GB2028087A

GB2028087A - Apparatus for cutting hedges, roadside bushes and like growths

Info

Publication number: GB2028087A
Application number: GB7927453A
Authority: GB
Original assignee: Poema Maschinenbau Wittmar Wolfgang Poetzsch
Current assignee: Poema Maschinenbau Wittmar Wolfgang Poetzsch
Priority date: 1978-08-11
Filing date: 1979-08-07
Publication date: 1980-03-05
Also published as: DE2835244C3; DE2835244A1; GB2028087B; DE2835244B2

Abstract

Apparatus for cutting hedges, roadside bushes and like growths is disclosed which comprises a motor vehicle 1 to which a hydraulically drivable cutting rotor 14' is articulated by a cantilever linkage 2, there being means for hydraulically adjusting the cutting rotor in a plane extending at right angles to the intended direction of travel of the apparatus and for pivoting the rotor axis from a vertical position into a horizontal position and vice versa. The cutting rotor is in the form of a high-speed cutter shaft to which is fixedly attached a plurality of cutter blades 21 and which is mounted in a support member 7 positioned behind it with respect to the intended direction of travel. The cutting circle described by the cutter blades is preferably as small as possible and preferably less than 100 mm. <IMAGE>

Description

SPECIFICATION Apparatus for cutting hedges, roadside bushes and like growths This invention relates to apparatus for cutting hedges, roadside bushes and like growths.

It has previously been proposed to provide apparatus for cutting hedges, roadside bushes and like growths which apparatus comprises a hydraulically-driven cutting rotor which is articulated to a motor vehicle, such as a tractor, by means of a cantilever linkage, and which is hydraulically adjustable in a plane extending at right angles to the intended direction of travel of the vehicle, there being means for pivoting the rotor axis from a vertical position to a horizontal position.

In such apparatus, the cutting rotor is constituted by a flail drum, on the envelope of which flail knives are mounted for swinging about axle bolts which extend parallel to the rotor axis. During the rotation of the flail drum the flails are drawn by their centrifugal force into an outwardly directed radial position.

They yield from this position when they strike woody material such as branches and trunks, so that not only is their cutting force reduced, but their cutting edges also strike the material at an unfavourable angle of cut; the edges scrape and cut into the wood. Then, after overcoming each obstacle, the flails fly forward and again strike the material at a poor angle of cut in their front swinging position.

This results in an untidy hedge trim with badly splintered wood cuts.

But the greatest disadvantage is that it is necessary for the cutting rotor to have a very large cutting circle diameter due to the requirement to generate large centrifugal forces in the flails and to impart the required strength to the flail shaft and flail bearings.

This diameter is approximately 400 to 600 mm. When clipping bushes which project for some distance the whole of the material to be cut off has to be chopped and cut up by the flails up to the width of the cutting circle diameter. This means an unfavourably large amount of cutting work, high requirement of driving power, slow working speed and heavy wear. Furthermore the length of the flail drum can only be made short, both due to the necessary high dead-weight and also due to the out-of-balance vibrations which occur.

It is an object of the invention to provide a hedge cutting or like apparatus, with which, for a small amount of cutting work, it is possible to achieve a fast working speed with a low driving power requirement and at the same time to ensure a tidy cut even when thick wooden parts occur. Furthermore, it is desirable that a cutting rotor, of the apparatus, whilst having a low dead-weight, should be as long as possible in order to achieve a large working width.

According to the present invention there is provided apparatus for cutting hedges, roadside bushes and like growths, wherein a hydraulically-drivable cutting rotor is articulated by a cantilever linkage to a motor vehicle, there being means for hydraulically adjusting the cutting rotor in a plane extending at right angles to the direction of travel and for pivoting the rotor axis from a vertical position into a horizontal position and vice versa, and wherein the cutting rotor is constituted by a highspeed cutter shaft to which is fixedly attached a plurality of cutter blades and which is mounted in a support member extending behind it in the intended direction of travel of the apparatus.

The provision in the present apparatus of a shaft with fixed cutter blades permits the apparatus to have a small cutting circle diameter, so that when clipping projecting shrubbery only a narrow band corresponding to the cutting circle diameter needs to be cut and chopped. Furthermore the tidy cut obtained with fixed cutters is achieved. These advantages are achieved in conjunction with the high cutter shaft speed. Preferably means are provided for driving the cutter shaft at a speed of 6,000 to 10,000 r.p.m. It is also a necessary condition for achieving a narrow gap that the support member extends behind the cutter shaft.

Due to the small amount of cutting work which may be necessary with the present apparatus, a high working speed can be attained and only a small driving power is required. Branches and trunks are always dealt with at the optimum angle of cut; the finished cut is tidy. Furthermore, the cutting rotor can be constructed approximately twice as long as the previously proposed flail drums, with the result that fewer working passes are necessary for high hedges. Moreover the low dead-weight of the apparatus facilitates and accelerates its operability and improves the manoeuvrability of the motor vehicle, e.g. a tractor. The assembly time for exchanging the cutter blades is shorter than in the case of a large number of flails.

The best effect is obtained if the knife cutting circle has the smallest diameter possible for the design and is preferably less than 1 00mm. It is further desirable for the support member to have a width smaller than the diameter of the cutting circle and not to project beyond the latter in the direction of travel, so that in use, it does not displace the hedge and the cut material.

If the cutter shaft is subdivided into a plurality of shaft sections and the shaft sections are mutually connected by pins, then the shaft sections can be exchanged more easily and the costs of replacement parts are lower.

The maintenance work and replacement part costs can be reduced if a plurality of mutually adjacent cutter blades of equal length are fitted in each shaft section.

A favourable distribution of the torque peaks, and hence particularly silent running, are obtained if the cutter blades of each shaft section are staggered at 90 with reference to the adjacent shaft section.

The cantilever linkage should be designed so that the cutting rotor is mounted so as to be pivotable into a transport position behind or above the motor vehicle. It should also permit the cutting rotor to be positioned in a horizontal working position, namely both in the raised and in the low position, in order to be able to cut hedges close above the ground.

In order to enable the invention to be more readily understood, reference will now be made to the accompanying drawings, which illustrate diagrammatically and by way of example an embodiment thereof, and in which: Figure 1 is a rear elevation, viewed in the direction of travel, of a hedge-cutting apparatus, Figure 2 is a left-hand side elevation to an enlarged scale of the apparatus in the direction of the arrow A in Fig. 1 and Figure 3 is a plan view of the apparatus along the line BC in Fig. 1.

Referring now to the drawings, there is shown a hedge-cutting apparatus comprising a motor vehicle 1 which carries on a hydraulically pivotable cantilever linkage 2 an approximately horizontal terminal arm 3 pointing outwards to the left in Fig. 1. At its free end the arm 3 carries two straps 4 between which a horizontal bracing arm 6, directed forward (relative to the intended direction of travel of the vehicle) in the work position, is pivotably mounted about a vertical bolt 5. A support member 7 constituted by a rectangular tube and extending vertically upwards is fixed to the front of the bracing arm 6 and stiffened by a transverse strut 8. The length of the support member 7 corresponds to the length of a cutting rotor.

Four bearings 10 are screwed to the support member 7 in front in the intended direction of travel 9 of the vehicle, namely one each at the top and bottom and two others at uniform intervals between them. The bearings 10 are aligned with a common rotor axis 1 3 and a three-part cutter shaft 14 is mounted in them. The cutter shaft 14 is in three sections 14' which are connected together by pins 1 5 mounted in the bearings 10 on the front of the support member 7. A pin 16 projecting below the bottom bearing 10 is connected by a Vee-belt transmission 1 7 to a hydraulic motor 18, the Vee-belt transmission 1 7 having a protective cover 1 9.

The cutter shaft 14 is flattened on two mutually opposite sides as shown in Fig. 3, and a plurality of mutually adjacent cutter blades 21 of equal length are fixed on the flattened portions 20 by screws 22 so that their cutting edges 23 project beyond the shaft 14 and form a common cutting circle 24. It will be seen that the cutter shaft is provided with mutually opposite cutter blades 21 the edges 23 of which are staggered at 180 . The diameter of the cutting circle of the cutting edges is made as small as possible and is 90 mm. in the example illustrated. The cutting circle projects slightly beyond the width of the support member 7 which is a box-shaped construction, extends approximately along the length of the cutter shaft and is fixed to the cantilever linkage.

Each of the three shaft sections 14' of the cutter shaft 14 carries on each flattened portion 20 four cutter blades 21 which are arranged in juxtaposition with no gaps between them and fill the interval between two adjacent bearings 1 0. The flattened portions 20 and the cutter blades 21 of the top and bottom shaft sections of the cutter shaft 1 4 are staggered at 90 with reference to those of the central shaft section as shown in Fig. 2.

A forwardly-directed and projecting separator wedge 25 is screwed on each of the bearings 10 and is formed as a cone facing forward in the intended direction of travel.

Behind the cutter shaft 14, a guard plate 26 is arranged on the inside of the support member 7, and extends with the same width along the entire length of the support member 7 so as to constitute a cover means with reference to the vehicle driver. The guard plate 26 is stiffened at its outer edge by a tube 27 which is braced against the support member 7 at uniform intervals by struts 28.

Claims

1. Apparatus for cutting hedges, roadside bushes and like growths, wherein a hydraulically-drivable cutting rotor is articulated by a cantilever linkage to a motor vehicle, there being means for hydraulically adjusting the cutting rotor in a plane extending at right angles to the direction of travel and for pivoting the rotor axis from a vertical position into a horizontal position and vice versa, and wherein the cutting rotor is constitiuted by a highspeed cutter shaft to which is fixedly attached a plurality of cutter blades and which is mounted in a support member extending behind it in the intended direction of travel of the apparatus.

2. Apparatus as claimed in claim 1, wherein the cutting circle described by the cutter blades has the smallest diameter possible for the design.

3. Apparatus as claimed in claim 1 or 2, wherein the diameter of the cutting circle described by the cutter blades is less than 100 mm.

4. Apparatus as claimed in any one of claims 1 to 3, wherein the support member has a width smaller than the diameter of the cutting circle described by the cutter blades and does not project beyond the latter in the intended direction of travel.

5. Apparatus as claimed in any one of claims 1 to 4, wherein means are provided for driving the cutter shaft at a speed of 6,000 to 10,000 r.p.m.

6. Apparatus as claimed in any one of claims 1 to 5, wherein the edges of the cutter blades extend parallel to the rotor axis.

7. Apparatus as claimed in any one of claims 1 to 6, wherein the cutter shaft is subdivided into a plurality of shaft sections, and wherein the shaft sections are mutually connected by pins.

8. Apparatus as claimed in any one of claims 1 to 7, wherein the support member is of box-shaped construction, extends approximately along the length of the cutter shaft and is fixed to the cantilever linkage.

9. Apparatus as claimed in claim 7 or claims 7 and 8, wherein the pins are mounted in bearings on the front (relative to the intended direction of travel of the apparatus) of the support member.

10. Apparatus as claimed in claim 9, wherein the bearings are each associated with a forwardly-directed and projecting separator wedge.

11. Apparatus as claimed in any one of claims 7 to 10, wherein a plurality of mutually adjacent cutter blades of equal length are fitted in each shaft section.

1 2. Apparatus as claimed in any one of claims 1 to 11, wherein the cutter shaft is provided with mutually opposite cutter blades, the edges of which are staggered at 180 .

13. Apparatus as claimed in claim 12, wherein the cutter shaft has two mutually opposite flattened portions on which the blades are fixed by screws.

14. Apparatus as claimed in any one of claims 7 to 13, wherein the cutters of each shaft section are staggered at 90" with reference to the adjacent shaft section.

1 5. Apparatus as claimed in any one of claims 1 to 14, wherein the cutting rotor is mounted so as to be pivotable about a bolt of the cantilever linkage into a transport position behind or above the motor vehicle.

1 6. Apparatus for cutting hedges, roadside bushes or like growths substantially as hereinbefore described with reference to the accompanying drawings.