Patent Description:
Off-highway vehicles or working machines are for example those used in construction industries configured to transport loads over a surface (e.g. backhoe loaders, slew excavators, telescopic handlers, forklifts, skid-steer loaders etc.). These working machines typically have a body supported by a ground-engaging propulsion structure such as front and rear wheels, or a pair of endless tracks. To propel the working machine, a drive arrangement, including for example a transmission and a prime mover such as an internal combustion engine or electric motor, provides motive power to the ground-engaging propulsion structure. Working machines typically have a working arm pivotally mounted to the body of the machine, and a working implement, such as a bucket or a grabber, attached to the end of the arm via a coupling device. Attachment of the working implement enables the working machine to perform a variety of tasks on a work site.

Some of these tasks involve changing the driving direction of the machine (i.e. from forward to reverse, or from reverse to forward) many times; for example when the machine is used for loading or unloading. To change the driving direction of a working machine, it is common for the operator to brake the working machine and to select an intended driving direction of the working machine via a gear selector. When a new intended driving direction is selected whilst the working machine is still in motion, the drive arrangement applies a torque to the ground-engaging propulsion structure, which acts to decelerate the working machine until stationary, before moving the working machine in the new intended driving direction.

A problem with such a direction changing process is that it causes significant stresses to act on the drive arrangement, which can reduce the lifetime of the drive arrangement. Moreover, it has been found that using the drive arrangement primarily to decelerate a working machine during a change in driving direction can cause the machine to jolt on initiation of the direction changing process.

<CIT> describes a running control device for an industrial vehicle which generates no speed change shock when the traveling direction is switched to the opposite direction by the forward-reverse selection member during the running of the vehicle. The running control device comprises a forward-reverse selected direction detection sensor which detects the selected traveling direction, a transmission which has a forward clutch and a reverse clutch that switch the traveling direction between the forward direction and reverse direction, and which transmits the driving torque of the engine to the driving wheels via the clutches, a brake which applies braking to the vehicle, a vehicle speed sensor which detects the vehicle speed, and a controller which gradually decelerates the vehicle by means of the brake when the selected traveling direction that has been detected is switched, and controls the engaging force of the forward or reverse clutch corresponding to the selected traveling direction and the braking force of the brake before the detected vehicle speed reaches zero, thus controlling the deceleration torque and acceleration torque so that the fluctuation in the acceleration around the point of time at which the traveling direction is reversed is weakened. <CIT> discloses a working machine with the features of the preamble of present claim <NUM>.

The present teachings seek to overcome or at least mitigate one or more problems associated with the prior art.

The present invention provides a working machine and a method for changing the driving direction of a working machine according to the appended claims.

A first aspect of the present invention provides a working machine pursuant to independent claim <NUM>.

Advantageously, the configuration of the braking system, control system and sensor assembly enables automated braking of the working machine based on a determined output of the drive arrangement, which may simplify control of the working machine. The working machine may comprise a forward-neutral- reverse drive selector to select an intended driving direction of the working machine. The control system may be configured to actuate the braking system in response to an input from the drive selector selecting a new intended driving direction of the working machine.

Advantageously, actuating the braking system when a new intended driving direction is indicated via the drive director (i.e. via the forward/neutral/reverse (FNR) selector) enables the working machine to be decelerated automatically via the braking system instead of using the transmission to effect deceleration of the working machine. By using the braking system instead of the transmission, the working machine can be decelerated in a smooth manner, which may improve the driving experience of the operator of the working machine. Moreover, by using the braking system, less stress may be imparted onto the transmission during a direction change, which may help to increase the lifespan of the components of the transmission.

The control system may be configured to control or restrict a rotational speed of the drive arrangement in response to an input from the drive selector selecting a new intended driving direction of the working machine.

Advantageously, restricting a rotational speed of the drive arrangement when a new driving direction is indicated may help to reduce the travel speed of the working machine and enable smoother gear changes during a direction change.

The control system may be configured such that the first braking force applied to the ground engaging propulsion structure is proportional to the determined speed of travel of the working machine or rotational speed of the drive arrangement.

Advantageously, applying a braking force which is proportional (i.e. directly proportional or inversely proportional) to the speed of travel or rotational speed of the drive arrangement may help to ensure the working machine is decelerated smoothly by inhibiting jolting of the working machine.

The control system may be configured such that the first braking force applied to the ground engaging propulsion structure is substantially constant.

The output of the drive arrangement may be determined through one or more of: a speed of travel of the working machine; a rotational speed of the drive arrangement; a torque output of the drive arrangement; and/or a torque within a transmission of the drive arrangement.

The control system may be configured to apply the first braking force to the ground engaging propulsion structure when a rotational speed of the drive arrangement is below a pre-determined threshold.

Applying a braking force when the rotational speed of the drive arrangement is below a pre-determined threshold may help to decelerate the working machine automatically when the operator has released a drive pedal of the working machine.

The working machine may comprise a forward-neutral-reverse drive selector to select an intended driving direction of the working machine. The control system may be configured to apply the first braking force to the ground engaging propulsion structure in response to a rotational speed of the drive arrangement being below a pre-determined threshold only when the working machine is in neutral.

The control system may be configured to apply the first braking force to the ground engaging propulsion structure when a speed of travel of the working machine is below a pre-determined threshold.

Applying a braking force when the speed of travel of the working machine is below a first pre-determined speed threshold may help to automatically decelerate the working machine to stationary when initially travelling at low speed, and subsequently keep the working machine stationary, without the operator needing to actuate the braking system manually.

The working machine may comprise a forward-neutral-reverse drive selector to select an intended driving direction of the working machine. The control system may be configured to apply the first braking force to the ground engaging propulsion structure in response to a speed of travel of the working machine being below a pre-determined threshold only when the working machine is in neutral.

The braking system may be a hydraulic braking system actuated by hydraulic fluid pressure, and wherein the hydraulic fluid pressure applied to provide the first braking force is proportional to the determined speed of travel or rotational speed of the drive arrangement.

Advantageously, the hydraulic braking system may use pressurised hydraulic fluid from a hydraulic fluid system of the working machine to enable the control system to automatically actuate the brakes. Applying a hydraulic fluid pressure that is proportional to the determined speed of travel and/or rotational speed of the drive arrangement, may help to ensure that the working machine decelerates smoothly.

The control system may be configured to adjust the hydraulic fluid pressure by controlling a position of a valve, e.g. a solenoid valve, of the braking system.

Controlling a valve to adjust the hydraulic fluid pressure enables accurate and robust control of brake actuation by the control system.

The braking system may be a hydraulic braking system that is actuated by hydraulic fluid pressure and comprises at least one hydraulic power brake to apply a braking force to the ground engaging propulsion structure.

The control system may be configured to actuate the braking system such that the working machine is decelerated at a predetermined rate.

Decelerating the working machine at a predetermined rate may help to ensure that the working machine is decelerated in a smooth fashion.

The magnitude of the first braking force may be based on one or more of: the speed of travel of the working machine; a rotational speed of the drive arrangement; the mass of the machine; a load carried by the working machine; and/or the position of the arm relative to the body.

The control system may be configured to actuate the braking system such that the first braking force applied increases as the speed of travel of the working machine decreases.

Increasing the applied first braking force as the speed of travel decreases may help to ensure that the working machine is decelerated in a smooth fashion, for example, by inhibiting jolting of the working machine.

The control system may be configured to actuate the braking system such that the first braking force applied is inversely proportional to the speed of travel of the working machine.

The control system may be configured to actuate the braking system such that the first braking force applied decreases as the speed of travel of the working machine decreases.

Decreasing the applied first braking force as the speed of travel decreases may help to ensure that the working machine is decelerated in a smooth fashion, for example, by inhibiting jolting of the working machine.

The control system may be configured to actuate the braking system such that the first braking force applied is proportional to the speed of travel of the working machine.

The working machine comprises a brake pedal for operation by an operator, wherein the brake pedal is configured to actuate the braking system to apply a second braking force based on a position of the brake pedal relative to a rest position of the brake pedal.

The brake pedal may enable the operator of the working machine to actuate the braking system manually, for example, during routine operation and/or in an emergency.

The braking system is configured such that, when first and second braking forces are being applied simultaneously, the greater of the first and second braking forces is applied to the ground engaging propulsion structure.

Applying the greater of the first and second braking forces may enable the brake control input device to override the control system when the operator of the working machine wishes to apply a greater braking force than that implemented by the control system. This may improve the safe operation of the working machine since it may enable the operator to rapidly decelerate the working machine in an emergency for example.

The braking system may be a hydraulic braking system actuated by hydraulic fluid pressure, and wherein the braking system comprises a shuttle valve comprising first and second inlets arranged to receive hydraulic fluid associated with the first and second braking forces and comprises an outlet to transmit hydraulic fluid to actuate the braking system.

The arrangement of the shuttle valve provides a robust and effective means to enable the brake pedal to override the control system when desired, with minimal moving parts and requiring no electrical power.

The working machine may comprise an inclination sensor configured to determine an inclination of the working machine. The control system may be configured to actuate the braking system to apply the first braking force when an inclination of the working machine is above a pre-determined inclination threshold and the speed of travel of the working machine is less than or equal to a pre-determined travel speed threshold.

Applying a braking force when an inclination of the working machine is above a pre-determined inclination threshold and the speed of travel of the working machine is below a second pre-determined speed threshold may help to keep a working machine stationary when on an incline, such as a hill, without the operator needing to actuate the braking system manually.

A second aspect of the teachings provides for a method for changing the driving direction of the working machine of the first aspect, the method comprising the steps of: selecting a new intended driving direction via a drive selector; and applying the first braking force to the ground engaging propulsion structure via the braking system based on an output of the drive arrangement.

Another aspect of the present invention provides for a method for operating the working machine of the first aspect, the method comprising the steps of: determining whether the speed of travel of the working machine is below a pre-determined threshold and/or whether a rotational speed of the drive arrangement is less than pre-determined threshold; and applying the first braking force to the ground engaging propulsion structure via the braking system when the determined speed of travel of the working machine is less than the pre-determined threshold or when the determined rotational speed of the drive arrangement is less than the pre-determined threshold.

Embodiments are now disclosed by way of example only with reference to the drawings, in which:.

Referring to <FIG>, a working machine <NUM> is illustrated. The working machine <NUM> may be considered to be a load handling machine. In this embodiment, the working machine <NUM> is a telescopic handler. In other embodiments the working machine <NUM> may be a rotating telescopic handler, a forklift, an excavator, a skid-steer loader, a compact track loader, a wheel loader, a telescopic wheel loader, or a tractor, for example. Such working machines may be denoted as off-highway vehicles or as non-road mobile machinery.

The working machine <NUM> includes a body <NUM>. The body <NUM> may include, for example, an operator's cab <NUM> from which an operator can operate the machine <NUM>. The operator cab <NUM> may be mounted on the body <NUM> so as to be offset from a centre of the body. Although in alternative arrangements, the cab <NUM> may be substantially central. The body <NUM> includes an undercarriage <NUM> or chassis, and a superstructure <NUM>. The superstructure <NUM> is rotatable (e.g. about a substantially vertical axis) relative to the undercarriage <NUM>. Put another way, the superstructure may be rotatable relative to the ground engaging propulsion structure. In the illustrated arrangement, the operator cab <NUM> is mounted onto the superstructure <NUM>.

The working machine <NUM> has a ground engaging propulsion arrangement. The ground engaging propulsion arrangement or structure supports the body <NUM>. The ground engaging propulsion structure includes a first, or front, axle A1 and a second, or rear, axle A2, each axle being coupled to a pair of wheels <NUM>, <NUM>. Put another way, the ground engaging propulsion structure includes front and rear wheels. In other embodiments, the ground engaging propulsion structure may include a pair of endless tracks.

The working machine <NUM> includes a drive arrangement <NUM> configured to provide motive power to the ground engaging propulsion structure <NUM>, <NUM>, so as to move/drive the working machine <NUM> over a surface. The drive arrangement <NUM> includes a primer mover <NUM> and a transmission <NUM>. The prime mover <NUM> may be an internal combustion engine, an electric motor, or may be a hybrid comprising both an internal combustion engine, an electric motor. The drive arrangement <NUM> is configured to provide motive power to the ground-engaging propulsion structure <NUM>, <NUM> from the prime mover <NUM> via the transmission <NUM>.

A working arm <NUM> is pivotally connected to the body <NUM>. In the arrangement shown, the working arm <NUM> is pivotally mounted to the superstructure <NUM>. The working arm <NUM> is connected to the body <NUM> by a mount <NUM> proximate a first end, or proximal end, of the working arm <NUM>. The working arm <NUM> can be moved with respect to the body <NUM> and the movement is preferably, at least in part, rotational movement about the mount <NUM>. The rotational movement is about a substantially transverse axis of the machine <NUM>. Rotational movement of the working arm <NUM> with respect to the body <NUM> is, in an embodiment, achieved by use of at least one lifting actuator (not shown) coupled between the arm <NUM> and the body <NUM>.

The working arm <NUM> may be a telescopic arm, having a first section <NUM> connected to the mount <NUM> and a second section <NUM> which is telescopically fitted to the first section <NUM>. In this embodiment, the second section <NUM> of the working arm <NUM> is telescopically moveable with respect to the first section <NUM> such that the working arm <NUM> can be extended and retracted. Movement of the second section <NUM> with respect to the first section <NUM> of the working arm <NUM> may be achieved by use of an extension actuator (not shown), for example a double acting hydraulic linear actuator, an electric linear actuator, a telescopic extension ram, multiple extension rams, and/or a chain and pulley system. As will be appreciated, the working arm <NUM> may include a plurality of sections, for example two, three, four or more sections. Each arm section may be telescopically fitted to at least one other section, and an actuator may be provided therebetween. In alternative arrangements, the working arm <NUM> may not be telescopic and may include a first arm pivotally mounted to the mount <NUM>. In such arrangements, the working arm <NUM> may also include a second arm pivotally mounted to the first arm.

A working implement is mounted to a second, or distal, end <NUM> of the working arm <NUM>. In the illustrated arrangement, the working implement includes a carriage <NUM> including a pair of spaced apart forks <NUM> mounted thereto. In alternative arrangements, it will be appreciated that any suitable working implement may be mounted to the working arm <NUM> to suit the application. In such alternative arrangements, the working implement may be a bucket, a shovel, or a basket, for example.

The working machine <NUM> includes a braking system <NUM> actuatable to apply a first braking force to the propulsion structure <NUM>, <NUM>.

The working machine <NUM> includes a sensor assembly <NUM> configured to determine an output of the drive arrangement <NUM>. In the arrangement shown, the sensor assembly <NUM> is configured to determine an output of the drive arrangement <NUM> in the form of a speed of travel of the working machine <NUM> and/or a rotational speed of the drive arrangement <NUM> and to provide an output to a control system <NUM>. It will be appreciated that the output of the drive arrangement <NUM> may be based upon a torque output of the prime mover <NUM>, torque within the transmission <NUM> or any other suitable output from the prime mover <NUM>. The control system <NUM> is configured such that the first braking force applied to the propulsion structure <NUM>, <NUM> is based on the determined output of the prime mover <NUM>.

The sensor assembly <NUM> includes a rotational speed sensor <NUM> configured to determine a rotational speed of the drive arrangement <NUM>. In embodiments in which the prime mover <NUM> is an internal combustion engine, the rotational speed determined by the rotational speed sensor <NUM> may correspond to a rotational speed of the engine's crankshaft. In embodiments in which the prime mover <NUM> is an electric motor, the rotational speed determined by the rotational speed sensor <NUM> may correspond to a rotational speed of the rotor and/or output shaft of the motor. Alternatively, the rotational speed determined by the rotational speed sensor <NUM> may correspond to a rotational speed of the transmission <NUM>; e.g. a rotational speed of an input shaft to a gearbox of the transmission <NUM>. The sensor assembly <NUM> includes a travel speed sensor <NUM> configured to determine a speed of travel of the working machine <NUM>. The travel speed sensor <NUM> may determine the travel speed of the working machine <NUM> via any suitable means such as via sensing of the rotational speed of the wheels <NUM>, <NUM> or the axles A1, A2, or via GPS. The control system <NUM> is configured such that the first braking force applied to the propulsion structure <NUM>, <NUM> is based on the determined speed of travel of the working machine or rotational speed of the drive arrangement.

The working machine <NUM> includes control inputs to control operation of the working machine <NUM>. The working machine <NUM> includes a drive selector <NUM>. The drive selector is a forward/neutral/reverse (FNR) selector <NUM>. The drive selector <NUM> engages drive in a selected direction, or selects a neutral gear. The drive selector <NUM> is configured to be operated by an operator of the working machine <NUM> to indicate an intended driving direction of the working machine <NUM>, i.e. forward or reverse. The drive selector <NUM> may be located within the cab <NUM>.

In a first mode of operation, the control system <NUM> is configured to control/actuate the braking system <NUM> to apply a braking force F1 to the ground-engaging propulsion structure <NUM>, <NUM> when the input from the drive selector <NUM> indicates a new intended driving direction of the working machine <NUM>. Put another way, the control system <NUM> is configured to control/actuate the braking system <NUM> to apply a braking force F1 to the ground-engaging propulsion structure <NUM>, <NUM> when the drive selector <NUM> has been operated to indicate an intended change in driving direction, for example, from forward to reverse, or from reverse to forward.

In the first mode of operation, the control system <NUM> may be configured to actuate the braking system <NUM> such that the braking force F1 is proportional (i.e. directly proportional or inversely proportional) to the determined output of the drive arrangement <NUM>. Put another way, the control system <NUM> is configured to actuate the braking system <NUM> such that the braking force F1 is proportional (i.e. directly proportional or inversely proportional) to the determined speed of travel or the determined rotational speed of the drive arrangement <NUM>. Alternatively, in the first mode of operation, the braking force F1 may be substantially constant, and the control system <NUM> is configured to apply and remove the braking force F1.

In the first mode of operation, the control system <NUM> may be configured such that the braking force F1 applied to the ground-engaging propulsion structure <NUM>, <NUM> is based on the determined output of the drive arrangement <NUM> by the sensor assembly <NUM>, as has been discussed above. Put another way, in the first mode of operation, the control system <NUM> may be configured such that the braking force F1 applied to the ground-engaging propulsion structure <NUM>, <NUM> is based on one or more of: a speed of travel of the working machine <NUM>; a rotational speed of the drive arrangement <NUM>; a torque output of the prime mover <NUM>; a torque within the transmission <NUM>; or any other suitable output from the prime mover <NUM>.

In the first mode of operation, the control system <NUM> may be configured to control the drive arrangement <NUM> when the input from the drive selector <NUM> indicates a new intended driving direction of the working machine <NUM>. Put another way, the control system <NUM> may be configured to control, limit or restrict a rotational speed of the drive arrangement <NUM> (i.e. the prime mover <NUM>) when the input from the drive selector <NUM> indicates a new intended driving direction of the working machine <NUM>. The control system <NUM> monitors the rotational speed of the drive arrangement <NUM> via the input from the rotational speed sensor <NUM>. The control system <NUM> may send a signal (e.g. a TSC1 signal) to a controller of the prime mover <NUM> to reduce the rotational speed of the prime mover <NUM> such that the rotational speed is less than or equal to a first predetermined rotational speed threshold in response to the input from the drive selector <NUM> indicating a new intended driving direction. The control system <NUM> may be configured to control the drive arrangement <NUM> such that the torque supplied from the drive arrangement <NUM> to the ground-engaging propulsion structure corresponds to the intended driving direction. The control system <NUM> may send a signal to a controller of a gearbox of the transmission <NUM> to change gear in response to an operation of the drive selector <NUM> indicating a new intended driving direction of the working machine <NUM>. In embodiments where the prime mover <NUM> is in the form of an electric motor, the control system <NUM> may send a signal to a controller of the prime mover <NUM> to provide a torque to the ground-engaging propulsion structure which corresponds to the intended driving direction.

The working machine <NUM> includes a brake pedal <NUM>. The braking system <NUM> is configured to apply a braking force to the wheels <NUM>, <NUM>. The braking system <NUM> is configured such that it is actuated by the brake pedal <NUM> to apply the braking force to the ground engaging propulsion structure <NUM>, <NUM>. In the illustrated embodiment, the braking system <NUM> is a hydraulic braking system that is actuated by hydraulic fluid pressure. The brake pedal <NUM> supplies fluid to brakes <NUM> at one or more of the wheels <NUM>, <NUM>. The brake pedal <NUM> is configured to be operated by an operator of the working machine <NUM>, and may be located in the cab <NUM>.

The control system <NUM> is configured to actuate the braking system <NUM> to apply a first braking force to the ground-engaging propulsion structure <NUM>, <NUM>. The brake pedal <NUM> is configured to actuate the braking system <NUM> to apply a second braking force to the ground-engaging propulsion structure, where the second braking force applied is based on a position of the brake pedal <NUM> relative to a rest position of the brake pedal <NUM>. The braking system <NUM> is configured such that when the control system <NUM> actuates the braking system <NUM> to apply the first braking force to the ground-engaging propulsion structure, and the brake pedal <NUM> is operated to actuate the braking system <NUM> to apply the second braking force to the ground-engaging propulsion structure simultaneously, the greater of the first and second braking forces is applied to the ground engaging propulsion structure <NUM>, <NUM>.

The braking system <NUM> includes a hydraulic brake <NUM>. It will be appreciated that each wheel <NUM>, <NUM> may include an associated brake <NUM> to apply a braking force thereto. The braking system <NUM> includes a control valve <NUM>. The control system <NUM> is configured to adjust a hydraulic pressure by controlling a position of the control valve <NUM>. As such, the pressure of the hydraulic fluid supplied to the braking system <NUM> can be controlled by the control system <NUM>. In the illustrated, the control valve <NUM> is a solenoid-controlled valve, and the signal sent from the control system <NUM> to the control valve <NUM> corresponds to an electrical current to be supplied to the solenoid.

The braking system <NUM> includes a shuttle valve <NUM>. The hydraulic brake <NUM> is in fluid communication with an outlet 58a of the shuttle valve <NUM>. In this way, the hydraulic brake <NUM> is actuated via hydraulic fluid transmitted from the outlet 58a of the shuttle valve <NUM> to the hydraulic brake <NUM>.

The shuttle valve <NUM> includes a first inlet 58b configured to receive hydraulic fluid in response to an output from the control system <NUM> (i.e. via the control valve <NUM>). When the control system <NUM> actuates the braking system <NUM> to apply the first braking force to the ground-engaging propulsion structure <NUM>, <NUM> via control of the control valve <NUM>, the first inlet 58b of the shuttle valve <NUM> receives hydraulic fluid at a first pressure corresponding to the first braking force. The shuttle valve <NUM> includes a second inlet 58c configured to receive hydraulic fluid in response to depression of the brake pedal <NUM>. When the brake pedal <NUM> is operated to actuate the braking system <NUM> to apply the second braking force to the braking system <NUM>, the second inlet 58v of the shuttle valve <NUM> receives hydraulic fluid at a second pressure corresponding to the second braking force.

The shuttle valve <NUM> is configured such that hydraulic fluid exiting the outlet 58a is a pressure equal to the greater of the two hydraulic fluid flows. Thus, when the control system <NUM> actuates the braking system <NUM> to apply the first braking force and the brake pedal <NUM> actuates the braking system <NUM> to apply the second braking force simultaneously, hydraulic fluid is transmitted from the outlet 58a of the shuttle valve <NUM> to the hydraulic brake <NUM> at a pressure corresponding to the greater of the first braking force and the second braking force. Put another way, the hydraulic brake <NUM> is actuated to apply the greater of the first and second braking forces to the ground-engaging propulsion structure <NUM>, <NUM>. This enables the operator of the working machine <NUM> to override the control system <NUM> in order to apply a large braking force to the ground-engaging propulsion structure than that implemented by the control system <NUM>.

In <FIG>, only one hydraulic brake <NUM> is shown. However, the working machine <NUM> may include two or more hydraulic brakes <NUM>, for example, three or more, or four or more hydraulic brakes <NUM>, where each hydraulic brake <NUM> is in fluid communication with the outlet 58a of the shuttle valve <NUM>. In alternative embodiments, the braking system <NUM> may be a pneumatic, an electronic, or a hybrid braking system. For example, the braking system <NUM> may be an electronic braking system including an electronically actuated brake, which may be actuated by both the control system and the brake pedal to apply a braking force to the ground-engaging propulsion structure.

In a second mode of operation, the control system <NUM> is configured to apply a braking force F2 to the ground engaging propulsion structure <NUM>, <NUM> when a rotational speed of the drive arrangement <NUM> is below a pre-determined threshold and/or when a speed of travel of the working machine <NUM> is below a pre-determined threshold.

In the second mode of operation, it will be appreciated that the braking force applied may be a substantially constant braking force. Alternatively, the control system <NUM> may be configured such that the braking force applied to the ground-engaging propulsion structure16, <NUM> is based on an output of the drive arrangement <NUM>.

In such arrangements, the control system <NUM> may be configured such that the braking force F2 applied to the ground-engaging propulsion structure <NUM>, <NUM> is based on the determined output of the drive arrangement <NUM> by the sensor assembly <NUM>, such as one or more of: a speed of travel of the working machine <NUM>; a rotational speed of the drive arrangement <NUM>; a torque output of the prime mover <NUM>; a torque within the transmission <NUM>; or any other suitable output from the prime mover <NUM>. In the second mode of operation, the control system <NUM> may be configured such that the braking force F2 applied to the ground-engaging propulsion structure <NUM>, <NUM> is also and/or alternatively based on; a position of the throttle; a requested drive arrangement rotational speed; and/or a requested drive arrangement torque. one or more of: a speed of travel of the working machine <NUM>; a rotational speed of the drive arrangement <NUM>; a torque output of the prime mover <NUM>; a torque within the transmission <NUM>; or any other suitable output from the prime mover <NUM>.

In the second mode of operation, the control system <NUM> may only apply the braking force to the ground engaging propulsion structure <NUM>, <NUM> when it is determined that an operator of the working machine <NUM> is requesting to stop the working machine <NUM>. It may be determined that an operator of the working machine <NUM> is requesting to stop the working machine <NUM> when the drive selector is placed in neutral and/or when the operator has released a drive/accelerator pedal of the working machine <NUM>. Applying a braking force when the speed of travel of the working machine <NUM> is below a pre-determined speed threshold and/or when a rotational speed of the drive arrangement <NUM> is below a pre-determined threshold helps to automatically bring the working machine <NUM> to a stop when initially travelling at low speed and requesting to stop, without the operator needing to actuate the braking system <NUM> manually. It will be appreciated that the braking force applied may differ between when an operator lifts off the throttle, but remains with forward or reverse drive selected, and when the drive selector is placed in neutral.

The sensor assembly <NUM> may include an inclination sensor <NUM>. The inclination sensor <NUM> is configured to determine an angle of inclination of the working machine <NUM>. The inclination sensor <NUM> provides an output of the determined inclination angle to the control system <NUM>. In arrangements where the working machine <NUM> includes the inclination sensor <NUM>, the control system <NUM> is configured, in a third mode of operation, to actuate the braking system <NUM> to apply a braking force when an inclination of the working machine <NUM> is above a pre-determined inclination threshold. In the third mode of operation, the control system <NUM> may be configured such that it only applies a braking force to the ground engaging propulsion structure <NUM>, <NUM> when the speed of travel of the working machine <NUM> is less than or equal to a pre-determined travel speed threshold. In the third mode of operation, the control system <NUM> may be configured such that it only applies a braking force to the ground engaging propulsion structure <NUM>, <NUM> when it is determined that an operator of the working machine <NUM> is requesting to stop the working machine <NUM>. It may be determined that an operator of the working machine <NUM> is requesting to stop the working machine <NUM> when the drive selector is placed in neutral and/or when the operator has released a drive/accelerator pedal of the working machine <NUM>.

In the third mode of operation, the braking force applied may be a substantially constant braking force. Alternatively, the control system <NUM> may be configured such that the braking force applied to the ground-engaging propulsion structure <NUM>, <NUM> is based on an output of the drive arrangement <NUM> (e.g. based on the speed of travel of the working machine, a rotational speed of the drive arrangement <NUM>, a torque of the drive arrangement <NUM>, etc.), in a similar manner as has been described above, and/or may be based on the angle of inclination detected by the inclination sensor <NUM>.

In one arrangement, the control system <NUM> is configured to actuate the braking system <NUM> such that the braking force F1 increases as the determined speed of travel decreases. For example, the control system <NUM> may be configured to actuate the braking system <NUM> such that the braking force F1 is inversely proportional to the determined speed of travel. Controlling the braking force F1 such that it increases as the determined speed of travel reduces helps to ensure that the working machine <NUM> is decelerated smoothly such that jolting of the working machine <NUM> at the point when the brakes are applied is reduced.

In another arrangement, the control system <NUM> is configured to actuate the braking system <NUM> such that the braking force F1 decreases as the determined speed of travel decreases. For example, the control system <NUM> may be configured to actuate the braking system <NUM> such that the braking force F1 is proportional to the determined speed of travel. Controlling the braking force F1 such that it decreases as the determined speed of travel reduces helps to ensure that the working machine <NUM> is decelerated smoothly to a stop such that jolting of the working machine <NUM> when the machine comes to a standstill is reduced.

The control system <NUM> may be configured to actuate the braking system <NUM> such that the braking force F1 applied to the ground-engaging propulsion structure decelerates the working machine <NUM> at a predetermined rate, i.e. at a predetermined rate of deceleration or at a predetermined jerk. Actuation of the braking system <NUM> (i.e. the magnitude of the first braking force) may be based on one or more of: the determined speed of travel of the working machine <NUM>; a rotational speed of the drive arrangement <NUM>; the mass of the machine; a load carried by the working machine <NUM>; or the position (i.e. inclination and extension) of the arm <NUM> relative to the body <NUM>.

Although not illustrated, it will be appreciated that the working machine <NUM> may be provided with an operator input so as to enable the operator to manually enable and disable the control system <NUM>, or to manually enable and disable one or more of the features of the control system <NUM> discussed above.

Although not illustrated, it will be appreciated that the sensor assembly <NUM> may be provided with a terrain sensor configured to determine characteristic of the ground over which the working machine <NUM> is travelling. In such arrangements, it will be understood that the braking force applied in each of the described modes of operation may be based on the characteristics of the ground determined by the terrain sensor.

The working machine <NUM> may be configured to indicate to an operator that the control system <NUM> is actuating the braking system <NUM>. The working machine may be provided with an indicator, such as an audio and/or visual indicator, and the control system <NUM> may be configured to activate the indicator when it actuates the braking system <NUM>. The working machine <NUM> may be configured to provide a tactile indicator to an operator that the control system <NUM> is actuating the braking system <NUM>, for example this may be done by changing the resistance in the brake pedal <NUM>.

With reference to <FIG>, a method for changing the driving direction of the working machine <NUM> will be described in the following.

In step S200, the working machine <NUM> is driven in a first driving direction (i.e. forward or reverse). In step S202, the operator of the working machine <NUM> operates the drive selector <NUM> to select a new, or second, driving direction. In step S204, the control system <NUM> determines whether the determined rotational speed of the drive arrangement <NUM> is less than a predetermined rotational speed threshold.

If the determined rotational speed is greater than the predetermined rotational speed threshold ('No'), the method moves to step <NUM>. In step S206, the control system <NUM> sends a signal to the drive arrangement <NUM> to control or restrict the rotational speed of the drive arrangement <NUM>. This can be used to reduce the rotational speed of the drive arrangement <NUM> so as to be less than the predetermined rotational speed threshold.

If the determined rotational speed is less than the predetermined rotational speed threshold ('Yes'), then the method moves to step S208. In step <NUM>, the control system <NUM> determined whether the determined speed of travel of the working machine <NUM> is less than a predetermined travel speed threshold.

If the determined speed of travel is greater than the predetermined travel speed threshold, the method moves to step <NUM>. In step <NUM>, the control system <NUM> actuates the braking system <NUM> to apply the braking force F1 to the ground-engaging propulsion structure <NUM>, <NUM>. The braking force F1 may be based on the determined speed of travel and/or the rotational speed of the drive arrangement, as previously discussed. The braking force F1 may be applied until the speed of travel is less than or equal to the predetermined travel speed threshold, at which point the control system <NUM> ceases actuating the braking system <NUM>.

If the control system <NUM> determines that the determined speed of travel is less than or equal to the first predetermined travel speed threshold, the method moves to step S212. In step <NUM>, the control system <NUM> sends a signal to the drive arrangement <NUM> to provide motive power to the ground-engaging propulsion structure <NUM>, <NUM> to move the working machine <NUM> in the new, or second, travel direction. In step <NUM>, the working machine <NUM> is driven in the second driving direction.

Claim 1:
A working machine (<NUM>) comprising:
a body (<NUM>);
a ground-engaging propulsion structure supporting the body;
a drive arrangement (<NUM>) configured to provide motive power to the ground engaging propulsion structure;
a braking system (<NUM>) actuatable to apply a braking force to the ground engaging propulsion structure;
a control system (<NUM>);
a sensor assembly (<NUM>) configured to determine an output of the drive arrangement and to provide an output to the control system; and
a brake pedal (<NUM>) for operation by an operator,
wherein the control system (<NUM>) is configured to control the braking system (<NUM>) to apply a first braking force to the ground engaging propulsion structure that is based on the determined output of the drive arrangement,
wherein the brake pedal (<NUM>) is configured to actuate the braking system (<NUM>) to apply a second braking force based on a position of the brake pedal (<NUM>) relative to a rest position of the brake pedal (<NUM>), characterised in that
the braking system (<NUM>) is configured such that, when first and second braking forces are being applied simultaneously, the greater of the first and second braking forces is applied to the ground engaging propulsion structure.