Slewing work machine with primary and secondary fuel tanks and detachable counterweight mount

Abstract

A work machine (1, see fig 1) such as an excavator comprises with a secondary fuel tank 70 mounted behind the primary fuel tank 60 in place of a counterweight (50), which is moved to the rear and mounted of the slewing upper frame (20). The first and second tanks are connected fluidically to each other via a fuel line 80, the fuel line including a non-return valve 81 so that fuel may only flow in one direction via gravity, responsive to differential fuel pressure. A second aspect of the invention is detachable (30, see fig. 20) part which is removed, and the counterweight replaced in the position of the secondary fuel tank to convert the machine back to a standard configuration. The rear end portion comprises a principal part (24, see fig. 9) included in a first counterweight mount (25) and a second counterweight mount (35 see fig. 21) where the counterweight may be mounted alternatively on the first or second mount. The lower frame of the work machine may comprise at least one pontoon, the work machine being floatable on water with said pontoon.

Description

Technical Field

[0001] This disclosure relates to work machines such as excavators that are equipped with primary and secondary fuel tanks for extended run time, for example when used for amphibious operation, and particularly where the slewing upper frame is adapted to accommodate the secondary fuel tank in front of the counterweight. Background

[0002] In this specification, a work machine means any machine that is arranged to manipulate a work tool to carry out work in the vicinity of the machine, including especially vehicular machines that can move over the worksite, e.g. on wheels or tracks.

[0003] Slewing work machines such as excavators have an upper frame pivotably mounted on a lower frame, with an arm extending forwardly from the upper frame to manipulate a bucket or other work tool at the distal end of the arm, and a counterweight at the rear end of the upper frame to counterbalance the arm.

[0004] In order to allow operation on boggy ground or shallow water, such machines may be mounted on buoyant pontoons or on a supporting raft. In such conditions it is often difficult to move the machine to a refuelling point, and so it is common to install a large, secondary fuel tank in order to provide extended run-time without refuelling. Typically the secondary fuel tank is installed in front of the counterweight.

[0005] In such arrangements it is necessary to adapt the upper frame or the counterweight to accommodate the secondary fuel tank, and to adapt the fuel supply system to supply fuel from both the primary and secondary fuel tanks to the engine.

[0006] US7681556 discloses an excavator having a slewing upper frame with a mounting member at the rear, which would normally support the counterweight. A secondary fuel tank is mounted on the mounting member, and the counterweight is mounted on an extended portion of the mounting member, to the rear of the secondary tank. A smaller, primary fuel tank is mounted forward of the secondary fuel tank. The primary and secondary fuel tanks are mounted at the same level on the upper frame, and a junction tank is arranged at a lower level to receive fuel from both the primary and secondary fuel tanks.

[0007] US10538179 discloses a work vehicle such as a ride-on mower having twin fuel tanks, each connected via a respective supply pipe to a junction that supplies the fuel pump. Each of the supply pipes has a check valve that opens responsive to the differential pressure generated by suction from the fuel pump and the level of fuel in the respective fuel tank. The arrangement ensures that fuel is drawn from the fuel tank with the higher level of fuel, and so equilibrates fuel level and weight distribution across the vehicle. Summary of the Disclosure

[0008] In accordance with the present disclosure there is provided a work machine for use with a work tool.

[0009] The work machine includes, in a normal use position: a lower frame, an upper frame, an arm, a counterweight, a primary fuel tank, and a secondary fuel tank.

[0010] The upper frame has a forward end portion, a rear end portion, and a mid-portion arranged between the forward end portion and the rear end portion, and is mounted on the lower frame, at the mid-portion, to slew about a pivot axis relative to the lower frame.

[0011] The arm is mounted on the upper frame and extends in use, forwardly from the upper frame, to support the work tool at a distal end of the arm. The counterweight is mounted on the rear end portion to face rearwardly from the upper frame, away from the arm.

[0012] The secondary fuel tank is mounted on the rear end portion, between the counterweight and the forward end portion, and the primary fuel tank is mounted on the upper frame between the secondary fuel tank and the forward end portion.

[0013] In a first aspect of the disclosure, the work machine further includes a fuel line, the fuel line including a non-retum valve having an inlet and an outlet and configured to open to allow flow through the non-return valve in a forward flow direction from the inlet to the outlet, and to close to prevent flow through the non-return valve in a reverse flow direction from the outlet to the inlet.

[0014] Each of the primary and secondary fuel tanks contains a fuel in use, and has a respective flow opening at a base of the respective fuel tank. The flow openings are arranged in fluid communication via the fuel line.

[0015] The flow opening of the primary fuel tank is arranged in fluid communication with the outlet of the non-retum valve so that, in use, a weight of the fuel contained in the primary fuel tank applies a first fuel pressure Fpl to the outlet of the non-retum valve. The flow opening of the secondary fuel tank is arranged in fluid communication with the inlet of the non-return valve so that, in use, a weight of the fuel contained in the secondary fuel tank applies a second fuel pressure Fp2 to the inlet of the non-return valve.

[0016] The fuel line is configured to allow the fuel to flow in the forward flow direction through the non-return valve, by gravity, from the secondary fuel tank into the primary fuel tank, responsive to a positive differential fuel pressure Fp2-Fpl.

[0017] In a second aspect of the disclosure, the rear end portion includes a principal part, and a detachable part.

[0018] The principal part includes a first counterweight mount.

[0019] The detachable part is detachably connected to the principal part and includes a second counterweight mount.

[0020] The first counterweight mount is arranged between the second counterweight mount and the mid-portion. The secondary fuel tank is mounted detachably above the first counterweight mount, and the counterweight is mounted detachably on the second counterweight mount. The counterweight is mountable alternatively on the first counterweight mount when the secondary fuel tank and the detachable part are detached from the principal part. Brief Description of the Drawings

[0021] Further features and advantages will be appreciated from the illustrative embodiment that will now be described, purely by way of example and without limitation to the scope of the claims, and with reference to the accompanying drawings, in which:

[0022] Figs. 1 and 2 show a work machine configured as an excavator with a single (primary) fuel tank, standard tracks, and an arm in a standard configuration, wherein Fig.2 shows the upper frame slewed through 90° from the position of Fig. 1.

[0023] Figs. 3 and 4 show the same work machine in the same positions as Figs. 1 and 2, respectively, and converted for amphibious operation in accordance with a first embodiment of the disclosure, wherein a detachable part is added to the upper frame to support the counterweight immediately behind an additional (secondary) fuel tank, and with the standard tracks replaced by pontoons.

[0024] Fig. 5 shows the same work machine in the same position as Fig. 3, with the arm extended.

[0025] Fig. 6 shows the same work machine in the same position as Fig. 5, but fitted with a replacement arm having an extended reach configuration.

[0026] Figs. 7 and 8 illustrate the rocking motion of the work machine of Fig. 6 when operating in shallow water and supported buoyantly on the pontoons.

[0027] Figs. 9-12 show the upper frame of the work machine of Figs. 1-2, without the detachable part, wherein: Fig. 9 is a top view; Fig. 10 is a bottom view; Fig. 11 is a side view; and Fig. 12 is a rear end view.

[0028] Figs. 13-15 show the counterweight of the work machine of Figs. 1 -8, wherein: Fig. 13 is a rear view; Fig. 14 is a side view; and Fig. 15 is a top view.

[0029] Figs. 16-19 correspond to Figs. 9 - 12, respectively, showing the counterweight mounted on the first counterweight mount of the upper frame without the detachable part.

[0030] Figs. 20 - 24 show the detachable part of the upper frame, wherein: Fig. 20 is a top view; Fig. 21 is a bottom view; Fig. 22 is an end view; Fig. 23 is a rear view also showing some of the fixings; and Fig. 24 is a front view, which is to say, it shows the forwardly facing surfaces that abut the upper frame in use.

[0031] Fig. 25 is a section at XXV - XXV of Fig. 21.

[0032] Fig. 26 is a section at XXVI - XXVI of Fig. 20.

[0033] Fig. 27 is a section at XXVII - XXVII of Fig. 20.

[0034] Fig. 28 shows the section of Fig. 27 in the installed position of Figs. 33 - 37, with the second mounting bar received in the second recess.

[0035] Figs. 29 - 32 show the secondary fuel tank, wherein: Fig. 29 is a rear view; Fig. 30 is an end view; Fig. 31 is a top view; and Fig. 32 is a bottom view.

[0036] Figs. 33 - 37 show the detachable part of Figs. 20 - 24 installed on the upper frame of Figs. 9 - 12, wherein: Fig. 33 is a top view; Fig. 34 is a side view; Fig. 35 is a rear end view; Fig. 36 is a bottom view before fitting the stiffener plates; and Fig. 37 is a bottom view after fitting the stiffener plates.

[0037] Figs. 38, 39 and 40 correspond to Figs. 33, 34 and 35, respectively, and show the counterweight mounted on the second counterweight mount of the detachable part.

[0038] Figs. 41-44 show the assembly of Figs. 38-40 with the secondary fuel tank mounted on the platforms of the detachable part, in front of the counterweight and above the first counterweight mount, wherein: Fig. 41 is a top view; Fig. 42 is a bottom view; Fig. 43 is a side view; and Fig. 44 is a rear end view.

[0039] Fig. 45 is a schematic view of the fuel supply arrangement of the work machine including the primary and secondary fuel tanks connected together by a fuel line with a non-return valve.

[0040] Figs. 46 - 49 illustrate how the non-retum valve is arranged to replenish the primary fuel tank from the secondary fuel tank as the work machine rocks back and forth as illustrated in Figs. 7 and 8.

[0041] Reference numerals and characters that appear in more than one of the figures indicate the same or corresponding elements in each of them. Detailed Description

[0042] Figs. 1 and 2 show a work machine 1 for use with a work tool 2. The illustrated work machine is configured as an excavator having a lower frame 10 with standard (i.e. conventional) tracks 4, and an upper frame 20 that supports an engine (e.g. a diesel engine) 3, a primary fuel tank 60 containing fuel F (e.g. diesel fuel) for the engine 3, an operator cab 5, a counterweight 50, and an arm 40'.

[0043] When the machine is standing in a normal use position on a horizontal ground surface as shown, the upper frame 20 is aligned with a horizontal plane Ph. The upper frame 20 also supports the power systems 6 including the hydraulic pumps and transmission that provide power to the tracks 4 that move the machine over the ground surface, and to the hydraulic actuators 7 that control the motion of the arm 40', responsive to operator control signals from the controls located in the cab 5.

[0044] The upper frame 20 has a forward end portion 21, a rear end portion 23, and a mid-portion 22 arranged between the forward end portion 21 and the rear end portion 23. The upper frame 20 is mounted on the lower frame 10 at the mid-portion 22 to slew about a vertical pivot axis Xp relative to the lower frame 10.

[0045] In this specification, the forward direction FD means the direction of the upper frame from the rear end portion towards the forward end portion, and the rearward direction RD is the direction opposite to the forward direction. The terms forwardly and rearwardly refer to the forward and rearward directions, respectively. (It will be understood that this definition does not apply to the forward and reverse flow directions through the non-return valve 81, further discussed below.)

[0046] The arm 40' is mounted on the upper frame 20 to extend forwardly from the upper frame 20, to support the work tool 2 at a distal end 43 of the arm 40'. In the illustrated example, the work tool is a bucket which is operable to scoop and dump loose material. The counterweight 50 is mounted on the rear end portion 23 to face rearwardly from the upper frame 20, away from the arm 40', to counterbalance the weight of the arm 40' and the loaded work tool 2.

[0047] As illustrated, the arm 40' may include a boom 41' and a stick 42' pivotably connected together in series relation. Note that the stick 42' is often referred to as the arm; however, in this specification, the term arm is used to refer to the entire assembly including the boom 41' and the stick 42'.

[0048] Figs. 9-12 show the upper frame 20 with the outer panelling removed. The pivot axis Xp is the central vertical axis of an annular mount 90 for the slewing ring bearing (not shown) that connects together the upper and lower frames 20, 10. The mount 91 defines the pivot axis for the proximal end of the boom 41, and the mounts 92 define the pivot axes for the boom actuators 7.

[0049] As shown in Figs. 9 - 12, the permanent, fixed part of the rear end portion 23 of the upper frame is defined herein as the principal part 24. The principal part 24 includes a first counterweight mount 25. As illustrated, the first counterweight mount 25 may include a pair of first mounting bars 26 spaced apart in parallel relation and defining opposite sides 27' of a first recess 27 which opens rearwardly of the principal part 24.

[0050] The counterweight 50 may be a solid block, e.g. of cast iron or cementitious material, as shown in Figs. 13 - 15.

[0051] As shown in Figs. 16 - 19, when the secondary fuel tank 70 and the detachable part 30 (further described below) are detached from the principal part 24, the counterweight 50 is mountable on the first counterweight mount 25 using fixings (not shown) via fixing holes 93 as known in the art. This defines the standard, compact configuration of the excavator for normal terrestrial operation as shown in Figs. 1 and 2.

[0052] Figs. 3 and 4 illustrate how the work machine is adapted to include a secondary fuel tank 70 to provide extended run time between refuellings, for example, for amphibious operation.

[0053] For amphibious operation the lower frame 10 may include at least one pontoon 11 so that the work machine 1 is floatable on water on the at least one pontoon 11. As illustrated, the standard tracks 4 may be replaced by a pair of amphibious tracks 12 that travel around a pair of pontoons 11. This enables the machine to move over soft ground covered by shallow water.

[0054] As shown in Fig. 5, in the standard configuration of the arm 40', the boom 41' and stick 42' extend to a maximum distance DI from the upper frame 20. Fig. 6 shows how at least one component of the arm 40' can be detached and interchanged with a corresponding, alternative component to define an alternative, extended reach configuration of the arm 40 with a greater maximum distance D2 that makes it easier to excavate below the waterline in amphibious operations. In the illustrated embodiment, both the boom 41' and the stick 42' are replaced by longer equivalents 41, 42. The machine 1 can be converted back to the standard configuration by detaching the at least one component 41, 42 (or the entire arm 40) and replacing it with the standard length component 41', 42' or arm 40'.

[0055] Figs. 7 and 8 show the machine 1 in the extended reach configuration in operation in shallow water. As the arm 40 extends and retracts, the centre of gravity shifts along the forward-rearward axis of the upper frame, so that the machine rocks slightly forward and backward as shown by the arrow.

[0056] As shown in Figs. 29 - 32, the secondary fuel tank 70 may be relatively wider and taller compared with its forward-rearward dimension, with a form factor similar to the counterweight 50, so that it can be mounted in use on the rear end portion 23 of the upper frame 20, between the counterweight 50 and the forward end portion 21, with the primary fuel tank 60 being mounted on the upper frame 20 between the secondary fuel tank 70 and the forward end portion 21.

[0057] A flow opening 71 is arranged at the base 72 of the secondary tank 70, through which the fuel F is drawn off to the engine 3. The flow opening 71 may communicate with a fuel outlet connector 73 as shown. Drain connectors 74 may be arranged for maintenance, e g. to drain off any water accumulating at the base of the tank. Mounting brackets 77 are arranged to support the base 72 of the tank. The tank may include internal stiffeners and baffle plates (not shown) which transfer mechanical forces to the mounting brackets.

[0058] In the illustrated embodiment, the base 72 is at the same level across the width of the tank.

[0059] Alternatively, as illustrated in broken lines in Fig. 29, the base 72 may be locally lowered to define a central well 75, with the flow opening 71 being arranged in the central well 75. In the installed position of the secondary fuel tank 70, the central well 75 is received in a central recess 39 of the detachable part 39 as illustrated in broken lines in Fig. 44 and further described below. This further helps the secondary tank 70 to drain completely.

[0060] The flow opening 71 may be an aperture formed in the base 72 or the central well 75, or an opening into a pipe that terminates at the base 72 or in the central well 75.

[0061] Referring now to Figs. 33 - 37, in the amphibious configuration as shown in Figs. 3 - 8 the rear end portion 23 of the upper frame 20 includes a detachable part 30 which includes a second counterweight mount 35.

[0062] The detachable part 30 may include a main part defining the second counterweight mount 35, and a pair of stiffener plates 34 which are fixed between the main part and the principal part 24 of the upper frame 20 to strengthen the connection.

[0063] The detachable part 30 is detachably connected to the principal part 24, e.g. via fixings 94 (Fig. 23) that engage in fixing holes 93, so that the first counterweight mount 25 is arranged between the second counterweight mount 35 and the mid-portion 22 of the upper frame 20.

[0064] The secondary fuel tank 70 is mounted detachably above the first counterweight mount 25, e.g. by fixings (not shown) which may engage the mounting brackets 77 at the base of the tank via fixing holes 93.

[0065] As shown in Figs. 38 - 40, the counterweight 50 is mounted detachably on the second counterweight mount 35, e.g. via fixings (not shown) and fixing holes 93.

[0066] Referring also to Figs. 20 - 28, the second counterweight mount 35 may include a pair of second mounting bars 36 spaced apart in parallel relation. In the installed position as shown in Figs. 33 - 37, each of the second mounting bars 36 extends rearwardly from the upper frame 20 in collinear relation with a respective one of the first mounting bars 26. Advantageously, this allows the counterweight 50 to be mounted on either of the first or second counterweight mount 25, 35 without needing to adapt the fixing holes or other mounting features of the counterweight 50.

[0067] The respective upper surfaces of the first and second mounting bars 26, 36 may lie in a common horizontal plane Ph when the machine 1 is standing on a horizontal ground surface. Advantageously, this allows the counterweight to be mounted at the same height on either of the first or second counterweight mount 25, 35, so that the counterweight 50 does not need to be adapted to maintain the designed height of the machine.

[0068] The detachable part 30 may define a pair of second recesses 28, with each of the second mounting bars 36 being received in a respective one of the second recesses 28 in the installed position. This provides a secure connection with surfaces that abut in multiple directions to transfer moment and linear forces between the detachable part 30 and the principal part 24.

[0069] The detachable part 30 may include a central portion 37 that extends forwardly in the installed position, into the first recess 27 between the first mounting bars 26, which further stiffens the connection.

[0070] The fuel line 80 may extend through a fuel line aperture 31 of the detachable part.

[0071] The detachable part 30 may include a pair of platforms 38. In the installed position, each platform 38 extends laterally from a respective one of the first mounting bars 26, away from the first recess 27. The platforms 38 provide a stable base for the secondary fuel tank 70 to minimise stresses in the walls of the tank.

[0072] As shown in Figs. 41 - 44, the secondary fuel tank 70 is mounted detachably on the platforms 38 above the first counterweight mount 25, immediately forward of the counterweight 50.

[0073] In the installed position as shown, the base 72 of the secondary fuel tank 70 (or, if a central well 75 is provided, the main portion of the base 72 outside the central well) may be raised slightly relative to the base 62 of the primary fuel tank 60. This helps the secondary fuel tank 70 to drain completely.

[0074] The central portion 37 may define a central recess 39 located inbetween the platforms 38, which receives the central well 75 of the secondary fuel tank 70 as shown in broken lines in Fig. 44. A web 33 may extend across the central recess 39 to further stiffen the assembly. A maintenance aperture 32 may be formed in the web 33 to provide access to the flow outlet connector 73 and drain connectors 74.

[0075] The secondary fuel tank 70 may have a larger capacity than the primary fuel tank 60. For example, the primary fuel tank 60 may contain about 3501 - 4501, while the secondary fuel tank 70 contains about 7001 - 8001.

[0076] The machine 1 can be converted back to the standard, more compact configuration by detaching the secondary fuel tank 70 and counterweight 50, and then removing the detachable part 30 of the upper frame before re-mounting the counterweight 50 on the first counterweight mount 25. The upper frame 20 is shorter in the compact configuration than in the amphibious configuration by the length of the second mounting bars 36, which may be for example about 400mm. [0077| Fuel supply

[0078] Referring now to the schematic view of Fig. 45, each of the primary and secondary fuel tanks 60, 70 contains the same fuel F, e.g. diesel fuel, which is supplied to the tank via a filler inlet 66, 76 at the top of the tank. The primary fuel tank 60 has a flow opening 61 at the base 62 of the tank, in a similar position to the flow opening 71 of the secondary fuel tank 70, through which the fuel F is drawn off to the engine 3. The flow opening 61 may be an aperture formed in the base 62 of the tank, or an opening of a pipe that terminates at the base 62. The flow opening 61 may communicate with a fuel outlet connector 63 as shown. The filler inlets 66, 76 may be arranged to admit air into the respective fuel tanks 60, 70 so as to allow the fuel F to flow by gravity out of the flow openings 61,71.

[0079] The flow openings 61, 71 of the primary and secondary fuel tanks 60, 70 are arranged in fluid communication via a fuel line 80 (which is to say, a flowpath, e.g. a pipe) which includes a non-return valve 81 having an inlet 82 and an outlet 83. The non-return valve 81 may be mounted on or proximate the fuel outlet connector 63 of the primary tank 60, as illustrated, or at another position in the fuel line 80 in-between the two flow openings 61,71.

[0080] The non-return valve 81 is configured to open to allow flow through the non-return valve 81 in a forward flow direction from the inlet 82 to the outlet 83, and to close to prevent flow through the non-retum valve 81 in a reverse flow direction from the outlet 83 to the inlet 82.

[0081] (Note that the forward and reverse flow directions relate only to the direction of flow through the valve 81 with respect to its inlet and outlet. Since the body of the valve 81 can be oriented physically in any desired direction, the forward and reverse flow directions should not be confused with the forwardrearward axial directions of the upper frame 20 and the rocking motion of the machine.)

[0082] The flow opening 61 of the primary fuel tank 60 is arranged in fluid communication with the outlet 83 of the non-return valve 81 so that, in use, a weight of the fuel F contained in the primary fuel tank 60 applies a first static fuel pressure Fpl to the outlet 83 of the non-retum valve 81.

[0083] The flow opening 71 of the secondary fuel tank 70 is arranged in fluid communication with the inlet 82 of the non-return valve 81 so that, in use, a weight of the fuel F contained in the secondary fuel tank 70 applies a second static fuel pressure Fp2 to the inlet 82 of the non-retum valve 81.

[0084] A fuel pump 84 may be arranged in fluid communication with the outlet 83 of the non-return valve 81 via a branch 86 of the fuel line to draw fuel from the primary fuel tank 60 via the flow opening 61 of the primary fuel tank 60. The fuel F is supplied to the engine 3, e.g. via a fuel filter 85. The fuel pump 84 and fuel filter 85 may be arranged in any convenient position, at, above or below the level of the fuel line 80.

[0085] Each flow opening 61,71 may be in direct and uninterrupted fluid communication with the non-return valve 81 via the fuel line 80, in the sense that the fuel F can flow freely by gravity from the secondary fuel tank 70 via the fuel line 80 to the non-retum valve 81, and in both directions into the primary fuel tank 60 from the non-retum valve 81 via the fuel line 80, and out of the primary fuel tank 60 to the non-return valve 81 via the the fuel line 80. The fuel line 80 may define a flowpath that opens only through the flow openings 61,71 and through the branch 86 of the fuel line that leads to the engine 3, e.g. via the fuel pump 84.

[0086] The fuel line 80 is configured to allow the fuel F to flow in the forward flow direction through the non-return valve 81, by gravity, from the secondary fuel tank 70 into the primary fuel tank 60, responsive to a positive differential fuel pressure Fp2 - Fpl.

[0087] It will be understood that when the differential fuel pressure is defined as (Fp2 - Fpl), that differential fuel pressure will be positive when Fp2 >Fpl, and negative when Fp2 <Fpl.

[0088] The differential fuel pressure will fluctuate with the attitude of the machine in the forward-rearward direction about its centre of gravity which lies around the position of the pivot axis Xp, and so will be influenced by the rocking motion of the machine 1 in the forward - rearward direction FD - RD of the upper frame 20, which may be particularly apparent in amphibious operations as illustrated in Figs. 7 and 8.

[0089] Figs. 46 - 49 illustrate the operating principle.

[0090] In operation, the machine 1 will rarely stand on level ground, and so the level of the fuel F in the secondary tank 70 will often fall below the level in the primary tank 60. As shown in Fig. 46, movement of the arm 40 in the rearward direction RD (Fig. 8) will move the centre of gravity rearward with respect to the upper frame 20, slightly raising the primary tank 60 relative to the secondary tank 70.

[0091] If the level of the fuel F in the primary tank 60 rises above that of the secondary fuel tank 70 as shown, a negative differential fuel pressure Fp2 <Fpl arises which causes the non-retum valve 81 to close, so that fuel F does not flow from the primary fuel tank 60 to the secondary fuel tank 70.

[0092] As the arm 40 extends forward (Fig. 7), the centre of gravity of the machine 1 moves foward, raising the secondary tank 70 relative to the primary tank 60.

[0093] As shown in Fig. 47, a level of fuel F in the secondary tank 70 higher than that in the primary tank 60 generates a positive differential fuel pressure Fp2 >Fpl, causing the non-retum valve 81 to open so that the fuel F flows by gravity from the secondary fuel tank 70, via the fuel line 80 and non-retum valve 80 and into the primary fuel tank 60.

[0094] As shown in Fig. 48, if the machine were to remain in this position for long enough, the level of fuel F would eventually equalise in both tanks 60, 70 causing the differential fuel pressure to reach equilibrium (Fp2 = Fpl).

[0095] As shown in Fig. 49, if the machine 1 then were to return to horizontal from the position of Fig. 48, the resulting fuel level in the primary fuel tank 60 would rise above that in the secondary fuel tank 70, again causing a negative differential fuel pressure Fp2 <Fpl which causes the non-retum valve 81 to close, so that fuel F does not flow back from the primary fuel tank 60 to the secondary fuel tank 70.

[0096] It will be appreciated that a repeated rocking motion of the machine in the forward-rearward direction FD - RD thus causes a slight, incremental pumping action that transfers fuel progressively from the secondary fuel tank 70 to the primary fuel tank 60.

[0097] The pumping action will cease once the fuel level in the primary tank 60 rises above that in the seondary tank 70 by a sufficient amount to maintain a negative differential fuel pressure Fp2 <Fpl across the valve 81.

[0098] As the fuel level drops in the secondary fuel tank 70, the rocking motion of the machine 1 may be slightly accentuated due to the reduced mass of the secondary fuel tank 70. The repeated pumping action progressively empties the secondary fuel tank 70 to replenish the primary fuel tank 60, so that the machine can continue to run until the secondary fuel tank 70 is substantially empty.

[0099] The non-return valve 81 may be configured to open responsive to any positive differential fuel pressure Fp2 - Fpl greater than 0 kPa.

[00100] The filler inlet 66, 76 of each fuel tank may be closed by a cap. The cap of the primary fuel tank 60, or of both primary and secondary fuel tanks 60, 70, may be arranged to retain positive pressure in the respective fuel tank, so as to prevent the fuel tank from overflowing via its filler inlet in case the machine should be working at a severe angle. The cap (not shown) may include a check valve to allow air to flow into the respective filler inlet 66, 76 as the fuel level falls in the tank. In such arrangements, the raised fuel level in the primary fuel tank 60 compared with that of the secondary fuel tank 70, generated by the rocking motion of the machine, will be somewhat less than illustrated, since it will be limited by the rise in pressure in the primary fuel tank due to slight compression of the gas in the headspace as fuel flows forwards through the nonreturn valve 81. The functional principle however remains the same.

[00101] As illustrated, the fuel line 80 may be arranged so as to be no higher than an upper one of the flow openings 61, 71 of the primary and secondary fuel tanks 60, 70 when the upper frame 20 is aligned with a horizontal plane Ph, which ensures complete filling of the fuel line 80 and so assists the pumping action. Industrial Applicability

[00102] With reference to the first aspect of the disclosure, since the object of a secondary fuel tank is to increase the run time of the machine without refuelling, it is desirable to ensure that the secondary fuel tank can be fully emptied in use.

[00103] By arranging the secondary fuel tank and counterweight to the rear of the primary fuel tank, and at the opposite end of the length axis of the upper frame from the work tool, the novel fuel supply arrangement uses the typical fore-and-aft rocking motion of a generally conventional slewing machine to generate a repeated pumping action that transfers fuel F from the secondary fuel tank 70 to the primary fuel tank 60. Even when both fuel tanks 60, 70 are mounted at approximately the same height on the upper frame 20 to keep the centre of gravity low, the novel arrangement makes it possible to draw off the entire contents of the secondary fuel tank 70 without the need for any additional pump or intermediate tank.

[00104] In accordance with the second aspect of the disclosure, the detachable part 30 can be used to adapt the slewing upper frame 20 of an otherwise conventional excavator or other work machine 1 to mount a secondary fuel tank 70 in the position conventionally occupied by the counterweight 50, with the counterweight 50 being supported by the detachable part 30 to the rear of the secondary fuel tank 70. The detachable part 30 can be fitted to an otherwise conventional upper frame 20, so that by removing the detachable part 30, the machine 1 can be converted back to a more compact, standard configuration suitable for terrestrial operation on standard tracks 4.

[00105] The secondary fuel tank 70 is particularly useful for amphibious operations which preclude frequent refuelling. An amphibious machine will often be mounted on buoyant pontoons 11, and often the work tool 2 will be mounted on an arm 40 with extended reach so that it can excavate below the waterline. As illustrated in Figs. 7 and 8, both adaptations will tend to augment the typical fore-to-aft rocking motion of the machine 1 as the work tool 2 is extended and retracted from the upper frame 20.

[00106] Advantageously therefore, although either of the first and second aspects of the disclosure can be applied independently of the other, both aspects may be be used in combination to provide a slewing work machine 1 that is more readily and simply adaptable between terrestrial and amphibious configurations.

[00107] In summary, a work machine 1 such as an excavator is converted, e.g. for amphibious operation, with a secondary fuel tank 70 mounted behind the primary fuel tank 60 in place of the counterweight 50, which is moved to the rear and mounted on a detachable part 30 of the slewing upper frame 20. The detachable part 30 is removed and the counterweight 50 replaced in the position of the secondary fuel tank 70 to convert the machine 1 back to a standard configuration. In another aspect, the secondary fuel tank 70 is arranged supply fuel to the primary fuel tank 60 by gravity flow through a fuel line 80 having a non-retum valve 81 that opens and closes responsive to a differential fuel pressure Fp2 - Fpl as the machine 1 rocks fowards and backwards in use.

[00108] In alternative embodiments, the work machine need not be configured as an excavator; for example, it could be configured for dredging or reed cutting or piling or any other terrestrial or amphibious operation. For amphibious operations the machine may be mounted on standard tracks and operated on a barge.

[00109] In alternative embodiments, the machine might be controlled remotely rather than from an on-board operator cab. Other power transmission arrangements are possible.

[00110] Many further adaptations are possible within the scope of the claims.

[00111] In the claims, reference numerals and characters are provided in parentheses, purely for ease of reference, and should not be construed as limiting features. LIST OF ELEMENTS TITLE: SLEWING WORK MACHINE WITH PRIMARY AND SECONDARY FUEL TANKS AND DETACHABLE COUNTERWEIGHT MOUNT FILE: 23-1222 GB01 1 Work machine 2 Work tool 3 Engine 4 Standard track 5 Operator cab 6 Power systems 7 Hydraulic actuators 10 Lower frame 11 Pontoon 12 Amphibious track 20 Upper frame 21 Forward end portion of upper frame 22 Mid-portion of upper frame 23 Rear end portion of upper frame 24 Principal part of rear end portion 25 First counterweight mount 26 First mounting bar 27 First recess 27' Side of first recess 28 Second recess 30 Detachable part of rear end portion 31 Fuel line aperture of detachable part 32 Maintenance aperture of detachable part Web of detachable part Stiffener plate of detachable part Second counterweight mount Second mounting bar Central portion of detachable part Platform of detachable part Central recess of detachable part Arm (extended reach configuration) Arm (standard configuration) Boom (extended reach configuration) Boom (standard configuration) Stick (extended reach configuration) Stick (standard configuration) Distal end of arm Counterweight Primary fuel tank Flow opening of primary fuel tank Base of primary fuel tank Fuel outlet connector of primary fuel tank Filler inlet of primary fuel tank Secondary fuel tank Flow opening of secondary fuel tank Base of secondary fuel tank Fuel outlet connector of secondary fuel tank Drain connector of secondary fuel tank Central well of secondary fuel tank Filler inlet of secondary fuel tank Mounting bracket of secondary fuel tank Fuel line Non-retum valve 82 Inlet of non-return valve 83 Outlet of non-return valve 84 Fuel pump 85 Fuel filter 86 Fuel line branch to engine 90 Slewing ring bearing mount 91 Mount for boom 92 Mount for boom actuator 93 Fixing hole 94 Fixing DI Maximum distance (reach) in extended reach configuration D2 Maximum distance (reach) in standard configuration F Fuel F FD Forward direction Fpl First fuel pressure Fp2 Second fuel pressure Fp2 - Fpl Differential fuel pressure Ph Horizontal plane RD Rearward direction Xp Pivot axis

Claims

What is claimed is:

1. A work machine (1) for use with a work tool (2); the work machine (1) including, in a normal use position:a lower frame (10),an upper frame (20),an arm (40),a counterweight (50),a primary fuel tank (60), anda secondary fuel tank (70);the upper frame (20) having a forward end portion (21), a rear end portion (23), and a mid-portion (22) arranged between the forward end portion (21) and the rear end portion (23);the upper frame (20) being mounted on the lower frame (10), at the midportion (22), to slew about a pivot axis (Xp) relative to the lower frame (10);the arm (40) being mounted on the upper frame (20) and extending in use, forwardly from the upper frame (20), to support the work tool (2) at a distal end (43) of the arm (40);the counterweight (50) being mounted on the rear end portion (23) to face rearwardly from the upper frame (20), away from the arm (40);the secondary fuel tank (70) being mounted on the rear end portion (23), between the counterweight (50) and the forward end portion (21);the primary- fuel tank (60 being mounted on the upper frame (20) between the secondary fuel tank (70) and the forward end portion (21);and further including a fuel line (80), the fuel line (80) including a nonreturn valve (81) having an inlet (82) and an outlet (83) and configured:to open to allow flow through the non-return valve (81) in a forward flow direction from the inlet (82) to the outlet (83), andto close to prevent flow through the non-retum valve (81) in a reverse flow direction from the outlet (83) to the inlet (82);each of the primary and secondary fuel tanks (60, 70) containing a fuel (F) in use, and having a respective flow opening (61, 71) at a base (62, 72) of the respective fuel tank (60, 70);the flow openings (61, 71) of the primary and secondary fuel tanks (60, 70) being arranged in fluid communication via the fuel line (80);the flow opening (61) of the primary fuel tank (60) being arranged in fluid communication with the outlet (83) of the non-return valve (81) so that, in use, a weight of the fuel (F) contained in the primary fuel tank (60) applies a first fuel pressure Fpl to the outlet (83) of the non-retum valve (81);the flow opening (71) of the secondary fuel tank (70) being arranged in fluid communication with the inlet (82) of the non-retum valve (81) so that, in use, a weight of the fuel (F) contained in the secondary fuel tank (70) applies a second fuel pressure Fp2 to the inlet (82) of the non-return valve (81);the fuel line (80) being configured to allow the fuel (F) to flow in the forward flow direction through the non-return valve (81), by gravity, from the secondary fuel tank (70) into the primary fuel tank (60), responsive to a positive differential fuel pressure Fp2 - Fpl.

2. A work machine (1) according to claim 1, wherein the non-return valve (81) is configured to open responsive to any positive differential fuel pressure Fp2 - Fpl greater than 0 kPa.

3. A work machine (1) according to claim 1, wherein, when the upper frame (20) is aligned with a horizontal plane (Ph), the fuel line (80) is no higher than an upper one of the flow openings (61, 71) of the primary and secondary fuel tanks (60, 70).

4. A work machine (1) according to claim 1, wherein the lower frame (10) includes at least one pontoon (11), the work machine (1) being floatable on water on the at least one pontoon (11).

5. A work machine (1) according to claim 1 or claim 4, wherein the rear end portion (23) includes:a principal part (24), anda detachable part (30);the principal part (24) including a first counterweight mount (25);the detachable part (30) being detachably connected to the principal part (24) and including a second counterweight mount (35);the first counterweight mount (25) being arranged between the second counterweight mount (35) and the mid-portion (22);the secondary fuel tank (70) being mounted detachably above the first counterweight mount (25);the counterweight (50) being mounted detachably on the second counterweight mount (35);the counterweight (50) being mountable alternatively on the first counterweight mount (25) when the secondary fuel tank (70) and the detachable part (30) are detached from the principal part (24).

6. A work machine (1) according to claim 5, wherein a central portion (37) of the detachable part (30) defines a central recess (39), and the base (72) of the secondary fuel tank (70) defines a central well (75); the flow opening (71) of the secondary fuel tank (70) being arranged in the central well (75); the central well (75) being received in the central recess (39).

7. A work machine (1) according to claim 5, wherein the arm (40) includes a boom (41) and a stick (42) pivotably connected together in series relation to extend to a maximum distance (DI) from the upper frame (20);the arm (40) including at least one component (41, 42) defining an extended reach configuration of the arm (40);the at least one component (41, 42) of the arm (40) being detachable and interchangeable with a corresponding alternative at least one component (41', 42') to define an alternative, standard configuration of the arm (40');the maximum distance (DI, D2) being greater in the extended reach configuration than in the standard configuration.

8. A work machine (1) for use with a work tool (2); the work machine (1) including, in a normal use position:a lower frame (10),an upper frame (20),an arm (40),a counterweight (50),a primary fuel tank (60), anda secondary fuel tank (70);the upper frame (20) having a forward end portion (21), a rear end portion (23), and a mid-portion (22) arranged between the forward end portion (21) and the rear end portion (23);the upper frame (20) being mounted on the lower frame (10), at the midportion (22), to slew about a pivot axis (Xp) relative to the lower frame (10);the arm (40) being mounted on the upper frame (20) and extending in use, forwardly from the upper frame (20), to support the work tool (2) at a distal end (43) of the arm (40);the counterweight (50) being mounted on the rear end portion (23) to face rearwardly from the upper frame (20), away from the arm (40);the secondary fuel tank (70) being mounted on the rear end portion (23), between the counterweight (50) and the forward end portion (21);the primary fuel tank (60) being mounted on the upper frame (20) between the secondary fuel tank (70) and the forward end portion (21);wherein the rear end portion (23) includes:a principal part (24), anda detachable part (30);the principal part (24) including a first counterweight mount (25);the detachable part (30) being detachably connected to the principal part (24) and including a second counterweight mount (35);the first counterweight mount (25) being arranged between the second counterweight mount (35) and the mid-portion (22);the secondary fuel tank (70) being mounted detachably above the first counterweight mount (25);the counterweight (50) being mounted detachably on the second counterweight mount (35);the counterweight (50) being mountable alternatively on the first counterweight mount (25) when the secondary fuel tank (70) and the detachable part (30) are detached from the principal part (24).

9. A work machine (1) according to claim 8, wherein the first counterweight mount (25) includes a pair of first mounting bars (26) spaced apart in parallel relation and defining opposite sides (27') of a first recess (27), the first recess (27) opening rearwardly of the principal part (24); andthe second counterweight mount (35) includes a pair of second mounting bars (36) spaced apart in parallel relation, each of the second mounting bars (36) extending rearwardly in collinear relation with a respective one of the first mounting bars (26).

10. A work machine (1) according to claim 9, wherein the detachable part 30 includes a pair of second recesses 28, and each of the second mounting bars 36 is received in a respective one of the second recesses 28.

11. A work machine (1) according to claim 9, wherein the detachable part (30) includes a central portion (37) extending forwardly into the first recess (27) between the first mounting bars (26).

12. A work machine (1) according to claim 11, wherein the central portion (37) defines a central recess (39), and a base (72) of the secondary fuel tank (70) defines a central well (75) having a flow opening (71), the central well (75) being received in the central recess (39).

13. A work machine (1) according to claim 9, wherein the detachable part (30) includes a pair of platforms (38), each platform (38) extending laterally from a respective one of the first mounting bars (26), away from the first recess (27); the secondary fuel tank (70) being mounted detachably on the platforms (38).

14. A work machine (1) according to claim 8, wherein the lower frame (10) includes at least one pontoon (11), the work machine (1) being floatable on water on the at least one pontoon (11).

15. A work machine (1) according to claim 8, wherein the arm (40) includes a boom (41) and a stick (42) pivotably connected together in series relation to extend to a maximum distance (DI) from the upper frame (20);the arm (40) including at least one component (41, 42) defining an extended reach configuration of the arm (40);the at least one component (41, 42) of the arm (40) being detachable and interchangeable with a corresponding alternative at least one component (41', 42') to define an alternative, standard configuration of the arm (40');the maximum distance (DI, D2) being greater in the extended reach configuration than in the standard configuration.Application No: GB2402832.6Examiner: Mr Robin JonesClaims searched: 1-7Date of search: 5 September 2024Patents Act 1977: Search Report under Section 17Documents considered to be relevant:Category Relevant to claims Identity of document and passage or figure of particular relevance X 1-3 JPH10217777 A (HITACHI CONSTRUCTION MACHINERY ) - See Abstract Accession No. 1998-500706 and in particular translation of paras. [0029-0030] disclosing non return valve 13 between main fuel tank 10 and secondary tank 12. X 1-3 JP2003326989 A (CATERPILLAR MITSUBISHI LTD) - See WPI Abstract, Accession No.2003-889693 and in particular figure 4 and translated para. [0020] A - US 2021 / 070168 Al (HITACHI CONSTRUCTION MACH CO) - See para. [0040] and figure 2 for background information.Categories:X Document indicating lack of novelty or inventive step A Document indicating technological background and / or state of the art. Y Document indicating lack of inventive step if P Document published on or after the declared priority date but combined with one or more other documents of same category'. before the filing date of this invention. & Member of the same patent family E Patent document published on or after, but with priority date earlier than, the filing date of this application.Field of Search:International Classification:Subclass Subgroup Valid From B60K 0015 / 03 01 / 01 / 2006 B60K 0015 / 063 01 / 01 / 2006 B60K 0015 / 067 01 / 01 / 2006 B60K 0015 / 077 01 / 01 / 2006 E02F 0009 / 08 01 / 01 / 2006Application No: GB2402832.6Examiner: Mr Robin JonesClaims searched: 8-15Date of search: 15 May 2025Patents Act 1977Further Search Report under Section 17Documents considered to be relevant:Category Relevant to claims Identity of document and passage or figure of particular relevance Y Y 8-13 8-13 US 2008 / 0000916 Al (HWANG) - See whole document, in particular para. [0039] and figure 5 showing mounting 5 and attachment member 5 a. US 2018 / 0195253 Al (IWAMOTO et al.) - See whole document, in particular paras. [0043-0043] disclosing adjustable mounting surfaces 20 for the counterweight.Categories:X Document indicating lack of novelty or inventive step A Document indicating technological background and / or state of the art. Y Document indicating lack of inventive step if p Document published on or after the declared priority date but combined with one or more other documents of same category. before the filing date of this invention. & Member of the same patent family E Patent document published on or after, but with priority date earlier than, the filing date of this application.Field of Search:International Classification:Subclass Subgroup Valid From B60K 0015 / 03 01 / 01 / 2006 B60K 0015 / 063 01 / 01 / 2006 B60K 0015 / 067 01 / 01 / 2006 B60K 0015 / 077 01 / 01 / 2006 E02F 0009 / 08 01 / 01 / 2006

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