GB2093418A

GB2093418A - Spacing device

Info

Publication number: GB2093418A
Application number: GB8204971A
Authority: GB
Original assignee: Individual
Current assignee: Individual
Priority date: 1981-02-20
Filing date: 1982-02-19
Publication date: 1982-09-02
Also published as: GB2093418B

Abstract

A spacing device enables a marking tractor (12) and a slave tractor (15) to be driven parallel with one another over a field, at a substantially constant lateral spacing (14) to set up a tramline system for subsequent use in cultivating the field. A cable (18) wound on a drum (26) rotatable about on a fore-and-aft axis has its free end connected to the slave tractor (15), and if the spacing between the two tractors varies, a mark on the cable (18) will move horizontally in relation to a fixed reference post so that the driver of the marking tractor (12) can maintain approximately equal spacing between the two tractors by steering the marking tractor (12), so that the mark remains at a more-or-less constant position in relation to the post. Changes in the length of the cable (18) may alternatively be detected by indicator means actuated in response to rotation of the drum (26). <IMAGE>

Description

SPECIFICATION Spacing device This invention relates to a device enabling two vehicles to be driven at an approximately constant distance apart and one application of the invention is to the method of setting up a system of tramlines on a field to be farmed. The term tramlines is given to the parallel lines left on a field after a tractor has passed, and for efficient farming it is necessary that adjacent sets of tram lines are equally spaced apart by a distance known as the bout width corresponding to the width of the farmer's apparatus. When first setting up the tramlines two tractors can be used with one tractor following a tramline made in a previous pass by a marking tractor, and the marking tractor being driven at a controlled distance from the slave tractor to set up the next pair of tramlines.

According to the present invention a device enabling two vehicles to be driven at an approximately constant distance apart comprises a cable drum arranged to be attached to one vehicle, several turns of cable on the drum for attachment at the free end of the cable to the other vehicle, and means comprising a visual indication to the driver of the one vehicle of changes in the amount of cable which has been paid out.

If the cable is kept reasonably taut and the driver steers the one vehicle so that the amount of cable that has been paid out is pretty well constant, then the two vehicles will be driven at a constant distance apart corresponding to the amount of cable paid out providing the cable is pretty well perpendicular to the direction of movement which is achieved by the driver of the one vehicle driving at a speed to keep his vehicle in line with the rear of the other vehicle.

The cable drum is conveniently mounted for rotation about a fore-and-aft axis and conveniently on a mounting post which is capable of being secured to any of a number of different tractor weight carriers. There may be an arrangement such that the back of the drum can be seen by the driver and can have radial markings so that he can easily see if the drum is rotating showing that cable is being paid out or being wound back on the drum because the distance between the vehicles is changing. Then there is conveniently an indicator wheel driven from the drum through gearing so that for each revolution of the drum the indicator wheel is turned through an angle equal to the spacing between successive digits marked on the wheel.The digit which appears in a window on the mounting will represent the number of turns of cable that have been paid out and thus it will represent the distance between the vehicles.

In another arrangement an indicator mark, for example, a piece of ribbon, is applied to the cable itself at a point which, when the two vehicles are spaced apart at the required distance, will lie next to a fixed index marker, for example a vertical rod, carried by the vehicle on which the drum is mounted, in a location on the same side of the drum as the second vehicle is to travel. Thus, in use, any deviation of the vehicle carrying the drum from the required lateral spacing from the second vehicle will immediately be indicated to the driver -of the first vehicle by the corresponding displacement of the indicator on the cable from ,the fixed index mark, in a direction indicating the sense of that deviation, and can at once be corrected by the driver.

Two vertical rods may be provided, fixed one on either side of the drum to the front of the tractor, for alternative use as the fixed index mark depending on which side of the first vehicle the second vehicle is to travel. These rods may also act as guide rods to keep the cable clear of the front of the tractor so that lower guide rods in front of the tractor front wheels may be dispensed with.

There may be a spring loaded connection of the fixed end of the cable to the drum providing a tensioning force in the cable which tends to cause the drum to turn to pull in any slack in the cable.

The tensioning means might be an arrangement of mechanical springs or a stalled electric motor or a pneumatic or hydraulic arrangement.

Conveniently, the length of cable on one turn on the drum is equal to a metre so that the spacing between the two vehicles can be set by counting rotations of the drum as the cable is paid out.

There is preferably a fitting at the free end of the cable adapted to be mounted on the rear suspension points of a tractor constituting the other vehicle, and there will be an arrangement of guides for keeping the cable clear of the front wheels of the one vehicle and the rear wheels of the other.

The invention includes a device when mounted between two tractors with the cable drum being visible to the driver of one tractor and the free end of cable attached to the other tractor.

The invention also includes â method of setting up a tramline system in a field according to which a slave tractor constituting the other vehicle is driven along tram lines made by a previous pass of a marking tractor constituting the one vehicle and the driver of the marking tractor uses the spacing device to maintain the spacing between the two tractors approximately constant.

The invention may be carried into practice in various ways, and two embodiments will now be described by way of example, with reference to the accompanying drawings, of which: FIGURE 1 is a plan view showing marking and slave tractors marking tramlines on a field by use of the invention; FIGURE 2 is a rear view of the slave tractor in use; FIGURE 3 is a front view of the marking tractor in use; and FIGURE 4 is a view looking forwards from the driver's seat of the drum, cable and fixed index rods attached to the front of a tractor in a second embodiment.

When a tractor is driven over a field it leaves behind it a pair of parallel lines such as 11 in FIGURE 1 where the wheels have been and these are known as tramlines. In modern farming methods it is desired that a tractor always passes down the same tramlines and also that the adjacent pairs of tram lines should be accurately spaced apart by what is known as bout width to suit the width of tools to be towed, such as fertiliser spreaders, sprayers and so on. In FIGURE 1 the marking tractor 12 is shown pulling a fertiliser spreader 13 and it will be appreciated that the bout width 14 should be equal to the width of the spreader 1 3 so that in successive passes of the tractor along adjacent tram lines the area treated will be just to the side of the area previously treated.

An object of the present invention is to provide a means for initially setting the bout width to suit the equipment that the farmer is using. Once the width has been set the markings will be preserved as a tractor moves over the previously marked tramlines.

To provide the accurate spacing of adjacent tramlines, a slave tractor 1 5 is driven along the tramlines 16 previously marked by the marking tractor 1 2 and a spacing device indicated generally at 1 7 is used to assist the driver of the marking tractor 12 to drive his tractor slightly to the rear of the slave tractor and spaced from it by the desired bout width.

The spacing apparatus 1 7 comprises a string or cable 1 8 attached at its free end to the rear of the slave tractor by means of a transverse bar 1 9 held on the tractor rear suspension points with a central R-shaped fastener 21 for the end of the cable 18 and from which the cable can slide if an obstacle is encountered and great tension is generated in the cable, and also canying a pair of vertical guides 22 which act to keep the cable from coming into contact with the rear wheels of the slave tractor.

At the other end the cable passes through a guide eye 24 (Figure 3) up to a guide eye 25 and then around a drum 26 mounted for rotation about a fore and aft axis 27.

The drum comprises front and rear plates and six pins holding them apart near the periphery and defining a path for turns of cable, each of which turns is equal to one metre in length. In the example being described the drum carries 20 turns of cable so that it is 20 metres long. At the inner end it is fastened to a tensioning arrangement, for example a pair of coil springs or possibly a stalled electric motor or a pneumatic or hydraulic device ensuring that slack in the cable is taken up by rotation of the drum about its axis.

The drum is mounted at the upper end of a vertical post 28 at the front of the marking tractor 12 so that the rear face of the drum can be clearly seen by the driver. That face has a diametral white line 29, separating a red half 31 from a green half 32.

Geared to the rear face of the drum 26 is a counter wheel 33, arranged to be turned through a small angle 36 for each complete revolution of the drum 26. The wheel 33 is marked on front and back in integers from 1-20 so that as the cable is unwound and turns the drum, a different number will appear in a window 37 in a fixed vertical post 38 for each complete drum revolution. Thus the number (9 in Figure 3) seen by the driver on the side facing him indicates the number of metres of cable that have been pulled from the drum and thus indicates the spacing between the centres of the slave and marking tractors when the free end of the drum is secured to the centre of the slave tractor and the cable is taut. The driver steers the marking tractor to try to keep the white diametral line 29, in line with the post 38.Any increase or decrease in the spacing between the tractors will result in the white line moving to one side or the other of the post 38 and will give a clear indication to the driver.

The marking tractor 12 also has a pair of vertical guides 41 for keeping the cable 18 clear of the front wheels 42. The height of the cable 18 as determined by the lower eye 24 is about the height of the axle of the wheel 42. A weight 43 on the cable near its connection 21 with the slave tractor tends to prevent any slack in the cable being taken up too rapidly by the tensioned drum.

The precise method of tensioning the drum is not of great importance provided the slack in the cable can be taken up, whatever length of cable has been pulled off the drum to set the bout width.

At the end of a pass the marking tractor can stop, perhaps one bout length from the end of the field while the slave tractor is driven round the front of the marking tractor and back to its rear to drive down the tramlines just marked by the marking tractor. Then the marking tractor is started again and follows a path displaced further to one side by the bout width. It will be appreciated that on this pass the cable 18 will extend to the opposite side of the marking tractor.

If on the first pass the colour of the disc seen by the driver in line with the post 38, was red when the marking tractor tended to get too close to the slave tractor, then on the second pass the same colour will be seen if the marking tractor tends to get too close but of course the steering to correct that will be to the other side.

In the embodiment shown in FIGURE 4, the top of the tractor bonnet is shown at 48, and parts of the front wheels at 49. The drum is shown at 50, being spring-loaded in the direction of the arrow 'A' to keep the cable 51 taut as it extends upwardly from the drum through a guide eye 52 mounted on a vertical post 53 above the drum and thence extends nearly horizontally to its attachment to the rear of the second tractor (not shown).

Two vertical rods 54A and 54B are mounted on the front of the tractor, one on either side of the drum as shown, so that the cable will pass close to one of these rods, 548 as shown, as it extends to the other vehicle. A short piece of coloured marker ribbon 55 is attached to the cable at the point thereof which will be adjacent to that rod 1 4B when the two vehicles are travelling at the required spacing. Any deviation from that spacing resulting in cable being wound in or paid out from the drum 50, will be immediately indicated to the driver by the displacement of the marker ribbon 55 to left or right of the guide rod 54B and can be immediately corrected.

Claims

1. A device enabling two vehicles to be driven at approximately constant distance apart, comprising a cable drum arranged to be attached to one vehicle, several turns of cable on the drum for attachment at the free end of the cable to the other vehicle, and means comprising a visual indication to the driver of the one vehicle of changes in the amount of cable which has been paid out.

2. A device as claimed in Claim 1 in which the cable drum is mounted for rotation about a foreand-aft axis.

3. A device as claimed in either of the preceding claims including a mounting for the cable drum including a post which will be generally vertical when secured to the front of a tractor.

4. A device as claimed in any of the preceding claims arranged so that when mounted the back of the drum can be seen by the driver of the one tractor.

5. A device as claimed in any of the preceding claims including an indicator mark applied to the cable itself.

6. A device as claimed in Claim 5 in combination with the fixed index marker at one or at each side of the drum.

7. A device as claimed in Claim 6 in which the/or each fixed index marker comprises a generally vertical rod passed which the indicator mark can move as cable is paid out, and which can keep the cable clear of the front of the one tractor.

8. A device as claimed in any of Claims 1-4 including an indicator wheel driven by the drum through gearing and giving the driver of the one tractor a digital indication of the amount of cable that has been paid out.

9, A device as claimed in any of the preceding claims including a spring-loaded connection or other tensioning means between the fixed end of the cable and the drum.

10. A device as claimed in any of the preceding claims including a fitting at the free end of the cable adapted to be mounted at the rear of the other vehicle.

11. A spacing device constructed and arranged substantially as herein specifically described with reference to FIGURES 1-3 or FIGURE 4 of the accompanying drawings.

12. A spacing device as claimed in any of the preceding claims when mounted between two tractors with the cable drum being visible to the driver of one tractor, and the free end of the cable attached to the other tractor.

13. A method of setting up a tramline system in a field according to which a slave tractor is driven along tramlines made by a previous pass of a marking tractor, and the driver of the marking tractor uses a spacing device as claimed in any of the preceding claims to maintain the spacing between the two tractors approximately constant.