Backhoe loader and controller configured to control a backhoe loader

Abstract

A working machine comprising: a prime mover; a variable displacement hydraulic pump drivable by the prime mover; a working arm moveable by one or more hydraulic actuators driven by the hydraulic pump and / or an output to a working device; wherein the working machine is operable in a first mode and a second mode, and wherein in the first mode the prime mover is operable to run up to a first maximum operating speed and the hydraulic pump is configured to displace up to a first maximum volume of hydraulic fluid per revolution thereof, and wherein in the second mode the prime mover is operable to run up to a second maximum operating speed lower than the first maximum operating speed and a second maximum pump displacement greater than the first maximum pump displacement.

Description

[0001] BACKHOE LOADER AND CONTROLLER CONFIGURED TO CONTROL A BACKHOE LOADER

[0002] FIELD

[0003] The present teachings relate to a working machine. In addition the present teachings relate to a controller for a working machine.

[0004] BACKGROUND

[0005] Backhoe loaders are a type of working machine comprising a working arm pivotable about a horizontal axis and extending forward of a body of the machine (referred to as a loader) and an excavating arm, referred to as a backhoe, extending rearwardly of the body. The body comprises a ground engaging propulsion structure (such as wheels) and, usually, an operator station. Such machines typically utilise a prime mover in the form of an internal combustion engine powered by diesel, but potentially also compressed natural gas (CNG), hydrogen, or a blend of these. Such machines may alternatively use one or more electric motors as the prime mover, powered either by a hydrogen fuel cell or electricity stored in one or more batteries.

[0006] An attachment, such as a shovel (sometimes referred to as a bucket), is mounted on the free end of the loader with its opening facing forward, and is also pivotable about a horizontal axis with respect to the arm. This enables the loader to scoop and move loose material such as soil, aggregates, sand and deposit it in other locations on worksites. The backhoe is typically used for operations such as trenching, with the machine stationary and supported on rear stabilisers and the front shovel, rather than its pneumatic tyres, for enhanced stability. During backhoe operations, the operating speed of the prime mover is typically set to a fixed value using a hand throttle, so the operator can concentrate on the backhoe operations, knowing that the prime mover is supplying adequate power to a hydraulic pump of the machine, and therefore to the actuators causing the backhoe to move.

[0007] For demanding operations, the operator may set the operating speed to a high value, close to the maximum operating speed, to supply maximum power to the backhoe. However, this has a knock-on effect to energy consumption (in terms of fuel or electrical energy). Such an operating speed may not be required for all operations, however, meaning that energy is wasted, and undue noise and machine wear is caused.

[0008] SUMMARY OF THE INVENTION

[0009] The present teachings seek to overcome, or at least mitigate, one or more problems of the prior art. According to a first aspect of the present teachings there is provided a working machine according to claim 1 of the appended claims. A controller is also provided according to a second aspect of the teachings according to claim 15 of the appended claims. The controller may be configured to control the working machine of the first aspect.

[0010] An embodiment of the present teachings provides a working machine which may comprise: a prime mover; and / or a variable displacement hydraulic pump drivable by the prime mover; and / or a working arm moveable by one or more hydraulic actuators driven by the hydraulic pump and / or an output to a working device; and / or wherein the working machine may be operable in a first mode and a second mode, and wherein in the first mode the prime mover is operable to run up to a first maximum operating speed and the hydraulic pump may be configured to displace up to a first maximum volume of hydraulic fluid per revolution thereof, and wherein in the second mode the prime mover may be operable to run up to a second maximum operating speed lower than the first maximum operating speed and optionally a second maximum pump displacement greater than the first maximum pump displacement.

[0011] Advantageously, this enables the working machine to maintain productivity for the majority of tasks in the second mode, but to have the prime mover running at a speed where efficiency is maximised, for example, because it is operating at an optimal part of its torque and power curve. The configuration has further benefits in terms of lower wear on the prime mover and other moving parts, and depending on the type of prime mover, lower emissions and lower noise levels. Nevertheless, the first mode is available to provide maximum power for high intensity operations that demand it.

[0012] The machine may be configured to automatically reduce the prime mover speed when entering the second mode.

[0013] Advantageously, this may be more convenient for the operator and also results in savings in energy consumption (e.g., fuel consumption) being automatically enabled.

[0014] The working machine may further comprise a first prime mover speed control to set an operating speed of the prime mover to a value that requires no further user intervention and a second prime mover speed control, the second mode only being functional for inputs from the first prime mover control. The first prime mover control is typically used for operations when the working machine is static, such as excavating operations, where the second mode is most beneficial for efficiency.

[0015] The first prime mover speed control may be a hand operated device.

[0016] Such a hand operating device is commonly referred to as a hand throttle and is convenient for setting a constant operating speed of the prime mover.

[0017] The second prime mover speed control may be a foot operated device that is biased to a low operating speed.

[0018] Such a foot operating device is commonly referred to as a foot throttle and is convenient for controlling the prime mover operating speed in mobile handling operations using a loader arm

[0019] The prime mover speed may be configured to reduce to a lower level, e.g., an idle level after a predetermined period of no operator demand for operation of the working arm.

[0020] Advantageously, this allows for further improvement in energy consumption efficiency to be achieved.

[0021] The working machine may be further configured to return to the set speed when an operator demand is subsequently detected.

[0022] Advantageously, this retains the user convenience despite the savings in efficiency being achieved.

[0023] The working machine may further comprise an operator display of prime mover operating speed, wherein the display comprises an indicator of a suggested operating speed range, and the indicator may be configured to adjust when the operation moves from the first mode to the second mode.

[0024] Advantageously, this indicator assists the operator in knowing the most effective engine speed settings to utilise.

[0025] In the second mode the pump may be controlled so as to permit operation at at least a maximum torque that is greater than a maximum torque permitted in the first mode. Advantageously this may allow the operator controls to have a similar feel or responsiveness in the first and second modes.

[0026] The working machine may further comprise a controller, wherein the controller may be configured to sense demand directly or indirectly on the hydraulic pump and to switch between the first mode and second mode automatically, based on said demand.

[0027] Advantageously this may improve user convenience by not requiring intervention to switch between modes, and enhance machine efficiency by ensuring that the machine is set to the most appropriate mode to the required task.

[0028] The variable displacement pump may be a swash plate piston pump.

[0029] Advantageously, such pumps are able to adapt their displacement rapidly to the operator demands whilst efficiently converting prime mover power into movement of the working arms.

[0030] The pump may comprise electronic load sensing and may comprise electronic control of the pump displacement based on load,

[0031] Advantageously, this permits adaptable control of the pump based on prevailing operating conditions, operator demand and the operating mode that is selected.

[0032] The pump may comprise electronic torque control.

[0033] Advantageously, this allows the responsiveness or "feel" of the hydraulic system to be adjusted so as to be similar across the first and second modes, as well as ensuring the hydraulic system is not overloaded.

[0034] The working machine may further comprise an auxiliary hydraulic service and wherein in the second mode a maximum flow of the auxiliary hydraulic service may be lower than in the first mode.

[0035] Advantageously, this ensures that the cooling performance of the machine can be maintained in particular in circumstances where a forced air cooling is reliant on the operating speed of the prime mover. The working machine may be being an excavating machine in which the working arm comprises a boom and dipper arm.

[0036] The working machine may be a backhoe loader having a loading arm and a backhoe excavating arm.

[0037] A further embodiment of the present teachings provides a controller configured to control a working machine according to the preceding embodiment.

[0038] A further embodiment of the present teachings provides a controller configured to control a working machine comprising: a prime mover; a variable displacement hydraulic pump drivable by the prime mover; a working arm moveable by one or more hydraulic actuators driven by the hydraulic pump or an output to a working device; wherein the controller may be configured to signal the working machine to operate in a first mode and a second mode, and wherein in the first mode the controller may provide a signal permitting the prime mover to run up to a first maximum operating speed and may provide a signal permitting the hydraulic pump to displace up to a first maximum volume of hydraulic fluid per revolution thereof, and wherein in the second mode controller may provide a signal permitting the prime mover to run up to a second maximum operating speed lower than the first maximum operating speed and may provide a signal permitting the hydraulic pump to displace up to a second maximum pump displacement greater than the first maximum pump displacement.

[0039] BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Embodiments will now be described with reference to the accompanying drawings, in which:

[0041] Figure 1 is a side view of backhoe loader working machine of the present teachings comprising a shovel;

[0042] Figure 2 is a schematic hydraulic and electrical diagram of a pump and control system of the working machine of Figure 1;

[0043] Figure 3 is a plan view of an operator station of the working machine of Figure 1;

[0044] Figure 4 is a plan view of an operator seat of the working machine of Figure 1;

[0045] Figures 5A and 5B are views of a display of the operator station of Figure 3; and Figure 6 is a flowchart illustrating an aspect of the operation of the working machine of Figure 1.

[0046] DETAILED DESCRIPTION OF EMBODIMENT(S)

[0047] In the following detailed description, numerous specific details are set forth in order to provide a thorough understanding of various embodiments and the teachings. However, those skilled in the art will understand that: the present teachings may be practiced without these specific details or with known equivalents of these specific details; that the present teachings are not limited to the described embodiments; and, that the present teachings may be practiced in a variety of alternative embodiments. It will also be appreciated that well known methods, procedures, components, and systems may not have been described in detail.

[0048] Terms such as front, rear, lateral, side, upper and lower as used herein are with reference to the orientation of the working machine on level ground. They are used for ease of understanding and should not be taken as limiting.

[0049] With reference to Figure 1 a working machine in the form of a backhoe loader 10 of the present teachings is illustrated. A backhoe loader 10 is a known type of loader working machine. The backhoe loader 10 comprises a loader arm 12 pivotable about a horizontal axis and extending forward of, and either side of, a body 14 of the machine. The body 14 comprises a ground engaging propulsion structure 16 (wheels in this embodiment, but tracks in other embodiments) and an operator station 18 in the form of an enclosed cab. A shovel 20 is mounted on the free end of the loader arm 12. The shovel is pivotable about a horizontal axis with respect to the loader arm 12 by a hydraulic actuator and linkage assembly as is well known, and indicated generally at 15. This arrangement enables the backhoe loader 10 to, for example, drive the shovel 20 into a pile of material when it is lowered and scoop the material into the shovel, then move the backhoe loader 10, lift the arm 12 and tip the material from the shovel 20 at another location, such as into a trailer (not shown). As such it is a versatile tool that is found on various worksites including construction sites, quarries, farms etc.

[0050] The backhoe loader 10 additionally comprises a rear mounted backhoe 22, that is a form of excavating arrangement that comprises a boom 24 and dipper arm 26 (stick) that are pivotable about horizontal axes, with the boom also being slewably mounted to the body 14. The free end of the dipper is typically fitted with a smaller bucket 28 and or other attachments (not shown) to be used for trenching operations and the like. The backhoe loader 10 also includes a rear right and rear left stabilisers 44 having a ground engaging foot (only rear left stabiliser visible). Each stabiliser can be independently moved between a retracted position and a deployed position via a control device 45 (Figure 3) mounted proximate the rear of the operator station 18.

[0051] The backhoe loader 10 is powered by a prime mover 30, such as an internal combustion engine, and / or one or more electric motors (not shown). The internal combustion engine is typically powered by diesel fuel, but may alternatively use CNG or hydrogen as fuel.

[0052] The prime mover 30 also provides power to operate a hydraulic pump 32 (Figure 2) of a hydraulic system 33 (Figure 2) which can selectively provide pressurised hydraulic fluid to the various linear actuators 27 of the machine via a main control valve block 34 to operate the loader arm 12, shovel 20, boom 24, dipper 26, bucket 28, stabilisers 44 etc., to enable material to be loaded and excavated. The hydraulic pump 32 may also supply hydraulic fluid to and auxiliary service (not shown) at the end of the dipper arm 26, e.g. to power a breaker, planer, mower, hedge trimmer etc. (not shown), and to the steering and brakes of the backhoe loader 10.

[0053] With reference to Figures 1, 3 and 4 the operator station 18 has an operator seat 19. The operator station 18 is also provided with operator controls such as a steering wheel 36, foot brake 35, first and second prime mover operating speed controls (foot throttle 38, hand throttle 40), transmission drive lever 41 and working arm control levers 42a, 42b. The operator station 18 is also provided with a display 46 on which status information for the machine 10 is displayed. The display is shown in more detail in Figures 6A and 6B and in this embodiment is displaying the operating speed (rpm) of the prime mover 30. In addition, a mode switch 48 is provided in the operator station 18 to change an operating mode as described in more detail below.

[0054] As shown in Figures 1 and 3 the operator seat 19 is facing forwards. The operator seat 19 is rotatable and can be rotated so as to face the rear of the machine 10 within the operator station 18. In the forward position, the operator is suitably orientated for performing loading operations by manoeuvring the machine 10 as a whole using the steering wheel 36 transmission drive lever 41, foot throttle 38 and foot brake 35, whilst operating the loader arm 12 with the working arm control lever 42b. This forward facing position is also used for roading and moving the machine 10 around a worksite. In other embodiments, the entire operator station 18 may rotate with respect to the body 14 between the forward and rearward positions. When the operator seat 19 is facing rearwards, the hand throttle 40 and stabiliser control device 45 are readily accessible by the operator and the backhoe 22 is in their line of sight. This position is primarily used for operating the backhoe 22 to perform trenching, grading breaking operations and the like.

[0055] Referring now to Figures 2, 3 and 4, it can be seen that the working arm control levers 42a and 42b are mounted to the operator seat, particularly to the left and right arm rests thereof. In this embodiment, the machine comprises electro-hydraulic (EH) control of the machine hydraulic system 33. That is to say, that the working arm control levers 42a and 42b generate an electronic control signal that is transmitted to relevant hydraulic control valves, such as the main hydraulic control valve 34 and control those valves using electric solenoid control. This enables the seat 19 to rotate without requiring hydraulic pilot or mechanical connections to the rest of the machine to be accommodated. Instead the rotating connection only requires the transmission of an electrical signal via a suitable wired or wireless connection. In other embodiments, pilot hydraulic or mechanical control via a suitable linkage to the hydraulic system of the machine 10 may be used, and separate control levers (not shown) may be provided for the loader arm 12 and the backhoe 22, which are in fixed locations in the operator station 18, rather than being rotatable with the seat 19.

[0056] It can be seen that in this embodiment the working arm control levers 42a and 42b are in the form of joysticks 42a, 42b that are able to pivot in an X and Y direction relative to the seat 19. Additionally, the control levers include additional user inputs mounted thereon in the form of buttons 50a, 50b, 50c, and 50d, and roller switches 50e, 50f and 50g, which control additional hydraulic or other machine functions. In this embodiment, the control levers also include LEDs 51a, 51b to provide an user output.

[0057] An excavator / loader control selector switch 52 is also located on the right arm rest adjacent the control lever 42b. This switch has three positions, a central locked position where the control levers 42a and 42b are disabled, a forward position for normal to seat operation and a rear position for opposite to seat operation. Selecting these positions changes the working arm control levers between functions which control movement of the loader arm 12 and further features associated therewith, or functions that control the backhoe 22 or further features associated therewith. Backhoe 22 operation typically requires both control levers to be used in accordance with a known control pattern (ISO or SAE), whereas loader operation requires just the second joystick 42b, leaving the operator's left hand free to steer the machine 10 during loading operations. The control signals from the control levers 42a, 42b, switches 50a to 50g and loader / excavator selector switch 52 are transmitted to a controller 54 e.g. using a CAN bus. The controller 54 interprets those signals and transmits further signals to other components of the working machine 10 in accordance with its control logic.

[0058] The controller may comprise: control circuitry; and / or processor circuitry; and / or at least one application specific integrated circuit (ASIC); and / or at least one field programmable gate array (FPGA); and / or single or multi-processor architectures; and / or sequential / parallel architectures; and / or at least one programmable logic controllers (PLCs); and / or at least one microprocessor; and / or at least one microcontroller; and / or a central processing unit (CPU), to perform the described methods. The controller may include an associated memory or the memory may be located locally to the controller or remotely. The memory may be a non-volatile flash memory.

[0059] Figure 2 schematically illustrates a portion of the hydraulic system 33 and electronic control system of the backhoe loader 10, in particular those parts relating to control of the hydraulic pump 32. From Figure 2, it can be seen that the controller 54 further receives input signals from the hand throttle 40, a mode switch 48 and a seat position switch 49, and is able to output signals to the display 46 within the operator station 18. In some embodiments the display 46 may be a touchscreen display also capable of receiving user inputs. The controller 54 is further able to send control signals to the prime mover 30, for example, to adjust the operating speed thereof and / or to start the prime mover, and is also able to receive signals therefrom, e.g., relating to the operating speed of the prime mover 30.

[0060] The controller 54 is further able to interact with a dedicated pump controller 56 which integrates with the pump 32 hardware and is able to control pump operation. In other embodiments the controller 54 itself may directly interface with and control the pump 32.

[0061] In this embodiment, the pump 32 is a swash plate control variable displacement piston pump. A barrel 58 of the pump 32 is mechanically driven by the prime mover 30 and the amount of fluid displaced by each rotation of the pump is adjusted by changing the swash angle of the swash plate of the pump. This is achieved by use of a bias piston 60 which biases the swash plate to its maximum angle. This acts in conjunction with a control piston 62 which can overcome the biasing force of the bias piston to alter the swash angle and therefore the pump displacement. A control piston rod of the control piston 62 is provided with a sensor 64 to output the swash angle and optionally hydraulic fluid temperature to the pump controller 56. The pump controller 56 also reads the pressure of the hydraulic fluid downstream of the pump 32 via a sensor 66, as well as a load sense pressure via a pressure sensor 68 at the main control valve 34. Utilising these inputs, as well as the demand signals from the controller 54, the pump controller 56 adjusts pilot pressure to the control piston 62 via a solenoid operated pressure compensator valve 70 using a pulse width modulation (PWM) signal.

[0062] This electronic control of the pump output allows for a finer, more flexible control of the pump according to prevailing operating conditions and operator demand. An example of a suitable pump to achieve this is an eOC-BODAS controlled swash plate piston pump manufactured by Bosch Rexroth of Lohr am Main, Germany.

[0063] This control system is used to enable a second operating mode for the working machine 10, in particular one that is suited for excavating operations.

[0064] In the first or standard operating mode, selected by the mode switch 48, the operator is able to access the full range of operating speed of the prime mover 30. For a diesel powered IC engine as prime mover 30, this may be a speed between approx. 700rpm (idle) and 2200rpm. However for working operations an engine speed of between 1200rpm and 1700rpm is advised, as depicted by the engine speed band 72a on the display 46 in Figure 5A. This is an optimal range for demanding operations. In this mode, the pump controller 56 is programmed to restrict the swash angle to maximum displacement per revolution that is lower than the maximum displacement the pump 32 is physically capable of. For example, if the pump 32 has a maximum displacement of 88cm3 / revolution (88ccr) the pump controller may be programmed to limit the maximum displacement to 74ccr. In other words, the pump 32 is, in effect, oversized for the machine 10 in which it is fitted. However depending upon operator demand, prime mover 30 speed and optionally other parameters, such as permitted pump torque, the actual displacement may be lower than this maximum.

[0065] In the second or "eco" mode, when selected by the operator via the mode switch 48, the hand throttle 40 input is remapped electronically, so for a given physical input position, the controller 54 signals the prime mover 30 to operate at a lower speed (rpm). In this embodiment the mapping is approximately 300rpm lower than standard mode and the operating speed is limited to a range of 700-1600rpm, so engaging the second mode at an operating speed of 2100rpm will bring down the speed by 500rpm. The re-mapping may be altered according to the particular operating characteristics of the prime mover. So, if the prime mover 30 is a hydrogen fuelled IC engine with differing torque and power output characteristics, the remapping may be adjusted accordingly.

[0066] In addition, the pump controller 56 is configured in this mode to allow the full capacity of the pump (88ccr) to be obtainable and the recommended engine speed band 72b of 1150 to 1350rpm is provided on the display 46 of Figure 5B.

[0067] Therefore, despite the lower operating speed, for all but the most demanding working operations, the productivity of backhoe 22 may be maintained, and the sensitivity of the working arm control levers 42a and 42b can be retained (i.e. the movements of the backhoe do not become sluggish or over sensitive in comparison to the standard mode), as the lower pump 32 rotational speed is compensated for by the higher displacement per rotation.

[0068] Beneficially, because the diesel IC engine prime mover is operating at a more fuel-efficient point of its operating map, and closer to its peak torque output in the second mode, the performance is achieved with a lower fuel consumption than standard mode. Further the lower speed may lead to a reduction in wear of components, lower emissions, and lower noise levels, which are also advantageous for the operator and other personnel present on the work site.

[0069] An impact of the lower prime mover 30 speed may be a lower performance of the cooling system for the prime mover 30 and hydraulic system 33, if a fan speed for the forced air cooling is directly linked to prime mover speed. To mitigate this, in some embodiments, maximum hydraulic flow to an auxiliary service of the backhoe 22 may be reduced by the controller 54 to limit the heat generated. This can be achieved by the controller 54 limiting the opening of the relevant spool of the main hydraulic control valve 34 for the auxiliary service. In other embodiments, a larger fan (not shown) may be fitted, or the fan may be driven independent of prime mover speed via a separate variable speed electric or hydraulic motor (not shown).

[0070] To further reduce fuel consumption, the aforesaid operating modes may be combined an "auto-idle" function provided in the controller 54. The controller 54 monitors demand signal from the working arm control levers 42a, 42b. If no demand is seen for a predetermined period (e.g. 3 seconds) then the controller 54 overrides the hand throttle 38 setting and instead instructs the prime mover 30 to reduce its operating speed to an idle level, at which a minimum hydraulic supply remains available for functions such as brakes and steering. Once a demand is sensed, the controller 54 then signals the prime mover 30 to return to its operating speed as set by the hand throttle 40, so the hydraulic system returns to being fully operable. If the mode switch 48 is actuated during the idle phase, the controller 54 signals the prime mover to return to a the corresponding speed of the other mode (300rpm higher or lower than that of the other mode in the present embodiment, but within the relevant upper and lower bounds).

[0071] In a further alternative embodiment, the controller 54 may monitor the hydraulic demand on the hydraulic system 33 and if it is below a certain threshold, and the machine is in the first mode, it may determine that the machine may operate more efficiently in the second mode and switch to the second mode automatically. An alert may be provided to the operator in advance of making the change, and the change may be capable of being overridden. Similarly, if the machine 10 is in the second mode, but the hydraulic demands on the hydraulic system 33 are above a certain threshold, the controller 54 may automatically switch the machine 10 to the first mode, again with a suitable alert and possibility of override.

[0072] Referring to Figure 6, a flowchart describing operation of the hydraulic system 33 according to the first and second embodiments is shown.

[0073] At step S100, the controller 54 commences the control algorithm by reading the swash angle (pump displacement) via displacement sensor 64, the engine 30 speed, and the state of mode switch 48.

[0074] The process then moves to step S104 at which it is determined if the pump is in load sense mode and what the pressures measured by the pressure sensors 66 and 68 are. If the pump is not in load sense mode, the process also moves to step S110 and instructs the pump 32 to move to its minimum displacement value as this is indicative of it being on standby. If the pump 32 is in load sense mode, the controller determines if the working machine 10 is in its first mode (standard mode) or its second mode (eco mode) by reading the state of the mode switch 48.

[0075] If the working machine 10 is in its first (standard) mode, the process moves to step S114, in which the full engine speed range is available, but pump displacement is limited to being less than its maximum value as described above. In addition, in this embodiment, the pump torque may be limited to less that its maximum allowable value. This may help to ensure the feel and response of the controls remains similar across both modes and to ensure engine stability at lower engine speeds can be maintained. If the working machine 10 is in its second (eco) mode, the process moves to step S108, in which the maximum engine speed is limited a maximum of 1600rpm and the hand throttle is remapped to an engine speed that is approx.. 300rpm lower than in the first mode, in the present embodiment. In addition, at step SI 12, the controller 54 instructs the availability the full amount of pump displacement (e.g. up to 88ccr rather than a lower limit, such as 74ccr), and also imposes limits on pump torque, which are dependent upon engine speed.

[0076] Although the process is described with distinct start and end points in Figure 6, whilst the machine 10 is operating the process described is repeated periodically to monitor for changes in operator demand, engine 30 or pump 32 parameters, and changes from the first to the second mode, or vice-versa.

[0077] Whilst a backhoe loader 10 is described, it will be appreciated that the eco mode of the present teachings are also applicable to other types of working machines, such as wheel loaders, skid-steer loaders, tracked loaders, articulated telescopic loaders, telehandlers, excavators, agricultural tractors and the like. For an agricultural tractor, the hydraulic pump is typically provided to power hydraulic functions of separate implements the may be attached to the tractor, such as hydraulic actuators of tipping trailers, ploughs, sprayers etc. and / or well as hydraulic actuators on the tractor to lift and lower arms of a three- point linkage at a rear and / or front thereof.

[0078] The one or more embodiments are described above by way of example only and it will be appreciated that the variations are possible without departing from the scope of protection afforded by the appended claims.

Claims

Claims1. A backhoe loader comprising: a prime mover; a variable displacement hydraulic pump drivable by the prime mover; a loading arm and a backhoe excavating arm each moveable by one or more hydraulic actuators driven by the hydraulic pump and / or an output to a working device; wherein the working machine is operable in a first mode and a second mode, and wherein in the first mode the prime mover is operable to run up to a first maximum operating speed and the hydraulic pump is configured to displace up to a first maximum volume of hydraulic fluid per revolution thereof, and wherein in the second mode the prime mover is operable to run up to a second maximum operating speed lower than the first maximum operating speed and a second maximum pump displacement greater than the first maximum pump displacement.

2. The backhoe loader of claim 1, wherein the machine is configured to automatically reduce the prime mover speed when entering the second mode.

3. The backhoe loader of claim 1 or claim 2, further comprising a first prime mover speed control to set an operating speed of the prime mover to a value that requires no further user intervention and a second prime mover speed control, , the second mode only being functional for inputs from the first prime mover control.

4. The backhoe loader of claim 3 wherein the first prime mover speed control is a hand operated device.

5. The backhoe loader of claim 3 or claim 4 wherein the second prime mover speed control is a foot operated device that is biased to a low operating speed.

6. The backhoe loader of any preceding claim, wherein the prime mover speed is configured to reduce to a lower level, e.g., an idle level after a predetermined period of no operator demand for operation of the loading arm or backhoe excavating arm.

7. The backhoe loader of claim 6, further configured to return to the set speed when an operator demand is subsequently detected.

8. The backhoe loader of any preceding claim, further comprising an operator display of prime mover operating speed, wherein the display comprises an indicator of a suggestedoperating speed range, and the indicator is configured to adjust when the operation moves from the first mode to the second mode.

9. The backhoe loader of any preceding claim, wherein in the second mode the pump is controlled so as to permit operation at at least a maximum torque that is greater than a maximum torque permitted in the first mode.

10. The backhoe loader of any preceding claim further comprising a controller, wherein the controller is configured to sense demand directly or indirectly on the hydraulic pump and to switch between the first mode and second mode automatically, based on said demand.

11. The backhoe loader of any preceding claim, wherein the variable displacement pump is a swash plate piston pump.

12. The backhoe loader of any preceding claim wherein the pump comprises electronic load sensing and electronic control of the pump displacement based on load.

13. The backhoe loader of any preceding claim wherein the pump comprises electronic torque control.

14. The backhoe loader of any preceding claim, wherein the machine further comprises an auxiliary hydraulic service and wherein in the second mode a maximum flow of the auxiliary hydraulic service is lower than in the first mode.

15. A controller configured to control a backhoe loader comprising: a prime mover; a variable displacement hydraulic pump drivable by the prime mover; a loading arm and a backhoe excavating arm each moveable by one or more hydraulic actuators driven by the hydraulic pump or an output to a working device; wherein the controller is configured to signal the backhoe loader to operate in a first mode and a second mode, and wherein in the first mode the controller provides a signal permitting the prime mover to run up to a first maximum operating speed and a signal permitting the hydraulic pump to displace up to a first maximum volume of hydraulic fluid per revolution thereof, and wherein in the second mode controller provides a signal permitting the prime mover to run up to a second maximum operating speed lower than the first maximum operating speed and provides a signal permitting the hydraulic pumpto displace up to a second maximum pump displacement greater than the first maximum pump displacement.

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