WO1997001269A1

WO1997001269A1 - Self-propelled work machines

Info

Publication number: WO1997001269A1
Application number: PCT/GB1996/001455
Authority: WO
Inventors: Alfred Fyffe Robertson
Original assignee: Alfred Fyffe Robertson
Priority date: 1995-06-28
Filing date: 1996-06-18
Publication date: 1997-01-16
Also published as: GB2302638A; GB9612683D0; AU6130796A

Abstract

A self-propelled timber harvester (10; 100) which is based on a conventional tracked excavator (12; 112) from which the conventional excavator arm has been removed and replaced by a parallel motion timber crane (24; 124) mounted on the slewable platform (16; 116) by means of a tilting crane boom (32; 132) carrying a secondary slewing mechanism (34; 134). The secondary slewing mechanism (34; 134) enables a harvesting head (26) to be steered between standing trees for thinning to be carried out without the overhanging back (22; 122) of the platform (16; 116) colliding with trees. Controlled tilting of the crane boom (34; 134) enables tilting of the secondary slewing axis to match the slope of ground on which trees are standing, enabling faster working with less damage.

Description

SELF-PROPELLED WORK MACHINES

This invention relates to self-propelled work machines, and relates more particularly but not exclusively to self-propelled timber harvesters .

Mechanised timber harvesters are now in common use in the United Kingdom and in Scandinavia. There are two principal variants of self-propelled timber harvester:-

(1) Purpose-built timber harvesters which are generally mounted on a wheeled-base unit with a crane capable of slewing through 180 degrees.

(2) Tracked-base timber harvesters which use a standard caterpillar-tracked excavator base as the power source. Such conversions have a full 360 degree slewing capability and use the pre-existing excavator digging arm as the crane/loader, on the end of which the harvester head is mounted.

Of these two principal types of timber harvester, the purpose-built machines are very expensive and suffer from reliability problems especially when used in the United Kingdom where typical operating conditions are not those for which such machines were specifically designed. On the other hand excavator-based timber harvesters are relatively reliable but suffer from at least two major disadvantages:

(A) Excavator-based timber harvesters are unable to work successfully in a standing crop of timber in order to carry out a thinning operation due to the slewing action of the harvester causing the harvester body to strike the standing trees.

(B) Excavator-based timber harvesters are similarly disadvantaged as described above in paragraph (A) when working on a slope, due to the knuckle of the crane/digging arm striking trees in the standing crop.

Notes: in this specification and in the appended claims, the following terms have the meanings ascribed to them below:

(i) "Thinning" means a timber harvesting operation performed in relation to a plurality of trees standing in a given area which results in selected trees in that area being cut at or near ground level and either left there or removed to a collection point while leaving intervening trees standing and preferably substantially undamaged;

(ϋ) "Clearfell" means a timber harvesting operation performed in relation to a plurality of trees standing in a given area which results in substantially all the trees in that area being cut at or near ground level and either left there or removed to a collection point. According to a first aspect of the present invention there is provided a self-propelled work machine comprising a platform constructed or adapted to be co- operatively fitted to and carried by a vehicle which has wheels or tracks by which the vehicle is rendered mobile, said platform being capable of controllably effecting a slewing movement relative to the vehicle when the platform is fitted on the vehicle, a manipulator linkage means co-operatively fitted to and carried by said platform, said manipulator linkage means being constructed or adapted to have a work-head mounted on said manipulator linkage means, and manipulator slewing means permitting the manipulator linkage means to be controllably slewed with respect to said platform.

Said manipulator slewing means preferably incorporates or is operatively associated with tilting means by which the slewing axis of the manipulator linkage means may be controllably tilted with respect to said platform.

According to a second aspect of the present invention there is provided a self-propelled work machine comprising a platform constructed or adapted to be co- operatively fitted to and carried by a vehicle which has wheels or tracks by which the vehicle is rendered mobile, said platform being capable of controllably effecting a slewing movement relative to the vehicle when the platform is fitted on the vehicle, a manipulator linkage means co-operatively fitted to and carried by said platform, said manipulator linkage means being constructed or adapted to have a work-head mounted on said manipulator linkage means, and manipulator tilting means permitting the manipulator linkage means to be controllably tilted with respect to said platform.

Said manipulator tilting means preferably incorporates or is operatively associated with manipulator slewing means permitting the manipulator linkage means to be controllably slewed with respect to said platform.

According to a third aspect of the present invention there is provided a self-propelled work machine comprising a platform constructed or adapted to be co¬ operatively fitted to and carried by a vehicle which has wheels or tracks by which the vehicle is rendered mobile, said platform being capable of controllably effecting a slewing movement relative to the vehicle when the platform is fitted on the vehicle, a manipulator linkage means co-operatively fitted to and carried by said platform, said manipulator linkage means being constructed or adapted to have a work-head mounted on said manipulator linkage means, and manipulator tilting/slewing means permitting the manipulator linkage means to be controllably tilted and/or slewed with respect to said platform.

In said first, second and third aspects of the invention, said work-head may be a timber-harvesting head.

According to a fourth aspect of the present invention there is provided a self-propelled mobile work machine comprising the combination of a vehicle which has wheels or tracks by which the vehicle is rendered mobile, and a work machine according to one of the first, second and third aspects of the present invention, the platform of said work machine being co- operatively fitted to and carried by said vehicle. Power for the self-propelled mobile work machine may be provided by a prime mover mounted on said platform.

According to a fifth aspect of the present invention there is provided a self-propelled timber harvester comprising a base having a laterally spaced-apart pair of endless tracks which can be mutually independently powered to provide the harvester with controlled mobility, a platform mounted on the tracked base by means of a primary slewing means enabling the platform to be controllably slewed about a primary slewing axis with reεpect to the base, a crane boom mounted on the platform by means of a secondary slewing means enabling the crane boom to be controllably slewed about a secondary slewing axis with respect to the platform, a crane arm mounted on the crane boom for controlled movement relative thereto, and timber harvesting means mounted on the crane arm to be selectively positioned relative to the platform by controlled movement of the crane arm and the crane boom.

The secondary slewing axis is preferably substantially offset from the primary slewing axis.

The secondary slewing means is preferably mounted on the platform through a pivot means having a pivot axis which is substantially normal to a notional plane including the secondary slewing axis and the primary slewing axis, the harvester further comprising tilt control means operable to effect controllably variable tilting of the secondary slew axis with respect to the platform.

According to a sixth aspect of the present invention there is provided a self-propelled timber harvester comprising a base having a laterally spaced-apart pair of endless tracks which can be mutually independently powered to provide the harvester with controlled mobility, a platform mounted on the tracked base by means of a primary slewing means enabling the platform to be controllably slewed about a primary slewing axis with respect to the base, a crane boom mounted on the platform through a pivot means having a pivot axis which is substantially normal to a notional plane including the primary slewing axis, tilt control means operable to effect controllably variable tilting of the crane boom with respect to the platform, a crane arm mounted on the crane boom for controlled movement relative thereto, and timber harvesting means mounted on the crane arm to be selectively positioned relative to the platform by controlled movement of the crane arm and the crane boom.

The crane boom is preferably mounted on the pivot means by means of a secondary slewing means enabling the crane boom to be controllably slewed about a secondary slewing axis with respect to the platform, the tilt control means being operable to effect controllably variable tilting of the secondary slew axis with respect to the platform.

Embodiments of the invention will now be described by way of example, with reference to the accompanying drawings wherein:

Fig. 1 is a side elevation of a first embodiment of timber harvester in accordance with the invention with its boom extended forwards; Fig. IA is a fragmentary view, to an enlarged scale, of part of the first embodiment;

Fig. 2 is a side elevation of a second embodiment of timber harvester in accordance with the invention, with its boom extended forwards;

Fig. 3 is a front elevation of the second embodiment, with its boom slewed leftwards; and

Fig. 4 is an exploded fragmentary view, to a much enlarged scale, of parts of the second embodiment.

Referring first to Fig. 1, a first embodiment of timber harvester 10 comprises a proprietary excavator base unit 12 minus the standard excavator digging arm. The base unit 12 has a laterally spaced-apart pair of endless tracks 14 (only one of which is visible in Fig. 1) which support the harvester 10 on the forest floor or other ground over which the harvester travels in use. The tracks 14 are independently powered by hydraulic motors (not shown) such that the harvester 10 is fully manoeuvrable in known manner.

The tracked base unit 12 mounts a platform 16 by way of a primary slewing unit 18 comprising a turntable bearing and a hydraulically-powered slewing motor (not visible) enabling the platform 16 to be controllably slewed or rotated about a vertical axis with respect to the base unit 12. (The primary slewing axis is vertical when the base unit 12 is resting on level ground; the primary slewing axis will tilt from vertical when the ground is not level but the inclination of the axis to the base will not vary and the term "vertical" will be used accordingly.) The front of the platform 16 mounts a control cabin 20 for housing the operator of the harvester 10 in operational proximity to the controls (not visible) for operating the various functions of the harvester. The control cabin 20 is arranged such that the operator will have a clear view of the operation of the harvester 10 and of the ground over which the harvester may be travelling. Provision may be made for optional remote control of the harvester 10.

The back of the platform 16 houses a prime mover 22 in the form of a diesel engine. The diesel engine 22 drives hydraulic pumps which power the various hydraulic motors (both rotary and linear) which power the various functions of the harvester 10 under the control of the operator manipulating the controls in the cabin 20. The engine 22 is preferably provided with automatic controls for optimisation of performance. The hydraulic pumps, motors and controls are conventional and may be those utilised in self- propelled excavators. The back of the platform 16 has a substantial overhang with respect to the primary slewing axis (the rotation axis passing vertically through the centre of the primary slewing unit 18) such that the weight of the prime mover 22 and of the associated hydraulic machinery forms a counter-balance for static and dynamic loading on the front of the platform 16, arising from parts and functions of the harvester 10 now to be described.

The parts of the harvester 10 thus far described are those of a conventional tracked excavator. As already mentioned, the standard excavator digging arm is removed, and substituted in the harvester 10 by a proprietary parallel-motion forestry crane 24. A proprietary tree-harvesting head 26 is mounted on the far end 28 of the crane 24. (The tree-harvesting head 26 is schematically depicted in Fig. 1.)

The near end 30 of the crane 24 is mounted on the front end of the platform 16 by means of a tilting crane boom 32 which carries a secondary slewing unit 34 (also shown, in enlarged detail, in Fig. IA) . The near end 30 of the crane 24 is attached to the turret 36 of the secondary slewing unit 34 such that operation of the secondary slewing motor 38 can slew the entire crane 24 (and with it, the harvesting head 26) relative to the platform 16, without the platform 16 slewing relative to the tracked base unit 12. This has the advantage that when the harvester 10 is thinning a standing crop of timber, the tree-harvesting head 26 can be steered to selected trees without slewing of the platform 16 relative to the base unit 12, thus avoiding damage to standing trees by collision with the overhanging rear of the platform 16 as it swings round during primary slewing. Crane steering by secondary slewing alone without primary slewing (i.e. by operation solely of the secondary slewing unit 34 without operation of the primary slewing unit 18) also mitigates the risk of injury to persons standing near the back of the harvester 10.

The conventional hydraulic circuitry of an excavator can be modified such that either operation of the primary slewing unit 18 or operation of the secondary slewing unit 34 can be effected by the operator's manipulation of a conventional slewing control in the control cabin 20. The circuit modification can take the form of a solenoid-operated diverter valve (not shown) in the slewing circuit, the direction of valve output (i.e. to the primary slewing unit 18 or, alternatively, to the secondary slewing unit 34) being selectable by operation of a solenoid-energising switch (not shown) in the control cabin 20.

The crane boom 32 is mounted on the front of the platform 16 by means of a pivot 40 having a horizontal pivot axis which is transverse to the platform 16. The crane boom 32 can be controllably raised and lowered around the pivot 40 by means of a hydraulically-powered linear motor or piston/cylinder assembly 42. In the configuration shown in Fig. 1, the secondary slewing axis (i.e. the axis of rotation of secondary slewing unit 34) is substantially parallel to the primary slewing axis (i.e. the axis of rotation of the primary slewing unit 18). However, controlled shortening or lengthening of the linear motor (or piston/cylinder assembly) 42 tilts the secondary slewing axis respectively backwards or forwards and hence off parallelism with the primary slewing axis. This controllable tilting of the secondary slewing axis enables the secondary slewing axis to be restored to true vertical whenever the harvester 10 is working on a slope, such that the primary slewing axis is off true vertical due to the underlying ground being non- horizontal.

Conversely, when the base unit 12 is standing on level ground but the harvester 10 is working on trees standing on a slope, the platform 16 can be slewed about the primary slewing axis by operation of the primary slewing unit 18 until the front of the platform 16 is facing the slope, whereupon the piston/cylinder assembly 42 can be controllably shortened or lengthened (according to whether the harvester is facing upslope or downslope) until the secondary slewing axis is at right angles to the slope to be worked over. This controllable tilting of the secondary slewing axis has the advantage that the tree-harvesting head 26 can be steered between trees to be left unharvested without damaging these trees .

The provision and utilisation of the tilting crane boom 32 allows the fitting and utilisation of a timber crane 24 of the parallel motion type and hence much faster operation in timber harvesting than would be possible with retention and use of a standard excavator digging arm in place of the parallel motion crane arm.

Secondary slewing and boom tilting functions as described above can be utilised independently of each other, and as such the structure appropriate to one of these functions can be omitted from the harvester 10 without affecting the advantages obtainable from use of the other function alone.

Referring now to Figs. 2 and 3, these show a second embodiment of timber harvester 100. By comparing Fig. 2 to the equivalent Fig. 1, it will be seen that the second embodiment 100 has the same fundamental features that were described above in respect of the first embodiment 10, but differing in certain details that will be subsequently specified. Accordingly, those parts and assemblies of the second embodiment 100 which are identical or analogous to parts and assemblies in the first embodiment 10 will be given the same reference numeral but preceded by a "1" (i.e. certain of the reference numerals in Figs. 2 and 3 are the corresponding reference numerals from Figs. 1 and IA, plus "100"). The following description of the second embodiment 100 will concentrate on certain distinctions from the first embodiment 10, and hence for a full description of any parts of the second embodiment 100 not dealt with below, reference should be made to the foregoing description of the identical or analogous parts of the first embodiment 10.

In the harvester 100, the tracked base unit 112 and the platform 116 and constituted by the relevant parts of a Caterpillar "320N" excavator. The parallel motion forestry crane 124 is constituted by a Mowi "EGS 170 L" parallel harvester crane, and the tree-harvesting head 126 fitted on the remote end 128 of the crane 124 is a Mowi 50-centimetre harvester head. The base of the crane 124 incorporates a force-balanced double-ram rack-and-pinion secondary slewing drive 138 which enables the slewing turret 136 to be controllably rotated. The base 132 of the secondary slewing drive 138 is formed with the transverse pivot 140 which enables the secondary slewing axis to be tilted with respect to the harvester platform 116. Trunnions 150 which support the pivot 140 are mounted on the outboard end 152 of a static link boom 154. The inboard end 156 of the link boom 154 is immovably secured to the front end of the platform 116 by means of pin joints 158 and 160 which link the boom 154 to pre-existing fastening points originally intended for the excavator arm (absent from the harvester 100). The crane-tilting hydraulic piston/cylinder assembly 142 extends from a pivot 162 adjacent the upper pin joint 158 to a pivot 164 on the back of the base 132 of the secondary slewing drive 138.

Controlled shortening or lengthening of the piston/cylinder assembly 142 tilts the secondary slewing unit 134 respectively backwards or forwards with respect to the platform 116.

Selective pressurisation of the rams forming the motors of the secondary slewing drive 138 controllably slews the turret 136, and with it the crane 124, about the secondary slewing axis (i.e. the nominally vertical rotation axis of the secondary slewing unit 134). In Fig. 2, the crane 124 is slewed to extend directly forwards of the platform 116, while in Fig. 3, the crane 124 is slewed ninety degrees leftwards.

The link boom 154 is shown assembled into the harvester 100 in Fig. 2, and is shown separately in elevation and to an enlarged scale in Fig. 4 (along with associated parts of the slewing drive base 132 and its tilting mechanism in exploded view) . Dimensions indicated in Fig. 4 are in millimetres.

While certain exemplary embodiments, together with modifications and variations thereof, are described above, the invention is not restricted thereto and other embodiments, modifications and variations can be adopted without departing from the scope of the invention as defined in the appended claims.

Claims

1. A self-propelled work machine comprising a platform constructed or adapted to be co-operatively fitted to and carried by a vehicle which has wheels or tracks by which the vehicle is rendered mobile, said platform being capable of controllably effecting a slewing movement relative to the vehicle when the platform is fitted on the vehicle, a manipulator linkage means co-operatively fitted to and carried by said platform, said manipulator linkage means being constructed or adapted to have a work-head mounted on said manipulator linkage means, and manipulator slewing means permitting the manipulator linkage means to be controllably slewed with respect to said platform.

2. A work machine as claimed in Claim 1 wherein said manipulator slewing means incorporates or is operatively associated with tilting means by which the slewing axis of the manipulator linkage means may be controllably tilted with respect to said platform.

3. A self-propelled work machine comprising a platform constructed or adapted to be co-operatively fitted to and carried by a vehicle which has wheels or tracks by which the vehicle is rendered mobile, said platform being capable of controllably effecting a slewing movement relative to the vehicle when the platform is fitted on the vehicle, a manipulator linkage means co-operatively fitted to and carried by said platform, said manipulator linkage means being constructed or adapted to have a work-head mounted on said manipulator linkage means, and manipulator tilting means permitting the manipulator linkage means to be controllably tilted with respect to said platform.

4. A work machine as claimed in Claim 3 wherein said manipulator tilting means incorporates or is operatively associated with manipulator slewing means permitting the manipulator linkage means to be controllably slewed with respect to said platform.

5. A self-propelled work machine comprising a platform constructed or adapted to be co-operatively fitted to and carried by a vehicle which has wheels or tracks by which the vehicle is rendered mobile, said platform being capable of controllably effecting a slewing movement relative to the vehicle when the platform is fitted on the vehicle, a manipulator linkage means co-operatively fitted to and carried by said platform, said manipulator linkage means being constructed or adapted to have a work-head mounted on said manipulator linkage means, and manipulator tilting/slewing means permitting the manipulator linkage means to be controllably tilted and/or slewed with respect to said platform.

6. A work machine as claimed in any preceding claim, wherein said work-head is a timber-harvesting head.

7. A self-propelled mobile work machine comprising the combination of a vehicle which has wheels or tracks by which the vehicle is rendered mobile, and a work machine as claimed in any preceding claim, the platform of said work machine being co-operatively fitted to and carried by said vehicle.

8. A work machine as claimed in Claim 7 wherein power for the self-propelled mobile work machine is provided by a prime mover mounted on said platform.

9. A self-propelled timber harvester comprising a base having a laterally spaced-apart pair of endless tracks which can be mutually independently powered to provide the harvester with controlled mobility, a platform mounted on the tracked base by means of a primary slewing means enabling the platform to be controllably slewed about a primary slewing axis with respect to the base, a crane boom mounted on the platform by means of a secondary slewing means enabling the crane boom to be controllably slewed about a secondary slewing axis with respect to the platform, a crane arm mounted on the crane boom for controlled movement relative thereto, and timber harvesting means mounted on the crane arm to be selectively positioned relative to the platform by controlled movement of the crane arm and the crane boom.

10. A timber harvester as claimed in Claim 9, wherein the secondary slewing axis is substantially offset from the primary slewing axis.

11. A timber harvester as claimed in Claim 9 or Claim 10, wherein the secondary slewing means is mounted on the platform through a pivot means having a pivot axis which is substantially normal to a notional plane including the secondary slewing axis and the primary slewing axis, the harvester further comprising tilt control means operable to effect controllably variable tilting of the secondary slew axis with respect to the platform.

12. A self-propelled timber harvester comprising a base having a laterally spaced-apart pair of endless tracks which can be mutually independently powered to provide the harvester with controlled mobility, a platform mounted on the tracked base by means of a primary slewing means enabling the platform to be controllably slewed about a primary slewing axis with respect to the base, a crane boom mounted on the platform through a pivot means having a pivot axis which is substantially normal to a notional plane including the primary slewing axis, tilt control means operable to effect controllably variable tilting of the crane boom with respect to the platform, a crane arm mounted on the crane boom for controlled movement relative thereto, and timber harvesting means mounted on the crane arm to be selectively positioned relative to the platform by controlled movement of the crane arm and the crane boom.

13. A timber harvester as claimed in Claim 12, wherein the crane boom is mounted on the first means by means of a secondary slewing means enabling the crane boom to be controllably slewed about a secondary slewing axis with respect to the platform, the tilt control means being operable to effect controllably variable tilting of the secondary slew axis with respect to the platform.

14. A timber harvester as claimed in Claim 13 wherein the secondary slewing axis is substantially offset from the primary slewing axis.