16 October 1998

DEUTZAGROTRON120

&#8226 Setup: Twin rams/accumulators working on swinging arm

&#8226 90mm total travel, 11deg oscillation

&#8226 Price premium: £5,000 all models

&#8226 Available on: Agrotron 105hp-260hp. From 120hp, sprung cab is standard with axle, optional below.

DEUTZ-FAHRS entry complicates the picture by bringing permanent cab suspension. Up front things are different too: a short subframe cradles the front axle, pivotting aft of a conventional unit but nowhere near as far back as the Deere. Two stubby rams sited close to the pivot control vertical movement, with remote accumulators supplying the springing.

Flying over dyke-top cobbles at 40km/hr with a trailer this Deutz rides and steers very well, even without spring help. On a smooth road with 14t behind it the Deutz was the best of the bunch, showing no vertical bounce at any speed with or without axle suspension. At speed on uneven cobbles just the biggest ripples made the driver slow, especially towards the tractors 50km/hr maximum. Cab suspension must take the credit here – it feels to be working hard to isolate the driver from road shocks, with confirmation coming from the considerable relative movement between the cab floor and gearstick.

Adding front suspension helped dyke road ride, but not that much; the cab is still doing a lot of work so the driver rides easy. And watching the front axle showed small bumps dont provoke much reaction, particularly at or under 40km/hr. Its support rams are positioned very close to the subframes pivot, suggesting that strong springing will be needed to control axle movement: could this explain the systems subjective small-bump blindness? Only by cranking up speed is the front end visibly forced to contribute, at which point its extra smoothing effect lets the whole outfit truck along securely at 50km/hr.

In the field, the unsprung Deutz jumped about as much as the Case, and like all the others calmed down on moving up to 12km/hr. Work here was possible but not comfortable, despite the cabs contribution. And after travelling maybe 50m down the field with axle suspension apparently locked out, some movement crept back in.

Switching in the front suspension improved ride enough for a passenger with closed eyes to notice. Having said that, the tranquilising effect doesnt seem as great as with the Deere and Fendt. Like Cases independent system the Agrotron axle has 90mm total movement, and neither looked to run out of travel over some pretty fierce ridges. But during cultivation the cab often seemed to be fighting with the front end, so although the tractor itself moved relatively calmly over the ground the operator bobbed and jumped around more.

&#42 Science says:

Needs more weight

Instrumentation shows that running light, nose movement for the unsprung Deutz is exactly average. With suspension and no plough, movement at the nose is low. And under the seat its substantially below any other tractors, which is both good for the driver and a direct consequence of cab suspension.

Cab springing still does its stuff when the tractor is carrying a plough, with the all speeds/surfaces average showing the Deutz to have the lowest seat area disturbance of the bunch. Averaged nose movement also comes out as the least of any tractor – so why did we see so little action from the axle on the road? Maybe because the cobble surface has relatively gently-ramped bumps compared with the more abrupt test strip ridges, so accelerations coming into the axle often werent high enough to move it. This would explain why on the road, the axle looked (and felt) to contribute more as speed went up. On a slightly different tack, test strip results at 10km/hr showed cab-floor jiggle to be much higher than for any other tractor, though the values are buried in the graph average. That squares well with drivers impressions: its the same shaking that turned up in cultivation, and which, through a disturbing effect on the operator, hinders work in the critical speed band more than helps it.

&#42 Conclusion

Front suspension + cab suspension = comfort. Science says the Deutz is the winner and testers bottoms generally agree. Yet thanks to the cabs sometimes disquieting effect over rough going, the Deere rules overall.

&#8226 Setup: Twin rams/accumulators working on swinging arm

&#8226 90mm total travel, 11deg oscillation

&#8226 Price premium: £5,000 all models

&#8226 Available on: Agrotron 105hp-260hp. From 120hp, sprung cab is standard with axle, optional below.