Controls and adjustments

Many of the adjustments on reversible and con­ventional ploughs are made in the same way. The plow share on the right hand furrow must be aligned next to the furrow in order to do a clean job. It is recommended that the tractor rear wheels be set so the right tire runs in the previous furrow.

I order to trail properly with a minimum effect on tractor steering, it is necessary to adjust the drawbar so that the plow is pulling as close to the tractor centerline as possible. Refer to the table below and fig. 6 dimension A. Note that for one bottom plows in particular, the ideal wheels tread width is too narrow for most tractors to obtain. In those cases, set the width as narrow as possible.

HitchingBefore attaching a reversible plough to a tractor it is important to check that both lift rods are the same length and there is equal air pressure in the rear tyres.

Accurate driving to align the lift arms with the hitch points on the plough headstock will make it easier to attach the plough and as most ploughs have automatic linkage there in no need to leave the cab. When hitching a mounted plough by hand, connect the lower left-hand lift arm first, then the lower right-hand lift arm and finally the top link. Remember “left-right-top”. Remove the links in the reverse order when detaching the plough.

After the lower lift arms and top link have been secured with lynch pins, adjust the top link to the mid position for transport and check that both lift rods are the same length. It may be necessary to shorten the top link on long multi-furrow ploughs to prevent the back of the plough striking the ground during transport to the field. As a general rule the check chains should be left slack, allowing the lower lift arms some lateral movement, but there are exceptions and the instruction book should always be con­sulted when attaching a plough for the first time.

Depth is adjusted with the draft control lever and its stop, or by the electronic depth control system, depending on the model of tractor. Large multi-furrow mounted ploughs have an adjustable depth wheel on the main frame and the rear wheel(s) provide additional depth control on semi-mounted models.

Levelling Both lift rods must be set at the same length as recommended in the instruction manual before attaching a reversible plough. If necessary, use the levelling box in the right-hand lift rod to align the lift arm with the plough cross-shaft. Make sure the lift rods are of equal length before starting work. Separate adjustments are provided on the headstock for the left- and right-hand bodies to ensure a level surface.

The levelling box on the right-hand lift rod is used to achieve a level finish with a conventional plough.

PitchAdjusted with the top link on all ploughs. Lengthen it if the heel iron rides clear of the furrow bottom and shorten it if the heel iron cuts a deep mark.

Too little pitch will make plough penetration difficult; too much will cause the shares to dig in produce rough work.

Front furrow widthTwo adjusting bolts are usually provided to change the front furrow width on a reversible plough. Once set, how it will rarely be necessary to use this adjustment. Incorrect front furrow width is due to faulty setting of the levelling adjustment in the headstock.

A lever on the cross-shaft is used to alter the furrow setting on conventional ploughs.

Incorrect front furrow width will cause very uneven work. It is quite easy to see the conse­quence of a wide or narrow front furrow with a high or low front furrow occurring in a regular pattern across the field. Check that the wheels are at the correct track setting for the plough. Wheel settings for different furrow widths will be found in the plough instruction manual.

A mounted implement such as a cultivator is pulled centrally behind a tractor. The line of pull, or the draft of a mounted plough will also pass through the centre of the rear axle, pro­vided that the rear wheels are at the correct track width. As a general rule the top link will be seen to run in a straight line behind the tractor when the plough is in correct alignment, and this is the only setting where the plough will not crab or have a detrimental effect on the steering. A plough which crabs will increase the side thrust on the plough bodies and there will be a high rate of wear on the landsides.

Figure 22. Line of draft of a plough with a sideshift headstock.

However, correct rear wheel track settings are less critical with some of the latest models of reversible plough. The position of the plough in relation to the tractor can be altered by moving the headstock across the width of the tractor with a screw adjuster or with a hydraulic ram while on the move. When the correct line of draft is achieved the tractor travels in a straight line without the need for frequent corrections with the steering wheel. The top link may not run in a straight line behind the tractor (see Figure 22.), but the plough will be correctly set and the top link will be pointing towards the centre of pull.

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