AU2016101597A4 - Traffic light mast arm - Google Patents

Abstract

Abstract A mast arm for a traffic light has an arm portion arranged to rotate relative to the vertical base pole. This allows for easier maintenance of the traffic light. 22----1 Fig. 1

Description

“TRAFFIC LIGHT MAST ARM”

Field of the Invention [0001] The present invention relates to mast arms such as those used for traffic lights.

Background to the Invention [0002] Mast arms are used to suspend traffic lights over a roadway, providing improved visibility when compared to traffic lights mounted on vertical poles. A typical mast arm includes a vertical pole portion located off the roadway, together with a lateral extension portion extending away from the top of the vertical pole portion over the roadway.

[0003] Typically, in order to maintain traffic lanterns affixed to mast arms, it is necessary to close at least part of the roadway to traffic.

[0004] It is considered desirable to provide a means by which the lateral extension portion can be rotated away from the roadway, both for maintenance purposes and to occasionally allow for the movement of unusually high loads. This objective has proved difficult to satisfactorily achieve.

[0005] Several factors have, to date, prevented rotational mechanisms from being used. They include the risk that the extension portion could separate from the vertical portion on impact, with the potential to become a missile. In addition, the suspended traffic light provides a large weight force acting a considerable distance from the vertical axis of the vertical pole portion. This applies a considerable bending moment to the connection. In order to provide additional strength both vertical portion and the extension portion are tapered, making bearing location difficult. Finally, manufacturing tolerances on traffic light poles are not generally high enough to guarantee secure fitting and alignment of a bearing within.

[0006] The present invention seeks to provide a useful mast arm having a rotating lateral extension portion.

Summary of the Invention [0007] According to one aspect of the present invention there is provided a mast arm having a generally vertical base pole having an axis, and a laterally extending arm portion; the base pole having an upper rim, a base flange being located about the upper rim, and the base pole having a generally hollow upper portion extending downwardly from the upper rim; the laterally extending arm portion having a lower rim, a mating flange being located about the lower rim; the laterally extending arm portion having a shaft extending axially downward from the mating flange along the axis of the base pole; the mast arm including a receiving sleeve, the receiving sleeve being arranged to be fixed in position relative to the upper portion of the base pole; and at least one bearing located between the receiving sleeve and the shaft, whereby the shaft is able to rotate relative to the receiving sleeve about the base pole axis. This permits rotation of the arm portion relative to the base pole about the base pole axis.

[0008] Preferably the mast arm includes two axially spaced bearings located between the receiving sleeve and the shaft.

[0009] Preferably the mast arm includes a releasable connection means connecting the base flange and the mating flange. The connection means may be moved between an engaged position whereby the connection means prevents rotation of the arm portion relative to the base pole, and a released position whereby rotation of the arm portion relative to the base pole is permitted.

[0010] The releasable connection means may comprise removable bolts passing through aligned apertures in the base flange and the mating flange.

[0011] In a preferred embodiment the receiving sleeve has an annular locating flange at its upper end thereof, arranged to locate in use between the base flange and the mating flange. The annular locating flange may include apertures arranged to align with the apertures of the releasable connection means.

[0012] The receiving sleeve may be fixed to the upper portion of the base pole by means of radial bolts.

Brief Description of the Drawings [0013] It will be convenient to further describe the invention with reference to preferred embodiments of the present invention. Other embodiments are possible, and consequently the particularity of the following discussion is not to be understood as superseding the generality of the preceding description of the invention. In the drawings: [0014] Figure 1 is a general schematic view of a mast arm in accordance with the present invention; [0015] Figure 2 is a schematic cross section through a rotating joint in the mast arm of Figure 1; and [0016] Figure 3 is a cross sectional view of a connecting apparatus from within the mast arm of Figure 1.

Detailed Description of Preferred Embodiments [0017] Referring to the Figures, there is shown a mast arm 10 for suspending a traffic light 12 over a roadway. The mast arm 10 has a generally vertical base pole 14 which is mounted to the ground 15, and a laterally extending arm portion 16 which extends across the roadway.

[0018] The base pole 14 in this embodiment is generally octagonal in cross section, with a narrowing taper from the ground 15 to an upper rim 18 of the base pole. It will be appreciated that the present invention is equally applicable to base poles of other cross sectional shape.

[0019] An upper portion 20 of the base pole 14 is shown in Figure 2. The upper portion 20 depends from the upper rim 18. In the embodiment shown the upper portion 20 constitutes the top 400mm of the base pole 14, representing about 10% of the height of the base pole 14.

[0020] An annular base flange 22 extends around the upper rim 18 of the base pole 14.

[0021] The arm portion 16 curves through close to 90° from a vertically aligned lower portion 24 to a nearly horizontal upper portion 26 to which the traffic light 12 is attached. The lower portion 24 terminates in a lower rim 28, which is fixed to an annular mating flange 30. The lower rim 28 is of similar diameter to the upper rim 18 of the base pole 14.

[0022] The mating flange 30 is of similar outer diameter to the base flange 22. The mating flange 30 has a smaller internal diameter than the base flange 22, extending inside the circumference of the lower rim 28. The internal diameter of the mating flange 30 is about half that of the lower rim 28.

[0023] A centrally aligned cylindrical shaft 32 extends downwardly from the mating flange 30, having a diameter similar to the internal diameter of the mating flange 30. The shaft 32 is on the opposite side of the mating flange 30 to the lower portion 24.

[0024] The shaft is about 400mm long.

[0025] The mast arm 10 has a connecting apparatus 40 arranged to connect the arm portion 16 to the base pole 14. The connecting apparatus 40 includes a receiving sleeve 42, which is hollow cylindrical in shape having an outside diameter similar to the nominal internal diameter of the upper portion 20 of the base pole 14; an annular locating flange 44 extending around an upper end of the receiving sleeve 42, and a lower bearing 46 and an upper bearing 48. The lower bearing 46 and upper bearing 48 are located internally of the receiving sleeve 42, and are fixed to the receiving sleeve 42 by suitable means such as a press fit. The lower bearing 46 and upper bearing 48 are arranged to receive the shaft 32, and to support rotation of the shaft 32 relative to the receiving sleeve 42.

[0026] The connecting apparatus 40 is fixed to the base pole 14 by radial bolts 50 passing through the upper portion 20 of the base pole 14 and into the receiving sleeve 42. It will be appreciated that suitable tightening of the bolts 50 allows the receiving sleeve 42 and thus the bearings 46, 48 to be located with a vertical axis, even if the size and shape of the base pole 14 may vary.

[0027] The mast arm 10 is assembled by locating the connecting apparatus 40 into the base pole 14 such that the locating flange 44 sits atop the base flange 22; bolting the connecting apparatus 40 into the correct position using the bolts 50, and then locating the arm portion 16 into position whereby the shaft 32 locates within the lower and upper bearings 46, 48, and the mating flange 30 sits slightly above the locating flange 44.

[0028] The mast arm 10 includes a releasable connection means, in the form of removable bolts 52 arranged to pass through aligned apertures 54 in the base flange 22, the locating flange 44 and the mating flange 30. When these removable bolts 52 are tightened within their apertures 54, movement of the three flanges 22, 30, 44 relative to each other is prevented. When the bolts 52 are removed, the weight of the traffic light 12 acts downwardly through the shaft 32 and prevents disconnection of the arm portion 16 from the base pole 14, however rotation of the shaft 32 within the bearings 46, 48 is permitted. This, in turn, allows rotation of the arm portion 16 relative to the base pole 14.

[0029] It will be appreciated that the use of the removable bolts 52 also acts to ensure that the arm portion 16 cannot be dislodged from the base pole 14 in the event of an impact of a vehicle.

[0030] Modifications and variations as would be apparent to a skilled addressee are deemed to be within the scope of the present invention. For instance, secondary bolts passing between the base flange 22 and the locating flange 44 could be used to assist in securing the connecting apparatus 40 to the base pole 14.

[0031 ] It will also be appreciated that the present invention can be applied as a ‘retrofit’, whereby the connecting apparatus 40 may be inserted into a preexisting base pole 14.

Claims (5)

1. Claims

   1. A mast arm having a generally vertical base pole having an axis, and a laterally extending arm portion; the base pole having an upper rim, a base flange being located about the upper rim, and the base pole having a generally hollow upper portion extending downwardly from the upper rim; the laterally extending arm portion having a lower rim, a mating flange being located about the lower rim; the laterally extending arm portion having a shaft extending axially downward from the mating flange; the mast arm including a receiving sleeve, the receiving sleeve being arranged to be fixed in position relative to the upper portion of the base pole; and at least one bearing located between the receiving sleeve and the shaft, whereby the shaft is able to rotate relative to the receiving sleeve about the base pole axis.
2. 2. A mast arm as claimed in claim 1, wherein the mast arm includes two axially spaced bearings located between the receiving sleeve and the shaft.
3. 3. A mast arm as claimed in claim 1 or claim 2, wherein the mast arm includes a releasable connection means connecting the base flange and the mating flange.
4. 4. A mast arm as claimed in claim 3, wherein the connection means may be moved between an engaged position whereby the connection means prevents rotation of the arm portion relative to the base pole, and a released position whereby rotation of the arm portion relative to the base pole is permitted.
5. 5. A mast arm as claimed in any preceding claim, wherein the receiving sleeve has an annular locating flange at its upper end thereof, arranged to locate in use between the base flange and the mating flange.