GB2468785A

GB2468785A - Trench cutting apparatus

Info

Publication number: GB2468785A
Application number: GB1004734A
Authority: GB
Inventors: Elfed Thomas
Original assignee: i3 Group Ltd
Current assignee: i3 Group Ltd
Priority date: 2009-03-20
Filing date: 2010-03-22
Publication date: 2010-09-22
Also published as: GB0904838D0; WO2010106378A2; WO2010106378A3; GB201004734D0

Abstract

A trench cutting vehicle 10 comprising a trench cutting apparatus 100 mounted to a movable mounting structure 110. A saw blade device on the mounting structure can be moved between storage and operational positions and allow lateral positioning of the saw blade device (fig 2a, 2b and 2c). The cutting device may also comprise water spraying nozzles and means for collecting and retaining the spoil material from the cutting process. The collecting process can be achieved by way of a suction device 14 mounted on the vehicle.

Description

Trench Cuttixi&Apparatu The present invention relates to a trench cutting apparatus and in particular to a trench cutting apparatus operable to cut a trench or microtrench adapted to facilitate thc installation of a cable such as an optical fibre.

s When installing new cable networks, in particular new data cable networks, it is common to install the cables for at least part of the network along a trench. The trench can then be filled in over the cable. This provides protection for the cable and ensures it does not interfere with the passage of persons or vehicles once laid.

Typically, a trench for laying a cable may be formed by digging and after the cable laying the trench is back filled with the spoil from the digging. Digging and re-filling in this manner will not necessarily create a level surface over the trench. It is therefore necessary to pay particular attention to levelling the surface after filling the trench, particularly if the trench runs across or along a road or public footway. Since such methods also generate a lot of spoil for replacement, they are relatively time is consuming. As such, when applied to public roads or foot paths they cause considerable disruption.

It is therefore an object of the present invention to provide a trench cutting apparatus that at least partially overcomes or alleviates the above problems.

According to a first aspect of the present invention there is provided a trench cutting vehicle comprising a movable vehicle body and a powered trench cutting apparatus wherein the trench cuffing apparatus is a trench cutting apparatus of the type operable to cut a trench by driving a saw blade and wherein the trench cutting apparatus is provided on a movable mounting structure such that it can be moved between a stowed position and an operational position.

This apparatus therefore provides a convenient means of forming a narrow trench or microtrench suitable for laying a cable in without digging. Since the trench is relatively narrow, its creation causes reduces disruption and reduces filling requirements.

The vehicle may comprise any form of vehicle. The vehicle may be a tracked or wheeled vehicle. The vehicle may be adapted such that it may carry an operator.

In particular, the vehicle may be an adapted digger, tractor or other plant vehicle. In another embodiment, the vehicle may comprise an adapted form of a street sweeper vehicle.

The mounting structure may be adapted to enable the trench cutting apparatus to be raised or lowered in relation to the vehicle. In particular, the structure may be adapted to raise the apparatus into a stowed position and to lower the apparatus into an operational position.

The mounting structure may be further operable to move the trench cutting apparatus laterally and/or longitudinally with respect to the vehicle. This can enable the trench cutting apparatus to be moved between a stowed position adjacent to the vehicle and an operational position extended from the vehicle.

The mounting structure may comprise a bracket to connect the mounting structure to the vehicle. The bracket may comprise a rotatable joint about which the mounting structure can rotate. The bracket may be adapted to fit a rail provided on the vehicle. The rail may allow the bracket to be displaced laterally relative to the s vehicle. This can help enable the stowing of the trench cutting apparatus.

Movement of the mounting structure and the trench cutting apparatus may be powered by one or more power sources provided on the vehicle. In this respect, movement of the mounting structure may be achieved by the use of hydraulic power.

Driving of the saw blade may be achieved by electrical power or hydraulic power as required or as desired.

The vehicle may be provided with one or more water spraying nozzles. The water spraying nozzles can dampen down loose material on the surface in which the trench is being cut and thereby reduce the amount of debris generated during trench cutting apparatus.

The vehicle may be provided with means for collecting and retaining spoil generated during the cutting of the trench. The collection and retention of spoil during operation provides a further reduction in the disruption caused during operation.

The spoil collecting means is preferably a suction device. The suction device is preferably adapted to have a suction opening through which spoil is sucked, The suction opening may be provided on an underside of the vehicle behind the trench cutting apparatus. The suction opening may be provided with a rim suitable to remain in contact with or close to the surface during operation. The rim may comprise a flexible material andlor a plurality of flexible bristles. The suction opening may be provided with wheels to minimise friction during operation. The suction opening may be adapted to be raised when cutting operation is not in progress.

The spoil may be retained in a tank connected to the suction device. Spoil in the tank may be retained for dumping in an authorised location. Alternatively, spoil may be used for re-filling a trench once a cable is laid therein.

The trench cutting apparatus may comprise a saw blade; and means for driving said saw blade such that motion of the blade will cut a trench in a surface to which the saw blade is applied. The trench cutting apparatus may further comprise a movable arm upon which the saw blade is mounted, the arm movable between at least a cutting position wherein the saw blade is applied to a surface for cutting and a non-cutting position wherein the saw blade is not applied to a surface for cutting. The trench cutting apparatus may also comprise a clamping device operable to clamp a clamping rim associated with the movable arm and thus retain the moveable arm in a desired position. The provision of the clamping device damps vibration of the apparatus during operation and ensures a consistent cutting depth.

The saw blade may be a rotary saw blade, The saw blade may have teeth adapted to cut a trench of a particular width. This may be achieved by the width or the teeth being substantially the same with as the desired width of the trench. The trench width may be of the order of the diameter of the cable to be lain in the trench.

The clamping device may be provided on a frame. The movable arm may be mounted on and movable in relation to said frame. The frame may have an arcuate portion upon which the clamping device is provided. The clamping rim may comprise a corresponding arcuate rim. The arcuate clamping rim may be an integral part of the movable arm or may be fitted to the movable arm so as to move with the movable arm. The clamping rim may be provided on a suitable projection of the movable arm. The clamping rim may be formed of a high friction material. The clamping device may be adapted to include damping means to damp vibrations transmitted along the movable arm from the saw blade.

The clamping device may be operable to clamp the movable arm in only the cutting and non-cutting positions. Alternatively, the clamping device may be operable to clamp the movable arm in a range of positions ranging between a non-is cutting position and plurality of cuffing positions. This can enable the apparatus to be adapted to cut trenches of varying depths.

The frame may be provided with a contact plate. The contact plate may be adapted to contact the surface in which the trench is to be cut. This can enable a surface level to be defined by the frame. This thus enables a particular trench depth to be cut by selection of an appropriate cutting position of the movable arm.

The contact plate preferably extends from the frame past the saw blade. In order that the contact plate does not impede the operation of the saw blade a suitable slot is provided in the contact plate allowing the saw blade to move between a cutting position and a non-cuffing position. The contact plate helps to contain spoil or debris generated during cutting. The contact plate may be provided with upturned ends.

This allows the contact plate to slide more evenly over an uneven surface.

The frame may be adapted to be connected to the mounting structure. The connection may be via a rotatable joint. This thereby allows the frame to be rotated relative to the mounting structure.

The saw blade may be covered by a shield. The shield may be adapted also to cover the moveable arm, the clamping device, the clamping rim and the frame. The shield may be removable when not in use. The shield helps to protect users of the apparatus and passers by from debris generated in cuffing the trench.

According to a second aspect of the present apparatus there is provided a is method of cutting a trench, the method comprising the steps of: providing a vehicle in accordance with the first aspect of the preset invention; applying the trench cutting apparatus of the vehicle to the surface in which the trench is to be cut; and moving the vehicle across the surface so as to move the saw blade of the trench cuffing apparatus across the said surface wherein the axis of the saw blade is aligned with the desired axis of the trench.

This therefore provides a convenient method of forming a narrow trench or microtrench suitable for laying a cable in without digging. Since the trench is relatively narrow, its creation causes reduces disruption and reduces filling requirements. The collection and retention of spoil during operation provides a S further reduction in the disruption caused during operation. Furthermore, if a trench cutting apparatus of the form above incorporating a clamping device is used to cut the trench, the provision of the clamping device damps vibration of the apparatus during operation and ensures a consistent cutting depth.

The method of the second aspect of the present invention may incorporate any or all features of the first aspect of the present invention as desired or as appropriate.

In parEiculai the method of the second aspect of the present invention may be carried out by use of a trench cutting apparatus of the type comprising a saw blade; means for driving said saw blade such that motion of the blade will cut a trench in a surface to which the saw blade is applied; a movable arm upon which the saw blade is is mounted, the arm movable between at least a cutting position wherein the saw blade --is applied to a surface for cutting and a non-cutting position wherein the saw blade is not applied to a surface for cutting; and a clamping device operable to clamp a clamping rim associated with the movable arm and thus retain the moveable arm in a desired position. In such embodiments, the method may involve the steps of: applying the apparatus to the surface at the desired start location of the trench; applying driving power to the saw blade; moving the movable arm into a desired cutting position; clamping the movable arm in the desired cutting position; and moving the vehicle along the surface so as to cut a trench along the desired route.

When the end of the route of the trench has been reached, the method may involve the steps of: releasing the clamping device; moving the arm back to a non-cutting position; and ceasing the application of power to the saw blade.

s The method may involve the preliminary steps of marking out the desired route for the trench.

According to a third aspect of the present invention there is provided a method of laying a cable comprising the steps of cutting a trench in accordance with the method of the second aspect of the present invention; placing a cable in the trench; and filling the trench.

This therefore provides a convenient method of laying a cable in a narrow trench or microtrench, without digging. Since the trench is relatively narrow, its creation reduces disruption and reduces filling requirements. The collection and retention of spoil during operation provides a further reduction in the disruption is caused during operation. Furthermore, if a trench cutting apparatus of the form above incorporating a clamping device is used to cut the trench, the provision of the clamping device damps vibration of the apparatus during operation and ensures a consistent cutting depth.

The method of the third aspect of the present invention may incorporate any or all features of the first or second aspects of the present invention as desired or as appropriate.

The cable may be any suitable form of cable. In particular, the cable may be a cable adapted to carry data. Most particularly, the cable may comprise one or more optical fibres.

The method may include the step of placing a dedicated cable conduit in the s trench. The cable may then be laid along the dedicated conduit. The trench may be filled with any suitable materials. This may include a sand layer directly over the cable and a layer of hard core over the sand. A layer of concrete, tarmac, asphalt, bitumen or other suitable sealing/paving surface may be provided over the hardcore if required or desired. The method may further include laying a warning tape between the sand and the hard core layers. The warning tape is adapted to be detectable by the provision of a metal strip inlay and/or being printed with a visible warning. The provision of a metal strip allows the tape to be detected by a scan of the area using an inductive detector. This may be routinely carried out prior to road excavation, The visible warning may comprise bright colours and/or distinctive patterns and/or a is written warning message such as "Warning Fibre Cable", or similar.

According to a fourth aspect of the present invention there is provided a network comprising one or more cables laid in trenches in accordance with the method of the third aspect of the present invention.

The network of the fourth aspect of the present invention may incorporate any or all features of the first, second or third aspects of the present invention as desired or as appropriate.

-10 -The network may be used for the transmission of data and/or power as required. Additional cables in the network may be laid using the method of the third aspect of the present invention and/or any other suitable method as desired or as appropriate. Other suitable method may include the laying of cables in sewers or in conventional trenches.

In order that the invention is more clearly understood, one embodiment will now be described thrther below, by way of example only and with reference to the accompanying drawings, in which: Figure 1 shows a vehicle according to the present invention with a trench cutting apparatus fitted thereto; Figure 2a shows a plan view of the vehicle of figure 1 with the trench cuffing apparatus provided in a first operational position; Figure 2b shows a plan view of the vehicle of figure 1 with the trench cutting apparatus provided in a second operational position; is Figure 2c shows a plan view of the vehicle of figure 1 with the trench cutting apparatus provided in a third operational position; Figure 3a shows a vehicle according to the present invention with a trench cutting apparatus provided in a stowed position; Figure 2b shows a plan view of the vehicle of figure 3a with the trench cutting apparatus provided in a stowed position; Figure 4 shows a view of a trench cutting apparatus according to the first aspect of the present invention in a stowed position; and s Figure 5 shows a view of a trench cutting apparatus according to the first aspect of the present invention in a cutting position.

The present invention relates to a vehicle 10 provided with a trench cutting apparatus 100. The vehicle 10 is operable to cut a trench in a surface suitable for laying a cable in by applying the trench cutting apparatus 100 to the surface and moving forward. The vehicle 10 is further adapted to reduce the disruption caused by debris generated during the cutting process as will be described further below.

Turning first to figure 1, one possible form of vehicle 10 is shown. In this particular example the vehicle 10 is a modified form of street sweeper. It would, of course be appreciated by the skilled man that alternative plant vehicles could be used as the basis for carrying the trench cutting apparatus 100. In particular, the vehicle adapted may be a form of digger, tractor or similar.

In figure 1, the vehicle 10 has a cab 11 in which an operator may sit and a rear portion 12. In the rear portion is provided a motor or engine. The trench cutting apparatus 100 is mounted on the front of the vehicle via a mounting structure 110.

-12 -The mounting structure 110 is connected to the vehicle 10 by way of bracket 111 and rails 13.

The mounting structure 110 is adapted to allow the trench cutting apparatus to be moved relative to the vehicle 10. One element of motion is provided by the s rotation of an upstanding limb 114 of the mounting structure 110 relative to a rotatable end mount 116. A second element of motion is provided by the rotation of an upstanding limb 112 of the mounting structure 110 within the bracket 111, As a result of this range of motion, the trench cutting apparatus 100 can be provided directly in front of the vehicle 10, as is also illustrated in the overhead view of figure 2a. By appropriate movement of the mounting structure 110 it is also possible for the trench cuffing apparatus 100 to be offset either to the left of the vehicle 10 as in figure 2b or to the right of the vehicle 10 as in figure 2c. This can enable a trench to be cut relatively closer to a lateral obstacle such as a roadside kerb than the centreline of the vehicle 10.

is A further element of motion is that the bracket ill is also adapted to slide along rails 13 when desired. This can allow the trench cutting apparatus 100 to be moved to a safe stowing position as is shown in figures 3a and 3b when not in use, If appropriate or desired, the vehicle 10 can be provided with a suction device (not shown), the suction device operable to such up spoil or debris from the cutting process or otherwise through a suction opening 14. The suction opening 14 is provided on the underside of the vehicle 10 behind the trench cuffing apparatus 100.

-13 -The suction opening 14 can optionally be provided with a rim comprising flexible material and or a plurality of flexible bristles. The rim can thus remain in contact with the surface during operation. The suction opening 14 can be provided with wheels 15 to minimise friction during operation. The suction opening 14 can also be raised when cutting operation is not in progress.

Spoil sucked up by the suction device is stored in tank provided in the rear portion 12 of the vehicle 10. This spoil may later be used to re-fill the trench or may be dumped at an authorised disposal site.

The vehicle 10 can also be provided with one or more spray nozzles (not shown). These spray nozzles can be operable to spray water onto the surface ahead of or during cutting. The water can help to damp down debris or spoil generated in the cutting process. The water may come from a tank provided in the rear portion 12 of the vehicle 10.

To further contain the spoil and debris, and also to protect passers by, the trench cutting apparatus is provided with a shield 140 covering its saw blade 131. the shield 140 may be removed to service the apparatus 100.

Turning now to figures 4 & 5, one particular form of trench cutting apparatus is shown, by way of example only. The skilled man will realise that other forms of apparatus comprising suitable powered saw blades may also be used for trench cutting in the present invention. In the example, the trench cutting apparatus 100 is fitted to vehicle 10 via the mounting structure 110 using bracket 111. As previously 14 -discussed, the bracket 111 is rotatably mounted to a first upright limb 112 of the structure 110. The structure further comprises a cross limb 113 and a second upright limb 114. The second upright limb 114 has a piston section 115 enabling a rotatable end mount 116 to be raised or lowered between a stowed position shown in figure 4 S and an operational position shown in figure 5 (and similarly between the raised, stowed position of figure 3 and the lowered operational position of figures 1 and 2).

In the stowed position, the apparatus 100 is raised so that it may readily be transported from location to location. Typically, the piston 115 is operated under hydraulic power.

Upon the rotatable end mount 116 is provided a frame 120. The frame 120 has an arcuate portion 121 upon which a clamping device 122 is provided. The clamping device 122 may take the form of pair of gripping jaws (not shown) operable to clamp onto an article placed therebetween.

Also connected to the frame 120 is a contact plate 123, The contact plate has IS upturned ends 124 and a linear slot 125. The upturned ends 124 help ensure the contact plate 123 does not become jammed when sliding along a surface.

Mounted on the frame is a movable arm 130. The arm 130 carries a rotary saw blade 131 and a motor 132 for powering the saw blade 131. The arm 130 is free to rotate about the frame 120 between a non-cutting position shown in figure 1 and a cutting position shown in figure 2. In the cutting position, the saw blade 131 is partly passed through the slot 125 allowing it to cut into a surface adjacent to the underside

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of contact plate 123. In the non cutting position the saw blade 131 is positioned such that it does not project past the contact plate 123. In the cutting position, the contact plate 123 also helps to contain the spoil or debris generated during cutting operation.

The arm 130 is also provided with an arcuate clamping rim 133. The clamping rim 133 is formed from a high friction material and is adapted to be clamped by the clamping device 122. This enables the movable arm 130 (and hence the saw blade 131) to be retained in the cutting position or the non-cutting position as desired. In operation, the clamping device 122 has the further benefit of damping vibration from the saw blade 131.

The cutting position of the arm 130 may be adjusted to provide a desired depth of trench. Essentially, the arm 130 is positioned such that the saw blade 131 projects below the contact plate by a distance substantially equal to the desired trench depth.

The clamping device 122 is then used to retain the arm 130 in the desired position.

The width of a trench cut using the apparatus is essentially determined by the thickness of the saw blade 131. In a preferred embodiment, the saw blade 131 is of a suitable thickness to enable a trench of the order of around 25mm width to be cut.

The maximum depth of trench is also partly determined by the dimensions of the saw blade 131 and the range of movement permitted. Preferably, the saw blade 131 and the arm 130 are adapted such that the apparatus can readily cut trenches of up to around 250 mm in depth. Most preferably, a suitable cutting depth for such trenches is of the order of around 150-250mm.

In order to cut a trench, the vehicle 10 is taken to the start of the trench or trench section with the apparatus 100 in the stowed position. The arm 130 is then moved in to a desired cutting position determined by the desired depth of trench and the clamping device 122 is then operable to clamp the arm 130 in position.

s The next step is to drive the saw blade 131 with motor 132. Once the blade 131 is being driven at operating speed, the piston 115 is used to lower the apparatus into the operating position. As the apparatus 100 is lowered, the blade 131 comes into contact with the surface and begins to cut a trench. When the contact plate 123 is in contact with the surface, the apparatus 100 can be lowered no further and the saw blade 131 is cutting a trench of the desired depth. The apparatus 100 is then moved across the surface along the desired line of the trench until the end of the trench or trench section is reached. The apparatus 100 is then raised to the stowed position, the arm l3Omay then also be moved to the non-cutting position and the driving of the saw blade 131 may be ceased.

is Changes of direction between trench sections can be achieved by raising the apparatus 100 as above, turning the vehicle 10, then reintroducing the apparatus 100 at a new orientation. Alternatively, this may be achieved by moving the vehicle 10 (and hence the apparatus 100) in a curved manner across the surface.

After a trench is cut, a cable may be laid at the base of the trench. The cable may be laid directly in the trench or in a dedicated conduit provided in the trench.

The trench may then be filled with any suitable material. Typically the trench may be -17 -filled with a layer of sand directly over the cable or conduit, Over the sand is typically laid tape having a metal strip inlay and/or being printed with a visible warning. Above the tape is typically provided hard core and/or concrete, tarmac, asphalt, bitumen or other suitable sealing/paving surface. In some embodiments this may include spoil or debris from the trench cutting operation. Cables laid in such trenches may be connected to one or more different cables (whether laid in such trenches or not) to provide a network.

It is of course to be understood that the invention is not to be restricted to the details of the above described embodiment which is described by way of example only. -18-

Claims

Claims 1. A trench cutting vehicle comprising a movable vehicle body and a powered trench cutting apparatus wherein the trench cutting apparatus is a trench cutting apparatus of the type operable to cut a trench by driving a saw blade s and wherein the trench cutting apparatus is provided on a movable mounting structure such that it can be moved between a stowed position and an operational position.
2. A trench cutting vehicle as claimed in claim 1 wherein the vehicle is a tracked or wheeled vehicle.
3, A trench cutting vehicle as claimed in claim 1 or claim 2 wherein the vehicle is adapted such that it may carry an operator.
4. A trench cutting vehicle as claimed in any preceding claim wherein the vehicle is an adapted digger, tractor or plant vehicle.
5. A trench cutting vehicle as claimed in any one of claims 1 to 3 wherein the is vehicle comprises an adapted form of a street sweeper vehicle.
6. A trench cutting vehicle as claimed in any preceding claim wherein the mounting structure is adapted to enable the trench cutting apparatus to be raised or lowered in relation to the vehicle.
7. A trench cutting vehicle as claimed in any preceding claim wherein the structure is adapted to raise the apparatus into a stowed position and to lower the apparatus into an operational position. -19
8. A trench cutting vehicle as claimed in any preceding claim wherein the mounting structure is operable to move the trench cutting apparatus laterally and/or longitudinally with respect to the vehicle.
9. A trench cutting vehicle as claimed in any preceding claim wherein the mounting structure comprises a bracket to connect the mounting structure to the vehicle.
10. A trench cutting vehicle as claimed in claim 9 wherein the bracket comprises a rotatable joint about which the mounting structure can rotate.
11. A trench cutting vehicle as claimed in claim 9 or claim 10 wherein the bracket is adapted to fit a rail provided on the vehicle.
12. A trench cutting vehicle as claimed in claim 11 wherein the rail allows the bracket to be displaced laterally relative to the vehicle.
13. A trench cutting vehicle as claimed in any preceding claim wherein movement of the mounting structure and the trench cutting apparatus is powered by one or more power sources provided on the vehicle.
14. A trench cutting vehicle as claimed in any preceding claim wherein movement of the mounting structure is achieved by the use of hydraulic power.
15. A trench cutting vehicle as claimed in any preceding claim wherein driving of the saw blade is achieved by electrical power or hydraulic power.
16. A trench cuffing vehicle as claimed in any preceding claim wherein the vehicle is provided with one or more water spraying nozzles.

-20 -
17. A trench cutting vehicle as claimed in any preceding claim wherein the vehicle is provided with means for collecting and retaining spoil generated during the cutting of the trench.
18. A trench cutting vehicle as claimed in any preceding claim wherein the spoil S collecting means is a suction device.
19. A trench cutting vehicle as claimed in claim 18 wherein the suction device is adapted to have a suction opening through which spoil is sucked.
20. A trench cutting vehicle as claimed in claim 19 wherein the suction opening is provided on an underside of the vehicle behind the trench cutting apparatus.
21. A trench cutting vehicle as claimed in claim 19 or claim 20 wherein the suction opening is provided with a rim suitable to remain in contact with or close to the surface during operation.
22. A trench cutting vehicle as claimed in claim 21 wherein the rim comprises a flexible material andlor a plurality of flexible bristles.is
23. A trench cutting vehicle as claimed in any one of claims 19 to 22 wherein the suction opening is provided with wheels to minimise friction during operation.
24. A trench cutting vehicle as claimed in any one of claims 19 to 23 wherein the suction opening is adapted to be raised when cutting operation is not in progress.
25. A trench cutting vehicle as claimed in any preceding claim wherein the spoil is retained in a tank connected to the suction device.
26. A trench cutting vehicle as claimed in claim 25 wherein spoil in the tank is retained for dumping in an authorised location or is used for re-filling a trench once a cable is laid therein.
27. A trench cutting vehicle as claimed in any preceding claim wherein the trench s cutting apparatus comprises a saw blade; and means for driving said saw blade such that motion of the blade will cut a trench in a surface to which the saw * blade is applied
28. A trench cutting vehicle as claimed in any preceding claim wherein the trench cutting apparatus comprises a movable arm upon which the saw blade is io mounted, the arm movable between at least a cutting position wherein the saw * blade is applied to a surface for cutting and a non-cutting position wherein the saw blade is not applied to a surface for cutting.
29. A trench cutting vehicle as claimed in claim 28 wherein the trench cutting apparatus comprises a clamping device operable to clamp a clamping rim associated with the movable arm and thus retain the moveable arm in a desired position.
30. A trench cutting vehicle as claimed in claim 27 wherein the saw blade is a rotary saw blade.
31. A trench cutting vehicle as claimed in any one of claims 27 to 30 wherein the saw blade has teeth adapted to cut a trench of a particular width.
32. A trench cutting vehicle as claimed in any one of claims 27 to 31 wherein the clamping device is provided on a frame.-22 -
33. A trench cutting vehicle as claimed in claim 32 wherein the movable arm is mounted on and movable in relation to said frame,
34. A trench cutting vehicle as claimed in claim 32 or claim 33 wherein the frame has an arcuate portion upon which the clamping device is provided.s
35. A trench cutting vehicle as claimed in claim 34 wherein the clamping rim comprises a corresponding arcuate rim.
36. A trench cutting vehicle as claimed in claim 35 wherein the arcuate clamping rim is an integral part of the movable arm.
37. A trench cutting vehicle as claimed in claim 35 wherein the arcuate clamping rim is fitted to the movable arm so as to move with the movable arm.
38. A trench cutting vehicle as claimed in claim 35 wherein the clamping rim is provided on a suitable projection of the movable arm.
39. A trench cutting vehicle as claimed in any one of claims 27 to 38 wherein the clamping rim is formed of a high friction material.is
40. A trench cuffing vehicle as claimed in any one of claims 27 to 39 wherein the clamping device is adapted to include damping means to damp vibrations transmitted along the movable arm from the saw blade.
41. A trench cutting vehicle as claimed in any one of claims 27 to 40 wherein the clamping device is operable to clamp the movable arm in only the cutting and non-cutting positions.
42. A trench cutting vehicle as claimed in any one of claims 27 to 41 wherein the clamping device is operable to clamp the movable arm in a range of positions ranging between a non-cutting position and plurality of cutting positions.
43. A trench cutting vehicle as claimed in any one of claims 27 to 42 wherein the frame is provided with a contact plate adapted to contact the surface in which the trench is to be cut.
44. A trench cutting vehicle as claimed in claim 43 wherein the contact plate s extends from the frame past the saw blade.
45. A trench cutting vehicle as claimed in claim 43 or claim 44 wherein a slot is provided in the contact plate allowing the saw blade to move between a cutting position and a non-cutting position.
46. A trench cutting vehicle as claimed in any one of claims 43 to 45 wherein the contact plate is provided with upturned ends.
47. A trench cutting vehicle as claimed in any one of claims 32 to 46 wherein the frame is adapted to be connected to the mounting structure.
48. A trench cutting vehicle as claimed in any one of claims 27 to 47 wherein the saw blade is covered by a shield.is
49. A trench cutting vehicle as claimed in claim 48 wherein the shield is adapted also to cover the moveable ann, the clamping device the clamping rim and the frame.
50. A trench cutting vehicle as claimed in claim 48 or 49 wherein the shield is removable.
51. A method of cutting a trench, the method comprising the steps of: providing a vehicle in accordance with any one of claims I to 50; applying the trench cutting apparatus of the vehicle to the surface in which the trench is to be cut; and moving the vehicle across the surface so as to move the saw blade of the -24 -trench cutting apparatus across the said surface wherein the axis of the saw blade is aligned with the desired axis of the trench.
52. A method as claimed in claim 51 wherein the method is carried out by use of a trench cutting apparatus of the type comprising a saw blade; means for driving said saw blade such that motion of the blade will cut a trench in a surface to which the saw blade is applied; a movable arm upon which the saw blade is mounted, the arm movable between at least a cutting position wherein the saw blade is applied to a surface for cutting and a non-cutting position wherein the saw blade is not applied to a surface for cutting; and a clamping device io operable to clamp a clamping rim associated with the movable arm and thus retain the moveable arm in a desired position.
53. A method as claimed in claim 52 wherein the method involves the steps of: applying the apparatus to the surface at the desired start location of the trench; applying driving power to the saw blade; moving the movable arm into a is desired cutting position; clamping the movable arm in the desired cutting position; and moving the apparatus along the surface so as to cut a trench along the desired route.
54. A method as claimed in claim 53 wherein the method involves the steps of: releasing the clamping device; moving the arm back to a non-cutting position; and ceasing the application of power to the saw blade, when the end of the route of the trench has been reached.
55. A method as claimed in any one of claims 51 to 54 wherein the method involves the preliminary steps of marking out the desired route for the trench. -2556. A method of laying a cable comprising the steps of cutting a trench in accordance with the method of any one of claims 51 to 55; placing a cable in the trench; and filling the trench.57. A method as claimed in claim 56 wherein the cable is a cable adapted to carry data.58. A method as claimed in claim 56 or claim 57 wherein the cable comprises one or more optical fibres.59. A method as claimed in any one of claims 56 to 58 wherein the method includes the step of placing a dedicated cable conduit in the trench.60. A method as claimed in claim 59 wherein the cable is laid along the dedicated conduit.61. A method as claimed in any one of claims 56 to 60 wherein the trench is filled with a sand layer directly over the cable and a layer of hard core over the sand.62. A method as claimed in claim 61 wherein a layer of concrete, tarmac, asphalt or bitumen is provided over the hardcore.63. A method as claimed in claim 61 or claim 62 wherein the method furthers include laying a warning tape between the sand and the hard core layers.64. A method as claimed in claim 63 wherein the warning tape is adapted to be detectable by the provision of a metal strip inlay andlor being printed with a visible warning.65. A network comprising one or more cables laid in trenches in accordance with the method of any one of claims 56 to 64.-26 - 66. A network as claimed in claim 65 wherein the network is used for the transmission of data and/or power.67. A network as claimed in claim 65 or claim 66 wherein additional cables in the network are laid in sewers or in conventional trenches.S