Horsch launched its Maestro precision ‘single grain’ planters back in 2011, trailed SW models with a choice of 12-, 16-, 18- or 24-rows were available by the time these started to arrive in the UK. Fast forward to 2021, and the current SV and SX variants arrived with completely revised metering units, new hoppers and wide changes to the related hardware.

KEEPING IT BRIEF

  • Maestro metering units are fitted to both trailed and mounted models
  • Soil wearing metal is common to the original and current AirVac and AirSpeed Maestro variants
  • Fertiliser coulters can mount separately on current models
  • Concentrate on condition. A high hectare count is to be expected

Horsch uses its Maestro seed only precision metering units across a wide variety of planters. It’s the letters after the Maestro name that will give you a better inkling of the fertiliser system (granular, liquid or micro-fert) employed and the configuration of the folding system and it if is a mounted or trailed machine. 

As a bit of a broad-brush overview, this is what you are looking at:

  • SW and current SV/SX range with 12- and 16-row models at 75cm spacing and 18- or 24-rows variants spaced at 50cm.
  • CC 8.75 and CC 12.50m are smaller trailed machines
  • RC 8.75m or 12.50m are mounted were subsequently offered.
  • Later alternatives to the SV/SX include 45cm to 80cm row adjustable
  • TX6 or TX 7 are a type, and entered production in 202?
  • RV/RX drills are 6.75m, 8.75m, 9.75 m and 12.50m wide and used a front-mounted fertiliser hopper.
  • Smaller trailed CV/CX 8-, 9- or 12-row drills at 50cm spacing or 9 -and 12-row variants at 75cm spacing. Even within the SW and current SV / SX range there are 12- and 16-row models at 75cm spacing and 18- or 24-rows variants spaced at 50cm.

One Maestro family name, but one that includes numerous models to include both toolbar and trailed variants.To simplify matters, here we take a broad look at the first-generation SW and subsequent SV/SX trailed models, the latter offering either AirVac or AirSpeed metering respectively; more on this later. We are aware that there will not be many used SW or later models on offer in the UK and even more so in Ireland, but all Maestro models share essentially the same metering systems.

One of the key features of these drills is the use of an independent electric motor to drive the metering disc of each seeder unit. At launch, much was made of the low current draw of these individual motors. This enabled up to 24 metering units to be run on a single drill without the risk of overloading the tractors electronics. 

A further design feature is the depth control system that automatically adjusts the seed coulter pressure to compensate for changing soil types and conditions. This system, which Horsch calls AutoForce, is claimed to deliver accurate depth control across the drilling width and along the rows for consistent germination.

On SW units, there is a seating disc that locates behind the metering disc, with a shim or shims taking up any excess clearance between the discs and the outer housing. If the disc if run too loose it can lead to seed not seating correctly in the disc notches, with too tight a fit putting a strain on the electric motor drive. If the latter happens, the increase in torque needed to turn the disc is picked up by the drill’s software, with an alert appearing on the ISObus display.

First generation SW metering units

On the SW drills, the metering unit motor has an integral controller that ensures the drive maintains a consistent seed rate at varying forward speeds and across the working width of the drill. To reduce the current draw of each motor, the stainless-steel disc in the metring unit does not run against the friction of a tight seal, with a powerful vacuum to draw seed into the notched edges of metering disc. 

As outlined in the picture captions, there are various components within the unit to activate the singulation of the seed and to ensure it is detached from the disc edge from where it is released to drop down into the tube leading to the seed coulter. 

Manufactured to tight tolerances, the original metering units are well-proven and rugged but there are several wear elements. Although this wear occurs gradually over an extended working period, close attention needs to be paid to the fit of the disc in the housing, with shims used to take up small amounts of wear. The discs themselves will also gradually wear at the seed cut out notches.

The metering drive motors and drive control module are mounted together. If either of these elements fail they will typically be replaced as a complete unit as these combined elements are ‘programmed’ to work with the drill, with new replacements needing calibrating on installation. As swapping to a replacement is not a difficult field repair, some users will carry a pre-calibrated spare module and motor just in case one fails in service. 

The original disc drive motors have an external push button that enables each individual motor to be activated on its own. This allows the metering unit to be both checked for running and calibration. The latter can be achieved either running from seed fed from the hopper or directly via seed fed into the unit via a calibration funnel. The latter system is typically employed when checking individual metering units for accuracy. 

For further detail, see picture captions.

SW drill users may carry a spare meter drive and drop sensor, both pre-calibrated to the drill to allow a speedy in-field repair should there be a problem. When the drill is cleaned and checked, it pays to detach the motor cable to ensure the connector has no corrosion and that the yellow seal is in good condition. If moisture gets in it can cause problems.

SV suck or SX blow

On SV/SX drill models, the metering unit had a complete redesign to make these models easier to maintain. The design does away with metering disc shims with a simplified swap of disc types when switching to different seeds. To reduce the cost of parts, key wear components are made from plastic. Although this material does not offer the same resilience to wear as the previous metal design, the parts that do wear are considerably cheaper and easier to renew. 

A further change is that the controller and motor are separate units. If either fails, they can be renewed separately. Calibration of the motors and controlled is also carried out automatically to make replacement ‘plug and play’. Again, see picture captions for more detail.

Viewed from underneath, the close coupling of the integral fertiliser coulters of the SW deign to the left is easy to see (above). The fertiliser coulters on SV/SX drills can be mounted separately to the front of the toolbar, so removing this element from the AutoForce depth control system for the drill elements (below). In certain conditions, this may lead to a faster reaction time to changing soil conditions for more precise depth control. On sidling land, however, the integral fertiliser and seed coulter design is not subject to the fertiliser element drifting either too close or too far from the seed furrow. Horsch continue to offer the original layout for those working in hilly terrain.

Another key change is that whilst the metering units of SV models work using the familiar AirVac vacuum system, SX variants employ vent pressurised air AirSpeed that in effect ‘blows’ seed onto the disc. 

On SV models, the AirVac system plays no role in the seeds progress once it has been singled out by the metering unit. It essentially falls, via the drop tube, into the furrow created by the seed coulter. Much the same way as with the previous generation SW in other words.

With the SX AirSpeed system, the metered seed is ‘captured’ by the air current flowing through the metering unit, the drop tube becoming more of a shoot tube, with metered seed effectively being blown down and into the soil furrow. To prevent the seed bouncing as it lands, the seed is embedded by a catch roller.

If you were to ask Horsch which system is better you will not get a direct answer but more the suggestion that an SV drill can be worked at speeds of up to 12km/hr, the SX up to 15km/hr. In the UK, most users will typically work at speeds nearer to 8km/hr. 

As a used buyer it obviously follows if you are after a Maestro metered drill your choice will be limited to what is available. Faced with the choice of an SV or an SX drill, seek advice. Horsch specialists may suggest an SX is more ‘versatile’ in that it may be operated at a higher working speed.

The original Horsch Maestro SW (left) has a different hopper and pneumatic distribution system to the current Maestro SV/SX models to the right but in terms of actual performance and accuracy it will give little away to its newer siblings. In terms of whole life operating costs, however, the newer drills should be both easier and cheaper to maintain.

What about the hoppers and running gear?

SW drills have a different hopper design and lids than the current SV/SX range, with the pneumatic blower system and hydraulics that control pressure on the toolbar also differing. From a used buyer’s perspective, these design changes will have no impact upon how the drills operate. The key is to check the pivot points, hose runs, connectors and running gear typically. The build of these trailed drills can be summed up in one word. Robust. Still check for corrosion and accident damage.

When it comes to the electronics and control software, you will be able to check this either via a dedicated Horsch display, which is a less common find these days, or via the ISObus head unit in the tractor. If you cannot hook a tractor up to the drill you will not be able to check the important control systems and run up the metering units to ensure they operate as they should. 

With reference to software, a Horsch dealer will ensure the drill will work with a tractor’s ISObus system. There should be no compatibility problems, but it is still worth checking.

The tool bar beam is used as an integral part of the vacuum system and is capped off by removable sealed ends. These bolt in place on SW drills, SV/SX models having a simple screw knob to allow the flaps to be removed easily. This should be done when the drills are stored, rodents eating into pipework or accessing the beam via the intake impellor finding the beam makes a cosey winter home.
A seed lubricant is recommended for use in all Maestro drills, particularly for maize. Periodic cleaning of sensors, coulter tubes and the various hose distribution heads is recommended.

What to look for

As these drills are specialist items of kit, with used examples thin on the ground, it follows your starting point will be to talk through your needs with a Horsch dealer who, in turn, will work with Horsch UK. The latter know where all Maestro SW and current SV/SX models are and if any are available used. 

The additional micro granule application tube behind the seed coulter is a fairly common option on UK Maestro drills. These and the seed coulter outlets do need a periodic clean, as do the sensors.
Horsch dealers can order a spares pack for Maestro drills that will contain key electronic components including sensors and drive motors. This system enables a fitter mechanic to have ready access to possible parts needed to get a drill up and running without having to guess what may be needed before leaving the depot.

An outline of the basic metering unit checks is listed in the picture captions, with less attention focusing upon the hopper and tool bar elements. This is not to suggest the latter an unimportant when it comes to checks but more that it is the ‘Maestro’ drill elements that should be you core focus.

On all SW drills, the fertiliser disc coulters are integral with the seed coulters, with no independent depth control. Although the AutoForce depth control system will work well enough in varied soil conditions, the added weight of the fertiliser coulters can slow the system, leading to potentially compromised depth control in certain conditions. Later SV/SX drill may have the fertiliser coulters mounted separately and to the front of the toolbar. This also enables their working depth to be more easily varied.

As to choosing between and SW or later SV / SX drills, the former are equally as capable as their successor models. The downside if they are not as easy to look after and when parts within the metering system need to be renewed those parts will also be more expensive. 

SW drill models that are available are likely to be in good order and should make a sound buy but you will need to keep on top of maintenance and really look after the drill. Well maintained SW drills should continue to retain a strong residual value, but you do need to accept that as these variants are no longer in production, they will not be worth as much further down the line.

The seed coulter discs are wearing items, the pictured unit showing a noticeable gap between it and the rear of the metal share. Although this is a good indicator of wear these items will only need replacing if the disc pairs do not both rotate when just one is turned by hand. The depth control wheels rubber tyre (right) should run up against the coulter discs, removable shims taking up wear. When there are no shims left and a gap opens it is time for new rubber (although this will only be necessary on drills that have done a tremendous amount of work). The core seed to soil engagement system is used on SW and SV/SX drills.
The seed furrow closing wheels adjustment angle is altered via a simple notched lever system with the same design used on SW and SV/SX drills. The furrow press wheel option (right) can be raised out of work on SW drills but are fixed on later SX models. A coulter pressure of between 150 kg and 350 kg is achieved by altering the pressure on hydraulic depth control cylinders.

If you have deeper pockets and are looking to keep the drill for an extended period it follows that the later SV/SX models can make a better longer-term investment.  No surprises there of course. You get what you pay for. But when it comes to a fight between which one will do the better job, then there is not a lot in it. 

There are numerous differences between SW and SV/SX drill hoppers, the capacity of fertiliser to seed varying in accordance with the original buyer’s preferences. What has not changed is the hopper lids need to have a tight seal, the insert in the hopper rim losing its soft sealing ability if the lids are clamped tight shut in storage. On SW lids, the clamps are adjustable, the later drills having a simpler spring tension system that needs no attention.

Prices 

With so few used examples of trailed SW and later SV/SX drills to choose from, pricing is perhaps a bit tricky. If you consider the 16-row examples as listed, these may retail for perhaps £85,000 and £145,000 respectively. Look around, and you may find an SW selling for a bit less. But in the simplest of terms, consider a Maestro SW drill costing upwards of £5,500 a row and holding back around £1,000 per row to pay for new wearing metal. Later drills with the less expensive metering unit internals are not ‘better’ drills but they will be easier and potentially less costly to look after. 

Other noticeable differences between SW and SV / SX Maestro drills include the layout of the pressure dials at the front of the hopper. They do the same jobs, with an ‘analogue’ view of pressure and vacuum settings. Fan speed is shown on the in-cab ISObus screen. The adjacent toolbox should be checked as it can house alternative fertiliser metering wheels, seed discs and drill spares.

Summary

If you are interested in a Maestro SW or later SV/SX model, the used buying advice is simple. Talk to users and Horsch dealers. As to other drills with the Maestro metering units, these are more widely available and will of course offer the same levels of per row performance. Where the ‘S’ models score is in their ability to drill large areas without stopping. 

Mounted in the toolbar beam, the vacuum reading from this sensor will show on the vacuum gauge at the front of the drill.
Large guard at the front of the hydraulically powered impellor gives clue to the volume of air gulped in by these drills. A dealer check will be needed to ensure the pneumatic and vacuum systems are up to the job.
The flexible section of hose leading to the distribution head is made from a special material that enables it to fold without damage. It should be flattened when no air is passing through the system, inflating as the pneumatic system starts up. Note the second distribution head, this feeding the microgranular system. All the grey corrugated hoses are directional and must be replaced with the correct design to prevent air retractions. A mounting arrow is printed on the hose to show the correct alignment when fitting a new length.
To ease retrofitting, all SV/SX drills leave the factory with mounting brackets for microgranular hoppers.
As drills become wider, the impact of speed differentials between the metring units in a curve becomes exaggerated. As an option, Horsch offer its ContourFarming system to help minimise the seed spacing anomalies that will arise between the inside and outside of a turn. Radars mounted at each end of the toolbar detect speed differentials and data from this is used to adjust the speed of the metering unit drive motors.
Arguably one of the most neglected items of trailed equipment is the drawbar hitch. In this case, the Scharmueller ball hitch system did not show any sign of wear, but a simple measurement gauge to check the ball is the only way to really determine if the hitch is in good order.
Horsch continues to offer a dedicated drill display but most users will hook up to the tractor’s integral ISO control panel. If you are looking over a drill, ensure it is hooked up to a tractor so you can check the ISObus control system and run through the drill’s various operation menus. This will also list the total hours the drill has run and how many hectares it has covered. Designed for intensive use, these drills can easily cope with substantial annual workloads, a high area tally only being a worry if a used buy presents poorly. A well-used but equally well looked after drill will still command a high price.
The AutoForce depth control system operates by altering the pressure on the seed coulter to compensate for differing soil conditions. The factory diagrams above illustrate how the system is designed to maintain an even sowing depth for each individual row.

With thanks to: R C Moore & Son, Bishops Itchington, Warks, Robert Tuckwell Contracting, Mursley, Bucks, Matthew Kennedy, Olivers, Tingewick, Bucks and Thomas Mold, Horsch UK .

James de Havilland

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