GB2151446A - Mower - Google Patents

Abstract

A mower, especially intended for agricultural or horticultural use and of the kind having one or more discs (17, Fig. 1) mounted on skids (19) and provided with outwardly projecting cutting blades, the or each disc being rotatable about a vertical axis, is arranged in use to be connected at its front end to the rear of a tractor (11) whilst the rear end of the mower has ground-engaging support wheels (13) which are mounted on arms (14) which are pivotally connected at their front ends (15) to the frame (12) of the mower. Fluid-pressure actuable ram means 26 are provided for lifting the discs and skids clear of the ground when desired and further fluid-pressure actuable ram means 24 are connected between the ground-engaging wheels or associated arms and the frame in order to form a suspension system which, in operation of the mower, maintains the contact pressure between the skids and the ground substantially constant. The first-mentioned ram means 26 is connected via 27 to the tractor hydraulic system and the further ram means 24 is connected in use to a separate pressurised fluid circuit on the mower which includes a pump 31 and an adjustable pressure relief valve 34. <IMAGE>

Description

SPECIFICATION Mower This invention relates to a mower which is especially intended for agricultural or horticultural use, the mower being of the kind having crop cutting means which comprises one or more discs mounted on skids and provided with outwardly projecting cutting blades the or each disc being adapted to be rotated in use about a generally vertical axis, the mower being arranged at its front end to be connected to the rear of a tractor whereby it may be traversed over the ground and having at its rear end ground-engaging support wheels.

Said wheels are mounted on the rear ends of wheel arms which are pivotally connected at their front ends to the frame of the mower and the aforesaid discs will be disposed in a longitudinal direction between the support wheels and the front end of the mower.

With such an arrangement, the total weight of the mower in use may be distributed between (a) the connection between the mower and the tractor (b) the ground-engaging support wheels and (c) the skid or skids above which the cutter disc or discs rotate, a suspension system connected between said wheel arms and the frame of the machine being commonly used to assist in providing the desired weight distribution. It is however necessary to arrange that the skid or skids can be lifted clear of the ground when the mower is to be towed by the tractor in a non-working position. This has been hitherto achieved in known mowers by hydraulically actuated ram means connected to said wheel arms. The aforementioned suspension system also serves to compensate for undulations in the ground over which in use the mower is traversed.

Such suspension system, if adjustable, may also be used to vary the weight distribution and therefore vary the downward pressure that is exerted on the ground by said skid or skids.

In known examples of agricultural mowers, the aforesaid suspension system comprises one or more coil springs connected in compression between the wheel arms and the machine frame. However, such an arrangement possesses some disadvantages. Thus in order to be strong enough to support a large proportion of the weight of the mower, the springs need to be of heavy gauge wire and in order that they can exert as near as possible a constant load when they are compressed, they need to have a large number of coils. Both these factors entail the use of very large and heavy springs. Furthermore, constant diameter coil springs give a constant rate in terms of load per unit length of compression and this means that when the springs are further compressed (as when the support wheels ride over a bump in the ground) they will exert an increased force - i.e. the skid reaction on the ground decreases.Conversely when the wheels fall into a hollow, the skid reaction on the ground will increase.

Moreover to adjust the skid reaction or "flotation" pressure, it is necessary to change the preload in the springs. This is a manual adjustment which entails a great deal of effort and time in view of the loads involved and in any case it is difficult to judge how much change is taking place whilst such adjustment is being made.

The object of the present invention is to provide an improved construction of mower which overcomes the above-mentioned disadvantages.

In accordance with the invention there is provided a mower of the kind specified wherein fluid-pressure actuable ram means are provided for lifting said skid or skids clear of the ground when it is desired to traverse the mower over the ground in a non-operative position and further fluid-pressure actuable ram means are provided which are connected to said ground-engaging wheels or the associated wheel arms to form a suspension system therefor, said first-mentioned ram means and said further ram means being connected in use to separate pressurised fluid circuits.

Preferably, said first-mentioned fluid pressure actuable ram means comprises a single acting ram disposed on one side of the mower. Likewise, the further fluid-pressure actuable ram means preferably comprises a single acting ram. Conveniently, said single acting rams are combined to form a doubleended ram embracing the "lift" ram and the "suspension" ram. The ground-engaging wheels would be connected together so that they are arranged to move together on actuation of the "lift" ram and similarly where said crop cutting means comprises more than one disc and skid assembly such assemblies would be connected together so as to be movable in unison on actuation of the "suspension" ram.

The pressurised fluid circuit connected to the first mentioned ram means (i.e. the "lift" ram) is conveniently provided in use by the hydraulic system of the tractor to which the mower is connected whilst the pressurised fluid circuit connected to the further ram means (i.e. the "suspension" ram) is conveniently provided by a separate hydraulic system mounted on the mower.

The invention will now be more particularly described with reference to the accompanying drawings wherein: Figure 1 is a schematic side view of one example of a mower constructed in accordance with the invention, the mower being shown when connected to a tractor and in an operative position, and Figure 2 is a schematic view of one example of the fluid pressure actuable ram means, together with associated components, that may be incorporated in said mower.

Referring now to the drawings, one example of a mower constructed in accordance with the present invention is generally indicated in Figure 1 by reference numeral 10. The mower is connected at its front end to the rear of a tractor 11 and such connection includes couplings to the tractor hydraulic system and the tractor power take-off system in the known manner. The mower 10 is provided with a frame 1 2 and at its rear end the mower is provided with a pair of laterally spaced ground-engaging wheels of which one, indicated by reference numeral 1 3, is seen in Figure 1. Each of said wheels is connected to a wheel arm 14 which is pivotally connected at pivot 1 4 to the frame 1 2 of the mower.

The mower also includes a pair of laterally spaced rotatable drums of which one is indicated by reference numeral 1 6 in Figure 1, each of said drums being rotatable in use about a vertical axis by means of said power take-off mechanism of the tractor which is connected to said drums via a suitable gearbox. Each rotatable drum is connected to a disc 1 7 which rotates with the associated drum and which is provided with a plurality of outwardly projecting cutting blades 1 8 which are thus adapted to cut grass or other crops over which the mower is traversed when the drums and cutter discs are rotated as above described.Disposed beneath each of said rotatable cutter discs 1 7 is a non-driven, freely rotating skid such as skid 1 9 which engages the ground over which the mower is traversed.

The mower is also provided with fluid pressure actuable ram means for lifting the skids 1 9 clear of the ground when it is required to traverse the mower in a non-operative position as for example when it is being towed along a road or when the mower is being turned at a headland in a field.In addition there is provided further fluid-pressure actuable ram means which act as a suspension system for the ground engaging wheels 1 3. Said further fluid-pressure actuable ram means comprises the lower part of a doube-ended cylinder 20 which is pivotally connected at its opposite ends to one of the wheel arms 1 4 and to a convenient lug 21 connected to or forming part of said frame 1 2 of the mower, the two wheel arms 1 4 associated respectively with the two wheels 1 3 being connected together in any convenient way. Said cylinder 20 contains a pair of pistons namely an upper piston indicated by reference numeral 24 and a lower piston indicated by reference numeral 26.The upper piston 24 together with the associated upper end of the cylinder 20 forms the aforementioned suspension or flotation ram. Similarly the aforesaid lower end of the cylinder 20, together with the piston 26.

comprises the lift ram for the ground-engaging wheels 13.

The lift ram has at its upper end an hydraulic connection 27 which is connected to the hydraulic system of the tractor itself. The lower end of the flotation or suspension ram having the piston 24 is connected via a connection 29 to an hydraulic circuit which is mounted on the mower itself and which is separate from the tractor hydraulic system.

The mower hydraulic system also includes a pump 31 which is arranged in use to be driven by the power take-off of the tractor, a reservoir 32, a filter 33, an adjustable pressure relief valve 34 and a pressure gauge 35.

When the mower is in its operative or working condition the lift ram is in a contracted position so that the piston 26 occupies the full line position shown in Figure 2 at the upper end of the lower part of the cylinder 20. On the other hand the suspension ram incorporating the piston 24 is arranged so that said piston occupies a normal position which is approximately midway between the upper and lower ends of the upper part of the cylinder 20, as shown in full lines in Figure 2.

This is achieved by applying pressure, generated by the pump 31, through the connection 29, the adjustable relief valve 34 being adjusted so that the pressure applied will move the said suspension ram piston 24 to the desired more or less central position when the mower is being traversed over level ground.

In this position the weight of the mower will be distributed between the tractor draw bar, the skids 1 9 and the wheels 1 3, the weight which is being taken by said skids 1 9 being counterbalanced by a reaction, indicated by arrows 36 in Figure 1 applied by the ground.

If however said wheels 1 3 pass over a bump in the ground or over a hollow the wheel arms 14 will pivot on their pivots 1 5 and will thus cause the piston 24 to rise or fall temporarily in its suspension cylinder. During such movement however the pressure in the suspension cylinder will remain the same, being governed by the relief valve 34 so that the pressure or weight applied to the ground by the skids 1 9 will remain substantially constant. Such pressure of course can be adjusted by varying the pressure applied to the suspension ram, such variation of pressure being achieved by adjusting the relief valve 34. Such adjustment of the relief valve mav be effected manually or for example by power-operated means comprising a small electric motor drivingly connected to the relief valve and electrically connected to the electrical system of the tractor.

When however it is desired to lift the discs 1 9 clear of the ground, hydraulic pressure is applied to the lift cylinder containing the piston 26 via the hydraulic connection 27 and once this pressure exceeds the pressure applied to the underside of the suspension piston 24 then the lift ram will expand so that the piston 26 will move to the lower end of the lower part of the cylinder 20 to assume the dotted line position indicated by reference numeral 26a. At the same time the suspension ram piston will also assume a lower position indicated by the dotted line 24a. This will cause the wheel arms 14 to pivot relative to the frame of the mower to such a degree that the skids 1 9 and with them the cutter discs 1 5 will be lifted so that said skids 1 9 are clear of the ground.

To lower the mower from the lifted position the hydraulic pressure of the tractor hydraulic system is released so that the piston 26 assumes its full line position again and the suspension or flotation system provided by the suspension ram having the piston 24 takes over again as previously described. As mentioned above the pressure in the suspension ram will remain substantially constant for any particular setting of the relief valve 34 and this will result in a substantially even skid load at all times for that particular setting of the relief valve. This is a condition which is not obtainable by the hitherto used coil spring suspension of the wheel arms 14. Furthermore, as is mentioned above the aforementioned skid load can be easily and quickly adjusted to suit the conditions in which the mower is being used by an adjustment of the aforesaid relief valve 34.

In an alternative arrangement, the "suspension" ram means may comprise a pair of rams disposed on opposite sides of the mower and comprising a master piston and cylinder assembly and a slave piston and cylinder assembly connected respectively to the two cutting disc/skid assemblies where two such assemblies are provided. Likewise, the "lift" ram means may comprise a pair of rams forming a master piston and cylinder assembly and a slave piston and cylinder assembly connected respectively to the two ground-engaging wheel arms where two such wheel arms are provided. With such an arrangement, all the piston and cylinder assemblies may be combined to form, on each side of the mower, a double-ended ram embracing, on the one side, the master "suspension" ram and the master "lift" ram, and, on the other side, the slave "suspension" ram and the slave "lift" ram. Also, although in the above-described example the "suspension" ram hydraulic circuit is referred to as being mounted on the mower, it would be possible, in an alternative example, to use the hydraulic system of the tractor instead.

Claims (7)

1. A mower of the kind specified wherein fluid-pressure actuable ram means are provided for lifting said skid or skids clear of the ground when it is desired to traverse the mower over the ground in a non-operative position and further fluid-pressure actuable ram means are provided which are connected to said ground-engaging wheels or the associated wheel arms to form a suspension system therefor, said first-mentioned ram means and said further ram means being connected in use to separate pressurised fluid circuits.

2. A mower as claimed in Claim 1 wherein said first-mentioned fluid-pressure actuable ram means comprises a single acting ram and said further fluid-pressure actuable ram means comprises a single acting ram, said two single acting rams being combined to form a doubleended ram comprising a cylinder and two pistons.

3. A mower as claimed in Claim 2 wherein said two pistons have piston rods which extend respectively through the opposite ends of said cylinder and which are connected respectively to an arm carrying a ground-engaging wheel and to a part of the frame of the mower.

4. A mower as claimed in Claim 1 wherein said first-mentioned fluid-pressure actuable means comprises a pair of rams forming a master piston and cylinder assembly and a slave piston and cylinder assembly and wherein said further fluid-pressure actuable means also comprises a pair of rams forming a master piston and cylinder assembly and a slave piston and cylinder assembly, said piston and cylinder assemblies being combined to form, on each side of the mower, a doubleended ram embracing, on one side, the two master piston and cylinder assemblies and, on the other side, the two slave piston and cylinder assemblies.

5. A mower as claimed in any one of the preceding claims wherein the first-mentioned fluid-pressure actuable means is adapted to be connected to a first hydraulic circuit and wherein there is provided on the mower a second hydraulic circuit which is connected to said further fluid-pressure actuable means and which includes an adjustable pressure relief valve.

6. A mower as claimed in Claim 5 wherein said pressure relief valve is adjustable by power-actuated means such as an electric motor.

7. A mower of the kind specified and substantially as hereinbefore described with reference to and as shown in the accompanying drawing.