GB2203465A - Trencher - Google Patents

Abstract

A trencher, adapted to be towed behind and driven from a tractor, comprises a plurality of driven wheels 16 carrying cutting blades 18 and a hopper 28 for containing gravel. There are a plurality of gravel outlets 30 each arranged behind a respective wheel 16. A baffle arrangement 32 is placed between each wheel 16 and its respective gravel outlet 30 so as to prevent a trench dug by the wheel collapsing or filling with soil before being filled with gravel. This arrangement allows the digging of a plurality of surface drainage trenches very much more quickly than hitherto. <IMAGE>

Description

TRENCHER This invention relates to a trencher in particular for the digging of drainage trenches in sports fields and the like.

Grass fields, in particularly sports fields such as football pitches and the like, usually reauire some form of drainage to prevent them becoming flooded or waterlogged. A typical drainage system would comprise a drainpipe laid within a trench filled with gravel, the top of the trench being positioned six to ten inches below the surface of the top soil. However, it has been found that in order to cope with heavy rain further trenches should be provided intersecting with the main drains and being located within the top soil layer. This is especially so with certain sports fields where the earth can be compacted rendering it less permeable to water.

The provision of such surface drainage trenches has hitherto been carried out by employing a tracked vehicle having a hydraulically operated chain digger capable of digging a trendh six to ten inches deep and two inches wide. The freshly dug trench is filled with gravel after which the top soil is raked over and grass is re-seeded.

This operation is relatively expensive since it will normally require five working days to treat the average size football pitch.

The invention seeks to provide a trencher capable of digging such surface drainage trenches very much more quickly than hitherto.

According to the present invention there is provided a trencher adapted to be towed behind and driven from a tractor which comprises a plurality of driven wheels carrying cutting blades and a hopper for containing gravel with a plurality of gravel outlets each arranged behind a respective wheel.

Preferably, a plough or baffle arrangement is placed between each wheel and its respective gravel outlet so as to prevent a trench dug by the wheel collapsing or filling with soil before being filled with gravel. Conveniently there are four wheels, and associated gravel outlets, mounted transversely of the device, for example on a common axis. The wheels are driven by a suitable gear box and drive arrangement, for example a chain drive, from the towing vehicle power takeoff.

The wheels may be relatively narrow in section, typically half an inch, but the blades which may be mounted on both sides thereof take the cutting width of each wheel to the desired level, for example two inches.

Advantageously the machine is provided with adjustment means for adjusting the depth of cut of the cutting wheels and independent means for adjusting the depth of back fill of gravel.

The invention will be described further, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a side elevation of a device in accordance with the invention; Figure 2 is a similar view to figure 1 partly in section; Figure 3 is a plan view; and Figure 4 is a front elevation.

Referring to the drawings, a trencher generally designated 10 comprises a housing 12 capable of being towed behind a vehicle such as a tractor, conveniently employing the conventional three link coupling. Within the casing 12, mounted on a common axle 14, are four cutting wheels 16 each of which is provided with a plurality of blades 18.

The axle 14 is driven by means of a chain drive 20 from a shaft 22 connected via a gear box 24 to the tractor power takeoff 26.

Mounted on the rear of the casing 12 is a hopper 28 for receiving gravel, aggregate, or the like trench filling medium. The hopper is provided with four dispensing openings 30, one in line with each of the cutting wheels 16. A plough 32 is mounted between each orifice 30 and its respective cutting wheels 16.

In use, the hopper 28 is filled with gravel or aggregate and the device towed behind a tractor. The cutting blades 18 of the wheels 16 cut out four parallel trenches of a width determined by the cutting blades, typically two inches and of a depth, usually between six and ten inches, set by means of a depth wheel 34 which adjusts the height of the axle 14 with respect to the chassis 12. As the trenches are cut the ploughs 32 maintain them open and prevent soil back filling. Immediately following the ploughs 32 are the outlet orifices 30 which fill the trenches with gravel. The bases of the outlet orifices 30 are positioned within the trenches and therefore prevent excess gravel being dispensed by effectively preventing further flow once the channel has filled to the level of the base of the orifice.Thus, provided the orifice is large enough, the level of gravel dispensed is largely independent of the speed of movement of the device. If it is desired to dispense a smaller quantity of gravel, the orifices 30 can be partially blocked off by suitable means. The normally desired level of gravel is to within a short distance of the top of the trench leaving sufficient space for top soil to be raked over the gravel followed by re-seeding with grass.

The height of the base of the orifices 30 can be adjusted independently of the cutting depth by, for example, adjusting the top link of the three link coupling to raise or lower the hopper level with respect to the cutting wheels.

In one method of operation the device of the invention is coupled to a tractor and driven across, for example, a sports field. In order to maintain the hopper fall, and prevent frequent stops, a second vehicle can be driven along side the first and used to continuously or intermittently keep the hopper topped up with gravel.

Preferably, a third operative follows behind checking that the trenches have been properly cut and filled with gravel. Although this mode of operation requires three workman, an average sized sports pitch can be completed in a day compared to five working days required by the prior art methods. The pitch is ready for use once again as soon as the grass has re-grown.

The blades 18 can be adjusted to take up wear, which can be fairly rapid if they are constructed of ordinary steel.

However, if more expensive hardened forms of steel are employed the wear on the cutting wheels will be less rapid. The device of the invention has a further advantage that no ridges are left on the pitch in contrast with some of the earlier methods. Furthermore, if desired, a narrow cut through the grass (for example half an inch) can be made using an appropriate form of cutting wheel. When this is done, the pitch can be played on again within one week and this method is therefore suitable for emergency treatment mid-season.

The device of the invention provides a simple and effective method of cutting feeder trenches for the drainage of fields.

Claims (7)

1. A trencher adapted to be towed behind and driven from a tractor which comprises a plurality of driven wheels carrying cutting blades and a hopper for containing gravel with a plurality of gravel outlets each arranged behind a respective wheel.

2. A trencher as claimed in claim 1 wherein a plough or baffle arrangement is placed between each wheel and its respective gravel outlet so as to prevent a trench dug by the wheel collapsing or filling with soil before being filled with gravel.

3. A trencher as claimed in either of claims 1 or 2 in which there are four wheels and associated gravel outlets mounted transversely of the device on a common axis.

4. A trencher as claimed in claim 3 in which the wheels are driven by a chain drive from the towing vehicle power takeoff.

5. A trencher as claimed in any of claims 1 to 4 in which the wheels have blades mounted on both sides thereof.

6. A trencher as claimed in any of claims 1 to 5 additionally provided with adjustment means for adjusting the depth of cut of the cutting wheels and independent means for adjusting the depth-of back fill of gravel.

7. A drainage trencher substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.