GB2249011A - Mower - Google Patents

Abstract

A mower particularly for cutting roadside verges has a series of arms 18, 20 extending between a tractor 10 and the actual mowing head 24, with fluid pressure rams 30, 40, 50 for varying the angular position of the arms so as to control the reach, height and cutting angle. Two of the rams are connected together so that as one arm is lowered the other is raised and vice versa, which can enable the reach to be varied by the use of a single control valve and without changing the height or angle, or the height to be varied without changing the other parameters in the same manner. <IMAGE>

Description

IMPROVEMENTS IN MACHINES This invention relates to machines of the kind comprising a series of arms pivoted together end-to-end with a fluid pressure ram connected across each pivot, the series extending from a mounting at one end to for example a tool at the other end.

One example of such a machine, without limitation, is a roadside mower. In such a machine, the arms are pivoted on a tractor and can extend laterally of the direction of movement of the tractor along a road. A mower head can be mounted on the outer end of the arms, and adjustment of the ram lengths enables the three relevant parameters to be adjusted namely reach - that is the spacing between the tractor and the head, height, and angle relative to the ground. However, adjustment to the length of the first or second ram (counting from the tractor) also affects the second arm and or the head.

Thus, extension of the first ram to raise the head swings the head in an arc about the mounting point on the tractor and in a 90 deg. movement takes the head from the position for topping a hedge to a position for siding a hedge. While all three adjustments are necessary in order to position the head as required, minor adjustments during the course of a single operation for example hedge topping necessarily involve adjustment of at least two of the rams for these reasons.

In practice, the hedge to road distance may vary, or the tractor may need to swerve slightly to avoid an obstacle. The need to adjust two control valves whilst also driving the tractor calls for a high degree of skill on the part of the operator and/or limits the speed of the operation.

Previous attempts to solve this problem have, for example, used a parallelogram linkage or a scissors linkage, but these tend to be more complex and expensive if they are to have the needed rigidity, and they lack the versatility of the two arm system.

The object of the invention is to provide improvements.

According to the invention, a machine of the kind referred to is characterised in that means are provided for interconnecting two of the rams so that as one arm is lowered the other is raised and vice versa.

Preferably the invention is brought into use or excluded by the use of a diverter valve for the pressure fluid. Hence the ordinary versatility of a two arm system may be retained, but the convenience of substantially straight line movement by operation of a single valve may be attained when the diverter valve is in use.

One embodiment of the invention is now more particularly described with reference to the accompanying drawings in which: Figure 1 is an elevation of a mower and Figure 2 is a CAD plot of possible positions of parts of the same.

In the drawing, Figure 1, the tractor (10) has wheels (12) and a mounting bracket (14) on which is pivoted, at (16) first arm (18). Second arm (20) is pivoted at point (22) to the end of the first arm, and a mowing head (24) is pivoted at point (26) at the outer end of the second arm.

First ram (30) extends between pivots (32 34) on the bracket and on the first arm. Admission of hydraulic (in this instance) fluid at end (32) extends the ram to swing the first arm upwardly and lift the second arm and head bodily. It will be understood that fluid exhausts from end (34) at such time, and that lowering is accomplished by a vice versa operation. So ram (30) may be called the lift ram.

A second ram (40), called the reach ram is pivoted at points (42 44) to the first and second arms and operates in similar fashion.

Third ram (50) is pivoted at (52 54) and is called the angling ram and controls head angle.

As so far described, the arrangement is conventional. Operation of the lift ram alone may swing the head (24) from a point well below the level of the ground on which the tractor stands, so as to be useful for cutting downwardly sloping embankments, to a position well above the tractor, for example for cutting high hedges. If used alone the head will move through a similar angle relative to the ground.

The machine of this embodiment has all three rams individually controllable, but additionally, and according to the invention, two of the rams (in this embodiment) the first and second rams can be linked via diverter valves. The effect of this is that as hydraulic fluid is supplied to end (42) of the reach ram so as to extend the reach, fluid is also supplied to end (34) of the lift ram to lower the head. Extending the reach has the effect of lifting the head, so the contraction of the lift ram compensates for this. The result is increase in the reach without changing the height of the mower head.

Where the positioning of the first and second ram and the relationship of their sizes is as required there may be a simple circuit opened between the two rams: thus in the mentioned instance, as fluid is supplied to end (42) of the reach ram, fluid is necessarily exhausted from end (44) of the same, and this exhausted fluid can be led to end (34) of the lift ram to move the parts in the appropriate direction.

By these means the head can be moved between minimum and maximum reach at generally the same height by the use of a single control valve effecting the reach ram but also connected to the lift ram.

Similarly, the lift ram may be connected, in this instance so that as fluid is supplied to end (32) to raise the head, the fluid exhausting from end (34) is fed to end (42) of the reach ram to compensate, and lift the head substantially in a vertical direction without varying the reach. This would be useful for siding a hedge where the complete height cannot be cut in a single pass.

The hydraulic circuit preferably includes check valves to prevent undesired effects when either of the coupled rams reaches the end of its possible stroke.

The exact path followed by the head when the invention is in use will depend upon the geometry and ram parameters. Figure 2 shows the CAD plotted positions for one specific design, illustrating (reference 60) the lower possible position of the arms at full reach, the highest possible position at full reach (reference 62) and an intermediate position (reference 64). Each of the lines (66-76) plots the path of the pivots (26) (Fig.1).

For example, for the mid-position (64), the line (72) is plotted via points (80-96). It will be seen that the line is not an absolutely straight line, but for general pur-oses as in hedge cutting, roadside vegetation cutting etc., the line is acceptably straight over the normal operational portion of its length.

The references 100,102 show the respective positions of the head at widely spaced elevations when the invention is employed on the lift ram, and the references 104,106 similarly plot the head in hedge siding positions.

It is believed that the invention has applicability in fields other than mowers and other than agricultural machines. For example a two-arm and angling system is useful for loaders and other mechanical handling appliances.

Claims (4)

1. A machine of the kind comprising a series of arms pivoted together end-to-end with a fluid pressure ram connected across each pivot, the series extending from a mounting at one end to for example a tool at the other end, characterised in that means are provided for interconnecting two of the rams so that as one arm is lowered the other is raised and vice versa.

2. A machine as claimed in Claim 1 wherein the pressure fluid circuitry is arranged to allow individual and independent control of each ram, or the interconnection as mentioned via a diverter valve or valves.

3. A mower comprising a two-arm system with a first ram for lifting a mower head attached to one end of the system, a second ram for extending the reach of the head, and a third ram for angling the head, wherein means are provided for optionally interconnecting the reach and lift rams so that by operation of a single control those two rams may be adjusted in length so as to lift or lower the system without substantially varying the reach, or vary the reach without substantially affecting the height.

4. A mower substantially as described with reference to the accompanying drawings.

4. A machine substantially as described with reference ta the accompanying drawings.

5. A mower substantially as described with reference to the accompanying drawings.

AMENDMENTS TO THE CLAIMS HAVE BEEN FILED AS FOLLOWS 1. A mower of the kind comprising a series of arms pivoted together end-to-end with a fluid pressure ram connected across each pivot, the series extending from a mounting on a tractor at one end to a mower head at the other end, characterised in that means are provided for interconnecting two of the rams so that as one arm is lowered the other is raised and vice versa.

2. R mower as claimed in Claim 1 wherein the pressure fluid circuitry is arranged to allow individual and independent control of each ram. or the interconnection as mentioned via a diverter valve or valves.

3. A mower comprising a two-arm system with a first ram for lifting a mower head attached to one end of the system, a second ram for extending the reach of the head, and a third ram for angling the head, wherein means are provided for optionally interconnecting the reach and lift rams so that by operation of a single control those two rams may be adjusted in length so as to lift or lower the system without substantially varying the reach, or vary the reach without substantially affecting the height.