Foden's twin-steers
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• Foden Trucks may not be at the Motor Show, but that hasn't stopped it from getting on the new vehicle bandwagon. Its long-awaited 4000 Series twin-steer tractive unit will be available "in early 1989".
Twin-steer 4000 tractors will be sold in two standard wheelbases, with others available on request in line with Foden's normal 'custom-build' policy.
The shortest of the two "standard" models has an outer axle spread of 3.46 metres, allowing a 20.33-tonne GVW, while the longer model, with a 3.81m outer spread, has a 22.36-tonne GVW.
Both twin-steers have a design gross combination weight of 45 tonnes (allowing for any increase to 40-tonnes) with axle design ratings of 6.7,6.1 and 10.5 tonnes respectively.
The air-suspended positively-steered second axle has a trailing arm design featuring a single, asymmetric spring with an air bag and rear double shackle. According to Foden, the new twin-steer design offers good front and midaxle tyre life, and improved roll stiffness with low maintenance.
All twin-steer tractors come with an air dump operated from inside the cab which temporarily reduces air bag pressure on the second steered axle, transferring maximum load onto the drive axle for extra traction. A similar system is already fitted on Foden 6x2 tag-axle 4000 Series artics.
The current Foden 4000 Series engine options of 10 and 14-litre Cummins; Caterpillar 3306B and 3406B; Gardner 6LXDT; and Perkins Eagle 800 will be carried over onto twinsteer tractors. The uprated 231kW (310hp) version of the Gardner 6LXDT (launched at the Motor Show this week) is also expected to eventually fin+ its way into the 4000 Series tractive unit line-up.
Foden quotes a kerbweight of 6,577kg for a 3.81mwheelbase sleeper-cab twinsteer 4000 with the recentlyintroduced 242kW (325hp) gross air-to-air charge-cooled Cummins LTAA10-325 engine, 22 litres of fuel, and steel wheels and fuel tank.
The same twin-steer, with the 224kW (300hp) Cat 3306B engine, tips the scales at an impressive 6,566kg.
New rectangular-section fuel tanks have been developed to fit within the close-axle spacirn of the twin-steer chassis. A 332-litre (73 gal) tank is offered on both the 3.4 and 3.8m-wheelbase models, while a larger capacity 468-litre (103gal) tank is optional on the 3.8m wheelbase twin-steer.
The development of a twinsteer tractor marks yet another move beyond Foden's previously idiosyncratic, American-influenced preferene for double-drive tractors.