16 October 1998

CASESTEYR CS120

HOT off the press, the just-finalised test CS 120 was trucked in direct from Steyrs factory. Rather than using in-house suspension it carried Carraros proprietary front axle, which is unique in having automotive-style independent springing. Its complicated with lots of pivots and 18 grease points against the oppositions maximum of four.

Thats for the future. Right now this Case (which is not part of the companys UK line-up) steers accurately without a trailer, wanders a little unsprung over bumps, then tracks straighter with springing engaged. Pump-up isnt a fast process; several long seconds pass while suspension rises to height, and the operation draws significant engine power.

The 40kph unsprung cobble-road test was tough work for the Case, and it proved best not to stick at that speed for long. The suspension smoothed away all the big hits and let the driver exploit a 47kph top speed.

But while the sprung ride is significantly better, its not as compliant as the Deere or as supple as the Deutz. The Cases axle doesnt seem to see small bumps, leaving the tractors nose restless; the worst goes but its no magic carpet.

Smooth-road bounce with the trailer peaks uncomfortably at 33kph. Adding front suspension cuts most of it but theres still a definite nodding; the tyres are deflecting but the springs arent. Again the system seems too stiff to notice these small disturbances though the driver does.

Out in the field, unsprung cultivation in the 10-11kph bracket lifted the front wheels clear with vicious bouncing. Slowing solved the problem but work rate suffered, speeding up to 12kph turned life bearable if unruly. Does front suspension help? You bet. Suddenly its possible to travel comfortably smack in the danger zone or push faster without fear of crunches. Good suspension travel copes with everything the conditions threw at it.

Generally the Cases field ride is on the hard side. And when crossing ridges diagonally the suspension often doesnt help, as the axle just pivots around its centre rather than making the independent halves work.

An extra switch lets the driver raise or drop the stationary tractors nose progressively. While this could help coupling front equipment, it serves to highlight significant changes in front-end geometry. As these must happen when suspension is active, there could be some impact on tyre life.

&#42 Science says: Only

good in parts

Crystal clear from the Cologne teams measurement is that with or without springing and with nothing on the hitch, the Cases seat base sees bigger vertical accelerations than any other. This backs up our cultivation and trailer impressions; the fact that the Cases unsprung hardness didnt stand out more while pulling a trailer might stem from a 2.5t downward hook load, which bulges the fat back Michelins and so partly blurs the difference between makes.

Results show that switching on suspension cuts front end movement but has very little effect at cab level, again implying the driver wont get much benefit unless theres something on the hook or linkage. Adding a plough brings cab movement right down by forcing the rear tyres to work.

Switching on front suspension drops front-end movement again, but still leaves cab-level disturbance just over average.

Why should the Case ride so hard unladen? Maybe because the driver looks to be sitting more over the rear axle than with any other make. Shocks from the back pass straight to the cab on all but the Deutz, and the further back a driver sits the more he feels.

&#42 Conclusion

A system that doesnt bring results in proportion to its complication. Some help on the street and field, but from a drivers standpoint the worst of the bunch.

&#42 Stop press

To soften ride, Case has lowered accumulator pressure in production by 5dBA.

&#8226 Setup: Centre pivot plus upper/lower wishbones, torsion springs, rams/accumulators.

&#8226 90mm total travel, 11deg oscillation.

&#8226 Special feature: Only car-style independent system on offer.

&#8226 Price premium: TBA.

&#8226 Available on: In UK, CS 150 initially.