GB2169181A

GB2169181A - Mowing machines

Info

Publication number: GB2169181A
Application number: GB08516772A
Authority: GB
Inventors: Ralph Winstanley
Original assignee: Individual
Current assignee: Individual
Priority date: 1985-01-07
Filing date: 1985-07-02
Publication date: 1986-07-09
Also published as: GB8516772D0; GB8500297D0; GB2169181B

Abstract

A rotatable cylinder type mowing machine is provided with a blade cylinder (10) engaged by a bottom blade (18) the opposite ends of which are carried by respective pivoted levers (20), means being provided for adjusting the positions of the levers so that the bottom blade can be adjusted towards or away from the blade cylinder. So that the bottom blade (18) can move away from the blade cylinder (10) if a large foreign object is fed into the machine, the levers (20) are normally held in engagement with respective positive stops (25) by respective hydraulic rams (22) to hold the bottom blade in its operative position. <IMAGE>

Description

SPECIFICATION Mowing and like machines The invention relates to rotatable cylinder type mowing and the like machines and in particular to such a machine intended for very heavy duty use, for example by farmers mowing silage crops and by council workmen mowing roadside verges and trimming hedgerows for example.

Cylinder type mowing machines are very well known for domestic use and are either of the push type or driven by power means such as a petrol engine or electric motor. The cutting blades extend helically between a plurality of spaced discs to form a cutting cylinder. A so-called bottom blade extends across the underside of the machine and cooperates with each of the cutting blades in turn as the cutting cylinder rotates. The bottom blade is generally fixed rigidly in position with respect to the frame of the machine, although it is known for the bottom blade to be held in position by spring means so that it bears against the cutting blades of the rotatable cylinder for any wear of the blades to be automatically taken up.

A domestic mower of the rotatable cylinder type has a relatively lightweight cutting cylinder and consequently if some obstruction finds its way into the machine, the cylinder is brought to an immediate halt without undue damage being caused. However, a very much larger and heavier rotatable cylinder such as might be required in a mowing or like machine to be used by a farmer in place of a forage harvester type of machine cannot be brought to a halt as suddenly without severe damage being caused.

The invention has for its object to provide a solution to this problem.

According to the invention, a rotatable cylinder type mowing or like machine is provided with a bottom blade which is pivotally mounted in frame structure of the machine for movement of an operative part thereof away from the rotatable blade cylinder in the event of a very substantial foreign body being fed into the machine, the bottom blade normally being held in its operative position against a positive step by means of a pair of hydraulic rams at its opposite ends. The pair of hydraulic rams may be connected to the hydraulic system of a tractor by which the machine is carried so that the operative part of the bottom blade can be pivoted away from the blade cylinder in response to movement of a control iever.Alternatively, the hydraulic rams may contain a fixed amount of oil and act as resilient means holding the operative part of the blade in its operative position against the positive stop. The positive stop against which the bottom blade is normally held in its operative position may be constituted by respective screws which have screwthreaded engagement with threaded holes in fixed frame parts of the machine at opposite ends of the blade cylinder, the lower ends of said screws acting against forwardly projecting portions of respective pivoted levers by means of which the opposite ends of the bottom blade are carried.In this case, if the blade cylinder is enclosed by a casing open only on its underside, the respective screws which constitute the positive stop against which the bottom blade is normally held in its operative position will preferably be capable of being adjusted from outside the casing, whereby fine adjustments to the operative position of the bottom blade can safely be made while the machine is running.

In order that the invention may be fully understood and readily carried into effect, the same will now be described, by way of example only, with reference to the accompanying drawings, of which: Figure 1 is a perspective view of a part of a mowing or like machine embodying the invention, Figure 2 is a sectional view on the line 2-2 in Figure 1, and Figure 3 is a sectional view, drawn to a somewhat smaller scale than Figures 1 and 2, illustrating a possible modification which will be referred to.

Referring now to the drawings, the mowing or like machine there illustrated is for farm use and can be mounted on the 3-point linkage of a tractor. The machine includes a rotatable blade cylinder 10 mounted in bearings in side plates 12 of a frame structure. The rotatable blade cylinder includes cutting blades 14 which extend helically between a plurality of spaced discs 16. (In the illustrated embodiment the blade cylinder has three blades and the discs are shown to be of triangular shape.

However, it will be understood that the blade cylinder could quite well have more than three blades). A bottom blade 18 carried by a pair of levers 20, extends across the underside of the machine and co-operates with each of the cutting blades in turn as the cutting cylinder rotates. The machine is the same in principle as the normal cylinder type machine for domestic use but is of considerably greater size. For example, whereas the blades of a domestic machine might be 1/8" thick the blades of the present machine are about 3/4" thick and instead of being perhaps 18" in width are about 5 feet in width.

As shown, the bottom blade is pivotally located in the machine on the pair of levers 20 which are mounted on respective pivot pins 21 projecting inwards from the side plates of the frame structure.

The bottom blade is held in its operative position during normal operation of the machine by a pair of hydraulic rams 22 the cylinders of which are mounted on respective pivot pins 24 which project from the side plates of the frame structure and the piston rods of which are pivotally connected to the respective levers 20. The operation of the hydraulic rams is under the control of the tractor driver by means of a manually operable hydraulic control valve (not shown).Abutment means generally indicated 25 provide respective positive stops which act against the forwardly projecting portions of the levers 20 to determine the setting of the bottom blade during normal operation of the machine, the abutment means being constituted by respective screws 26 which have screwthreaded engagement with threaded holes in respective metal blocks 27 welded to the side plates 12. The screws can be locked in adjusted position by respective locknuts 28.

The arrangement is such that during normal operation of the machine the bottom blade is held rigidly in position and is not displaced by the passage through the machine of substantial sticks and small tree branches. Even small stones and foreign bodies such as building bricks will be unlikely to interfere with the normal operation of the machine. However, if a really substantial piece of metal, for example a piece of farm machinery, is by inadvertence caused to be fed into the machine so that the mechanism becomes jammed, the tractor driver can operate the control valve to actuate the hydraulic rams and to cause the bottom blade to swing away from the blade cylinder. When the obstruction has then fallen clear or has been removed, the control valve can be operated to return the bottom blade to its normal position.By virtue of the abutment of the levers 20 against the abutment means 25, the bottom blade is returned to exactly the position it previously occupied for cooperation with the blades of the blade cylinder.

When breakaway movement of the bottom blade has occurred, and after the obstruction has been cleared, the bottom blade can very quickly and easily be returned to its operative position.

The machine described above is mainly intended for mowing grassland for use as forage for cattle housed under cover. Such a machine can cut a much shorter standing crop than a forage harvester is capable of cutting and cuts the crop cleanly. Thus it is thought likely that, for example, four cuts may be taken over a growing season where only three cuts have previously been possible. However, it is not only capable of cutting grass; when mounted on a tractor mounted power-manipulated arm it will also be capable of trimming hedges and the like.

Various modifications may be made. For example, in Figure 3 there is illustrated a modification which has been made for the sake of safety in operation. It should perhaps be explained that it is useful if fine adjustments to the operative position of the bottom blade can be made while the machine is running.

This is because there is then a clearly audible indication of when the blades of the blade cylinder begin to make sliding contact with the bottom blade and a much finer adjustment is able to be made in this way than by the alternative method of bringing the bottom blade into contact with the stationary blade cylinder during which the user has little indication of when the required adjustment has been brought about. Clearly, however, the adjusting of the screws 26 and locknuts 28 of the machine illustrated in Figures 1 and 2, even by the use of special purpose box spanners, could be considered a hazardous operation in such close proximity to the rotating blade cylinder.Consequently, as shown in Figure 3, the blade cylinder is enclosed by a casing open onlyon its underside, the casing being indicated by chain-dotted lines, and the means whereby fine adjustments can be made to the operative position of the bottom blade can be operated from outside the casing. This has been brought about by extending the length of the screws 26 and by welding the locknuts 28 at the lower ends of respective sleeves 30, the latter extending rotatably through apertures in the casing and being provided at their upper ends with hexagon heads for engagement by a spanner. Thus it is possible in complete safety to make fine adjustments to the .operative position of the bottom blade with the blade cylinder rotating.

Various other modifications may be made. For example, the mechanism could be provided with an automatic break-out mechanism which would allow the bottom blade to swing away from the blade cylinder in response to a pre-determined threshold load. This could be a safety mechanism in addition to the simple re-set mechanism described above, its purpose being to prevent damage to the machine if a particularly large and solid obstruction is fed into it.

It will be understood that when the machine is arranged to be mounted on the usual 3-point linkage of an agricultural tractor, it can be driven by the power-take-off shaft of the tractor. However, it may be carried by the power lift forks of a tractor in which case it will probably be more convenient to drive the I cutting cylinder by means of a hydraulic motor.

Claims

1.A A rotatable cylinder type mowing or like machine provided with a bottom blade which is pivotally mounted in frame structure of the machine for movement of an operative part thereof away from the rotatable blade cylinder in the event of a very substantial foreign body being fed into the machine, the bottom blade normally being held in its operative position against a positive step by means of a pair of hydraulic rams at its opposite ends.

2. A machine according to claim 1, in which the pair of hydraulic rams are connected to the hydraulic system of a tractor by which the machine is carried so that the operative part of the bottom blade can be pivoted away from the blade cylinder in response to movement of a control lever.

3. A machine according to claim 1, in which the hydraulic rams contain a fixed amount of oil and act as resilient means holding the operative part of the blade in its operative position against the positive stop.

4. A machine according to any one of the preceding claims, in which the positive stop against which the bottom blade is normally held in its operative position is constituted by respective screws which have screwthreaded engagement with threaded holes in fixed frame parts of the machine at opposite ends of the blade cylinder, the lower ends of said screws acting against forwardly projecting portions of respective pivoted levers by means of which the opposite ends of the bottom blade are carried.

5. A machine according to claim 4, in which the blade cylinder is enclosed by a casing open only on its underside, and the respective screws which constitute the positive stop against which the bottom blade is normally held in its operative position can be adjusted from outside the casing, whereby fine adjustments to the operative position of the bottom blade can safely be made while the machine is running.

6. A rotatable cylinder type mowing or like machine constructed, arranged and adapted to operate substantially as hereinbefore described with reference to and as illustrated by Figures 1 and 2 or Figure 3 of the accompanying drawings.