GB2577544A - Tray support - Google Patents

Abstract

A cable tray assembly, in particular a fibre optic tray assembly used in telecommunications exchanges, comprises a frame and a stack of cable trays 1, 2, each tray being supported by a vertical spindle 10 and independently rotatable between a stowed position and an open position. One or more support flanges 8 are positioned to lie between the cable trays when the cable trays are in the stowed position, in order to support the trays at a point remote from the spindle and prevent collapse of the stack. Each tray may have a first vertical extent and a number of support flanges disposed apart by a second vertical extent which is a multiple of the first vertical extent, such that each support flange supports a plurality of cable trays when in the stowed position. The support flanges may be mounted on a cable guides 18 formed on the frame. The cable trays may each comprise one or more cable connection points, such as optical fibre splicing units, and a plurality of guide paths for locating cables to the splicing units.

Description

Intellectual Property Office Application No. GII1815840.2 RTM Date:21 March 2019 The following terms are registered trade marks and should be read as such wherever they occur in this document: Velcro Intellectual Property Office is an operating name of the Patent Office www.gov.uk /ipo Tray Support The invention relates to equipment trays, and in particular to fibre optic trays used in telecommunications exchanges. Such trays are mounted in stacks rotatably supported on a vertical axis, for example on a vertical spindle, so that individual trays can be swung out for attention to the optical equipment.

Because of the way the trays are mounted, with support only at the axis of rotation, they tend to sag over time, each tray therefore taking part of the weight of all the trays above it. In particular, when an individual tray is swung out for attention, the trays above it can drop slightly into the space normally occupied by the open tray. This can make it difficult to return the open tray to its stowed position, and damage may be caused to the trays and their mountings, and the optical fibres and other operational equipment in the trays if force is required to stow a tray after use. It can therefore also become increasingly difficult to open further trays, because of the weight of trays above them, and again damage may be caused if excessive force is used to swing a tray out from its stowed position. Damage may be caused not only to the equipment contained in the tray, but also to the tray mountings, and in the latter case this may cause the whole stack to collapse.

At the distal end from the spindle a strip of hook-and-pile fastener ("Velcro") is provided to stop the stowed trays swinging out, but this wears out over time and in any case provides no vertical support.

The present invention provides, in a first aspect, a cable tray stack assembly comprising a cable tray assembly comprising a frame, and a stack of cable trays, each cable tray being mounted at a first location for rotation relative to the frame about a vertical axis, and each tray being independently rotatable about the vertical axis between a stowed position and an open position, the frame further comprising one or more support flanges, each flange positioned to lie between two of the cable trays in the stack at a location remote from the first location when the cable trays are in the stowed position.

The invention also provides, in a second aspect, a method of supporting a stack of cable trays, each cable tray in the stack being mounted at a first location for rotation about a vertical axis between a stowed position and an open position, the method comprising locating one or more support flanges on a frame, fixed relative to the vertical axis, at a position remote from the first location, wherein each flange lies between two of the cable trays in the stack when the cable trays are in the stowed position.

In embodiments of the invention, each cable tray has a first vertical extent, and the support flanges are disposed apart by a second vertical extent which is a multiple of the first vertical extent, such that each support flange supports a plurality of cable trays when in the stowed position. The support flanges may be mounted on cable guides formed in the frame.

In embodiments of the invention, the cable trays each comprise one or more cable connection points, and a plurality of guide paths for locating cables to be connected to the splicing units. The cable connection points may be optical fibre splicing units.

In embodiments of the invention, the cable trays are rotatably mounted on, and supported by, a vertical spindle at their first end.

In a preferred embodiment the support brackets are bolted to cable guides within the stack assembly. Preferably the support brackets are spaced to each support a plurality of trays.

The embodiment to be described is intended for use with optical fibres, but can be applicable to other cable connections.

Embodiments will now be described, by way of example only, with reference to the accompanying drawings in which: Figure 1 depicts part of a stack, with one tray partially swung out for attention. Figure 2 depicts the same assembly with the tray fully swung out.

Figure 2a depicts the side and rear plate components of the assembly depicted in Figures 1 and 2 Figure 3 depicts a support bracket for installation according to an embodiment of the invention Figure 4 depicts two support brackets fitted to a stack according to an embodiment of the invention Figure 5 depicts the stack of Figure 2, with the bracket installed. Figure 6 is a side view of pad of the stack of Figure 5.

Figure 7 shows the use of the embodiment in an alternative construction.

Figures 1 and 2 depicts part of a cable tray stack. Typically a stack may comprise up to a hundred trays. The trays 1, 2, etc, ......... are attached to a spindle 10, so that the individual trays can be swung out (as depicted for tray 1), for attention to the equipment installed in the tray. Typically the equipment in each tray comprises one or more fibre splice units 11, 12, with fibre connections 13, 14 fed to them.

Other methods of rotatable mounting are possible. As shown in Figure 7, each tray 1, 2 has a circular boss 7, 27 on one face and a complementary cavity 6, 26 in the opposite face. The boss on each tray engages with the cavity in the adjacent tray. The boss is shaped to space the trays apart to allow the trays to rotate freely.

is The fibre tray stack is located in a housing having a side plate 15 and a back plate 16. As shown more clearly in Figure 2a, cable guides 18, through which the fibres 17 can be led, are formed by cut outs in the side plate 15.

Each tray has a hook-and-pile fastener 19 which, when in the closed position, engages with a complementary fastener strip 9 on the back plate 16, to prevent the trays swinging out when not required. However, such fastenings do not have a high resistance to shear forces, (parallel to the plane of the strip, i.e. vertical in the orientation depicted).

In order to allow the individual trays to be freely swung out for attention there has to be a small gap between each tray and its neighbours. This means that each tray is unsupported except at the corner closest to the pivot. However, over time they tend to sag, each one resting on the one below. This can result in considerable weight resting on the lowest members of the stack, which can cause buckling of the trays in the region of the spindle 10, or of the spindle itself, in turn causing potential collapse of the stack. Collapse is particularly likely when a tray towards the bottom of the stack is swung out for attention, leaving all the trays above unsupported except at the spindle. The sagging can also make it difficult to return a deployed tray to the stack, as a user may have to force the tray back into its place when it is returned to its stowed position, resulting in potential damage to that tray and its neighbours.

In order to prevent such damage occurring, this embodiment of the invention provides the stack with a series of support flanges 8 (two shown) disposed in a position such that when the trays 1, 2 etc are in the stowed position they are supported at a position remote from the spindle 10. In this embodiment a support flange 8 is placed between every third tray, but the spacing may be greater or less than this, depending on the maximum number of trays that can reliably support their own weight, and on any constraints on fitting the flanges.

The flanges may be integral with the frame, or may be fitted to an existing frame as shown in Figures 3 and 4. Figure 3 depicts a flange 8 having an arcuate element 80 and a flat flange element 81, the flange element extending from, and perpendicular to, one end of the arcuate element. The arcuate element 80 is shaped to fit, and be secured to, one of the cable guide cut-out elements 18 in the side plate 15. Securing can be by any suitable means, such as bolts (not shown) passing through holes in the cut-out 18 and the arcuate element 80.

As has been previously mentioned, the trays 1, 2 etc are installed with small gaps between them in order to allow the trays to swing freely. The flanges 8 can thus fit between the trays without increasing the overall height of the stack, as shown most clearly in Figures 6 and 7.