GB2487180A

GB2487180A - A bearing for a gantry and a gantry including such a bearing

Info

Publication number: GB2487180A
Application number: GB1020753.8A
Authority: GB
Inventors: Johan Mikael Stahl
Original assignee: SAFE ROAD BLG
Current assignee: SAFE ROAD BLG
Priority date: 2010-12-07
Filing date: 2010-12-07
Publication date: 2012-07-18
Also published as: GB201020753D0

Abstract

A gantry 1 designed to span a road R or similar includes a bearing B to allow rotational movement between first FC and second SC parts of the gantry 1. The bearing B comprises a first member 20, 100 arranged in association with the first part FC and having a substantially planar first surface 21, 102a, and a second member 30, 200 arranged in association with the second part SC and having a substantially convex second surface 31, 202a. The first and second surfaces 21, 31, 102a, 202a are arranged in pivoting contact to allow for rotational movement between the first and second members 20, 30, 100, 200 about a transverse axis of the bearing B under an applied load FB.

Description

A GANTRY

FIELD OF INVENTION

[0001] The invention relates to a gantry The invention particularly relates to a bearing for a gantry.

BACKGROUND TO THE iNVENTION

[0002] A gantry is a bridge-like structure comprising a boom supported by legs. Gantries may be arranged to span across a road, railway line, river, toll station * or any other suitable passage way. Gantries may be used to support lighting means, cameras, display means or any other suitable, means. For example, a gantry is spanning a carriageway of a motorway. may support traffic information display boards, road signs and/or speed cameras.

[0003] Figure 1 depicts an example of a conventional gantry (1) spanning a three lane-carriageway of a motorway (R) gantry comprises a boom (2) having a first end (2a) and a second end (2b). The first end of the boom is supported by a first leg (3a). The second end of the boom is supported by a second leg (3b). The legs are mounted on foundations (4a, 4b) located at the sides of the carriageway. Traffic information display boards (Sa, 5b, 5c) are mounted along the boom in association with each lane of the carriageway. The gantry is a rigid (i.e. fixed) structure whereby the legs are rigidly coupled to the boom and foundations.

[0004] Gantries are subject to destabilising loads during use. For example, a gantry may be subject to destabilising loads applied by buffeting wind forces, thermal expansion and contraction and/or the impact of an errant vehicle. The destabilising toads may apply overturning or twisting moments at the base of the gantry. Due to the rigid structure of the gantry1 the moments are transmitted to the foundations of * the gantry. Figures 2a to 2c are load diagrams depicting the shear stresses (Fx, Fy, Fz) and overturning moments (Mx, My and Mz) that may act on a conventional :4 gantry. The gantry may be subject to an overturning moment about the y-axis (My) when a shear stress (Fx) acts along the length of the boom, for example due to a thermal load. The gantry may be subject to an overturning moment about the x-axis *, .: (Mx) when a shear stress (Fy) acts in a direction perpendicular to the longitudinal axis of the boom, for example a horizontal (lateral) wind load. The gantry may be subject to a shear stress (Fz) acting in an upwardly vertical direction with respect to the gantry, for example by an uplifting wind load. The gantry may be subject to a twisting moment about the z-axis (Mz), for example when an errant vehicle impacts a gantry leg at an angle.

[0005] To satisfy design requirements, gantries must have a structural integrity to counteract destabilising loads. The foundations of gantries are typically over-designed to help provide structural integrity. Te over-designed foundation are configured to ensure the gantry is able to provide restoring moments that are greater than or equal to the overturning moments of destabilising loads. For example, a gantry may comprise a pile foundation system as depicted in Figures Sa and 3b. The pile foundation system (10) comprises a large reinforced concrete pile cap cli) and one or more piles (12) extending into the ground. The leg porOons (13a, 13b) of a gantry leg (3b) are rigidly coupled to an upper surface (ha) of the pile cap using bolts (14) and multiple piles (12a, 12b) extend into the ground from a lower surface (1 ib) of the foundation cap stone. Whilst over-designed foundations are able to provide a stabilising effect they are undesirably large and expensive to manufacture.

Moreover, the installation of over-designed foundations is time-consuming and complex. For example, the installation of the over-designed foundations may be susceptible to weather delays, requires engineering expertise, requires heavy plant and machinery and creates risk to the workiorce and travelling public.

SUMMARVOFTHEINVENTIP_N

(0006] Embodiments of the invention seek to obviate or at least alleviate the above-mentioned problems or shortcomings associated with gantries.

(00071 A first aspect of the invention relates to a bearing suitable for a gantry.

When located between gantry áomponent parts, the bearing is configured to allow for rotational movement of the gantry component parts about a predetermined axis ** ** underan applied load. a

* a a [0008] The bearing is configured to allow for rotatibnal movement of gantry component parts about a transverse axis of the bearing.

[0009] The bearing according to the first aspect of the invention comprises: a first member comprising a first surface and arranged in association with the first component part; a second member comprising a second surface and arranged in association with a second component part;.

whereby the first surface and second surface are arranged in pivoting contact to allow for rotational movement between the first member and second member about a transverse axis of the bearing under an applied load.

ooioj The bearing may be locatable between a gantry leg and a gantry foundation and configured to allow for rotational movement of the gantry leg relative to the gantry foundation about a transverse axis of the bearing under an applied load.

[00111 If the applied load generates a destabilising moment about an axis of the gantry, the bearing may be configured to allow for the gantry leg to rotate relative to the gantry foundation under the action of the estabilising moment. The rotational movement of the gantry leg relative to the gantry foundation at teast limits, preferably neutralizes the destabilising moment and thereby at least minimises, preferably prevents, the transmission of the estabilising moment to the gantry foundation.

[0012] More particularly, the bearing may allow for rotational movement of the gantry leg relative to the gantry foundation about the y-axis of the gantry when an overturning moment about the y-axis (My) is applied to the gantry. The rotational movement of the gantry leg relative to the gantry foundation about the y-axis at least limits, preferably counteracts, the overturning moment My and thereby at least reduces, preferably avoids the transmission of the overturning moment My to the.

gantry foundation. The y-axis of the gantry is an axis perpendicular to the longitudinal axis of the boom.

[0013) Preferably, one of the surfaces is a substantiallY planar surface and the other surface is a substantially convex surface curving in a transverse plane of

S

the bearing. ** S * S S * S.

[00141 preferably, the convex surface only curves in a transverse plane to the bearing. ccordingly, the bearing is configured to only allow for rotation, of gantry * component parts about a transverse axis of the bearing. Hence, the bearing will not allow gantry component parts to be rotated about different axes of the bearing.

Moreover, the bearing will only allow fo' the rotation of gantry components parts about one axis at any given time. For example, if the bearing is already configured to allow for rotational movement of the gantry leg relative to the gantry foundation about the y-axis of the gantry (as described above) then the bearing will not allow for S rotational movement of the gantry leg relative to the gantry foundation about the x axis of the gantry when an overturning moment about the x-axis (Mx) is applied to the gantry.

[0015] Preferably, the substantially convex surface comprises spherical graphite The spherical graphite helps to minimise friction and/or corrosion of the surface.

10016) Preferably, the first surface and second surface are arranged in pivotal contact to allow for the transmission of an applied toad between the first member and the second member. Accordingly, the bearing is configured to allow for vertical loads (shear stress Fz) acting on the gantry to be at least substantially transmitted to the gantry foundations.

(0017] Preferably, the substantially planar surface is a rear wall of a.receiving portion and the substantially convex surface is a domed wall of a protruding portion whereby the receiving portion is configured to form a pivotal joint with the protruding portion to allow for rotational movement between the first member and second member about the transverse axis of the bearing under an applied load.

(0018] Corresponding side walls of the receiving portion and protruding portion may be arranged in mating contact to allow for the transmission of an applied load between the first member and second member. Accordingly, the bearing may be configured to allow for perpendicular loads (shear stress Fy) acting on the gantry to be at least substantially transmitted to the gantry foundations. 0*s� * 30

[0019) The side walls of the receiving portion and protruding portion may be

S

arranged in mating contact to form a seal between the first member and the second *S S 5. *.t member.

S * S

(00201 The bearing may further comprise a compressible seal means arranged * between the first member and the second member. ** S S * * 0

[0021] The bearing may further comprise coupling means to couple the first member and second member so as to at least resist the effects of a separating load on the first member and second member.

(0022] Preferably, the coupling means is a coupflng pin extending through in internal bore hole defined by the first member and second member, whereby. a first end of the coupling means is coupled to the first member and a second end of the coupling means is coupled to the second member and optionally, the internal bore hole is configured to allow for rotational movement of the coupling pin.

(0023] Preferably, the degree of rotation of the gantry leg is selected to at least limit the destabilising moment and thereby at least limit the transmission of the destabUising moment to the gantry foundatbn The degree of rotation of the gantry leg may be approximately +1-0.35 radians.

[0024] The first member of the bearing may comprise a first peripheral flange for engagement with ihe first component part and the second member comprises a second peripheral flange for engagement with the second component part 10025) A second aspect of the invention relates to a gantry comprising a boom, legs for supporting each end of the boom and foundations, whereby each leg is pivotally mounted on the foundations using a bearing according to a first aspect of the invention.

BRIEF DESCRIPTiON OF THE DRAWINQ

[13026] For a better understanding of the present invention, and to show how it may be carried into effect, reference shall now be made by way of example to the accompanying drawings, in which: a * a Figure 1 is a perspective view of a conventional gantry spanning a road; * S * *5 * S5 a... 4 Figure2a is a load diagram of a front view of a part of a conventional gantry: a a * Figure 2b is a load diagram of a side view of the gantry depicted in Figure 2a; at * t a * at Figure 2c is a load diagram of a top view of the gantry depicted in Figure 2a; Figure3a is an end view of a foundation pile system for a gantry; Figure 3b is side view of the foundation pile system depicted in Figure 3a; Figure 4 depicts a cross-sectional view of a first embodiment of a bearing according to a first aspect of the invention; Figure 5 depicts a cross-sectional view of a second embodiment of a bearing according to a first aspect of the invention; Figure 6a depicts a perspective view of a bearing according to the first aspect. of the invention arranged between a gantry leg and gantry foundation; Figure 6b depicts a longitudinal view of the bearing arrangement depicted in Figure* 6a; Figure 6c depicts a transverse Aew of the bearing arrangement depicted in Figure 6a; Figure 7a is a cross-sectional view of a third embodiment of a bearing located between a gantry leg and gantry foundation according to a first aspect of the invention.

Figure 7b depicts ah enlarged view of the bearing depicted in Figure Ta; Figure Tc depicts a longitudinal view of the bearing depicted in Figure 7a; Figure Td depicts a top view of the bearing depicted in Figure 7a; S.... *

Figure 8 depicts a perspective cross-sectional view of the bearing depicted in Figure *. 0 a * * * *0 I

S aSSSS * .

Figure 9 depicts an embodiment of a gantry according to a second aspect of the invention: *S * -* a * *.

9ETAILE.D DEcR1PTION OFJHE INVENTI..QN [0027) A first aspect of the invention relates to a bearing that is suitable for allowing rotational movement between component parts of a gantry about a predetermined axis.

[0028) The bearing is locatable between a first component part and second component part of a gantry. The bearing comprises a first member locatable in association with a rst component part of the gantry and a second member locatablç in association with a second component part of the gantry.

(0029] The first member may be coupled or integrally formed with the first component part of the gantry. Likewise, the second member may be coupled or integrally formed with the second component part Of the gantry. The first member and/or second member may be. releasably coupled. to the respective component parts using releasably coupling means such as bolts, screws and the like.

(0030] The first member and second member are configured to form a pivotal joint to allow for rptational movement between the first member and second member about a transverse axis of the bearing under the application of a toad. The rotational movement at least minimises, preferably prevents, the transfer of the applied toad between the members and thereby component parts of the gantry. If the applied load induces a destabilising moment on a component part of the gantry, the bearing may be configured to allow for the member associated with the component part to rótate relative to the other member under the action of the destabilising moment. The rotational moment of the member at least lirtits, preferably neutralizes, the effects of the destabilising moment and thereby at least minimises, preferably prevents, the transmissiOn of the destabilising moment to the other member and component part.

(00311 The first member comprises a first surface arranged in pivoting contact with a second surface of the second member. The pivoting contact is preferably a line contact at least substantially along the length of the first and second surfaces. *I S * ** -. t*

[0032] So as to allow for rotation about the pivoting contact, the surface of one member is generally planar whilst the surface of the other member has a * * generally convex shape. Thus, the pivoting contact forms between the planar surface

S

and peakofthec0nvex5u.

(0033] So as to allow for rotation about a transverse axis of the bearing, the convex surface is curved in a transverse plane of the member.

[00341 The bearing is.preferably configured to only allow for rotation about the transverse axis and thereby at least minimise any rotation between the first member and second member about any other axis So as to prevent rotation about any axis other than the transverse axis of the bearing, the surface with a generally * convex formation is only curved in the transverse plane of the member.

(00351 The convex surface and/or planar surface may comprise spherical graphite so as to minimise friction andfor corrosion of the surface. The convex surface and/or planar surface may comprise a coating layer comprising spherical graphite. The convex surface may comprise cast metal having spherical graphite elementS.

(00361 The bearing is preferably configured to allow for the.transmission of certain loads between the first component part and second component part. This is achieved by forming a mating contact between the surfaces of the first member and second member where the certain load act on the bearing..

(0037) In an embodiment of a bearing depicted in Figures 4, the bearing (B) comprises a first member (20) and a second member (30). The first member (20) is integrally formed with a first component part of the gantry (FC) and comprises a planar surface (21) The second member (30) is integrally formed with a second component part of the gantry (SC) and comprises a substantially convex surface (31). The planar surface is arranged in mating contact with the peak of the convex surface to form a pivoting contact (P) so as to allow for rotation between the planar 0e.

surface and convex surface about a transverse axis of the bearing. Hence, if aIoad applied to the first gantry component induces a bending moment about the ". : transverse axis of the bearing, the first member rotates about the pivoting contact.

* The rotation of the first member at least minimises the transfer of the applied load * * (bending moment) to second member and thereby the second gantry component.

** S...

: Likewise, if a load applied to the second gantry induces a bending moment about the transverse axis of the bearing, the second member rotates about the transverse axis * relative to the first member. The rotation of the second member at least minimises

B

the transfer of the bending moment to the first member and thereby the first component part.

[00381 The mating of the planar surface and convex surface at the pivoting contact point (P) allows for the transfer of any load acting in a direction perpendicular to the bearing. For example, the bearing depicted in Figure 4 allows for the transfer of load Fa from the first component part to the second component part via the pivoting contact (P).

[00393 In the embodiment depicted in Figures.5 the bearing (B) comprises a first member (100) and a second member (200). The first member (100) comprises a first peripheral flange (101) and a female receiving portion (102). The second member (200) comprises a second peripheral flange (201) and a male protruding poçtion (202).

[0040] The. first peripheral flange (101) comprises apertures (lola) suitable for receiving bolts or other suitable coupling means so as to couple the first member to a first component part of the gantry. Likewise, the second peripheral flange (201) comprises apertures (201 a) for receiving bolts or other suitable coupling means so as to releasably couple the second member to a second component part of the gantry.

One or both of the peripheral flanges is preferably releasably coupled to the respective component part.

[0041] As shown in the Figure 5, the female receiving portion (102) of the first member may comprise a substantially planar rear wall (102a) and side walls (102b).

The male protruding portion (202) may comprise a domed upper wall (202a) and side walls (202b). The receiving portion is configured to receive the protruding portion such that the planar rear wall (102a) mates with the peak region of the domed upper 0�** wall (202b) at pivotal contact (P). Accordingly, the receiving portion and protruding portion form a pivotal joint (F), whereby the receiving portion can rotate with respect to the protruding portion about the transverse horizontal axis of the bearing.

(0042] In an embodiment depicted in Figures 6a to 6c, the bearing (B) is locatable between a gantry leg (L) and gantry foundation (F) to allow for rotational :. s movement of the gantry leg relative to the gantry foundation about a transverse axis * of the bearing. . [0043] The first member may be coupled or integrally formed with the gantry leg. More particularly, the first member may be coupled to a lower surface of the gantry leg or integrally formed with a lower region ol the gantry leg. The second member may be coupled or integrally formed with the respective gantry foundation of * 5 the gantry leg. More particularly, the second member may be coupled to an upper surface of the gantry foundation or integrally formed with an upper region of the * gantry foundation.

[00441 The bearing may be configured to allow the gantry leg to pivot under the action of an overturning moment induced by a destabilising load. The rotation of the gantry leg at least limits the effects of the overturning moment and thereby at least reduces the transmission of the overturning moment to the gantry foundation.

Indeed, the bearing is preferably configured such that the rotation of the gantry leg is sufficient to counteract the effects of the overturning moment and thereby prevent the * 15 transmission of the overturning moment to the gantry foundation.

[0045] The bearing may be configured to allow the gantry leg to pivot under the action of an overturning moment My applied by a destabilising load acting in a * direction parallel to the longitudinal axis of the boom (shear stress Fx). For example, the bearing joint may be configured to allow the gantry leg to pivot under the action of an overturning moment My applied by a thermal load Accordingly, the rotation of the gantry leg at least limits the transmission of overturning moment My to the gantry foundation. * [0046] The first member or second member may be configured to rotate up to approximately +1-0.35 radians about the transverse axis of the bearing. The degree of rotation may be selected in accordance with the design requirements of the gantry.

In order to comply with design requirements, a gantry must be able to at least substantially withstand the destabilising moments about the y-axis (My) that are generated by expansion and contraction of the boom and/or a residual impact of a vehicle. Accordingly, a bearing may be configured between a gantry leg and gantry foundation to allow for rotational movement of the gantry leg about the y-axis of the 0***Ie * * * gantry when an overturning moment about the y-axis (My) is applied to the gantry * and the degree of rotation may be selected so as to ensure the gantry leg is * : 35 sufficiently rotated about the y-axis to at least substantially counteract the * destabilising moment (My) and thereby at least substantially reduce the transmission of the destabilising moment (My) to the gantry foundation.

[0047] Providing a bearing to at least limit the transmission of an overturning moment to the foundations allows the design of the foundations may be simplified. By specifically limiting the transmission of an overturning moment My (about an axis that is perpendicular to the longitudinal axis of the boom), the width of the foundations may be reduced. Moreover, the need for stabilising piles is decreased. The simplified foundations may be spread foundations formed from pre-cast concrete. The* simplified foundations may be located above ground or in relatively shallow excavations. Hence, the foundations are smaller, quicker and easier to install and cheaper to manufacture. The foundations do not require heavy plant and machinery to install and so safety and installation time is improved. If a customer chooses to use traditional pile foundations or in an instance where the existing ground strengths are so low as to dictate an instance where pile foundations must be used, then the design of the pile foundations will be smaller and more cost effective than conventional pile foundations due to the absence of the overturning moment My on the foundations.

[0048] Figures 7a to 7d and 8 depict an embodiment of the bearing located * between a gantry leg (L) and a gantry foundation (F) where the first member (100) comprises a receiving portion (102) that it configured to receive a protruding portion (202) of the second member (200). The planar rear wall (102a) of the receiving portion forms a pivotal contact (P) with the peak of the domed wall (202a) of the protruding portion so as to allow the first member to rotate about a transverse axis of the bearing.

(0049] The bearing may be configured to allow for the transmission of perpendicular shear forces (Fy) from the gantry leg to the gantry foundation. This may be achieved by forming a mating contact between the surfaces of the first S....' member and the second member at the point, where the perpendicular shear force (Fy) may act on the gantry leg and thereby the bearing. In the embodiment depicted in Figures 7a to 7d and 8, the side walls (102b) of the receiving portion of the first member are configured to form at mating contact with the corresponding sides walls (202b) of the protruding portion of the second member at the point where the perpendicular shear force (Fy) may act. As a result, the perpendicular shear force (Fy) acting on the gantry leg is transmitted to the gantry foundation. The * perpendicular shear force (Fy) may be a lateral wind load acting on the gantry. 11 *

[0050] Since the pivotal mating contact (P) of the gantry leg to the gantry foundation is at the point where a vertical load (shear force Fz) may act on the gantry leg, the bearing is configured to allow for the transmission of vertical loads from the gantry leg to the gantry foundation. For example, the bearing may be configured to allow for the transmission of an uplifting wind load between the gantry leg and gantry' foundation.

[0051] The bearing may further comprise sealing means to form a seal between the first member and second member. The sealing means are provided to at least minimise The ingress of extraneous material that may hinder the operation of the bearing. For example1 the sealing means may at least minimise the ingress pf dust and other small particulates into the bearing. The sealing means may comprise compressible sOal means (300) located between a lip of the receiving portion of the first member and a lip of the protruding portion of the second member.

[0052] The mating contact between the side walls of the receiving portion of the first member and protruding portion of the second member may provide a further sealing effect.

[0053] Accordingly, a bearing with a double sealing effect may achieve an Ingress Protection (IP) first digit rating of at least 4 whereby the sealing means are able to prevent entry, of solid objects with a diameter or thickness greater than 1.0mm. The bearing with the double sealing effect may preferably achieve an Ingress Protection first digit rating of 5 whereby the sealing means are able to prevent the ingress of the amount of dust that would interfere with the operation of the equipment.

[0054] The bearing may further comprise coupling means to couple the first member and the second member. In the embodiment depicted in Figures 7a to 7d and 8, the coupling means comprises a pair of coupling pins (400) extending between the first member and the second member. The coupling pins couple the first S member and second member so as to minimise, preferably counteract, the effects of *.*** any overturning moments and/or loads acting in the direction parallel to the axis of the coupling pin. For example, the coupling pin may resist the effect of an uplifting °. : 35 load acting on the gantry and thereby help to securely couple the leg and foundation.

* The coupling pin preferably releasably couples the first member and second member so as to allow the removal of the gantry leg from the gantry' foundation as required,.

* [0055] Figure 7a to 7d and 8 depicts an embodiment of the bearing whereby each coupling pin is located in a coupling pin aperture (500). The coupling pin aperture is defined by corresponding apertures (SOOa, 500b) formed in the first member and second member. Each coupling pin aperture extends substantially vertically through the bearing from a first member recess (500c) to a second member recess (500d). The coupling pins are configured in the bearing so as to at least resist any uplifting loads acting on the gantry. The coupling pin comprises a bolt (400a), whereby the first end of the bolt protrudes into the first member recess (500c) and is releasably secured to the first member within the recess using a spherical washer (400b) and hexagonal bolt head (400c) and the second end of the bolt protrudes into the second member recess (500d) and is releasably secured to the second member using a spherical washer (400b) and hexagonal bolt head (400c).

[0056] The coupling pin aperture may be configured to allow the upper portion of the coupling pin to pivot relative to the lower portion of the coupling pin when the first member rotates relative to the second member. The aperture in the first member (500a) may have a conical formation so as to the upper portion of the coupling pin to pivot. The coupling pin aperture in the first member may have a diameter than the coupling pin to allow for pivotal motion. The' coupling pin aperture may allow for the coupling pin to rotate through an arc of approximately 4-6 degrees.

The degree of rotation may be selected in accordance with the design requirements of the gantry.

[0057] A second aspect of the invention relates to a gantry comprising a boom, legs to support each end of the boom and foundations, The legs are pivotally mounted on the foundations using the bearings according to the first aspect of the invention. * S 0**

[0058] The gantry may comprise one or more legs to support an end of the boom. For example, the gantry may comprise a pair of legs to support an end of the 5, boom. The pair of legs may be arranged in an A-frame formation. Each of the legs is S* * * * pivotally mounted on the foundations using a bearing according to the first aspect of the invention. Due to the arrangement of the legs, wind acting' in a direction perpendicular to the boom will apply a destabilising uplifting' load on the first leg and * a destabilising downward load on the second leg. Therefore, the bearings for each pair of legs may be matched to at least substantially resist corresponding destabilising uplifting loads and downward loads that may act of the gantry legs during use.

[0059] Figure 9 depicts an embodiment of a gantry according to the invention. The gantry spans across both carriageways of a motorway. Display systems, direction signs and other equipment are mounted on the boom. The legs (L) are pivotally mounted on spread cast foundations (F) using the bearings (B) according to the first aspect of the invention. The bearings are configured to at least substantially minimise destabilising moments acting about the y-axis of the gantry.

Accordingly, the foundations required to provide a stabilising effect on the gantry are substantially smaller than conventional pile foundations for gantries. The foundations are formed from pre-cast concrete and are at least substantially located above ground. The foundations are smalier in size and they are simpler and cheaper to manufacture and install than conventional pile foundations.

[00601 The features of the invention are applicable to all aspects of the invention and may be used in any combination.

[0061] Through out the description and claims of this specification, the words "comprise" and "contain" and variations of the words, for example comprising" and.

"comprise", means "including but not limited to, and is not intended to (and does not) exclude other moieties, additives, components, integers or steps.

[0062] Throughout the description and claims, the singular encompasses the pluralunless the context otherwise requires. In particular, where the indefinite article is used, the specification is to be understood as contemplating plurality as well as singuIarit, unless the context requires otherwise.

[0063] . Features, integers, characteristics or groups described in conjunction * 30 with a particular aspect, embodiment or example, of the invention are to be * understood to be applicable to any other aspect, embodiment or example described ** herein unless incompatible therewith.

I

II Ie** * I. . *I *

I I * II. 14.