AU2020213424B2

AU2020213424B2 - Mobile crane

Info

Publication number: AU2020213424B2
Application number: AU2020213424A
Authority: AU
Inventors: Peter Andrew DALLA RIVA
Original assignee: Westfield Nominees Pty Ltd
Current assignee: Westfield Nominees Pty Ltd
Priority date: 2019-01-30
Filing date: 2020-01-29
Publication date: 2023-02-02
Anticipated expiration: 2040-01-29
Also published as: WO2020154765A1; AU2020213424A1

Abstract

A pick and carry crane (10) comprises a chassis (11) having a front chassis portion (12), a rear chassis portion (13), and a front suspension system (29) supporting the front chassis portion (12) on a front axle (31). The front suspension system (29) comprises a suspension device such as a hydraulic cylinder (43) selectively operable in a mode to automatically vary suspension height as required. A planarity sensor (103) is provided to sense a spatial relationship of the front chassis portion (12). A controller (113) is provided to receive signals from the planarity sensor (103) and control operation of the front suspension system (29) accordingly to compensate for a variation from a permissible condition. The front suspension system (29) may comprise two hydraulic cylinders (43), one corresponding to each side of the front chassis portion 12. Each hydraulic cylinder (43) may function variously as a shock absorbing cylinder, a levelling cylinder, or a rigid link. A method of operating a pick and carry crane (10) is also disclosed.

Description

Mobile Crane

TECHNICAL FIELD

[0001 ] This invention relates to a mobile crane.

[0002] The invention is particularly applicable to a mobile crane in the form of pick and carry crane. Accordingly, it will be convenient to hereinafter disclose the invention in relation to that exemplary application. However, it is to be appreciated that the invention is not necessarily limited to a pick and carry crane, and may (where appropriate) be used in relation to other cranes required to lift and carry loads.

BACKGROUND ART

[0003] The following discussion of the background art is intended to facilitate an understanding of the present invention only. The discussion is not an acknowledgement or admission that any of the material referred to is or was part of the common general knowledge as at the priority date of the application.

[0004] Pick and carry cranes typically comprise an articulated chassis having front and rear chassis portions pivotally coupled together, and a crane boom associated with the front chassis portion. The front and rear chassis portions are each supported on wheels mounted on axles. An operator cab is associated with the front chassis portion.

[0005] A pick and carry crane is designed to be driven on roadways from one site to another, and to lift and carry a load in a suspended condition from one location to another, all with an operator seated in one position in the operator cab. The crane is completely self-supporting; that is, there are no outriggers to stabilise the crane.

[0006] A pick and carry crane normally has two modes of operation, one being a travel mode and the other being a crane mode. In the travel mode, the crane can be driven as a road vehicle, such as for example on roadways from one worksite to another. In the crane mode, the crane can lift a load into a suspended condition and carry the suspended load from one location to another.

[0007] Steering is achieved by the two chassis portions articulating to change the angular disposition of the chassis and hence tyre direction. [0008] A suspension system is provided, typically comprising leaf springs, airbags or hydraulics. The suspension system is designed to be operational only when the crane is in travel mode. In this mode, the crane can be driven at relatively high speeds on roadways, typically up to about 80 kph, for example. In crane mode, the suspension system is disabled; that is, the suspension is made rigid and the axles are fixed rigidly with respect to the chassis. The speed at which the crane can travel in the crane mode is restricted; typically to a maximum speed of about 1.6 kph, for example.

[0009] It is critical that a pick and carry crane be operated within the manufacturer’s specifications, including in particular allowable rated lifting capacity. The lifting capacity of the crane is derated according to various circumstances or adverse conditions encountered; for example, when traversing slopes or changing direction.

[0010] When operating in crane mode, a pick and carry crane is typically designed for use on firm, flat, level ground (to within 1 % gradient). In certain circumstances, it may be deemed permissible to operate a pick and carry crane on side slopes up to 5° (8.75% gradient). However, the load-lifting capacity of the crane is derated in such circumstances.

[001 1 ] With this in mind, it is important during crane mode to minimise any side tilt of the front chassis portion on which the crane boom is mounted. Side tilt of the front chassis portion can arise in various circumstances, not only upon encountering side-sloping ground, but also when depressions and potholes in the ground surface are encountered and during articulation of the chassis upon turning of the crane.

[0012] With a view to enhancing the safety and performance of a pick and carry crane during crane mode, it would be beneficial to provide an arrangement which may accommodate some sideways angular movement of the suspension without imparting adverse side tilt to the chassis and hence the boom.

[0013] It is against this background that the present invention has been developed.

SUMMARY OF INVENTION

[0014] According to a first aspect of the invention, there is provided a mobile crane comprising a chassis, a portion of the chassis being supported on an axle mounted on a wheel, a suspension system between the axle and the chassis, the suspension system comprising a suspension device selectively operable in a mode in which the suspension device is operable to vary suspension height, and means for sensing a spatial relationship of the chassis and operating the suspension system accordingly to compensate for a variation from a permissible condition.

[0015] The sensed spatial relationship may comprise roll angle (e.g. sideways tilt) or pitch angle, or any other spatial characteristic of the chassis as may be appropriate. The spatial relationship may be sensed in any appropriate way, such as by way of a planarity sensor.

[0016] Preferably, the mobile crane further comprises means for sensing suspension height.

[0017] The mobile crane may further comprise a controller configured to receive signals from the means for sensing a spatial relationship of the chassis and controlling operation of the suspension system. The controller may be further configured to receive signals from the means for sensing suspension height to provide an indication of suspension height as part of controlling operation of the suspension system.

[0018] With this arrangement, the suspension system may comprise a dynamic levelling suspension system in which the chassis of the mobile crane is automatically levelled as necessary.

[0019] The suspension system may further comprise a spring system between the axle and the chassis for cushioning the chassis by damping shock loads from bumps and holes encountered during travel of the mobile crane. The spring system may be of any appropriate form, including for example a mechanical spring system (e.g. leaf springs), a pneumatic spring system (e.g. air springs), or a hydraulic system with provision for damping fluid pulses.

[0020] The spring system may be separate from the suspension device. Alternatively, the spring system may include the suspension device, wherein the suspension device is adapted to facilitate cushioning; that is, the suspension device may be configured to selectively provide cushioning.

[0021 ] In the case in which the spring system includes the suspension device configured to selectively provide cushioning, such an arrangement provides a further mode in which the suspension device is operable. [0022] With this arrangement, the mobile crane may selectively operate in either one of two conditions; one condition being with the suspension system configured to operate in the mode whereby the suspension device is operable to vary suspension height for dynamic levelling, and the other condition being with the suspension device is operable as a shock absorber between the axle and the chassis.

[0023] The suspension device may also be operable in a mode in which the chassis is fixed with respect to the axle.

[0024] In this way, the suspension device may be selectively operable in any one of three available modes, wherein the three modes comprise a first mode in which the suspension device is operable as a shock absorber between the axle and the chassis, a second mode in which the suspension device is operable to vary suspension height, and a third mode in which the chassis is fixed with respect to the axle.

[0025] With this arrangement, the mobile crane may operate in a travel mode with the suspension system configured to operate in the first mode, whereby the suspension device provides cushioning between the axle and the chassis. Further, the mobile crane may operate in either one of two conditions in a crane mode; one condition being with the suspension system configured to operate in the second mode, whereby the suspension device is operable to vary suspension height for dynamic levelling, and the other condition being with the suspension system configured to operate in the third mode, whereby the suspension device is operable to fix the chassis with respect to the axle.

[0026] The suspension device may comprise a power device adapted to be selectively movable between extended and contracted conditions.

[0027] The power device may also be adapted to be selectively fixed against movement between the extended and contracted conditions.

[0028] The suspension system may comprise a hydraulic suspension system, in which case the power device may comprise a hydraulic cylinder. Other arrangements of the suspension system are contemplated, in which the power device may for example comprise a linear actuator operable either electrically or pneumatically.

[0029] The hydraulic cylinder may be responsive to fluid pressure for movement between the extended and contracted conditions. Further, the hydraulic cylinder may be fixed against any movement between the extended and contracted conditions by restricting fluid flow with respect to the hydraulic cylinder. Specifically, the hydraulic cylinder assumes a static condition in the absence of fluid flow (and is thereby fixed against any movement between the extended and contracted conditions).

[0030] The hydraulic suspension system may further comprise a hydraulic circuit in which the hydraulic cylinder is incorporated.

[0031 ] The hydraulic circuit may comprise a flow path operable to effect extension or contraction of the hydraulic cylinder for varying the suspension height and maintaining the hydraulic cylinder in a condition corresponding to a selected suspension height. In this way, the hydraulic cylinder can be moved into a condition which can at least to some extent accommodate uneven conditions (e.g. side slope) in the ground over which the mobile crane is traversing while in crane mode. With this arrangement, the hydraulic cylinder functions as a levelling cylinder.

[0032] The hydraulic circuit may also comprise means for absorbing hydraulic shock, thereby to provide cushioning between the axle and the chassis. The means for absorbing hydraulic shock may comprise an accumulator.

[0033] Accordingly, the hydraulic circuit may be configured to selectively provide first and second flow paths for hydraulic fluid communicating with the hydraulic cylinder, the first flow path incorporating or communicating with the means for absorbing hydraulic shock (e.g. the accumulator) and the second flow path bypassing the means for absorbing hydraulic shock (e.g. the accumulator). With this arrangement, the second flow path provides said flow path operable to effect extension or contraction of the hydraulic cylinder for varying the suspension height and maintaining the hydraulic cylinder in a condition corresponding to a selected suspension height

[0034] The first flow path may incorporate means such as a valve for selectively blocking fluid flow, thereby restricting the hydraulic cylinder against movement to provide shock absorption for cushioning.

[0035] The first flow path may incorporate means such as an extension locking valve between the hydraulic cylinder and the respective accumulator to permit hydraulic fluid flow from the accumulator to the hydraulic cylinder, but prevent flow in the reverse direction, unless actuated to permit the reverse flow. When so actuated, the extension locking valve permits flow in both directions. [0036] The second flow path is operable to effect extension or contraction of the hydraulic cylinder for varying the suspension height and maintaining the hydraulic cylinder in a condition corresponding to a selected suspension height. In this way, the hydraulic cylinder can be moved into a condition which can at least to some extent accommodate uneven conditions (e.g. side slope) in the ground over which the mobile crane is traversing while in crane mode. With this arrangement, the hydraulic cylinder functions as a levelling cylinder.

[0037] The second flow path may incorporate means operable to block fluid flow in the event of flow exceeding a prescribed flow rate. By way of example, such means may comprise a velocity fuse.

[0038] he mobile crane may comprise a pick and carry crane in which the chassis comprises an articulated chassis having front and rear chassis portions pivotally coupled together

[0039] A crane boom may be associated with the front chassis portion.

[0040] The front and rear chassis portions may each be supported on axle-mounted wheels.

[0041 ] The front chassis portion may be supported on an axle having a wheel mounted on each end. Typically, the axle would have a wheel set mounted on each end, wherein the wheel set comprises two wheels.

[0042] The suspension system may be provided on the front chassis portion and may comprise two of the hydraulic cylinders, one corresponding to each side of the front chassis portion. In this way, each hydraulic cylinder may function variously as a shock absorbing cylinder, a levelling cylinder for the respective side of the chassis portion, or a rigid link between a rigid link the axle and the respective side of the chassis portion.

[0043] Each hydraulic cylinder may be connected between the axle and the front chassis portion in a manner accommodating angular movement between the axle and the front chassis portion. In one arrangement, each hydraulic cylinder may be connected at its lower end to the axle by way of a lower spherical bearing and may be connected at its upper end to the front chassis portion by way of an upper spherical bearing. [0044] The means for sensing suspension height may comprise a sensor. The sensor may be mounted at any appropriate location; for example, between the chassis portion and the axle.

[0045] According to a second aspect of the invention, there is provided a mobile crane comprising a chassis, a portion of the chassis being supported on an axle mounted on a wheel, a suspension system between the axle and the chassis, the suspension system comprising a suspension device selectively operable in a mode in which the suspension device is operable to vary suspension height, and a mode in which the suspension device is operable as a shock absorber between the axle and the chassis.

[0046] According to a third aspect of the invention, there is provided a mobile crane comprising a chassis, a portion of the chassis being supported on an axle mounted on a wheel, a suspension system between the axle and the chassis, the suspension system comprising a suspension device selectively operable in a mode in which the suspension device is operable to vary suspension height, and a mode in which the chassis is fixed with respect to the axle.

[0047] According to a fourth aspect of the invention, there is provided a mobile crane comprising a chassis, a portion of the chassis being supported on an axle mounted on a wheel, a suspension system between the axle and the chassis, the suspension system comprising a suspension device selectively operable in any one of three available modes, wherein the three modes comprise a first mode in which the suspension device is operable as a shock absorber between the axle and the chassis, a second mode in which the suspension device is operable to vary suspension height, and a third mode in which the chassis is fixed with respect to the axle.

According to a fifth aspect of the invention, there is provided a method of operating a mobile crane according to any one of the preceding aspects of the invention, the method comprising selectively and optionally operating the mobile crane with the suspension system in a mode in which the suspension height is variable.

[0048] According to a sixth aspect of the invention, there is provided a method of operating a mobile crane having a chassis, an axle, and a suspension system between the chassis and the axle, the method comprising selectively and optionally operating the mobile crane with the suspension system in a mode in which the suspension height is variable. [0049] The method according to the fifth or sixth aspect of the invention may further comprise sensing a spatial relationship of the chassis and operating the suspension system accordingly to effect variation of the suspension height to compensate for a variation from a permissible condition.

[0050] The method according to the fifth or sixth aspect of the invention may further comprise selectively and optionally operating the mobile crane with the suspension system in a further mode to provide shock absorption between the axle and the chassis

[0051 ] The method according to the fifth or sixth aspect of the invention may further comprise selectively and optionally operating the mobile crane with the suspension system in a further mode in which the chassis is fixed with respect to the axle.

[0052] According to a seventh aspect of the invention, there is provided a method of operating a mobile crane having a chassis, an axle, and a suspension system between the chassis and the axle, the method comprising selectively and optionally operating the mobile crane with the suspension system in a first mode to provide shock absorption between the axle and the chassis, operating the mobile crane with the suspension system in a second mode in which the suspension height is selectively variable, and operating the mobile crane with the suspension system in a third mode in which the chassis is fixed with respect to the axle.

BRIEF DESCRIPTION OF THE DRAWINGS

[0053] Further features of the present invention are more fully described in the following description of several non-limiting embodiments thereof. This description is included solely for the purposes of exemplifying the present invention. It should not be understood as a restriction on the broad summary, disclosure or description of the invention as set out above. The description will be made with reference to the accompanying drawings in which:

Figure 1 is a perspective view of a first embodiment of a mobile crane according to the invention, the embodiment being in the form of a pick and carry crane and being shown in an articulated condition for turning;

Figure 2 is a side view of the crane (shown on a smaller scale than Figure 1 );

Figure 3 is a plan view of Figure 2; 2020/154765 PCT/AU2020/050057

Figure 4 is a detailed view of part of a front chassis portion of the crane as shown in Figure 2 (with wheels removed for clarity);

Figure 5 is a detailed view of part of the front chassis portion of the crane as shown in Figure 3;

Figure 6 is a front view of the front chassis portion of the crane;

Figure 7 is a detailed view of part of the front chassis portion of the crane as shown in Figure 6;

Figure 8 is a perspective view of a front suspension assembly of the front chassis portion of the crane;

Figure 9 is a front perspective view of the crane operating on level ground with zero tilt;

Figure 10 is a view similar to Figure 9, except that the crane is shown operating on ground having a side slope;

Figure 1 1 is a view of part of the front chassis portion when in the condition shown in Figure 9;

Figure 12 is a view of the front chassis portion when in the condition shown in Figure 10;

Figure 13 is a fragmentary side view of the front chassis portion, illustrated in the condition shown in Figure 9;

Figure 14 is a detailed view of part of the chassis portion shown in Figure 13;

Figure 15 is a fragmentary side view of the front chassis portion, illustrated in the condition shown in Figure 10;

Figure 16 is a detailed view of part of the chassis portion shown in Figurel 5;

Figure 17 is a schematic view of a hydraulic circuit incorporated in the first embodiment of the mobile crane to control the front suspension assembly;

Figure 18 is a schematic view of a control system incorporated in the first embodiment of the mobile crane; Figure 19 is a schematic view of a hydraulic circuit incorporated in a second embodiment of a mobile crane according to the invention to control a front suspension assembly of the mobile crane; and

Figure 20 is a schematic view of a hydraulic circuit incorporated in a third embodiment of a mobile crane according to the invention to control a front suspension assembly of the mobile crane.

[0054] The drawings shown are not necessarily to scale, with emphasis instead generally being placed upon illustrating the principles of the present disclosure.

[0055] The figures depict several embodiments exemplifying the principles of the present disclosure. The embodiments each illustrates a certain configuration; however, it is to be appreciated that the inventive principles can be implemented by way of many different configurations, as would be obvious to a person skilled in the art, whilst still embodying any of the inventive principles. These configurations are to be considered within the embodiments described herein.

DESCRIPTION OF EMBODIMENTS

[0056] In the following detailed description, the present invention is described in connection with several preferred embodiments. Flowever, to the extent that the following description is specific to a particular embodiment or a particular use of the present techniques, it is intended to be illustrative only and merely provides a concise description of the exemplary embodiment. Accordingly, the present invention is not limited to the specific embodiments described below, but rather the invention includes all alternatives, modifications, and equivalents falling within the true scope of the appended claims.

[0057] The embodiments will each be described with reference to a vehicle comprising a mobile crane 10 in the form of an articulated pick and carry crane.

[0058] The articulated pick and carry crane 10 comprises a chassis 1 1 having a front chassis portion 12 and a rear chassis portion 13. The two chassis portions 12, 13 are connected by front and rear pivot couplings 15, 17 which provide an articulation joint 19. The front and rear chassis portions 12, 13 articulate about joint 19 to provide steering for the crane 10. A power system (not shown), which includes two hydraulic cylinders WO 2020/154765 PCT/AU2020/050057 on opposed sides of the articulation joint 19, is provided for effecting pivotal movement between the front and rear chassis portions 12, 13 for steering purposes.

[0059] A telescopic boom 23 is provided on the front chassis portion 12.

[0060] An operator cab 25 is also provided on the front chassis portion 12.

[0061 ] The pick and carry crane 10 has a suspension system 27 which comprises a front suspension system 29 and a rear suspension system (not shown).

[0062] The front chassis portion 12 is supported on the front axle 31 onto which front wheels 33 are mounted. The front axle 31 has hubs 39 at the ends for mounting the front wheels 33 in known manner, as would be understood by a person skilled in the art. In the arrangement shown, the front wheels 33 are configured as two sets, with one set mounted on each side and each set comprising two wheels. Other wheel configurations are of course contemplated.

[0063] Similarly, the rear chassis portion 13 is supported on a rear axle 35 to which rear wheels 37 are on each side. Other wheel configurations are of course contemplated.

[0064] The front suspension system 29 is provided between the front axle 31 and the front chassis portion 12. The rear suspension system (not shown) is provided between the rear axle 35 and the rear chassis portion 13. The rear suspension system may be of any appropriate form, as would be understood by a person skilled in the art.

[0065] In the first embodiment, the pick and carry crane 10 is operable with the front suspension system 29 in any one of three available suspension modes. The suspension system 29 is selectively variable between the three suspension modes, typically by an operator seated in the operator cab 25.

[0066] The three suspension modes comprise a first suspension mode which constitutes a travel mode, and second and third suspension modes, each of which constitutes a crane mode, as will be described in more detail later.

[0067] In first suspension mode (which constitutes the travel mode), the crane 10 can be driven under certain conditions as a road vehicle on roadways, such as for example from one worksite to another. This suspension mode may be referred to as“travel mode”. [0068] In each of the second and third suspension modes (each of which constitutes one of two crane modes), the crane 10 can lift a load into a suspended condition and carry the suspended load from one location to another. In the second suspension mode (i.e.one crane mode), suspension height is variable dynamically to automatically facilitate levelling while the crane 10 is in motion (typically at low speeds). This suspension mode may be referred to as“crane mode dynamic levelling”. In the third suspension mode (i.e. the other crane mode), the front chassis portion 12 is fixed with respect to front axle 31. This suspension mode may be referred to as“crane mode locked”.

[0069] The front suspension system 29 in this embodiment comprises a hydraulic suspension system 42 which is illustrated schematically in Figure 17. The hydraulic suspension system 42 includes two hydraulic cylinders 43, one corresponding to each side of the front chassis portion 12. The two hydraulic cylinders 43 are identified individually as hydraulic cylinder 43a and hydraulic cylinder 43b.

[0070] Each hydraulic cylinder 43 is operable selectively to perform different functions for the respective side of the front chassis portion 1 1 ; specifically, each hydraulic cylinder 43 may function variously as a shock absorbing cylinder, a levelling cylinder, or a rigid link (as will be explained in more detail later).

[0071 ] Each hydraulic cylinder 43 is connected between the front axle 31 and the front chassis portion 12 in a manner accommodating angular movement between the axle and the front chassis portion. In this embodiment, each hydraulic cylinder 43 is connected at its lower end to the front axle 31 by way of a lower spherical bearing 45 and connected at its upper end to the front chassis portion 12 by way of an upper spherical bearing 47, as best seen in Figure 8.

[0072] In the arrangement shown, the front suspension system 29 also includes top torque rods 48 and bottom torque rods 49, which are of known kind and which are connected to the front chassis portion 12 in known manner.

[0073] Each hydraulic cylinder 43 is selectively operable in any one of three available conditions, reflecting the three suspension modes referred to above. The three conditions comprise: (i) a first condition in which each hydraulic cylinder 43 is operable as a shock absorber between the front axle 31 and the front chassis portion 12; (ii) a second condition in which each hydraulic cylinder 43 is operable to vary suspension height (as represented by, for example, the height of the adjacent side of the front chassis portion 12 above the front axle 31 ) for dynamic levelling; and (iii) a third condition in which hydraulic cylinder 43 is operable to fix the front chassis portion 12 with respect to the front axle 31.

[0074] In the second suspension mode, any difference in the respective suspension heights at the two sides of the front chassis portion 12 (as dictated by any difference in the extent of extension or contraction of the two hydraulic cylinders 43) induces a sideways tilt in the front chassis portion 12, the purposes of which is to compensate for any side slope of the ground with which the two front wheels 33 are engaged. The sideways tilt being induced in the front chassis portion 12, is with respect to the front axle 31 which itself tilts in response to one or more of the front wheels 33 encountering uneven ground. As such, the sideways tilt induced in the front chassis portion 12 is for the purpose of returning the front chassis portion 12 to a required level state (as depicted in Figure 10). In this embodiment, the required level state is deemed to be within about 0.5 degrees to horizontal, although of course other acceptable variations from horizontal are contemplated.

[0075] The hydraulic cylinders 43 are responsive to fluid pressure for movement between the extended and contracted conditions, as will be explained in more detail later. Further, the hydraulic cylinders 43 can be fixed (i.e. locked) against any movement between the extended and contracted conditions by restricting fluid flow with respect to the hydraulic cylinders, as also will be explained in more detail later. The hydraulic cylinders 43 each assume a static condition when fixed (i.e. locked) against movement between the extended and contracted conditions.

[0076] With this arrangement, the pick and carry crane 10 may operate in the“travel mode” with the front suspension system 29 operating in the first suspension mode, whereby the hydraulic cylinders 43 provide cushioning between the front axles 31 and the front chassis portion 11. Further, the pick and carry crane 10 may operate in either one of two conditions in the crane mode. One condition constitutes the“crane mode dynamic levelling” condition, in which the front suspension system 29 is configured to operate in the second suspension mode whereby the hydraulic cylinders 43 are able to undergo extension and contraction to vary the respective suspension heights and thereby induce sideways tilt in the front chassis portion 1 1 as necessary for dynamically levelling while the crane is in motion (at low speeds). The other condition constitutes the “crane mode locked” condition, in which the front suspension system 29 is configured to operate in the third suspension mode whereby the hydraulic cylinders 43 are locked against any extension and contraction, thereby effectively functioning as fixed links providing a rigid connection between the front chassis portion 12 and the front axle 31. In other words, the suspension system 29 is locked when in “crane mode locked” suspension mode.

[0077] The “crane mode locked” configuration is provided as an option in case an operator of the pick and carry crane 10 wishes to use that mode for some reason or as redundancy in the case of a fault with the“crane mode dynamic levelling” condition. Generally, the“crane mode dynamic levelling” configuration would be the option of choice, as there is no need to derate the lifting capacity of the crane. In the“crane mode locked” configuration, the load-lifting capacity of the crane may need to be derated when traversing slopes or changing direction, as is the case with prior art pick and carry cranes (as discussed previously).

[0078] The hydraulic suspension system 42 further comprise a hydraulic circuit 51 in which the hydraulic cylinders 43 are incorporated, as best seen in Figure 17. The hydraulic circuit 51 also comprises means for absorbing hydraulic shock, thereby to provide cushioning between the front axles 31 (and hence the front wheels 33) and the front chassis portion 12. In this embodiment, such means comprises an accumulator 53 associated with each the hydraulic cylinder 43.

[0079] The hydraulic circuit 51 is configured to selectively provide a first flow path 56 and a second flow path 57 for hydraulic fluid communicating with each hydraulic cylinder 43, as shown in Figure 17. The two first flow paths 56 are identified individually as first flow path 56a communicating with hydraulic cylinder 43a and first flow path 56b communicating with hydraulic cylinder 43b. Similarly, the two second flow paths 57 are identified individually as second flow path 57a communicating with hydraulic cylinder 43a and second flow path 56b communicating with hydraulic cylinder 43b. In each case, the accumulator 53 is incorporated in or is otherwise in fluid communication with the respective first flow path 55. The second flow paths 57 bypasses the accumulators 53.

[0080] Each first flow path 56 incorporates means such as a lock valve 59 for selectively blocking fluid flow, thereby limiting movement of the respective hydraulic cylinder 43 to that permitted by the respective accumulator 53 and thereby providing shock absorption for cushioning. [0081 ] Each first flow path 56 also incorporates an extension locking valve 61 comprising a directional valve of a type which permits flow in one direction and normally prevents flow in the reverse direction, but which is selectively operable to permit flow in the reverse direction. The directional valve may, for example, comprise a one-way solenoid poppet valve configured to allow flow freely in one direction and block flow in the other direction, unless the valve is actuated (i.e. electrically powered or depowered depending upon the solenoid configuration) to permit flow in both directions.

[0082] The extension locking valve 61 is incorporated in the first flow path 56 between the bottom section of each hydraulic cylinder 43 and the respective accumulator 53 to permit hydraulic fluid flow from the accumulator to the hydraulic cylinder, but prevent flow in the reverse direction, unless actuated to permit the reverse flow. When so actuated, the extension locking valve 61 permits flow in both directions.

[0083] With this arrangement, the extension locking valve 61 is operable to block fluid flow from the hydraulic cylinder 43 to the respective accumulator 53 when the hydraulic cylinder is required to fix the front chassis portion 12 with respect to the front axle 31. In other words, when the crane 10 is operating with the front suspension system 29 in the “crane mode locked” condition.

[0084] The extension locking valve 61 is actuated to permit flow freely in both directions when the front suspension system 29 is to provide cushioning. In other words, when the crane 10 is operating with the front suspension system 29 in the first suspension mode (i.e. “travel mode”). In the first suspension mode (i.e. during “travel mode”), the extension locking valve 61 is held open at all times.

[0085] Extension locking valve 61 is selectively actuated as required to permit flow the reverse direction when the front suspension system 29 is required to provide dynamic levelling. In other words, when the crane 10 is operating with the front suspension system 29 in the second suspension mode (i.e.“crane mode dynamic levelling”). More particularly, the extension locking valve 61 is selectively actuated to permit flow the reverse direction when the respective cylinder 43 is required to undergo extension during dynamic leveling; that is, whenever the respective cylinder 43 is commanded to extend.

[0086] The extension locking valves 61 are particularly useful when the crane 10 is articulating and operating at higher lift loads. In such circumstances, the opposite side hydraulic cylinder 43 may have a tendency to pull away from the axle 31. This is prevented by the respective extension locking valve 61 , which acts to blocks hydraulic fluid flow and thereby create a rigid connection between the respective side of the front chassis portion 12 and the axle 31.

[0087] In an alternative arrangement (not shown), the hydraulic cylinder 43 may be selectively locked against extension and contraction by other means; for example, a mechanical locking device.

[0088] Each second flow path 57 is operable to effect extension or contraction of the respective hydraulic cylinder 43 for varying the suspension height and maintaining the hydraulic cylinder in a condition corresponding to a selected suspension height. In this way, the hydraulic cylinders 43 can each be moved selectively and independently under the influence of fluid flow in the respective second flow path 57.

[0089] Each second flow path 57a, 57b may incorporate means operable to block fluid flow in the event of flow exceeding a prescribed flow rate. In the arrangement shown, such means comprises a velocity fuse 62. The purpose of the velocity fuse 62 is to prevent collapsing of the respective hydraulic cylinder 43 and consequently sudden movement of the crane boom 23, if there were to be a rupturing of the hydraulic circuit 51 and rapid loss of hydraulic fluid.

[0090] The hydraulic circuit 51 also includes a reservoir such as hydraulic tank 63 for a supply of hydraulic fluid (such as hydraulic oil) and a hydraulic pump 65 for delivering the hydraulic fluid under pressure. In this embodiment, the hydraulic pump 65 comprises a hydraulic piston pump.

[0091 ] The hydraulic circuit 51 also includes a pump control manifold 67, a main suspension control valve 69 and a suspension locking control valve 71.

[0092] The hydraulic pump 65 is connected to the main suspension control valve 69 by way of fluid pressure line 73 in which the pump control manifold 67 is incorporated. The pump control manifold 67 communicates with the suspension locking control valve 71 by way of fluid pressure line 75.

[0093] The suspension locking control valve 71 is in fluid communication with the hydraulic tank 63 by way of fluid line 77. The suspension locking control valve 71 is configured to provide control signals by way of signal line 79 to the lock valves 59 in the respective second flow paths 57 communicating with the hydraulic cylinders 43. In this embodiment, signal line 79 comprises a pressure hose which can be pressurised by hydraulic fluid to actuate the lock valves 59. In other words, signal line 79 comprises a fluid line which can be pressurised to provide a lock signal.

[0094] The pump control manifold 67 is configured to sense load on the hydraulic pump 65 by way of load sense line 81.

[0095] With this arrangement, the hydraulic pump 65 functions as a load-sensing variable hydraulic pump, supplying hydraulic fluid according to demand under the control of the pump control manifold 67. The hydraulic pump 65 delivers hydraulic fluid under pressure according to demand, under the control of the pump control manifold 67 In this way, hydraulic fluid flow occurs only when the hydraulic suspension system 42 requires it.

[0096] The pump control manifold 67 has two different relief pressure settings which are required when operating in the first suspension mode (i.e. travel mode) or the second suspension mode (i.e. crane mode dynamic levelling). Proportional valves (not shown) are incorporated in the pump control manifold 67 and are configured to allow control of the amount of hydraulic fluid flow. A dump valve (not shown) is also incorporated in the pump control manifold 67 to allow the crane 10 to be started in a high-pressure mode without engine stall.

[0097] Hydraulic fluid from the pump control manifold 67 is directed to the main suspension control valve 69 and to the suspension locking control valve 71.

[0098] The suspension locking control valve 71 is operable to switch the suspension system 29 between locked and unlocked conditions through actuation of the lock valves 59. When the lock valves 59 are actuated to block fluid flow along the first flow paths 56, the accumulators 53 are rendered inoperable, and as such the hydraulic cylinders 43 cannot yieldingly resist movement of the front axle 31 relative to the front chassis portion 12 to absorb shock loading and provide ride cushioning. In such circumstances, the hydraulic cylinders 43 are operable only in response to hydraulic fluid flow along the second flow paths 57 under the control of the main suspension control valve 69, with each hydraulic cylinder either undergoing extension or contraction to vary the suspension height and/or being maintained in a static (fixed) condition corresponding to a selected suspension height. [0099] The main suspension control valve 69 comprises a directional valve operable to selectively control hydraulic fluid flow along the two first flow paths 56a, 56b and the two second flow paths 57a, 57b.

[00100] The flow of hydraulic fluid along each second flow path 57a, 57b with respect to the respective hydraulic cylinder 43 may comprise inflow in the case of extension of the hydraulic cylinder 43 or outflow in the case of contraction of the hydraulic cylinder. The main suspension control valve 69 is operable to control flow along each second flow path 57a, 57b independently of the other. By way of example, in one case the flow in one flow path 57 may comprise an inflow and the flow in the other flow path 57 may comprise an outflow. In another case, both flows may be the same (either inflow or outflow), but at different flow rates. In yet another case, there may be flow in one flow path 57 but no flow in the other flow path 57. In still another case, the flows in the two flow paths 57a, 57b may be the same in terms of direction and flow rate.

[00101 ] The pick and carry crane 10 further comprises means 101 for sensing a spatial relationship of the chassis 11 and operating the hydraulic suspension system 42 accordingly to compensate for a variation from a permissible condition. The sense spatial relationship may comprise roll angle (e.g. sideways tilt) or pitch angle, or any other spatial characteristic of the chassis 1 1 as may be appropriate. In this embodiment, a spatial relationship comprising roll angle (e.g. sideways tilt) is sensed by way of a planarity sensor 103 mounted on the chassis 12, as best seen in Figure 2. In the arrangement shown, the planarity sensor 103 is mounted on front pivot coupling 15, although of course it may be mounted at any other appropriate location. Other ways of sensing the spatial relationship are of course also contemplated.

[00102] The pick and carry crane 10 further comprises means 105 for sensing the respective suspension heights at the two sides of the front chassis portion 12 (i.e. the suspension height associated with each set of front wheels 33). In the arranging shown, such means 105 comprises a height level sensor 107 associated with the respective hydraulic cylinder 43, as best seen in Figure 5. In other words, there are two height level sensors 107, one sensor 107a for sensing suspension height on the left side and the other sensor 107b for sensing suspension height on the right side.

[00103] The pick and carry crane 10 further comprises a control system 1 1 1 configured to receive signals from the planarity sensor 103 and the two height level sensors 107, and controlling operation of the suspension system 42. The control system 11 1 is illustrated schematically in Figure 18 and comprises a controller 1 13 in the form of an electronic control module (ECM). The controller 113 is in communication with not only the planarity sensor 103 and the two height level sensors 107, but also the pump control manifold 67, the main suspension control valve 69, and the suspension locking control valve 71. In addition, the controller 1 13 may be in communication with crane control system 1 15 and various systems 1 17 in the operator cab 25, including input devices (such as operator controls) and output devices (such as information and control displays).

[00104] In operation, the pick and carry crane 10 can be operated in the travel mode, or either one of the two crane modes (i.e. "crane mode dynamic levelling” or “crane mode locked”), as described previously.

[00105] In the travel mode, the suspension locking valve 71 is set (via control system 1 1 1 ) to open (unlock) the lock valves 59 incorporated in the first flow paths 56a, 56b. With the lock valves 59 open, hydraulic fluid can flow along the first flow paths 56a, 56b and the hydraulic cylinders 43 can yieldingly resist movement of the front axle 31 (and hence the front wheels 33), thereby absorbing shock loading to provide ride cushioning. In this mode, the accumulators 53 are active, responding to pulsations in hydraulic fluid arising from shock loadings on the hydraulic cylinders 43 and providing the cushioning. This allows the pick and carry crane 10 to be driven as a road vehicle on roadways from one worksite to another.

[00106] More particularly, In the "travel mode” configuration, hydraulic fluid can flow under the control of the main suspension control valve 69 along each second flow path 57 independently of the other, as previously described. The main suspension control valve 69 is set or controlled by the via control system 1 1 1. In such circumstances, the hydraulic cylinders 43 are operable in response to hydraulic fluid flow (as either inflow or outflow) along the respective the second flow path 57, with each hydraulic cylinder either undergoing extension or contraction to provide cushioning. In this configuration, the hydraulic cylinders 43 are set to provide a ride height, which is typically approximately two-thirds of their available travel. In this suspension mode, the accumulator locking valves 59 and the extension locking valves 61 are constantly open, allowing hydraulic fluid to flow freely to the accumulators 53, which is turn provide a springing or cushioning effect to deliver comfort while driving. [00107] When required to perform a lift and carry operation, the pick and carry crane 10 is set to one of the two crane modes (i.e. "crane mode dynamic levelling” or “crane mode locked”). In particular, the suspension locking control valve 71 is set (via control system 1 1 1 ) to close (lock) the lock valves 59 incorporated in the first flow paths 56a, 56b. With the lock valves 59 closed, hydraulic fluid is blocked from flowing along the first flow paths 56a, 56b, thereby rendering the accumulators 53 inoperative and restricting movement of the hydraulic cylinders 43.

[00108] More particularly, when the suspension system 29 is to be locked, the controller 1 13 sends a locking signal to the suspension locking valve 71. The suspension locking valve 71 incorporates small accumulator (not shown) which becomes pressurised by oil on line 75 from the pump, which in turn pressurises the hydraulic signal line 79. This locks the two lock valves 59 (i.e. close the lock valves). When the locking signal is removed, the pressure in the accumulator associated with the suspension locking valve 71 drops to the tank pressure via line fluid line 77, depressurising signal line 79 and unlocking the lock valves 59 (i.e. opening the lock valves blocking them open).

[00109] In“crane mode locked” configuration, the hydraulic cylinders 43 are locked against movement (because the lock valves 59 are closed and the directional valves 61 block fluid flow from the hydraulic cylinders 43 to the respective accumulator 53). In this configuration, the hydraulic cylinders 43 are retracted fully to lower the crane into its lowermost condition. Any stored hydraulic fluid is removed from the accumulators 53 The accumulator locking valves 59 and the extension locking valves 61 are closed or configured to block fluid flow, thereby preventing any flow into and out of the hydraulic cylinders 43 and this establishing a rigid connection. In this suspension mode, the vehicle can be operated as a crane for pick and carry loads at low vehicle speed. There is effectively no comfort, as this mode makes the front of the vehicle rigid. In this configuration, the load-lifting capacity of the crane may need to be derated when traversing slopes or changing direction, as is the case with prior art pick and carry cranes (as discussed previously).

[001 10] In“crane mode dynamic levelling” configuration, the lock valves 59 are closed at all times, preventing hydraulic fluid flow along first flow paths 56 to the accumulators 53. However, the hydraulic cylinders 43 remain responsive to hydraulic fluid flows (inflows or outflows) along the second flow paths 57 under the control of the main suspension control valve 69 to provide levelling. The main suspension control valve 69 in controlled by the control system 1 1 1 having regard to input signals received from the planarity sensor 103 and the two height level sensors 107a, 107b. If there is a determination by the control system 1 1 1 of a change in spatial relationship of the front chassis portion 12 (e.g. a sideways tilt) in response to an input from planarity sensor 103, the control system 1 11 actuates the main suspension control valve 69 to cause extension or contraction of either one or both of the hydraulic cylinders 43 (as necessary) to compensate for the change and return the front chassis portion 12 to the required level state. Each extension lock valves 61 will be caused to open to permit reverse fluid flow whenever an extension command is sent to the respective hydraulic cylinder.

[001 1 1 ] In this way, the hydraulic cylinders 43 function as levelling devices, actuating as required to maintain the required level state. Information provided by the two height level sensors 107a, 107b enables the control system 1 1 1 to make a determination as to which of the two hydraulic cylinders 43a, 43b should be actuated and the manner of actuation required, in order to provide appropriate compensation and return the front chassis portion 12 to the required level state (as depicted in Figure 10).

[001 12] Accordingly, the pick and carry crane 10 is dynamically levelled during the “crane mode dynamic levelling” configuration. In particular, the hydraulic suspension system 42 operates automatically (i.e. without operator input) to maintain the front chassis portion 12, and the boom 23 carried thereon, in the required level state if uneven ground is encountered during load lifting and load carrying. In other words, once the crane 10 is operated outside a designated slope value (as measured by the planarity sensor 103), the controller 113 will operate the front suspension system 29 to regulate hydraulic oil flow to the required hydraulic cylinder 43 to cause extension or retraction as required to level the front chassis portion 12. The controller 1 13 receives slope information (e.g. as an input from the planarity sensor 103) and depending upon the slope angle, activates the pump 65 and prescribes a flow rate to level the hydraulic suspension system 42 at the required speed. When the actual slope approaches the designated slope value (as measured by the planarity sensor 103), the controller 1 13 slows the flow rate (using the proportional valves) to ensure no over-shooting of the designated slope value. [001 13] When the suspension system 29 is to be unlocked, the controller 1 13 sends an unlocking signal to the suspension locking valve 71 , opening it in the opposite direction to release (i.e. reduce) hydraulic fluid pressure from signal line 79, thereby causing the two lock valves 59 to unlock (i.e. open). The suspension locking valve 71 may be caused to release pressure by exposure to a low pressure line in communication with a low pressure tank, thereby allowing stored pressure to drop (say to zero pressure).

[001 14] In this embodiment, the“crane mode dynamic levelling” configuration is selected by the operator, for example by way of a switch in the operator cab 25.

[001 15] Referring now to Figure 19, there is shown a hydraulic circuit 91 incorporated in a second embodiment of the mobile crane 10. The hydraulic circuit 91 is similar in many respects to hydraulic circuit 51 incorporated in the first embodiment of the mobile crane 10 (as described previously), and so similar reference numerals are used to identify similar parts. In particular, hydraulic circuit 91 is configured to selectively provide a first flow path 56 and a second flow path 57 for hydraulic fluid communicating with each hydraulic cylinder 43, as shown in Figure 19. In this second embodiment, various components of the hydraulic circuit 91 are integrated into other parts to provide common assemblies (and so are not seen in Figure 19). By way of example, assembly 93 which provides the main control valve 69 also incorporates the pump control manifold and suspension locking valve (which correspond to the pump control manifold 67 and suspension locking valve 71 in the first embodiment). Similarly, assemblies 95a, 95b each incorporate a respective hydraulic cylinder 43, together with an associated extension locking valve and velocity fuse (which correspond to the parts 61 and 62 in the first embodiment).

[001 16] In each of the two previous embodiments, the pick and carry crane 10 is operable with the front suspension system 29 in any one of three available suspension modes, being a first mode in which the hydraulic cylinders 43 are operable as shock absorbers between the axle and the chassis, a second mode in which the hydraulic cylinders 43 are operable to vary suspension height, and a third mode in which the front chassis portion 12 is fixed with respect to the front axle 31.

[001 17] The front suspension system 29 need not necessarily be configured to provide cushioning; specifically, the hydraulic cylinders 43 need not be operable as shock absorbers. More particularly, the hydraulic cylinders 43 may be selectively operable to vary suspension height or to fix the front chassis portion 12 with respect to the front axle 31 , and cushioning may be provided separately. Cushioning may, for example, be provided by way of a separate spring system between the front axle 31 and the front chassis portion 12 to cushion the chassis 11 by damping shock loads from bumps and holes encountered during travel of the mobile crane 10. The spring system may be of any appropriate form, including for example a mechanical spring system (e.g. leaf springs), a pneumatic spring system (e.g. air springs), or a hydraulic system with provision for damping fluid pulses, as would be understood by a person skilled in the art.

[001 18] Such an arrangement is featured in a third embodiment of the mobile crane 10. Referring now to Figure 20, in which there is shown a hydraulic circuit 101 incorporated in the third embodiment of the mobile crane 10, the hydraulic cylinders 43 are selectively operable in a mode to vary suspension height, and a mode in which the front chassis portion 12 is fixed with respect to the front axle 31. However, the front suspension system 29 is not configured to provide cushioning; specifically, the hydraulic cylinders 43 are not operable as shock absorbers.

[001 19] The hydraulic circuit 101 is similar in many respects to hydraulic circuit 51 incorporated in the first embodiment of the mobile crane 10 (as described previously), and so similar reference numerals are used to identify similar parts. In particular, hydraulic circuit 101 is configured to selectively provide a first flow path 56 and a second flow path 57 for hydraulic fluid communicating with each hydraulic cylinder 43, as shown in Figure 20. Each flow path 56a, 56b does not incorporate an accumulator or a lock valve (which correspond to the parts 53 and 59 in the first embodiment), as there is no cushioning,

[00120] Similar to the second embodiment, various components of the hydraulic circuit 101 are integrated into other parts to provide common assemblies (and so are not seen in Figure 20). By way of example, assembly 103 which provides the main control valve 69 also incorporates the pump control manifold and suspension locking valve (which correspond to the pump control manifold 67 and suspension locking valve 71 in the first embodiment). Similarly, assemblies 105a, 105b each incorporate a respective hydraulic cylinder 43, together with an associated extension locking valve and velocity fuse (which correspond to the parts 61 and 62 in the first embodiment). [00121 ] With this arrangement, the mobile crane 10 may selectively operate in either one of two conditions in a crane mode; one condition being with the suspension system configured to operate in the mode whereby the hydraulic cylinders 43a, 43b are operable to vary suspension height for dynamic levelling, and the other condition being with the suspension system configured to operate in the mode whereby the hydraulic cylinders 43a, 43b are operable to fix the front chassis portion 12 is fixed with respect to the front axle 31. Cushioning in the travel mode is provided separately, as described previously; for example, by way of a spring system (not shown) between the front chassis portion 12 and the front axle. The spring system may be of any appropriate form, including for example a mechanical spring system (e.g. leaf springs), a pneumatic spring system (e.g. air springs), or a hydraulic system with provision for damping fluid pulses.

[00122] In each of the previous embodiments, the pick and carry crane 10 is selectively operable with the front suspension system 29 in a mode in which the front chassis portion 12 is fixed with respect to the front axle 31. However, the pick and carry crane 10 need not necessarily have specific provision for operation in such a mode.

[00123] In a further embodiment (not shown), the pick and carry crane 10 may simply be operable in a mode in which the hydraulic cylinders 43 are operable to vary suspension height, and perform no other function. In such an arrangement, cushioning in the travel mode may be provided separately (as described previously); for example, by way of a spring system (not shown) between the front chassis portion 12 and the front axle. Such an embodiment would essentially be the same as the third embodiment when the latter is operating in the“crane mode dynamic levelling” configuration. In other words, it is essentially the same as the third embodiment without implementation of the “crane mode locked” configuration.

[00124] In yet another embodiment (not shown), the pick and carry crane 10 may be operable with the front suspension system 29 in a mode in which the hydraulic cylinders 43 are operable as shock absorbers between the axle and the chassis and further mode in which the hydraulic cylinders 43 are operable to vary suspension height. Such an embodiment would essentially be the same as the first embodiment when the latter is operating in the “travel” configuration and “crane mode dynamic levelling” configuration respectively. In other words, it is essentially the same as the first and second embodiments without implementation of the“crane mode locked” configuration. WO 2020/154765 PCT/AU2020/050057

[00125] From the foregoing, it is evident that the present embodiments each provides a dynamic levelling suspension system for the crane 10. It is believed that this would allow a high level of crane safety to be maintained without any deration of lifting capacity.

[00126] It should be appreciated that the scope of the invention is not limited to the scope of the embodiments described. In another embodiment, for example, the hydraulic suspension system could be applied to both front and rear suspensions. Further, it could be applied to multiple axles.

[00127] The foregoing disclosure is intended to explain how to fashion and use the particular embodiments described, rather than to limit the true, intended, and fair scope and spirit of the present disclosure. The foregoing description is not intended to be exhaustive, nor to be limited to the precise forms disclosed.

[00128] It should be appreciated that various modifications can be made without departing from the principles described herein. Therefore, the principles should be understood to include all such modifications within its scope.

[00129] While the embodiments described herein were primarily developed and discussed in relation to a pick and carry crane, it should be understood that the principles described herein may have application to various other vehicles having a travel mode and a load-lifting and carrying mode.

[00130] The terminology used herein is for the purpose of describing particular example embodiments only and is not intended to be limiting.

[00131 ] As used herein, the singular forms“a”,“an” and“the” may be intended to include the plural forms as well, unless the context clearly indicates otherwise.

[00132] The method steps, processes, and operations described herein are not to be construed as necessarily requiring their performance in the particular order discussed or illustrated, unless specifically identified as an order of performance. It is also to be understood that additional or alternative steps may be employed.

[00133] Reference to any positional descriptions, such as "top”, “bottom" and “side”, are to be taken in context of the embodiment described and are not to be taken as limiting the invention to the literal interpretation of the term but rather as would be understood by the skilled addressee.

[00134] Spatially relative terms, such as “inner,” “outer,” “beneath”, “below”, “lower”,“above”,“upper” and the like, may be used herein for ease of description to describe one element or feature’s relationship to another element(s) or feature(s) as illustrated in the figures. Spatially relative terms may be intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, elements described as“below” or“beneath” other elements or features would then be oriented“above” the other elements or features. Thus, the example term“below” can encompass both an orientation of above and below. The device may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly.

[00135] Although the terms first, second, third, etc. may be used herein to describe various elements, components, regions, layers and/or sections, these elements, components, regions, layers and/or sections should not be limited by these terms. These terms may be only used to distinguish one element, component, region, layer or section from another region, layer or section. Terms such as“first,”“second,” and other numerical terms when used herein do not imply a sequence or order unless clearly indicated by the context. Thus, a first element, component, region, layer or section discussed below could be termed a second element, component, region, layer or section without departing from the teachings of the example embodiment.

[00136] When an element or layer is referred to as being “on”, “engaged to”, “connected to” or“coupled to” another element or layer, it may be directly on, engaged, connected or coupled to the other element or layer, or intervening elements or layers may be present. In contrast, when an element is referred to as being“directly on,” “directly engaged to”,“directly connected to” or“directly coupled to” another element or layer, there may be no intervening elements or layers present. Other words used to describe the relationship between elements should be interpreted in a like fashion (e.g., “between” versus“directly between,”“adjacent” versus“directly adjacent,” etc.). As used herein, the term“and/or” includes any and all combinations of one or more of the associated listed items. [00137] Additionally, where the terms“system”,“device”, and“apparatus" are used in the context of the invention, they are to be understood as including reference to any group of functionally related or interacting, interrelated, interdependent or associated components or elements that may be located in proximity to, separate from, integrated with, or discrete from, each other.

[00138] Furthermore, in the embodiment described herein (including the following claims), the word“determining” is understood to include receiving or accessing the relevant data or information.

[00139] Throughout this specification, unless the context requires otherwise, the word "comprise" or variations such as "comprises" or "comprising", will be understood to imply the inclusion of a stated integer or group of integers but not the exclusion of any other integer or group of integers.

[00140] Furthermore, throughout the specification and the claims that follow, unless the context requires otherwise, the word “include” or variations such as “includes” or“including”, will be understood to imply the inclusion of a stated integer or group of integers but not the exclusion of any other integer or group of integers.

Claims

1. A mobile crane comprising a chassis, a portion of the chassis being supported on an axle mounted on a wheel, a suspension system between the axle and the chassis, the suspension system comprising a suspension device selectively operable in a mode in which the suspension device is operable to vary suspension height, and means for sensing a spatial relationship of the chassis and operating the suspension system accordingly to compensate for a variation from a permissible condition.

2. The mobile crane according to claim 1 wherein said means for sensing a spatial relationship of the chassis comprises a planarity sensor.

3. The mobile crane according to claim 1 or 2 further comprising a means for sensing suspension height.

4. The mobile crane according to claim 2 or 3 further comprising a controller configured to receive signals from said means for sensing a spatial relationship of the chassis and controlling operation of the suspension system.

5. The mobile crane according to claim 4 wherein the controller is configured to receive signals from said means for sensing suspension height to provide an indication of suspension height as part of controlling operation of the suspension system.

6. The mobile crane according to any one of the preceding claims wherein the suspension system further comprises a spring system between the axle and the chassis for cushioning the chassis by damping shock loads.

7. The mobile crane according to claim 6 wherein the spring system is selected from a group consisting of a mechanical spring system, a pneumatic spring system or a hydraulic system with provision for damping fluid pulses.

8. The mobile crane according to claim 6 or 7 wherein the spring system is separate from the suspension device.

9. The mobile crane according to claim 6 wherein the spring system comprises the suspension device, wherein the suspension device is adapted to facilitate cushioning.

10. The mobile crane according to any one of the preceding claims selectively operable in either one of two conditions in a crane mode, wherein in one condition the suspension system is configured to operate in the mode whereby the suspension device is operable to vary suspension height for dynamic levelling, and wherein in the other condition the suspension device is operable as a shock absorber between the axle and the chassis.

11. The mobile crane according to claim 10 selectively operable in a mode in which the chassis is fixed with respect to the axle.

12. The mobile crane according to claim 1 1 wherein the suspension device is selectively operable in any one of three available modes, wherein the three modes comprise a first mode in which the suspension device is operable as a shock absorber between the axle and the chassis, a second mode in which the suspension device is operable to vary suspension height, and a third mode in which the chassis is fixed with respect to the axle.

13. The mobile crane according to any one of the preceding claims wherein the suspension device comprises a power device adapted to be selectively movable between extended and contracted conditions.

14. The mobile crane according to claim 13 wherein the power device is further adapted to be selectively fixed against movement between the extended and contracted conditions.

15. The mobile crane according to any one of the preceding claims wherein the suspension system comprise a hydraulic suspension system.

16. The mobile crane according to claim 15 when dependent on claim 14 wherein the power device comprises a hydraulic cylinder.

17. The mobile crane according to claim 16 wherein the hydraulic suspension system further comprise a hydraulic circuit in which the hydraulic cylinder is incorporated.

18. The mobile crane according to claim 17 wherein the hydraulic circuit comprises a flow path operable to effect extension or contraction of the hydraulic cylinder for varying the suspension height and maintaining the hydraulic cylinder in a condition corresponding to a selected suspension height.

19. The mobile crane according to claim 17 or 18 wherein the hydraulic circuit further comprise means for absorbing hydraulic shock, thereby to provide cushioning between the axle and the chassis.

20. The mobile crane according to claim 19 wherein said means for absorbing hydraulic shock comprises an accumulator.

21. The mobile crane according to any one of claims 17 to 20 wherein the hydraulic circuit is configured to selectively provide first and second flow paths for hydraulic fluid communicating with the hydraulic cylinder, the first flow path incorporating or communicating with said means for absorbing hydraulic shock and the second flow path bypassing the means for absorbing hydraulic shock, wherein the second flow path provides said flow path operable to effect extension or contraction of the hydraulic cylinder for varying the suspension height and maintaining the hydraulic cylinder in a condition corresponding to a selected suspension height

22. The mobile crane according to claim 21 wherein the first flow path incorporates means for selectively blocking fluid flow, thereby restricting the hydraulic cylinder against movement to provide shock absorption for cushioning.

23. The mobile crane according to claim 20 or 21 wherein the first flow path incorporates means to permit hydraulic fluid flow from the accumulator to the hydraulic cylinder and prevent flow in the reverse direction, unless actuated to permit the reverse flow.

24. The mobile crane according to claim 21 , 22 or 23 wherein the second flow path is operable to effect extension or contraction of the hydraulic cylinder for varying the suspension height and maintaining the hydraulic cylinder in a condition corresponding to a selected suspension height.

25. The mobile crane according to any one of claims 21 to 24 wherein the second flow path incorporates means operable to block fluid flow in the event of flow exceeding a prescribed flow rate.

26. The mobile crane according to any one of the preceding claims configured as a pick and carry crane, wherein the chassis comprises an articulated chassis having front and rear chassis portions pivotally coupled together.

27. The mobile crane according to claim 26 wherein the suspension system is provided on the front chassis portion and comprises two of the hydraulic cylinders, one corresponding to each side of the front chassis portion.

28. The mobile crane according to claim 27 wherein each hydraulic cylinder is connected between the axle and the front chassis portion in a manner accommodating angular movement between the axle and the front chassis portion..

29. The mobile crane according to any one of claims 3 to 28 wherein said means for sensing suspension height comprises a sensor and wherein the sensor is mounted between the chassis portion and the axle.

30. A method of operating a mobile crane according to any one of the preceding claims, the method comprising selectively and optionally operating the mobile crane with the suspension system in a mode in which suspension height is variable.

31. A method of operating a mobile crane having a chassis, an axle, and a suspension system between the chassis and the axle, the method comprising selectively and optionally operating the mobile crane with the suspension system in a mode in which suspension height is variable.

32. The method according to claim 30 or 31 further comprising sensing a spatial relationship of the chassis and operating the suspension system accordingly to effect variation of the suspension height to compensate for a variation from a permissible condition.

33. The method according to any one of claims 30 to 32 further comprising selectively and optionally operating the mobile crane with the suspension system in a further mode to provide shock absorption between the axle and the chassis

34. The method according to any one of claims 30 to 33 further comprising selectively and optionally operating the mobile crane with the suspension system in a further mode in which the chassis is fixed with respect to the axle.

35. A method of operating a mobile crane having a chassis, an axle, and a suspension system between the chassis and the axle, the method comprising selectively and optionally operating the mobile crane with the suspension system in a first mode to provide shock absorption between the axle and the chassis, operating the mobile crane with the suspension system in a second mode in which the suspension height is selectively variable, and operating the mobile crane with the suspension system in a third mode in which the chassis is fixed with respect to the axle.