other housing is pivotally mounted to the first housing about a horizontal pivot (120,122) at the top of the first housing. |
| 49. | A lighting tower as claimed in claim 48, wherein the pivotable housing is pivotable between a first position in which flat vertical faces (104) of the two housings face each other and a second position in which the pivotable housing is pivoted through at least 180° so that it is positioned above the first housing. |
| 50. | A lighting tower as claimed in claim 49, wherein the pivotable housing is pivotable through an angle greater than 180°. |
Retractable lighting towers are used in circumstances where a relatively large area is to be floodlit temporarily, for example at a road works site. Typical lighting towers comprise a telescopic mast connected to a generator at its base and having a lighting array at its free end. In use the mast is extended to the desired height and the lighting array is lit by operating the generator. When not in use, the mast is retracted and pivoted downwardly onto the generator for stowage and/or transport.
Known lighting towers tend to be very heavy since they require the use of a generator to provide sufficient electrical power for the desired level of illumination.
As a result, most lighting towers take the form of a trailer which is transported by attaching it to a towing vehicle, which significantly reduces the transportability of the lighting towers.
In accordance with a first aspect of the present invention, a retractable tower comprises a housing and a telescopic mast which is extensible out of, and retractable into, the housing.
This results in a very compact construction which can be transported and manoeuvred much more easily than the prior art lighting towers.
Preferably, the mast is retractable substantially completely into the housing, i. e. when the mast is fully retracted it is enclosed substantially entirely within the housing.
In one embodiment, the retractable tower comprises illumination means located on one end of the telescopic mast. Preferably, the illumination means is also retractable into the housing.
In one embodiment, the illumination means is retractable substantially completely into the housing, i. e. when the mast is fully retracted the illumination means is received substantially completely within the housing.
In one embodiment, the housing comprises a recessed member shaped to receive the illumination means. The recessed member may take the form of a cup- or bucket-shaped member for receipt of the illumination means and through the base of which the mast is extensible and retractable.
Preferably, the housing is elongate and conveniently the axis of the mast is parallel, or even coaxial, with the longitudinal axis of the housing.
In one embodiment, the outer surface of the housing is generally cylindrical in shape.
The housing may comprise a plurality of elongate frame members and a panel between adjacent elongate frame members. One or both ends of the housing may be provided with one or more wheels which assist in the manoeuvring of the tower.
Conveniently, the housing may be provided with one or more handles for manoeuvring the tower. For example, there may be a handle at one or both ends of the housing.
The tower may further comprise a plurality of legs or stabilisers to help support the tower in an operative position, for example three legs or stabilisers.
Preferably, the legs or stabilisers are pivotally mounted, whereby they can be pivoted between an operative position in which they extend from the tower towards the ground and a stowage position. Preferably the legs or stabilisers lie adjacent to or against the housing in the stowage position. The housing may be recessed to receive the legs in the stowage position.
In one embodiment, the end of each of the legs or stabilisers is provided with a lamp, e. g. a flashing LED, which is lit when the legs or stabilisers are in the operative position. Illuminating the ends of the legs or stabilisers helps to alert people to the existence of the legs or stabilisers and thereby helps to prevent accidents caused by people tripping over an extended leg or support.
Each of the legs or supports is preferably extensible by means of a gas-filled strut. Preferably, the struts are of the type which can be locked in, or released from, a desired extension by operation of a catch. In this way, the legs can be lowered until each one pivots downwardly into contact with the ground, whereupon the struts, and the legs or stabilisers, can be locked in position. This allows the legs or stabilisers to support the tower even if the tower is positioned on an uneven or inclined surface.
In accordance with a second aspect of the present invention, a lighting tower comprises a telescopic mast, illumination means connected to one end of the mast and a plurality of legs or stabilisers for supporting the tower in an operative position.
This arrangement is particularly suitable for lighting towers which are not physically connected to a generator and which would otherwise lack the desired degree of stability.
In one embodiment, the tower comprises three legs or stabilisers.
Preferably, the legs or stabilisers are pivotally mounted, whereby they can be pivoted between an operative condition in which they extend towards the ground and a stowage position.
In one embodiment, the end of each of the legs or stabilisers is provided with a lamp, e. g. a flashing LED, which is lit when the legs or stabilisers are in the operative position. Illuminating the ends of the legs or stabilisers helps to alert people to the existence of the legs or stabilisers and thereby helps to prevent accidents caused by people tripping over an extended leg or support.
Each of the legs or supports is preferably extensible by means of a gas-filled strut. Preferably, the struts are of the type which can be locked in, or released from, a desired extension by operation of a catch. In this way, the legs can be lowered until each one pivots downwardly into contact with the ground, whereupon the struts, and the legs or stabilisers, can be locked in position. This allows the legs or stabilisers to support the tower even if the tower is positioned on an uneven or inclined surface.
In accordance with a third aspect of the present invention, a lighting tower comprises an extensible mast and illumination means at one end of the mast, wherein the illumination means comprises first and second sources which are movable relative to one another.
By having two relatively movable light sources, the pattern or area of illumination can be varied to suit different requirements or conditions.
In one embodiment, the first and second sources each comprise a housing which encloses an illumination source and wherein the two housings are movable relative to one another. Preferably, one of the housings is pivotable relative to the mast. Preferably, the housing is pivotable between a first position in which it shines in a direction generally opposite to the other housing and a second position in which it shines in generally the same direction as the other housing.
In one embodiment, the two housings are relatively pivotable about a generally horizontal axis between a first relative orientation in which the light outlets of the housings face away from each other and the housings lie generally back-to- back with one another and a second relative orientation in which one housing is positioned above the other.
In a preferred embodiment the two housings are generally semi-cylindrical.
One of the housings is fixed to the mast and the other housing is pivotally mounted to the first housing about a horizontal pivot located at the top of the first housing.
The pivotable housing is pivotable between a first position, in which flat vertical faces of the two housings face each other, and a second position in which the pivotable housing is pivoted through 180° (or slightly more) so that it is positioned above the first housing. By having the housing pivot through slightly more than 180 °, it is possible to direct the light from the pivotable housing in a more downward direction.
By way of example only, a specific embodiment of the present invention will now be described with reference to the accompanying drawings, in which: Fig. 1 is a perspective view of an embodiment of retractable lighting tower in accordance with the present invention, shown in an operative condition ; Fig. 2 is a perspective view from the front of the lighting tower of Fig. 1, shown in a stowed or transport condition; Fig. 3 is a perspective view from the rear of the lighting tower of Fig. 2; Fig. 4 is a perspective view of the lighting tower of Fig. 1, shown in a condition between the operative position of Fig. 1 and the stowed position of Fig. 2; Fig. 5 is a plan view of the lighting tower shown in Fig. 2; Fig. 6 is an inverted plan view of the lighting tower shown in Fig. 2; Fig. 7 is a plan view of a cup-or bucket-shaped receiving component of the lighting tower of Fig. 1; Fig. 8 is a horizontal cross-section through the mast of the lighting tower as shown in Fig. 2; Fig. 9 is a vertical cross-section through the mast of Fig. 8 ; Fig. 10 is a perspective view in more detail of the lighting head of the lighting head, shown in a first condition ; Fig. 11 is a perspective view in more detail of the lighting head of the lighting head, shown in a second condition.
Referring to the drawings, the embodiment of lighting tower in accordance with the present invention comprises a generally cylindrical housing 10 which, in use, is orientated with its longitudinal axis vertical and from whose upper end a telescopic mast 12, having a lighting head 13 secured to its upper end, is extensible and retractable.
The housing comprises a circular, generally planar base 14 from which extend three elongate parallel upright support beams 16 which are equally angularly spaced around the periphery of the base 14 and which extend perpendicularly to the plane of the base 14. The upper ends of the support beams 16 are secured to a cup-shaped receiver 18 forming part of the housing, for receipt of the lighting head 13 when the telescopic mast 12 is in its fully retracted position. The housing further comprises three curved, part-cylindrical elongate enclosing panels 20 a, b, c between the upright support beams 16. Two of the panels 20a, 20b are identical and towards their base each is provided with electrical input and output sockets 22a, 22b. The third panel 20c is generally the same as the other two panels 20a, 20b, but without the input and output sockets 22a, 22b. In addition, however, the third panel 20c is provided with a recess 24 towards its upper end which provides a face 26 upon which operating instructions can be provided. On a ledge 28 between the curved surface of the panel 20c and the face 26 is located a spirit level 30 and the face 26, ledge 28 and spirit level 30 are illuminated by a lamp 32 located on an overhanging surface 34 between the curved surface of the panel 20c and the face 26 above the ledge 28.
The lighting tower further comprises three identical stabilising legs 36, one end of each leg 36 being pivotally mounted at pivot 38 to the base of a respective one of the vertical support beams 16. Each leg is biased downwardly, away from its associated support beam 16, by means of a conventional lockable gas strut 40 extending between the leg and its associated support beam 16. Each stabilising leg 36 is pivotable between a support position in which the legs are inclined away from the support beams 16 into contact with the ground and a stowed position in which each leg lies flush against its associated beam 16 and in which it may be retained by a metal clip 41 which is pivotally attached to the support beam 16 and which can be hooked over the tip of the leg 36. Each beam is recessed to receive its associated stabilising leg 36 and gas strut 40 in the stowed position. The gas struts 40 are locked and unlocked by means of a handle 42 which actuates cables which simultaneously control each of the gas struts by either preventing fluid flow within the struts or allowing fluid to flow from one side of a piston to the other within each of the gas struts. The tip of each stabilising leg 36 is provided with a light emitting diode 44 which is arranged to flash to act as a warning whenever the handle 42 is actuated to release the legs from their stowed position. The outer face of each leg 36 is also provided with a longitudinally extending groove 46 which receives a complementarily-shaped silicone rubber insert 48 to act as a resilient bumper or fender.
The base 16 is also provided with a combined handle and support 48 which comprises an arcuate tube spaced apart from the undersurface of the base 16 by means of mounting lugs 50. Two wheels 52 are also secured to the undersurface of the base 16. The combined handle and support 48 and the wheels 52 are dimensioned such that the lighting tower can be supported on both of them simultaneously with the longitudinal axis of the housing extending vertically.
The cup-shaped receiver 18 (Fig. 7) at the opposite end of the housing 10 is provided with an annular tubular handle 54 which is spaced apart from the upper end of the receiver 18 by means of mounting lugs 56. A single wheel 58 is also provided on the handle 54, such that the lighting tower can be supported on the two wheels 52 at the base and the single wheel 58 at the opposite end of the housing.
The housing 10 contains a telescopic mast 12, the mast being retractable completely into the housing and being extensible out of the upper end of the housing through an aperture 60 in the base wall 62 of the cup-shaped lighting head receiver 18. The mast comprises four elongate telescopic sections 64,66,68,70. The mast sections are generally oval in cross-section and their longitudinal axes are arranged to be coaxial. The first, and outer, mast section 64 is secured to the base. The second, and next innermost, section 66 is displaceable out of the first section and, as will be explained, the relative movement of the second section with respect to the first section also results in displacement of the third and fourth sections 68,70.
The mast sections are separated from each other by means of self-lubricating nylon rods 72, four of which are located between each pair of sections which move relative to one another. The nylon rods are each located and secured (e. g. by glueing) in a recess 74a, 74b, 74c in the first, second and third mast sections 64,66,68 and extend parallel to the longitudinal axis of the mast sections and along the whole of their length. Each rod 72 bears against a complementarily-shaped longitudinal groove 76b, 76c, 76d in the next innermost mast section, each groove also extending parallel to the longitudinal axis of the mast section and along the whole of its length.
As mentioned previously, the second outermost section 66 is displaceable relative to the outermost mast section 64. The means for displacing the second section 66 comprises a screw-threaded bar 78 which is rotatably mounted on the base 14 and extends perpendicularly to the plane of the base, along the longitudinal axis of the mast sections. The screw-threaded bar 78 is rotatable by means of a reversible electric motor 80 mounted on the base 14, which engages with the screw-threaded bar 78 by means of a conventional worm drive. An internally threaded block 82 is threaded onto the bar 78 and engages with opposed recesses 84 in the opposed side walls at lowermost end of the second outermost mast section 66. The block is prevented from fouling on the third and fourth mast sections 68,70 by providing cut- outs 86,88 in the side walls at the base of each of the third and fourth mast sections.
By operating the motor, the block 82 which is prevented from rotation by engagement with the recesses 84 in the second section, is moved along the threaded bar 78 and carries the second mast section 66 with it, enabling the mast section to be displaced out of, or retracted into, the upper end of the housing 10.
As indicated previously, the movement of the second mast section 66 is also transmitted to third and fourth mast sections 68,70. This is achieved by a belt and roller system, as will be explained. The system is generally similar to the system used in conventional lighting towers, wherein belts are used instead of steel wires.
As will be seen from Fig. 9, a roller 90 is mounted on one side of the upper end of the second outermost mast section 66. One end of a rubber belt 91 is secured (e. g. by rivets) to the inner face of the outermost mast section 64 about 300mm from its top. The belt passes over the roller 90 on the upper end of the second mast section 66 and its other end is secured (e. g. by rivets) to the outer face of the third outermost section 68 about 300mm from its lower end.
Similarly, a second roller 92 is mounted on one side (the opposite side from roller 90) of the upper end of the third innermost mast section 68. One end of a second rubber belt 96 is secured (e. g. by rivets) to the inner face of the second innermost section 66. The second belt passes over the second roller 92 on the upper end of the third mast section 68 and its other end is secured (e. g. by rivets) to the outer face of the fourth, innermost mast section 70 about 300mm from its lower end.
As the second innermost section 66 is displaced upwardly by actuation of the motor 80, the first roller 90 is carried by it is also displaced upwardly. Since the belt 91 is of fixed length and its ends are secured to the two mast sections 64,68 immediately outward and inward respectively of the mast section 66 to which the roller 90 is connected, upward movement of the second mast section causes the belt 91 to pull the third innermost mast section 68 upwardly as well. The reverse motion is induced when the direction of the motor 80 is reversed.
Similarly, the second roller 94 is carried by a moving mast section 68 and since the second belt 96 is also of fixed length and its ends are secured to the two mast sections 66,70 immediately outward and inward respectively of the mast section 68 to which the second roller is connected, upward movement of the third mast section (which is itself induced by movement of the second mast section) causes the second belt 96 to pull the fourth, innermost mast section 70 upwardly as well.
The reverse motion is induced when the direction of the motor 80 is reversed.
The result is that all three movable mast sections 66,68,70 can be displaced simultaneously out of, or withdrawn into, the housing 10 by actuation of the motor 80.
The lighting head 13 is generally cylindrical in shape but, in fact, comprises two identical generally semi-cylindrical lighting units 100,102 which are hinged together. Each lighting unit comprises a casing in the form of a generally planar rear wall 104, a semi-circular roof 106 extending perpendicularly to the plane of the rear wall 104, a semi-circular floor 108 extending parallel to the roof 106 and a semi- cylindrical frosted borosilicate glass 109 which is sealed with respect to the rear wall 104, roof 106 and floor 108 by means of a silicone rubber gasket 110. The outer surfaces of the roof 106 and floor 108 are provided with ribs 112,114 to aid in the cooling of the unit. The casing encloses the source of light which, preferably, comprises two conventional metal halide lamps but which could be any light source of the required size and light output. Each casing preferably also contains reflectors behind the or each light source to direct light more towards the floor 108 of the lighting unit.
One of the lighting units 100 is secured to the uppermost end of the innermost mast section 70 but is otherwise identical to the other lighting unit 102. The outer surface of the roof 106 of each of the lighting units is provided with two planar spaced-apart lugs 116,118. The lugs 116,118 of the two lighting units 100,102 are aligned and each pair receives a respective hinge 120,122. This allows the second lighting unit 102 to pivot about a horizontal axis between a first position (shown in Fig. 10), in which the rear walls 104 of the two units face each other and the two units discharge light in generally opposite directions, and a second position (shown in Fig. 11) in which the roofs 106 of the two units face one another and the two units discharge light generally in the same direction. In fact, in the embodiment described, the second lighting unit pivots through an angle of slightly greater than 180°, to compensate for the fact that the light from the second unit is directed by its internal reflectors towards the floor 108 of the unit.
In the first extreme orientation, the lighting head provides 360° illumination and may also be received in the cup-shaped receiver 18 of the housing 10. In the second extreme orientation the lighting head provides 180'illumination. However, the second lighting unit may be pivoted to any desired angle between the two extremes and may, for example, be held at a desired angle by means of a bracket or brace.
In use, the lighting tower is transported in the condition shown in Fig. 2, in which the mast 12 and lighting head 13 are withdrawn to a position substantially entirely within the housing 10. The tower may then be manoeuvred as desired using the wheels 52,58 and handles 48,54 described previously. In particular, it should be noted that the lighting tower of the present invention is considerably more compact than known lighting towers and thus transportation of a relatively large number of the towers is significantly facilitated.
When it is desired to use the lighting tower, it is manoeuvred into position and is rested on the combined handle and support 48 and wheels 52 at the lower end of the housing. The metal clips 41 retaining the stabilising legs 36 are released and the handle 42 is actuated to unlock the gas struts 40 connected to the stabilising legs 36, whereby the legs are pivoted downwardly into contact with the ground. The legs 36 are effectively self-levelling in that they will not pivot any further once they have engaged a firm surface. Once the legs have been deployed, the housing can be manipulated manually to ensure that its longitudinal axis is vertical (as indicated by the spirit level 30) and when the desired orientation has been achieved the handle 42 is actuated to lock the gas struts 40 and thereby lock the stabilising legs securely in position. Upon deployment of the legs, the LEDs 44 at the end of each e. g. automatically illuminate by means of power from an internal rechargeable battery.
A source of electricity is connected to the input socket 22a. Electricity may also be conducted to further items of equipment (e. g. further lighting towers) by connecting an output lead to the output socket 22b. Once the electricity has been connected, an operating button (located in the recess of one of the support beams 16 and only accessible when the associated stabilising leg is pivoted downwardly) is depressed to extend the mast 12, as described previously. If the lighting head is to be used to provide 360'illumination, the mast 12 can simply be extended to the desired height and the lighting units can then be switched on by depressing another button located adjacent the first button. However, if the lighting head is to be used in any other configuration, the mast is raised until the lighting head 13 is just clear of the upper end of the housing. The pivotable lighting unit 102 is then pivoted to and, if necessary, secured in the desired orientation. The mast is then extended to the desired height and the lighting units are switched on.
When the lighting tower is no longer needed, the above steps are reversed, taking care to ensure that the lighting head is in its"360° configuration" (i. e. as illustrated in Fig. 10) before it is finally received in the cup-shaped receiver 18.
If an operator does not switch off the lighting units 100,102 before retracting the lighting head into the receiver 18, the units will be switched off when the lighting head 13 is in its stowed position, by virtue of a cut-out switch 124 on the base wall 62 of the receiver which is engaged by the floor 108 of the lighting unit 100 when in its fully retracted position.
If the source of electricity is removed or fails for some reason, the lighting units 100,102 will automatically switch off and the internal rechargeable battery (which is recharged whenever the source of electricity is connected) is sufficient to retract the mast, either automatically or upon depression of an actuating button.
The invention is not restricted to the details of the foregoing embodiment.
For example, preferably the lighting tower is arranged so that the mast 12 cannot be extended unless and until the stabilising legs 36 are locked in position and that if the stabilising legs 36 are unlocked while the mast is extended, the mast will automatically retract until the legs are locked in position again.
Indeed, although the present invention has been described with particular reference to a lighting tower, it is equally applicable to any extensible mast including, for example, an extensible antenna.