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On-test: Is the latest RoGator now the machine it should be?

It has been a bit of turbulent start in life for the Challenger RoGator self-propelled sprayer, but the firm thinks it has finally got it right. James Rickard test drives the latest incarnation.

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Has Challenger finally got it right? James Rickard test the RoGator #machinery #boystoys

When the all-new Challenger RoGator self-propelled sprayer arrived on the scene nearly five years ago it promised a lot in terms of productivity, level of spec, ease of use and operator comfort.


Since then, the machine has undergone several updates, mainly to address reliability.


Now in its third generation, sporting a ‘C’ in its model number, it promises even more, says the manufacturer.


The range is made up of three models; the 635C, 645C and 655C. All share the same chassis and are mainly differentiated by engines, power, wheel motors and spray tank sizes.


To find out what the updates have done for the latest generation machines, we checked out the mid-model RoGator 645C.


Machine configuration

Machine configuration

Underpinning the RoGator is a single-spine chassis, onto which everything is mounted/hung. Advantages include a tighter turning circle and more flexible and ideal positioning of components.


A particularly smart piece of positioning is the filling area and the engine bay, which are hung opposite each other across the width of the machine underneath the chassis, in between the front and rear axles. This allows weight to be kept low down and in a central area of the machine.


Access in this area is also decent, thanks to removable panels to get at major components such as hydraulic and spray pumps.


Impressive component positioning continues at the rear, whereby the spray boom is mounted on a parallelogram linkage which runs all the way back to the centre of the machine. This mounting point, is effectively on the pivoting point between the front and rear axle. As a result, less machine movement is transferred through the boom, compared to a boom mounted at the rear of the machine which takes a lot of the vertical shock loadings of the rear axle.


It is claimed when the boom is folded out, the machine has a 50:50 weight distribution from front to back, regardless of how much liquid is on board.

Spray pack

Spray pack

Chafer booms currently occupy the rear of the RoGator, however, as our test machine shows, these are due to be superseded by French-made Pommier booms at the end of the year.


Booms range in width from 12-36m, in various combinations. Those above 18m all get the same first section, with the ability to ‘bolt-on’ any boom configurations customers desire.


Nozzle options include manual five-way twist units, or dual select nozzles which are switchable from the cab.


Integrated into the booms are sensors which can work in one of two ways to follow contours; ground sensing or crop canopy sensing. In both instances, the boom will automatically adjust itself to maintain a set working height.


At the headland, various modes allow just the boom tips to lift, the whole boom to lift or a combination of the two.


A bit of a faff though is the boom folding, which requires a bit of button pressing. The addition of an automated system would be welcome.

From the filling station is a fold down induction hopper which can cope with 200 litres/minute of liquid or 30kg/minute of powder.


Various specs of filling station include all manual control via levers and taps, to fully automatic via the firm’s Opti Flow system which takes care of all filling, transferring and cleaning functions. Machines fitted with Opti Flow can also be controlled from the cab.


Standard plumbing for fill and transfer is via 50.8mm pipe work, 76.2mm optional.


Spray pump capacity is 800 litres/min courtesy of a Hypro centrifugal pump. It also only requires just 1,250 engine rpm to pump at full capacity.


Tank volume is measured using weigh cells, rather than level indicators, which the manufacturer says is much more accurate. In addition, products can also be flow metered when filling. The machine’s suspension also self levels for filling.



Final drive is carried out in each of the wheel hubs, which also incorporate wet disc brakes. Its new Bosch Rexroth wheel motors also take less stress due to them being mounted in the wheel legs and not taking the weight of the machine.


Moreover, redesigned cast wheel legs feature a slimmer and smoother design to reduce crop contact.


Twin ride height is afforded on the RoGator by positioning the all-round double wishbone, independent suspension in one of two positions. Depending on tyres, in its highest position, clearance under the cab can be up to 1.2 metres.


In addition, track width can also be hydraulically altered from 1.75m to 2.25m.


While the 635 and 645 are limited to 40kph, the 655 can be specified as an option with a 50kph transmission. More impressively though, is the newly found 30kph spraying speed.


It is achievable too, with the wheel and boom suspension doing a good job of keeping things stable. In fact, the more you push the machine, the more stable the boom seems to get, with very little of that fore and aft movement you can get with booms at high speed.


On the road, it is equally as pleasant and seems stable, helped by its road mode which sees the suspension lowered, and only two wheel steering used.

Cab and control

Cab and control

Cab-wise, it shares the same frame used on the firm’s MT900 series articulated wheeled tractors, as found in North America and Eastern Europe.


Operators used to the firm’s twin-track tractors will feel at home in this cab, which shares the same dash and similar right-hand console, albeit with the addition of sister firm Massey Ferguson’s Exclusive spec control lever.


It also gets category four filtration, with a high volume of air flow through the cab.


It is a quiet environment and overall a relatively decent place to work. However, it is a bit on the dark side and cab space can soon be eroded with the addition of the larger, TopCon X30 terminal, which takes care of variable rate, auto-steer and section control. The later can be done in 10 sections.


For all other machine functions and set-up, a smaller, standard screen integrated into the armrest is used.


For driving, one of three modes can be used; lever, pedal or hand throttle. The first two modes can be used to select travel speed, with the machine working out what transmission ratio and what engine revs to use. The latter affords more manual control, particularly if you want to maintain engine rpm. But in most cases, lever mode is the favoured option.


Cruise speeds can also be programmed simply by getting up to the desired speed then pressing and holding one of two buttons on the main lever.


  • There is no doubt the latest RoGator is a decent machine, but will it be more reliable than its predecessors? Unfortunately, only time will tell.


That said, its updates seem to have gone a long way in improving the RoGator, such as higher spraying speeds, slimmer wheel legs, new wheel motors and improved software.


Most impressively is the RoGator’s configuration which affords good balance from front to back and from side-to-side.


A couple of things which could do with addressing is the boom folding, which would be good if automated, and the position of the second screen in the cab, which could do with a reposition to take up less space.


As long as the RoGator can perform day-in, day-out as it did on our test day, then there should be some very satisfied customers.

RoGator family




Tank capacity



Four-cylinder, AgcoPower




Six-cylinder, AgcoPower

3,500- or 4,800-litres



Six-cylinder, AgcoPower

3,500-, 4,800- or 6,000-litres

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