Jane Carley speaks to two specialists about correct ballasting.
Working in a range of conditions and soils, with implements from drills to ploughs and subsoilers, getting all that power to the ground is key to making efficient use of a tracklayer.
Operators with new machines may raise concerns about how to use ballast for different tasks or in tricky terrain.
However, Case IH suggests that the design of the Quadtrac eliminates the need to adjust ballast in normal conditions.
Product specialist, Paul Freeman says: “As the Quadtrac is articulated, with the same surface area on each track unit, there should be equal weight on all four tracks.”
Operators can check the balance of any tracklayer, he points out, by looking at the footprint made by the front tracks and comparing it with those at the rear.
“If there is a big difference, the implement is pulling the back of the machine down and with a twin track machine this can be remedied with extra weight at the front. However, the Quadtrac pulls from the middle and distributes the weight between the two axles, so there should not be a difference.”
Where problems can occur, Mr Freeman comments, is if an implement is not level and thus is not in the same horizontal plane as the tractor drawbar, it can try to lift the tractor or conversely, push the back end down.
He adds that a rule of thumb is to use 45kg of ballast per horsepower, and that this is built into the Quadtrac, with 1,200kg of tombstone block as part of the frame.
“Some customers will actually remove this for light work such as drilling, and replace it for draft work.”
“One Quadtrac customer achieves a high level of precision by using an infra-red temperature gauge to assess whether the rear tracks are working harder than the fronts, and will add extra weight if necessary, although he also looks to rejig implements to put their weight further forward on the Quadtrac if it is not perfectly balanced.”
Mr Freeman points out that the Quadtrac will actually weigh heavier on its front axle if put on a weighbridge – this is designed to help the machine maintain its 50:50 balance when the fuel tank, which sits on the rear axle, is full to its 1,800 litre capacity.
Slippage can be caused by a lack of grip, which is often down to wear, but Mr Freeman comments that as few Quadtracs do any significant roadwork, their tracks tend to be replaced as a result of issues with the carcases rather than tread wear.
“If slippage is occurring, consider the conditions – they may not be suitable, and have a look at the implement to ensure that it is the right match and correctly set up. Quadtracs also have diff locks, which are not fitted to twin track machines, so if the tractor is slipping in a straight line, engaging the diff locks can help.”
Challenger National Sales Manager Stephen Sampson suggests that the advantage of the Challenger twin track machines is that they are relatively light and that weight can always be added to them as needed. But he suggests that operators need to consider balance as well as ballast.
He says: “You need to keep the tracks flat on the ground but you can actually have tracklayers too heavy in front by adding too much weight, in which case the balance would not be correct. An operator would notice the excessive weight in the form of track marks and ‘scuffing’ on headland turns.”
This, he says, defeats the object of having a low ground pressure power unit – a 16 tonne MT700 series Challenger can exert as little as 6psi.
He suggests that operators should always aim for good belt to ground contact. “A visual check of machine during operation reveals that the entire length of the belts are in contact with soil and there is no gap under the front idler when a mounted implement is lifted.”
Some operators go further, he suggests. “I have seen customers testing and diagnosing soil compaction using a penetrometer, which gives a true test when put into the soil behind the tractor in the track marks.”
Mounted implements do cause more issues than trailed implements, he points out, as the drawbar pulls from the centre of the machine.
Challenger offers factory fit ballast systems for its tracklayers and recommends that the tractor be ballasted up to its maximum permissable weight. However, the machine should also be balanced so that its centre of gravity, under load, is forward of the rear axle.
Several different weight types are available.
Front (suitcase) weights are recommended instead of idler weights when the machine is equipped with a mounted implement as they are more efficient for balancing the machine.
Not only do the suitcase weights provide ballast, but because of their location far forward of the tractor’s centreline, they also help to move the centre of gravity forward, improving balance.
“The complete set of weights can also be removed with one pin by one man with a forklift in about 10 minutes,” says Mr Sampson.
The MT 700 Series can be fitted with 16 individual suitcase weights plus a centre pack of four weights, each weighing 45kg.
Idler weights are recommended when the machine is equipped with a drawbar implement, as the weight is directly applied to the undercarriage for increased pulling and steering performance. However, they are more difficult to add and remove, say Mr Sampson.
All MT700 tractors have the option of front idler weights which weigh 57kg each and bolt to the face of the front idler wheel. Up to 24 idler weights can be installed on an MT700 and 36 on an MT800 inside and outside of each undercarriage.
Like front suitcase weights, the idler weights can also help improve the tractor’s balance due to their forward location. An equal number of weights has to be maintained on the inner and outer idlers and on the left and right undercarriages.
Track frame weights can now be fitted to take account of the higher horsepowers offered by the latest Challenger series.
“Track frame weights push the track down, which helps balance a linkage mounted implement without compromising manoeuvrability,” explains Mr Sampson.
The signs of under-ballasting are increased slip, first noticed on headland turns, and a feeling of the machine being ‘heavy’ in front, he points out, while over ballasting is evidenced by difficulty turning and by scuffing.
Track wear is rarely a concern and tends to be caused by roadwork rather than overballasting. “A set of tracks on a tractor of this size would last twice as long as a set of tyres in the same situation anyway.”
Most MT800 Series are specified with 1,596kg ballast from 28 idler weights, 1,936kg upfront and 32 track frame weights.
Mr Sampson says: “To swap from cultivations to drilling, you could simply take the track frame weights and front weights off, but it doesn’t need to be complicated or time consuming. The 500hp MT845 with front weights and 16 idler weights fitted would do most jobs without alteration.”
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