power Atlas changes

24 January 1997


power Atlas changes

Hydraulic active suspension is just one of a package of changes that characterise the latest Atlas self-propelled sprayer from Cleanacres. Peter Hill puts the machine through its paces

IF nothing else, the latest version of the Atlas sprayer shows that its maker, Glos-based Cleanacres Mach-inery, listens to its customers.

From a robust but fairly basic variation on the self-propelled sprayer theme, the Atlas has been transformed into a sophisticated contender. And, as Mark Curtoys of Cleanacres readily accepts, much of the impetus for change has come from existing and potential customers.

The result is a machine that retains the distinctive low profile of the original Atlas but gives the driver a more comfortable ride, has simplified sprayer controls, provides a more attractive operator environment, and packs as much as 191hp into its engines. These are now Perkins 1000-series liquid-cooled as opposed to VM air-cooled diesels.

In outline, the Cleanacres Atlas fits the mould of a typical UK-built self-propelled sprayer. It comes with a choice of 2000, 2500 and 3000-litre tanks, conventional and/or Airtec spraying systems, and 12m to 30m (39ft to 98ft) booms, including multiple working width options. The chassis features four-wheel hydrostatic drive and four-wheel "intelligent" steering that can be switched to two-wheel steer for road travel, or linked to the spray on/off master switch to give two-wheel steering in tramlines and automatic four-wheel steer for headland turns.

Yet it is the active hydro-pneumatic suspension that sets the Atlas apart. There is only one other machine with this feature and, though similar in principle, the two systems are quite different in execution.

"We realised that passive suspension, using springs or rubber blocks, has its limitations on a vehicle with big variations in operating weights," says Mr Curtoys. "We looked at air but concluded that awkwardly large and expensive bellows would be needed to support the machines weight."

The Cleanacres solution is to use two large hydraulic cylinders on each axle, coupled to gas accumulators, which provide the springing.

Electro-magnetic proximity sensors near the pivots of the axle locating arms register changes in ride height and prompt oil to be pumped into the cylinders or evacuated from them to maintain a constant ride height as the weight of the machine changes.

A potential difficulty with active suspensions is a too-rapid response to axle movements, which results in a pitching effect as the system is repeatedly charged and exhausted.

"This still tends to happen if the Atlas is operated with the system in auto mode," agrees Mr Curtoys. "Instead, we recommend filling the sprayer with the system in auto so it is calibrated and ready to go as soon as the tank is full, and then allowing the system to recalibrate itself once or twice by stopping at the headland and flicking to auto briefly."

The resulting set-up gives a remarkably compliant ride – albeit with the occasional firm bump at low speed with a light load – as a few turns around a field of soon-to-be-ploughed set-aside revealed. On flotation tyres, crossing pitch furrows at an angle was barely noticeable, but equally an energetic turn had neither the vehicle leaning alarmingly nor the boom adopting a crazy angle.

Indeed improved boom stability appears to be one of the advantages of chassis suspension and, despite no changes to the hydro-pneumatic boom suspension of the older Atlas, there appears to be no antagonism with the suspension. Certainly, the boom structure, as well as the rest of the vehicle for that matter, suffers none of the crashing stresses that come from barrelling along a rough farm track or pot-holed road surface. And up front, the driver retains positive steering and the feeling that the vehicle will go where he wants it to; there is none of the remote, floating character of vehicles equipped with simpler rubber or steel springing.

The machines hydrostatic drive, which employs Poclain dual-speed wheel motors, offers a total of four speed ranges and the opportunity to bias drive to the rear wheels. This, says Cleanacres, reduces the likelihood of the front wheels spinning through excessive torque when climbing hills and more or less obviates the need for the French companys costly traction control system.

Speed and direction control, via the usual multi-function lever alongside the drivers seat, is straightforward enough and no different to any similar machine.

Though it looks nothing special from the outside, the Atlas cab offers a high standard of accommodation, with all internal surfaces now clad in plastic mouldings.

Other changes over the original include a slightly curved windscreen (for better appearance and theoretically improved noise suppression) and a push-away steering column for easier entry/exit.

A revised control and instrument layout sees spray section on-off lights moved to the cab roof, where they are more visible than next to a window on a bright day, and a control panel simplified by moving controls for the indicators, lights, etc, on to a column stalk. Revised installation sets the RDS-made electronic spray controller, along with associated control switches, at a more convenient viewing and operating angle.

Things are simplified elsewhere. For example, where before the operator was confronted by four valve levers to set up the spraying system for filling, agitation or spraying, there are now just two control handles after the adoption of the latest five-port valves.

These are conveniently positioned alongside a drop-down stainless steel induction bowl and round the corner from the 230 litres/min (50gal/min) six-piston diaphragm pump, which is now fitted on the rear of the chassis.

On earlier Airtec-equipped Atlas sprayers, the spray pump was driven by a hydraulic motor with a shaft then driving the compressor through a step-up gearbox. This layout has the compressor running even when it is not needed, such as when filling the tank or spraying pesticides or liquid fertiliser through the conventional spray line.

Now, the spray pump and compressor are driven hydraulically through the same circuit but with a valve that can isolate drive to the compressor.

Overall, appearance of the Atlas is similar to the original machine except that the latest model sports glass-reinforced plastic bodywork down each side. This not only keeps the spray valves, pump, pipework and compressor clear of mud thrown up by the wheels (there are mud-guards as well), but also serves to protect these components from any drips from the folded booms. &#42

The Cleanacres Atlas is now a more sophisticated machine than the original model, with active hydro-pneumatic suspension added to four-speed hydrostatic drive and "intelligent" four-wheel steering. Prices start at £55,500, depending on final customer specification.

Above: Underbelly view shows the large steering ram and upright suspension cylinders. Converging arms form an "A" frame to locate each axle; an electro-magnetic proximity sensor near the pivot of each frame monitors changes in ride height. Left: Spray pump is relocated to the rear of the machine, and has variable-flow hydraulic drive for maximum filling rate at low engine speed. The same drive, with an on-off valve, also powers the compressor on Airtec versions.

Revised cab has fully clad interior, a push-away steering column, simplified switch gear and better instrument layout – cosseting comfort.

&#8226 Engine Choice of 110hp, 158hp and 191hp diesels.

&#8226 Transmission Four-speed hydrostatic, two-speed wheel motors.

&#8226 Steering Two/four-wheel, manual realign.

&#8226 Suspension Hydro-pneumatic on both axles.

&#8226 Tank capacity 2000, 2500 or 3000 litres.

&#8226 Boom 12m-30m (40ft-98ft) with conventional or Airtec twin fluid spraying systems.

&#8226 Options Skid unit for fertiliser spreader; 6m (20ft) pneumatic seed drill.

&#8226 Price From £55,500.

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