The present invention relates to improvements in and relating to slew devices, more particularly to periodically or predominantly mobile vehicles comprising working gear which is adapted to slew or rotate during the course of operations for which the vehicle is intended. In its preferred embodiment the present invention relates to means for self-levelling the upper body of such vehicle comprising working gear and/or to means for automatically locking such slew gear to prevent accidental or unintentional slewing when unattended.

Apparatus and vehicles comprising slewing working gear are of extremely useful application, both industrially and privately, for all kinds of construction, forestry, agriculture, mining, excavation, demolition operations in particular because of the ability to more easily manoeuvre the working gear to perform certain jobs, either simultaneously with manoeuvring the vehicle itself or from a fixed standing position of the vehicle. Due to the relatively large investment in obtaining such vehicles, it is not uncommon for individuals or companies to hire apparatus whereby frequent transport thereof across smaller or larger distances on the back of a truck or other transporter is also not uncommon. Moreover operators of such apparatus and vehicles are not necessarily expert in the requirements therefor. Moreover the industrial nature of such work often requires dedicated operation at a given site and on completion of that operation transport to another site to commence new operations.

In common practice locking mechanisms for slew devices comprise a simple manually activated pin or other catch which is engaged typically during

transport of the vehicle between sites, however it is easy for an operator to forget to engage the lock or in the case of handing over the vehicle to a transporter it is not always clear whose responsibility it is to ensure the safety lock is in place. Accordingly there is a need for a self-activating automatic dead man device to prevent accidents to other road users or pedestrians or operators in the vicinity of the device during transport or use.

It will be apparent that much of the working operation of such vehicles is on off road terrain, this prevents problems both in traversing the terrain using wheeled or tracked vehicles and in positioning the vehicle on a suitably flat base from which it is possible to access the point at which it is desired to commence operations. Moreover in certain applications it is necessary to take great caution in traversing the terrain which is fragile, for example in forestry the major obstacles comprise tree stumps which will provide new growth and should not be damaged more than is absolutely necessary. Whilst there is a preference to using tracked vehicles to spread the downward pressure of the vehicle and avoid permanently damaging tree roots causing the trees to die slowly over the course of a couple of years from the time of damaging, the problems with levelling a tracked vehicle are more acute.

Accordingly there is a need for vehicles, in particular for use in forestry and more particularly in tree harvesting on multi ten thousand hectare sites, for example the eucalyptus plantations in Uruguay and the like, which is able to traverse very rough conditions without causing damage to the environment, which is stable both for means of safety and for convenience of operation, which is reliably operable on soggy or marshy ground and which safely enables prolonged working hours due to improved comfort and reduced fatigue during operations.

The present invention provides a vehicle which is able to address all of these problems in admirable fashion, by means of provision of a self-levelling device for the upper body of the vehicle, which device is activated by the motion of the vehicle. Advantageously such vehicle may comprise one or two tracks instead of a wheelbase, whereby it can more easily manoeuvre across the necessary terrain, in particular soggy and marshy terrain, with minimum damage. In a further aspect of the invention there are provided disabling devices, in particular so called "deadman" devices to enhance the safety factor of slew devices in general and the self-levelling slew devices of the first aspect of the invention in particular.

Advantageously the disabling device of the invention comprises a resiliently biased member which is adapted to engage the slewing gear only on the deactivation of the disabling system. More particular the resiliently biased member is linked or associated with a driver recognition device, more preferably with a weight sensor associated with the driver's seat, standing or leaning support platform, whereby the disabling system is only deactivated when an operator is present in a control position.

Accordingly in its broadest aspect the invention relates to self-levelling and/or self-disabling mechanisms, in particular slew mechanisms.

There is thus provided in accordance with the first embodiment of the present invention, a vehicle comprising chassis means and body means wherein the body means is independently manoeuvrable with respect to the chassis means, in particular the body means is self-levelling whereby it is adapted to retain a substantially constant planar orientation despite any planar deviation of the chassis means, preferably to retain a substantially horizontal planar orientation

or attitude and/or minimise displacement of centre of gravity of the body means in the event of planar deviation of the chassis means.

Reference herein to body means is to any part of the vehicle which is intended for performing mechanical operations as hereinbefore defined, such as construction, demolition, excavation, forestry or other such operations, and/or to any part of the vehicle which is to be occupied by an operator.

Reference herein to chassis means is to any part of the vehicle which comprises a frame, support or other chassis-type structure accommodating wheels, track(s) or fixtures therefore for the purpose of periodically or otherwise transporting the vehicle.

Preferably the body means comprises a tilt frame which is adapted to oscillate with respect to the chassis means.

Preferably the tilt frame is adapted to oscillate in one or more vertical, or substantially vertical planes, more preferably in or substantially in two peφendicular opposed (substantially) vertical planes, or in a single (substantially) vertical plane which includes the trajectory of forward and reverse motion of the vehicle.

Preferably the body means is adapted to oscillate by means of motion of the chassis means and is adapted to lock in fixed attitude to the chassis means on cessation of motion of the chassis means. Advantageously this enables a substantially instantaneous response as a direct reaction to a deviation of the chassis means.

Preferably the oscillating means comprises one or more couples of compensating means arranged about the centre of gravity of the body means in or substantially in a plane and adapted to absorb a compression force applied to one side of a line of action of the centre of gravity and transmit this as a compensating extension force applied to an opposing side of the same line of action thereby self-levelling the body means.

For example and more preferably the oscillating means comprises one or more couples of hydraulic rams connected together, in couples or pluralities thereof.

Alternatively and preferably the oscillating means comprises a pivot (seat), pivotal joint, groove or bar means or a universal joint (seat) arranged at the centre of gravity of the body means or in the line of action thereof and adapted to cooperate with a corresponding pivot (seat), pivotal joint, groove or bar means or universal joint (seat) located on the chassis means, to provide tilt or oscillation to the body means in response to motion of the chassis means, or to isolate the motion of the body means from the motion of the chassis means.

Preferably the oscillating means comprises a combination of the foregoing hydraulic and pivotal means whereby the upper body load is distributed enabling finer response, due to a combination of isolated motion and reaction response.

Preferably the self-levelling mechanism comprises locking means which is manually or automatically engagable, preferably an automatically engagable locking means is adapted to be activated by cessation of motion of the chassis

means, more preferably it comprises a hydraulic locking means which is activated by the motion of the chassis means coming to neutral pressure.

The vehicle may operate on any desired system of wheels or tracking. However preferably the vehicle is a tracked vehicle comprising single or multiple tracks, preferably multiple tracks have independent drive means.

Preferably the tilt frame comprises two couples of oscillating means substantially in parallel planar arrangement, each hydraulically coupled to a track of the chassis means. Preferably the locking means of both couples is released by drive activation of either or both tracks.

Preferably the body means is able to oscillate up to 25° vertical angle with respect to its position with the chassis means at horizontal rest, preferably up to 20° , more preferably 8° to 15° , for example substantially 10° , depending on the nature of the slewing gear and the requirements for self-levelling.

Preferably the body means is adapted to pivot in a horizontal or tilted horizontal plane, suitably the body means is a slew means, comprising a rotating bearing track, gear or chain mounting between an upper body means, comprising an operators/control centre or cab and working gear, and a lower body means comprising the tilt frame, preferably the body means is able to rotate tlirough up to 360° or multiples thereof, or up to 180° . Preferably the body means rotation is controlled by a braked hydraulic "slew" motor or equivalent means adapted for controlling heavy loads or slew forces/swing.

Preferably the body means comprises working gear in the form of tree harvesting, demolition, excavation, or construction gear such as lifting,

cutting, stripping, digging, pendulum weight or transport gear or a combination thereof, preferably comprised in a double or triple jointed arm, more preferably adapted to be independently rotated with respect to the body means, suitably by means of a rotating track mounting between the upper body and the gear arm, preferably adapted to rotate through up to 180°, more preferably up to 90° arc. Preferably the working gear rotation is controlled by means of a braked hydraulic "slew" motor or equivalent as hereinbefore defined.

Preferably the vehicle comprises a disabling means adapted to disable any one or all mechanisms thereof, and preferably being automatically activated and deactivated, by means of recognition of an operators absence and presence respectively, or being manually activated by use of a suitable code or key.

Preferably any disabling means is concealed or comprised in a part of the vehicle which may be easily accessed by an operator but may not be accidentally activated, for example in a part of the operators/control centre remote from the control panels, preferably in a part thereof which is typically altered between an operational and non-operational position thereby enabling a further disablement, such as in the controllers seat or standing platform armrest or headrest which may be lowered during operation thereby enabling deactivation of the disabler.

Preferably independent locking or disabling means are provided for each independent mechanism of the vehicle. As hereinbefore mentioned the tilt/oscillation means is additionally also disabled or locked by cessation of motion of the chassis means. Such may also optionally apply where

appropriate for certain working gear slew arms and upper bodies where it is not intended to rotate these during motion of the vehicle.

Preferably the vehicle is adapted for use in off-road construction, forestry, agriculture, mining, excavation, demolition or other application, preferably in forestry where it is required to traverse uneven fragile terrain, more preferably for cutting trees and processing the timber by means of delimbing, sizing and transporting, which operations may be performed simultaneously with operation of the chassis, tilt and slew mechanisms of the vehicle.

Preferably the vehicle is self-powered or adapted to be powered by external means, for example where it is intended to be used in a fixed location and need only be transported between locations by means of temporarily or permanently affixed wheel or track means.

In accordance with the second aspect of the invention there is moreover provided a disabling system for a rotating or slewing mechanism comprising a resiliently biased engaging member adapted to disengage a rotating or slewing gear or portion thereof and a drive mechanism (portion) for the rotation or slew thereof, on the activation of the disabling system. Preferably the slew mechanism is prevented by suitable means from rotation or slew when (partially) disengaged.

Preferably the resiliently biased engaging member is a portion of a gear box, chain drive, braked hydraulic "slew" motor or bearing means or the like which is biased into cooperation with the corresponding portion of the slew mechanism, for example is a gear wheel or tooth base or the like.

Preferably the engaging member is linked or associated with a driver- recognition device, more preferably with a weight sensor associated with the drivers seat, standing or leaning/support platform.

More preferably the engaging member comprises hydraulically resiliently biased means such as spring or rubber compression means, as a weight sensor, to the operators seat or platform.

Preferably such disabling means is adapted to sense a minimum weight of the order of 45 kg or more, suitably of 60 kg or more, typically an adult weight, and is optionally adjustable to enable some degree of driver recognition.

Preferably the disabling system is coupled to an additional security system, such as a pedal-release lock arm or headrest located lock, more preferably requiring simultaneous occupation of the operators seat or platform and the foot control region.

Preferably the engaging member is mounted on a slide supported on either of the slewing gear or the drive mechanism with which the slewing gear is adapted to cooperate.

Preferably such disabling means is comprised in any industrial or private vehicle, stationary or mobile or adapted to be transported by suitable transport means, and comprising slew demolition, lifting, excavation, construction, mining, transporting, processing or cutting gear or a combination thereof. More preferably such disabling means is comprised in a vehicle comprising chassis means and body means which is self-levelling as hereinbefore defined.

The invention is now illustrated in non-limiting manner with reference to the figures, in which:

Figures 1-4 are side view, plan view, front elevation and rear elevation of a vehicle comprising self-levelling means according to the invention;

Figure 5 is a vertical section in a vehicle of Figure 1-4 comprising hydraulic and pivotal oscillating means;

Figures 6 and 7 are details thereof;

Figures 8 and 9 are vertical sections and plan views of a disabling system of the invention.

In Figure 1 a vehicle according to the invention, for example a tree harvester comprises chassis means (2), body means (1), self-levelling mechanism (3), working gear (4), track(s) (5), operators/control centre (6).

In Figure 2, the slew movement of working gear (4) is apparent, and of the body means.

In Figure 5, the self-levelling mechanism is illustrated comprising linked hydraulic rods (7) and pivot means (8).

In Figure 8, a suspension seat (9) is illustrated, which is linked by means of weight sensor (10) to pivot means (1 1) which is associated suitably by means of parallel link (12) to engaging means (13) which is under resilient bias (14) with relation to slewing mechanism (15).

In Figure 9 a detail of an engaging means (13) is illustrated comprising engaging mesh (16).

The invention for which it is desired to claim protection is thus apparent with reference to the foregoing description and the attached figures.