GB2299007A - Stump grinder - Google Patents

Abstract

A stump cutting arm 13 is provided with a cutting wheel W adapted for rotation about a cutting axis, the arm having an inner end adapted for demountable attachment to a chassis by the use of an interface unit 28. The arm incorporates slewing displacement rams on the arm side of the interface unit to provide for lateral displacement or slewing, of the arm relative to the interface unit. Typically the arm incorporates vertical displacement ram 33 to provide for vertical displacement of the arm relative to the interface. The arm can be composed of at least two parts capable of extension relative to one another to provide for the distance between the inner end and the cutting axis to be varied. A prime mover located on or by the arm is adapted to provide for rotation of the cutting wheel about the cutting axis by a power transmission system. In a further aspect there is provided a stump cutting vehicle comprising a self propelled chassis demountably equipped with a stump cutting arm of the described type.

Description

STUMP GRINDING This invention relates to stump grinding and involves a vehicle incorporating an arm for stump grinding. The term 'stump cutter' is used to describe a machine providing for the removal of the stumps of trees or other substantial ground growth of limited height. A stump cutter incorporates an 'arm' supporting a cutting or grinding member.

Known types of stump cutter comprise a specialised chassis with ground engaging wheels or tracks whereby the unit can be moved into position. Such a unit incorporates an arm with a cutter wheel. The arm extends from one end of the chassis in a logitudinal direction and to balance the arm a counterweight is usually provided at the other 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 power transmission system which can incorporate a hydraulic or belt drive system.

Such machines, especially of smaller size, are not usually self propelled and need to be placed in position by means of a tractor or wheel drive vehicle. Once located with the cutting wheel over the stump the stump grinding operation obliges an operator to stand by the machine and to operate the control. The rotating wheel is slewed from side to side across the stump and down into it so as to grind the stump into fragments. To provide for this the cutter provides for the arm to be provided with a limited degree both of slewing movement and of up and down movement relative to the chassis.

Stump cutters need to be capable of use in a wide variety of locations. Where there are a number of stumps to be dealt with a considerable degree of skill frequently needs to be exercised to get the stump cutter into a location adjacent a stump.

Current designs of stump cutter do not permit of safe use on significantly sloping ground nor for use under very adverse ground conditions such as arise from prolonged rain or disturbance during initial construction operations. Cutting can only be started when ground in the vicinity of a stump to be cut is stable enough to support the stump cutter in a position where the cutting wheel can be brought to bear on the stump. In such a situation the stable location of the stump cutter can be difficult, if not impossible, to achieve. Again adverse ground or weather conditions can delay matters when time is of the essence. Up to now these events lead to methods other than stump cutting/grinding needing to be used such as the use of cables and powerful hauling or excavating equipment.However such usage may adversely affect the ground in the vicinity of the stumps and involve a need for subsequent infilling or reclamation operations.

Another factor in the use of current stump cutters is the need for an operator to stand adjacent the stump cutter while operating it so as to maintain close observation of the cutter in operation. Such operation of the machine can be stressful involving the exposure of the operator to adverse weather, noise, flying cut material, and a position in the vicinity of a cutting wheel capable of inflicting serious, if not fatal, injury. In addition large scale stump clearance operations are generally carried out under time pressure in preparation for a subsequent operation such as building or road making and 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.

In my co-pending application 9418983 there is described a stump cutter comprising a chassis, an arm having one end mounted on the chassis and the other end to the one end provided with a cutting wheel characterised in that the chassis is in two parts; a first part provided with ground engaging wheels or tracks adapted for displacement at least in a first direction with the stump cutter on horizontal ground; and a second part on which the one end of the arm is mounted the second part being adopted for rotation about a vertical axis relative to the first direction on horizontal ground. A stump cutter of this type is referred to in what follows as being 'a stump cutter of the type described'.

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 has an inner end adapted for demountable attachment to a chassis by an interface unit; the arm incorporating slewing displacement means on the arm side of the interface unit to provide for lateral displacement. or slewing, of the arm relative to the interface unit.

According to a first preferred version of the first aspect of the present invention the arm incorporates vertical displacement means on the arm side, or as part, of the interface unit to provide for vertical displacement of the arm relative to the interface or the remainder thereof.

According to a second preferred version of the present invention or the first preferred version thereof the arm is composed of at least two parts enabling the distance between the inner end and the cutting axis 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 stump cutting arm is characterised by a prime mover located on or by the arm and adapted to provide for rotation of the cutting wheel about the cutting axis by a power transmission system.

According to a fourth preferred version of the first aspect of the present invention or the first or second preferred version thereof is characterised by a prime mover located other than on or by the arm and adapted to provide for rotation of the cutting wheel about the cutting axis by a power transmission system.

According to a fifth preferred version of the first aspect of the present invention or any preceding preferred version thereof the prime mover is an internal combustion engine and the power transmission system includes a belt drive. Typically the belt drive serves to rotate the cutting wheel directly..

According to a sixth preferred version of the first aspect of the present invention the the power transmission system of the third, fourth or fifth preferred versions includes a hydraulic pump and hydraulic drive.

According to a second aspect of the present invention there is provided a stump cutting vehicle comprising a self propelled chassis demountably equipped with a stump cutting arm according to the first aspect or any preceding preferred version thereof.

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 stump cutter incorporating a demountable arm according to a first embodiment the present invention Figure 2 is a plan view from above in the direction of arrow A in Figure 1; Figure 3 is a view from the front in the direction of arrow B in Figure 1; and Figure 4 is a side view of a demountable arm according to a second embodiment of the present invention; Figure 5 is a plan view from above in the direction of arrow C in Figure 4; Figure 6 is a side view of a demountable arm according to a third embodiment of the present invention; Figure 7 is a plan view from above in the direction of arrow E in Figure 7; First Embodiment (Figures 1 to 3) 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. 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 dozer 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 cab 18 is off set from centre line axis L' so that an operator seated in the cab 18 can observe the operation of arm 13 and in particular wheel W.

Ann 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 axis H1. 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. Ghost outlines W1 to W5 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.

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 S1, S2 relative to axis L'. This slewing action is that used to move the cutting wheel W from side to side in grinding down a stump lined up with axis L1 and in front of the cab 18 (and regardless of the angular alignment of axis L' with L).

Screens S1, S2 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 displaced in the stump grinding process. They are disposed so that an operator in the cab 18 can observes the contact area of the work wheel 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. The drive unit 35 has a power take-off 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 the wheel teeth 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 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 to allow the tracked part of the unit to be used for excavation or other function). 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.

The detached arm 13 can readily be re-attached to the chassis or to another vehicle having an appropriate mounting corresponding to mounting 19.

Second Embodiment (Figures 4 and 5) This embodiment is similar in most mechanical respects to that described in connection with Figure 1 to 3. However in this case arm 53 is provided with a self contained source of hydraulic power. Arm 53 as before is telescopic in operation and equipped with a cutting 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 W1 to W5. 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 to be pivoted (Figure 5) laterally relative to the straight ahead position S over arcs 63, 64.

Legs 65, 66 provide for the arm 63 to be stored in a convenient configuration for recovery by a tracked or other chassis for use.

Third embodiment (Figures 6 and 7) This embodiment is similar in many mechanical respects to the Second Embodiment described in connection with Figures 4 and 5. In this Third 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 W1 to W5.

Hydraulic slewing rams 77, 78 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 recovery by a tracked or other chassis for use.

Many possible embodiments of an arm for a stump cutter falling within the scope of the present invention providing 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.

Claims (12)

1 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 has an inner end adapted for demountable attachment to a chassis by an interface unit; the arm incorporating slewing displacement means on the arm side of the interface unit to provide for lateral displacement.

or slewing, of the arm relative to the interface unit.

2 A stump cutting arm as claimed in Claim 1 wherein the arm incorporates vertical displacement means on the arm side, or as part, of the interface unit to provide for vertical displacement of the arm relative to the interface or the remainder thereof.

3 A stump cutting arm as claimed in Claim 1 or Claim 2 wherein the arm is composed of at least two parts capable of extension relative to one another to provide for the distance between the inner end and the cutting axis to be varied in a controlled manner.

4 A stump cutting arm as claimed in any preceding claim characterised by a prime mover located on or by the arm and adapted to provide for rotation of the cutting wheel about the cutting axis by a power transmission system.

5 A stump cutting arm as claimed in Claim 1, Claim 2 or Claim 3 characterised by a prime mover located other than on or by the arm and adapted to provide for rotation of the cutting wheel about the cutting axis by a power transmission system.

6 A stump cutting arm as claimed in Claim 4 wherein the prime mover is an internal combustion engine and the power transmission system includes a belt drive.

7 A stump cutting arm as claimed in Claim 4 or Claim 6 wherein the power transmission system includes a hydraulic pump and hydraulic drive.

8 A stump cutting arm as claimed in Claim 7 wherein the transmission system also includes a belt drive.

9 A stump cutting arm as claimed in Claim 6 or Claim 8 wherein the belt drive serves to rotate the cutting wheel directly.

10 A stump cutting arm as hereinbefore described with reference to the accompanying drawings

11 A stump cutting vehicle comprising a self propelled chassis demountably equipped with a stump cutting arm according to any preceding claim.

12 A stump cutter as hereinbefore described with reference to the accompanying drawings.