TECHNICAL FIELD

This invention relates to stump cutting arm and vehicle. The term 'stump cutting' (also referred to as 'stump grinding') is applied to an operation providing for the removal of tree stumps or other substantial ground growth of limited height by means of a powered cutting wheel on an extended arm.

BACKGROUND ART

Known types of stump cutter unit comprise a specialised chassis with ground engaging wheels or tracks whereby the unit can be moved into position. The arm extends from one end of the chassis in a longitudinal direction and to balance the arm a counterweight is usually provided at the opposite end of the chassis to that from which the arm extends. The chassis includes an internal combustion engine linked to the cutting wheel by a hydraulic or belt drive power transmission system. Known stump cutters, notably those of smaller size, are not usually self propelled and need to be placed in position by means of a tractor or 4-wheel drive vehicle. Once the unit is located with its cutting wheel over the stump the stump cutting operation is undertaken under the control of an operator standing by, or seated on, the unit. The rotating cutting wheel is slewed from side to side across the stump and driven down into it so as to cut or grind the stump into fragments. To provide for this action the arm is provided with a limited degree of slewing movement, and of up and down movement, relative to the chassis.

Large scale stump clearance operations are generally carried out under time pressure in preparation for a subsequent major operation such as building or road making. To this end stump cutting operations have to be carried out quickly to meet a deadline and to control site operation and overall project costs. Stump cutting should only be started when ground in the vicinity of a stump to be cut is stable enough to support the stump cutter unit in a position where the cutting

SUBSTITUTE SHEET (RULE 26

wheel can be brought to bear on the stump. Current designs of stump cutter units do not readily, if at all, permit the safe use of the unit on significantly sloping ground nor for use under very adverse ground conditions such as can arise from prolonged soaking by flooding or by rain or from ground disturbance arising from initial construction operations.

In the event a conventional stump cutting unit cannot be used then methods other than stump cutting need to be applied. Typically these involve heavy cables and powerful hauling or excavating equipment. The application of such methods can adversely affect the ground in the vicinity of the stumps and involve a need for subsequent infilling or reclamation operations.

With most current stump cutter units an operator is obliged to stand adjacent the unit in order to maintain close observation of the cutter while in operation. Control of a unit under such conditions can be stressful as the operator is exposed to adverse weather, noise, flying cut material and other debris, and a location in the vicinity of a cutting wheel capable of inflicting serious, if not fatal, injury. In addition an operator aware of a need to meet a tight time schedule may well be disposed to take risks.

DISCLOSURE OF INVENTION

According to a first aspect of the present invention there is provided a stump cutting arm having a longitudinal axis and an outer end provided with a cutting wheel adapted for rotation about a cutting axis characterised in that the arm (13, 53, 73, 21) has an inner end (26,) adapted for demountable attachment to a chassis by an interface unit (28, 60); the arm (13, 53, 73, 21) incorporating slewing displacement means (41, 42; 61, 62; 77, 78) on the arm side of the interface unit to provide for lateral displacement, or slewing, of the arm (13, 53, 73, 21) relative to the interface unit (28, 60).

According to a first preferred version of the first aspect of the present invention is characterised in that the arm (13, 53, 73, 21) incorporates vertical displacement means (33, 61) on the arm side, or as part, of the interface unit (28, 60) to provide for vertical displacement of the arm (13, 53, 73, 21) relative to the interface (28, 60) or the remainder thereof.

According to a second preferred version of the first aspect of the present invention or of the first preferred version thereof the arm is characterised in being composed of at least two parts (25, 26) capable of extension or displacement relative to one another to provide for the distance between the inner end (28) and the cutting axis (W') to be varied in a controlled manner.

According to a third preferred version of the first aspect of the present invention or any preceding preferred version thereof the arm is characterised by a prime mover (59) located on or by the arm (53) and adapted to provide for rotation of the cutting wheel (W) about the cutting axis (W') by a power transmission system (56, 57, 58, P). Typically the prime mover is an internal combustion engine (59, 74). The power transmission system includes a hydraulic pump (58) and hydraulic drive (56, 57) and /or a belt drive (75, 76).

According to a second aspect of the present invention there is provided a stump cutter characterised by:

1 an arm (21, 13, 53, 73) as claimed in any preceding claim having the interface (28) for mounting the arm on the chassis (11-Fig 1; 12-Fig 4),

2 a chassis (11-Fig 1; 12-Fig 4) being in two parts: a first part (12-Fig 1; 14-Fig

4) provided with ground engaging wheels or tracks (13, 14-Fig 2; 15, 16-Fig

5) adapted to displace the stump cutter (10, 11) at least in a first longitudinal direction (L) with the stump cutter on horizontal ground; and a second part (15, 17) on which the interface (28) is mounted; the second part (15, 17) being adopted for rotation about a vertical axis (L, V) relative to the first direction (L) on horizontal ground.

According to a first preferred version of the second aspect of the present invention a stump cutter is characterised by a prime mover (16, M) mounted on the chassis

(11, 12) serving to provide propulsive power to the ground engaging wheels or tracks (13, 14; 15, 16).

According to a second preferred version of the second aspect of the present invention or the first preferred version thereof a stump cutter is characterised by an anchoring and /or levelling device (28, 22) whereby once the stump cutter (10, 11) has been positioned in a working location the anchoring means (28, 22) is operable to engage the ground independently of the ground engaging wheels or tracks (13, 14; 15, 16) to anchor the cutter (10, 11) against movement and /or to provide for the levelling of the cutter (10, 11).

According to a third preferred version of the second aspect of the present invention or any preceding preferred version thereof a stump cutter is characterised by a scraper blade (28, 22) mounted on the stump cutter (10, 11) to enable material generated by the cutter (10, 11) to be displaced on movement of the ground engaging wheels or tracks (13, 14; 15, 16) .

According to a fourth preferred version of the second aspect of the present invention or any preceding version thereof a stump cutter is characterised in that the chassis (11, 12) is equipped with a operating location (24, 18) for an operator of the vehicle provided with controls (27) for operating the cutting wheel (W) for operating the ground engaging wheels or tracks (13, 14; 15, 16).

A stump cutter comprising a chassis (11), an arm (21) having one end (20) mounted on the chassis (11) and the other end (22) to the one end (20) provided with a cutting wheel (W) characterised in that the chassis (11) is in two parts: a first part (12) provided with ground engaging wheels or tracks (13, 14) adapted to displace the stump cutter (10) at least in a first longitudinal direction (L) with the stump cutter (10) on horizontal ground; and a second part (15) on which the one end (20) is mounted; the second part (15) being adopted for rotation about a vertical axis (V) through 360° relative to the first direction (L) on horizontal ground.

To facilitate use a stump cutting arm according to the first aspect of the present invention is readily mounted on an existing chassis having a turntable on which the inner end of the arm is located to enable the arm to be rotated 360° about a vertical axis to any angle relative to the longitudinal axis of the vehicle. The cutter arm can either be assembled by mounting the arm on a standard chassis able to receive a number of alternate tools such as a bucket. Alternatively the arm can be incorporated in a chassis to provide a specialist vehicle. The use of a standard chassis or a specialist vehicle for stump cutting depends on the user and the type of application. Typically if the arm is normally stored separately it is readily conveyed as a separate unit to a work site where it can then be mounted on the standard chassis for use as a stump cutter. Once the cutting operation is complete the arm can then be recovered and the standard chassis equipped with some other tool for a further operation.

BRIEF DESCRIPTION OF DRAWINGS

Exemplary embodiments of the invention will now be describe with reference to the accompanying drawings of a stump cutting arm or a stump cutting vehicle of which:

Figure 1 is a side view of a first embodiment,

Figure 2 is a view from above, and

Figure 3 is a view from beneath;

Figure 4 is a side view of a stump cutter incorporating a demountable arm according to a second embodiment,

Figure 5 is a plan view from above in the direction of arrow A in Figure 4,

Figure 6 is a view from the front in the direction of arrow B in Figure 4;

Figure 7 is a side view of a demountable arm according to a third embodiment, and

Figure 8 is a plan view from above in the direction of arrow C in Figure 7;

Figure 9 is a side view of a demountable arm according to a fourth embodiment, and

Figure 10 is a plan view from above in the direction of arrow E in Figure 9.

SUBSTrrUTr! SHEET (RULE 26)

MODES FOR CARRYING OUT THE INVENTION

First Embodiment (Figures 1 to 3)

This provides a basic version of a stump cutting vehicle 10 according to the invention. The stump cutter 10 is provided with a chassis 11 made up of a lower section 12 on which are mounted tracks 13, 14 and an upper section 15 on which are mounted cutting and control units.

Lower section 12 has a longitudinal axis L and in addition to supporting the tracks 13, 14 carries a prime mover in the form of a diesel engine 16 coupled to a hydrostatic drive unit 17 providing power for driving the track 13, 14 and for other functions. Ring 18 serves to receive upper section 15 so that the upper section 15 can be driven by hydraulic motor 19 to rotate 360° about vertical axis V. Further means are provided to lock the upper section 15 in a selected angular alignment relative to lower section 12.

Upper section 15 supports inboard end 20 of arm 21 so as to enable the arm 21 to be pivoted vertically over vertical arc A ^v (Figure 1) and slewed horizontally over lateral arc A ^h (Figure 2) by hydraulic power. Outboard end 22 of arm 21 is equipped with a conventional cutting wheel 23 powered by a hydrostatic motor for rotation about cutting axis W.

A control position 24 is provided on the upper section 15 and comprises a cab 25 in which is provided a seat 26 and a control panel 27 whereby operations involving cutting by, and movement of, the stump cutter are carried out.

A scraper blade 28 is pivotably mounted on forward end 29 of the lower section 13 and is operable by hydraulic means to be raised or lowered over the arc B. The blade has several functions. It can be used as a conventional scraper blade to enable fragmented material generated by the operating cutter wheel 23 to be displaced (typically into a hole generated in the course of cutting a stump to a position beneath ground level). It can be used as an anchoring means for the

cutter 10 when in an otherwise unstable location. It can be used to raise one end of the machine relative to a slope to provide for level operation. Where no scraper blade is available or in addition to a blade a separate anchoring means can be provided such as one or more hydraulically displaceable anchor spades.

Second embodiment (Figures 4 to 6)

A stump cutter 11 comprises a chassis 12 on which is attached a demountable arm 13 on whose outer end there is mounted a cutting wheel W for rotation about cutting axis W'. The chassis 12 made up of a lower section 14 on which are mounted tracks 15, 16 and an upper section 17 on which is mounted a cab 18 and a mounting bracket 19 to which the demountable arm 13 can be readily attached and removed as will be described hereafter. In practice the chassis 12 can be a known type of excavator chassis adapted to receive a number of possible attachments by way of the mounting bracket 19.

The lower section 14 has a centre line longitudinal axis L and serves to support the tracks 15, 16. The upper section 17 has a centre line longitudinal axis L' and can be rotated about axis V relative to the lower section 14, The upper section 17 houses a prime mover M in the form of a diesel engine which is coupled to a hydrostatic drive unit H which provides power for a number of functions including: driving the track 15, 16; rotating the upper section 17 relative to the lower section 14; use of arm 13; winch 21 on the rear of the unit; and scraper blade 22 on the front of the unit. The terms 'front' and 'rear' are here used to refer to the working components relative to the upper section 17 with its longitudinal axis L'. Mounting bracket 19 is regarded as being on the front of cab 18.

The equipment and method whereby the upper section 17 is rotated relative to the lower section 14 is of conventional type and is not described further. It also

includes locking means enabling axis L' of the upper section 17 to be locked in place relative axis L of the lower section 14 to enable the arm 13 to be used regardless of the alignment of tracks 15, 16 relative to the arm 13.

Cab 18 contains a working position for an operator of the cutter including a seat and controls for hand and foot operation. The working position in cab 18 is off set from centre line axis L' to enable an operator seated in the cab 18 to readily observe the operation of arm 13 and in particular wheel W.

Arm 13 is telescopic in form with an outer tube 25 siding over inner tube 26 and powered by a ram 13'. The outer tube 25 supports wheel W by way of carrier 27. The inner tube 26 is mounted by means of interface section 28 on bracket 19 on the front part of upper chassis section 17. The bracket 19 has a lower horizontal mounting location 30 and an upper horizontal mounting location 31. Interface section 28 of the arm 13 is coupled to lower mounting location 30 by means of a horizontal pin 32 enabling the arm 13 to pivot about horizontal axis HI. Lifting ram 33 links the arm 13 to the bracket 19 and is operated by hydraulic power to drive the arm 13 in a vertical direction about axis HI. Ghost outlines Wl to W4 show the extremes of travel of wheel W available by use of the telescopic action of the arm 13 and of the lifting ram 33. Though this embodiment shows only a single lifting ram 33 to provide for vertical displacement a pair of rams can be used to facilitate such displacement typically with one ram pulling and the other pushing to displace the arm.

Apart from the ability of the upper chassis to rotate the arm 13 horizontally about vertical axis V the arm 13 also incorporates (Figure 2) separate lateral adjustment means in the form of hydraulic slewing rams 41, 42. The arm 13 is attached at its inboard end 43 to interface section 28 by a vertical pivot 44. The rams 41, 42 provide for movement in a horizontal plane over arcs SI, S2 relative to axis L'. This slewing action is provided for outboard of the interface 28 and is the normal action used to move the cutting wheel W from side to side in grinding down a stump lined up with axis LI in front of the cab 18 (and regardless of the angular alignment of axis L' with L).

Screens SI, S2 (Figure 3) are made up of chain and rubber sections are provided hanging from outriggers on the arm 13 to shield the cab 18 and adjacent areas from chips and other debris displaced in the stump cutting process. They are disposed so that an operator in the cab 18 can observes the contact area of the work wheel W with a stump being cut away.

Carrier 27 supports a hydraulic drive unit 35. Hoses 36, 37 serve to provide unit 35 with hydraulic fluid from hydraulic unit H in cab 18. The drive unit 35 has a power take-off in the form of a toothed cog driving a notched drive belt housed under cover 40. To provide for a degree of slippage on start up the hydraulic system can incorporate a relief valve providing for re-cycling of hydraulic fluid. In a system making use of further belt drive to transfer power from an internal combustion engine then a V-belt drive can be used between the engine and a final notched belt drive to provide for a degree of slippage on start up or when teeth of wheel W encounter a harder material or obstruction during the course of cutting a stump.

Hydraulic, electrical and control services needed for items provided on the arm 13 are supplied to the arm 13 by way of conventional readily demountably couplings in the vicinity of the interface 28 and the mounting bracket 19 so that the arm 13 and its associated service connections can be readily removed from and attached to the chassis.

The arm 13 is readily demountable from the rest of the unit 11 typically so as to allow the tracked part of the unit to be used for excavation or other function by replacing the arm 13 with another tool. To achieve this the arm 13 while on the unit is lowered so as to rest the wheel W on the ground and to align arm 13 approximately horizontally. Legs 45, 46, attached by a hinge to the arm 13, are then lowered to the ground and secured in place. The pins coupling arm 13 to mounting 19 are removed and the tracked unit 12 backed off to leave the arm 13 in a configuration from which it is readily re-attached to the unit 12 or to another vehicle having an appropriate mounting for interface 28.

Third Embodiment (Figures 7 and 8)

This embodiment is similar in most mechanical respects to the arm 13 described in connection with Figure 4 to 6. However in this case arm 53 is provided with a self contained source of hydraulic power. Arm 53 is telescopic in operation and equipped with a cutting wheel W adapted for rotation about cutting axis W'. The wheel W which is supported on the arm 53 by a carrier 54. The carrier 54 supports a hydraulic drive unit 55. However in contradistinction to the First Embodiment the drive unit 55 is coupled by hoses 56, 57 to a power unit P mounted on the arm and made up of a hydraulic pump 58 coupled to, and driven by way of, an internal combustion engine 59. A fuel supply tank 59 ^* for the engine 59 is also incorporated in the power unit P.

The arm 53 is connected to a mobile self propelled chassis in a similar way to that described in connection with Figures 1 to 3 to tracked vehicle 12 by way of a mounting bracket corresponding in form and function to bracket 19 of Figure 1. Mounting of the arm 53 is achieved by way of lower mounting 60 and upper hydraulic ram mounting 61. As before ram 61 provides for vertical movement of the arm 53 to enable the wheel W to be located in a variety of positions typically represented by outlines Wl to W4. Readily detachable couplings are used for electrical, hydraulic and fuel connection to the operating services mounted on the arm 53.

Hydraulic slewing rams 61, 62 are provided on the arm 53 to enable the arm 53 to be pivoted (Figure 5) laterally relative to the straight ahead position S over arcs 63, 64.

Legs 65, 66 provide for the arm 53 to be stored in a convenient configuration for recovery by a tracked or other chassis for use.

Fourth embodiment (Figures 9 and 10)

This embodiment is similar in many mechanical respects to the Third Embodiment described in connection with Figures 7 and 8. In this Fourth Embodiment a telescopic arm 73 for a cutting wheel W is provided on which is mounted its own power source for powering the wheel W. In this case an internal combustion engine 74 is used and drives the wheel W by way of a primary drive made up of a V-belt drive in housing 75, and a final drive made up of a toothed belt drive in housing 76. A cross shaft coupling 77 is used to link the primary and secondary drives so that power is readily transmitted from engine 74 to wheel W regardless of the vertical alignment of the primary and secondary drives and of the length of the arm 73. This enables the wheel W to be located in a variety of positions typically represented by outlines Wl to W4.

Hydraulic slewing rams 78, 79 are provided on the arm 73 to enable the arm to be pivoted (Figure 8) laterally relative to the straight ahead position S over arcs 79, 80.

Legs 81, 82 provide for the arm 73 to be stored in a convenient configuration for ready recovery.

INDUSTRIAL APPLICABILITY

By utilising a self propelled tracked chassis the present invention provides a number of substantial benefits over existing stump cutting machinery. It provides for a relatively compact machine to be readily manoeuvred by its operator to a convenient working locations even among a number of closely set stumps. Because the upper section 15 of the chassis can be rotated 360° relative to the lower part 12 the cutting head is readily presented to a stump for cutting regardless of the alignment of the chassis to the stump. This dispenses with the need for the vehicle to be aligned in a particular manner to a stump and provides for safe operation since the vehicle can be located on the most stable position (if

necessary using the scraper blade for anchorage and /or levelling of the cutter in the vicinity of the stump prior to a cutting operation.

The tracked configuration and the ability to anchor the stump cutter forming the present invention enables stump cutting operations to be carried out on ground rendered unusable by a wheeled vehicle such as can arise from weather conditions or from earlier operations carried out on the ground.

The combined use of a tracked vehicle and an anchorage means is particularly appropriate for use on sloping working areas. Such areas can be unusable by a wheeled vehicle even when the ground is otherwise in reasonable condition.

The provision on the vehicle of a seat and operating cab for an operator provides a number of substantial benefits by making operation of the cutter less hazardous, encouraging concentration on the part of the operator and sheltering him from adverse weather and noise levels.

Many possible embodiments of an arm for a stump cutter falling within the scope of the present invention and provide for the ready provision of a stump cutter vehicle for many possible applications by making use as far as possible of available proprietary components (such as a chassis and drive system) and providing an arm which can be readily attached to the chassis.