GB2232651A - Support with mobile counterweight - Google Patents

Abstract

A gantry apparatus for supporting a hedge cutter or like tool comprises a tripodal wheeled tower (not shown) with a mast (5) adjustable vertically and pivotally supporting a casing (8). The casing telescopically receives an arm (9) with a support point (10) for the tool. A weighted carriage (17) is movable along the casing so that as arm (9) is withdrawn or extended carriage (17) is moved rearwardly or forwardly by driving cards (14, 21) to provide a counterbalance moment compensating the load on point (10). The arrangement allows a tool supported at (10) to be used over a wide area whilst relieving the operator of the weight. <IMAGE>

Description

TITLE Supporting Portable Power Tools This invention relates to a mobile gantry apparatus from which portable power-operated tools, instruments and other equipment such as painting, welding, lighting, marking or video equipment may be suspended and directed into a working position.

Many such tools are heavy and, in some cases transmit vibrations to the user. Prolonged use therefore, can cause fatigue and so restricts the amount of work which can be done. Also, because of the weight of the tools, their application is restricted to that area which can be reached by the operator, whilst using both hands to support and direct the equipment.

Where it is necessary to use such equipment at above (or below) the levels easily reached by a person standing normally, then the work has to be done from supports, such as ladders, upturned boxes, temporary staging or scaffolding. Because of the transitory nature of the requirement, it is usually uneconomic to provide ancillary equipment and so the operation frequently becomes dangerous, fatiguing and time-consuming.

This invention seeks to provide a mobile apparatus which overcomes many of the aforementioned problems by effectively rendering the tool or equipment substantially 'weightless' over a working area, as well as permitting the positioning of the operator to best advantage.

In a preferred embodiment the apparatus comprises: i) a strong tripod frame including steps, upon which an operator may stand whilst working with the equipment; ii) castor wheels on the tripod, so that it can be moved into suitable working positions; iii) the tripod supporting and guiding a vertical mast fitted so that it can be caused to rise and fall along its axis, controlled by a cord and windlass system, operated by a lever and ratchet mechanism; iv) a module on top of the mast secured by means of a spigot bearing (which permits 3600 rotation about the vertical axis) and a pivot arrangement (which permits up to 600 inclination above and below the horizontal centre-line); v) the module comprising a body through the centre of which, a tubular suspension member may slide so as to extend or retract, the load being attached to the outer end of the suspension member; vi) the load being counterbalanced by one or more weights, secured to a carriage which moves along the axis of the body, the weights being pivoted from a point through which a plane passing vertically through their centres of gravity, intercepts the axial centre line of the tubular suspension member, whereby the counterbalancing action of the weights is substantially unaffected by inclination of the module; vii) the positioning of the counterweight(s) to suit the degree of extension of the suspension member, being effected by a duplex cord-and-pulley mechanism, which moves the weight carriage by half the amount of the movement by the suspension member, but in the opposite direction, fine adjustment of the carriage positioning being effected by shortening or lengthening the cords at their points of attachment to the suspension member.

Because of the apparent 'weightlessness' of the tool, the operator can now perform work using one hand only and, by attaching an extension handle, more remotely from his body.

Further details of the apparatus are shown by. way of examples in the accompanying drawings. Two alternative constructions are shown, the second arrangement providing for reduced encroachment of space to the rear of the apparatus.

By way of example, the apparatus is shown supporting a portable hedge-trimmer. Other tools may be supported in the same way such as chain saws, percussion rotary hammers, drills or tree pruners. Instruments such as heavy video cameras, lighting units for filming may also be supported.

In the drawings: Figure 1 shows a side elevation of a first embodiment, Figure 2 shows a side view of the counterbalancing module, Figures 3a and 3b show diagrammatically two positions of the counterbalancing components, Figure 4 is a section on 4-4 of Figure 2, Figure 5 is a side detail viewed in direction A of Figure 4, Figure 6 is a section on 6-6 of Figure 2, Figure 7 is a side detail viewed in direction B of Figure 6.

Figure 8 shows an alternative construction of counterbalancing module in side view, Figure 9 shows diagrammatically in plan view the position of the counterbalancing components in the arrangement of Figure 9.

Figure 10 shows a section through the counterbalance weight assembly of Figure 8, Figure 11 shows a side sectional view of the assembly of Figure 10, Figure 12 shows an embodiment in use.

Figure 13 shows a further construction of counterbalancing module in side view, Figure 14 shows a section through the counterbalance weight assembly A of Figure 13, Figure 15 shows a section on A-A of Figure 14, Figure 16 shows a section through the front load bearing end B of the module shown in Figure 13, Figure 17 shows a section on A-A of Figure 16, Figure 18 shows a section through the main assembly pivot C of the module of Figure 13, Figure 19 shows a section on A-A of Figure 18, Figure 20 shows a section through the rear reaction assembly D of Figure 13, and Figure 21 shows a section on B-B of Figure 20.

Referring firstly to Figure 1 of the drawings, a tripod support stand structure includes legs 1 which are braced by cross members 2 forming also treads on which a person may stand. The tripod structure includes both pivoting and fixed wheel units 3 preferably incorporating braking means. The structure has a central column 4 into which a telescoping mast 5 locates capable of being raised and lowered by means of a ratchet lever mechanism 6. The raising and lowering may be by means of a cord and windlass type of system. A counterbalancing module indicated generally as 7 is pivotally supported at the top of the mast 5 allowing 3600 rotation in the azimuth plane and up to 600 angular movement in the elevation plane.

The module 7 has a casing 8 which houses a movable counterweight balancing arrangement which is associated with an extensible arm 9 having a securing means 10 at an end for supporting load such as a power tool or a hedge cutter 11. Generally this arrangement is such that as the support arm 9 is moved outwardly, counterbalancing weights within casing 8 also move outwardly from the mast 5 in an opposite direction to maintain the system in near balance. Conversely, as the arm 9 is moved inwardly the weights move also inwardly relative to the mast 5 to thereby maintain balance.

A fixed support arm 12 serves to provide a guide for the moving arm 9 and also forms a support and guide for the counterbalance weight assembly.

Referring now to Figure 2 of the drawings, this shows the counterbalance arrangement in more detail with the casing 8 shown in broken lines.

The extensible arm 9 has adjacent the load bearing end, a fitment 13 to which a cord 14 is secured. The cord 14 extends to the rear end of casing 8 and passes around a pulley 15 mounted therein and further extends around a pulley 16 which is mounted on a carriage 17 to which the counterbalance weights 18 are secured. The cord has the other end secured at 19 to the casing 8.

The other end of the extensible arm 9 has a similar fitment 20 to which one end of a second cord 21 is secured. This cord extends through the casing 8 over guide pulleys 22 and 23 mounted on the counterbalance weight, around pulley 24 secured to a frame member attached to the other end of the casing 8 and thereafter around pulley 25 to return to an attachment point 26 on the frame member secured to the casing 8.

As may be seen more clearly from the diagrams of Figures 3a and 3b, as the extensible arm 9 is moved relative to the fixed guide part 12, the counterbalance weight carriage is caused to move along the fixed part 12 to substantially maintain the balance. Figure 3a shows the limit position with the extensible arm 9 fully extended and Figure 3b shows the limit position with the arm fully retracted.

Figures 4 and 5 show a detail of the central mast supporting arrangement wherein the mast 5 includes an attachment 50 with a pivot 51 about which the counterbalancing module is movable in a vertical plane.

Figures 6 and 7 show details of the counterbalance weight assembly comprising a carrier 60 positioned about the arm 12 and supported thereon by means of the guide rollers 22 and 23. Counterbalancing weights 61 and 62 are mounted to each side of the support 60. The counterbalance weights 61 and 62 are arranged to be readily detachable to enable them to be matched to the weight of various tools supported from the attachment 10 on arm 9.

In the further embodiments shown in Figures 8 to 11, an arrangement is provided wherein the required space to the rear of the assembly is reduced. This embodiment generally is similar to that previously described and more particularly referring to Figure 9, the extensible arm 9 with the load attachment point 10 is located within a frame member 90 by means of load bearing roller assemblies 91. The frame member 90 is pivoted to the upper end of the mast 5 generally at the point indicated by 92. The counterbalance weight carriage assembly 93 is positioned within the frame member 90 and includes rollers 94 which run along track members within a casing forming the frame member 90. The counterbalance carriage 93 includes weight assemblies 95 which are positioned to the outside of the frame member 90.A cord 96 is secured to the extending support member 9 at 97 and passes around pulley 98 attached to the body 90 and thereafter around pulley 99 attached to the counterbalance weight assembly with the other end of the cord secured to the frame member 90 at 100. A counteracting cord 101 is also secured to the extending member 9 at 102 and passes around pulley 103 attached to the frame member 90 and thereafter around pulley 104 attached to the counterbalance weight carriage 93 to be secured to the frame member 90 at 105. With this construction, as the extensible support 9 is moved outwardly, that is to the left as seen in the drawing, the carriage 93 is moved to the right to provide the necessary counterbalancing arrangement.It will be evident that as the support 9 is moved in the opposite direction, that is to the right, then the counterbalance weight assembly 93 will be moved to the left.

The securement points 100 and 105 may include adjusting or tensioning devices to maintain a tension in the cords and additionally to allow the counterbalance weight assembly 93 to be moved to provide the necessary position for balance.

Figure 12 of the drawings shows generally a construction of gantry apparatus using the embodiment of Figures 8 to 11, in this instance serving to support a hedge trimmer.

Figures 13 to 21 show a further embodiment wherein the load attachment point 10 is provided on the end of an extensible arm 9, positioned within a support frame member 200 pivotally connected at 201 with a support 202 secured to the upper end of the mast 5. The support 202 is carried by a tubular member 203 having a cross pin 204 which bears against a plastic plug 205 located in the top of mast 5. A support 202 is provided on each side of frame member 200 thus forming a yoke with a cross brace 206. At the load bearing end 10 the extensible arm 9 bears on a reaction roller 207 whereas the other end of arm 9 includes two rollers 208 which bear and run in tracks 209 on the inside of frame member 200. (See Figure 20).

The arm 9 may thus be drawn out of the frame member 200 from a most retractive position, as shown in Figures 13, 17 and 21, to a fully extended position in which the other end of the arm 9 is adjacent the pivot 201 as shown in Figure 19. In order to provide for appropriate counterbalancing of the assembly between the telescope to retracted position and the extended position, a counterbalance weight assembly is provided.

This counterbalance weight assembly shown generally as 210 moves from a position adjacent the pivot 201 as shown in Figure 13 to a position near the end of the frame member 200 remote from the extensible arm 9 as indicated generally by 210A. Referring more particularly to Figures 14 and 15, the counterbalance weight assembly comprises a generally U-shaped carrier member 211 including spigots 212 onto which weight members 213 may be located. The weight members are readily detachable so that by appropriate selection of the overall mass a load attached at 10 can be counterbalanced. The part 211 has a central support member 212 which carries rollers 213 each in turn bearing upon a runner rail 214 secured within the frame member 200. The underside of the frame member 200 has a longitudinal slot 215 to receive the part 212.

The counterbalance weight carriage assembly 211 (210) is moved by means of cords or cables 216 and 217 which are secured to posts 218 and 219 respectively.

These posts are rotatable and include adjuster means 220 and 221 respectively so that the cords can be suitable tensioned. The cord 216 extends around a pulley 222 positioned adjacent the pivot 201 and is secured to the end of the extensible arm 9 remote from the load bearing point 10. This securement point is shown as 223 in Figure 19. The other cord run 217 extends in an opposite direction to pass around a pulley 224 and similarly is secured at point 223.

With this arrangement, as the extensible arm 9 is moved telescopically within the frame member 200, the cords 216, 217 are moved by virtue of their attachment to arm 9 at 223 such that the counterbalance weight assembly 210 is moved an appropriate distance in an opposite direction, thereby to provide counterbalancing.

The arrangement using the adjusting means 220, 221, not only provides a suitable system for tensioning cords 216, 217 but also enables the positioning of the counterbalance weight assembly to be adjusted longitudinally of a frame member 200. The end of the extensible arm 9 may make provision for incorporating a removable compensation weight assembly 225 as shown in Figures 16 and 17. Conveniently the frame member 200 incorporates an end closure plate 226 with a plastic moulding 227 through which the extensible arm 9 passes.

This invention therefore broadly provides a supporting gantry for an appliance with an extensible supporting member able to move laterally and simultaneously displace counterbalance weight means in an opposed direction to relieve an operator of a substantial part of the weight of the appliance.

The apparatus can be easily dismantled for transit or storage, as:a) the counterweights are demountable for ease of handling, b) the top assembly module can be lifted off its spigot mounting, c) the legs of the tripod are hinged at the top and, after unpinning the crossbars, can be brought together to form a compact load.

Claims (16)

1. Gantry apparatus comprising a tower, a mast carried on the top of the tower, and a carrier pivotally mounted on the mast, the carrier comprising an elongate body with a support arm telescopically mounted thereon, a counterbalance assembly comprising a weighted carriage movable along the elongate body and a drive means coupling said support arm to said carriage whereby the carriage moves opposite to the direction of movement of the support arm.

2. Gantry apparatus according to Claim 1 wherein the tower is carried on ground engaging castor wheels.

3. Gantry apparatus according to Claim 1 or 2, wherein the mast is associated with a mechanism to raise or lower same relative to the tower.

4. Gantry apparatus according to any preceding claim wherein the carrier is mounted on the mast for pivotal movement in azimuth and elevation.

5. Gantry apparatus according to any preceding claim, wherein the tower includes cross-braces forming steps.

6. Gantry apparatus according to any preceding claim, wherein the elongate body is hollow, the support arm being slidable therein supported and guided by rollers.

7. Gantry apparatus according to any preceding claim wherein the carriage is coupled to the support arm by cabling or cording forming the drive means.

8. Gantry apparatus according to Claim 7, wherein the cabling or cording is disposed in two runs each being associated with a respective direction of movement of the carriage.

9. Gantry apparatus according to Claim 8, wherein pulleys are provided in spaced relationship within the elongate body, two cable runs passing around respective pulleys and secured adjacently at their one ends to the carriage and at their other ends to an end of the support arm.

10. Gantry apparatus according to Claim 9, substantially as described and shown in Figure 13 of the accompanying drawings.

11. Gantry apparatus according to Claim 8, wherein pulleys are provided on the body and carriage respectively, one cable run secured at one end to the front of the body passing around a carriage pulley and a front body pulley and secured at the other end to the rear end of the support arm, another cable run secured at one end to the rear of the body passing around a carriage pulley and rear body pulley and secured at the other end to the front end of the support arm, the carriage thereby moving at one half the displacement of the support arm.

12. Gantry apparatus according to Claim 11 substantially as described and shown in Figure 2 of the accompanying drawings.

13. Gantry apparatus according to any preceding claim wherein the body comprises a box-section with support and guide rollers for the arm, a part at least of the body having an elongate slot to accommodate a part of the carriage having wheels bearing on rails within the body.

14. Gantry apparatus according to any preceding claim, wherein the carriage has supporting members to receive weights.

15. A gantry apparatus as described herein and exemplified with reference to Figures 1 to 7 or Figures 8 to 11 or Figures 13 to 20 of the accompanying drawings.

16. A gantry apparatus according to any preceding claim, adapted and used to support a hand-tool or the like.