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TRAILER AXLES di, SUSPENSIONS
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Page 62
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• ArvinMeritor has introduced a new version of is proven Flexlite suspension, the XP9. It has been re-engineered mainly to make it easier for trailer builders to fit.
"That's important because it keeps the costs down to the end user," points out Tom Hughes, engineering director for ArvinMeritor's trailer running gear division. Hughes believes the spring location design makes Flexlite better suited to off road conditions than the fabricated trailing arms designs preferred by DaimlerChrysler/Hendrickson and SAF. "With our axle the stress is predictable because it is linear. Repairs are easier, too you simply have to undo the U-bolts."
DaimlerChrysler has now added TL5 and TL 4 steering axles to its trailer axle range. The TL5 has a new 22.5in rotor with a wear sensor. The axle weighs 549k, or 637kg with Hendrickson HT250 suspension. The TL4, with 19.5in brakes, comes in at 514kg bare. Both axles feahire cartridge bearings and enclosed king-pin bearings to reduce maintenance needs. There is a new locking mechanism and the axle is reset pneumatically using controls in the cab. Both the TL4 and TL5 have i2omm offset naves, to standardise with truck axles.
Although it is still committed to persuading operators that matching truck and trailer axles and EBS braking systems is the safest, most economic package, DaimlerChrysler has recognised that for some operators compatibility with their existing trailer fleet is more important than identical braking systems with the tractor. Hence, the zero-offset TZ5 axle, a 22.5in brake ver
sion of the TZ4.
Talk to any operator or manufacturer of trailer axles at the moment and the subject is bound to turn to wear rates on disc brakes. "Operators take reliable suspension for granted today. All the attention is focused on the wheel ends and brakes because that is where the service issues are," says Hughes.
ArvinMeritor is following DaimlerChrysler's lead and offering the same ELSA disc brake package on trailer axles as it fits on truck axles supplied to MAN and Renault and similar to the D Duco brake fitted by Volvo. While only ArvinMeritor can claim to make the brakes as well as the axles and suspensions, other trailer manufacturers do cus tomise the components to suit the characteristics of the axles.
BPW, for example, has developed a new disc brake for nine and io. tonnes axles, the S B43 o9T. Developed with Knorr-Bremse, the brake is a departure for BPW which has advocated small 370 diameter rotors in 22.5in wheels so that pads can be replaced without removing the wheels. The new brake has 430mm rotor, which BPW says gives it the higher foundation reserve necessary for high-wear applications.
Intradisc Plus Integral is the latest version of SAF's integrated axle-suspension design. It features a twopiece compound cast brake disc developed by SAF specifically to cope with heat problems. The casting combines the brake disc and the high-strength adapter together, creating a separable connection between the brake disc with adapter and the wheel hub. The disc can expand in a radial direction, preventing distortion.
Holland Europe's MTS (Modular Trailer System) is a complete under-chassis kit that includes axle, suspension, pneumatic piping, air tanks, fittings and wiring in a single sub-frame ready to bolt on to the chassis. All the trailer builder has to do is run the pipe and wiring down from the couplings. Fitting time is reduced from 70 hours for a typical trailer to seven hours, according to Holland Europe.
• There is a long tradition in the UK of converting light van chassis-cabs into more versatile vehicles by removing the standard suspension and replacing it with air suspension. It started with passenger transport vehicles but Is now common for operations such as vehicle recovery, mobile libraries and even recycling vehicles.
Mlni-artIcs are even more specialised, but Marks and Spencer is triallIng them, so perhaps their time has arrived. TVAC believes they could be a solution to the decreasing pool of drivers able to drive 73-tonners on a car licence. "They can drive a vehicle up to 3.5 tonnes and a trailer on a car licence." says sales manager Oliver Drinkwater.
TVAC shortens the wheelbase to about 2.8 metres and adds a compressor-driven air supply for the trailer. The trailer needs to be light, with a low centre of gravity, says Drinkwater. Train weights depend on the chassis, but range from 53 tonnes for a Renault Master to 8.7 tonnes for a Mascott.