I don't like my Al-Ko chassis

[Steve928]

Derek Uzzell - 2015-10-09 8:54 AM

 

With a ‘standard’ Ducato motorhome chassis (ladder-frame or panel-van type) the chassis sits above the rear axle and is attached to it by leaf springs. It’s possible – with a specialised ‘camping-car’ ladder-frame chassis - to decrease the chassis depth (to lower the height from the ground of the interior floor) and to increase the vehicle’s rear track (to improve the vehicle’s handling), but the ground clearance beneath the motorhome’s chassis will always be significant and a genuine ‘double floor’ design will not be a practicable proposition.

 

The Al-Ko motorhome chassis has independent rear suspension and the axle-tube passes through the chassis rather than being beneath it. The rear track is wider than standard and – because the of the relocated rear axle position – the top of an Al-Ko chassis is much closer to the ground and a double-floor becomes practicable. If a really low version of the Al-Ko chassis is chosen by the motorhome manufacturer, the ground clearance beneath that chassis will be much reduced and the rear axle’s spring-rate will need to be high to compensate.

 

Regarding the load height of the respective designs one also has to consider where each design locates the stub axle i.e. the hub centre in relation to the axle tube though. Yes, the cart spring design used by Sevel does place the axle beneath the chassis, but the stub axle carriers raise up from the axle tube and place the hub centre above the axle. Yes, the Al-Ko design does feature an axle tube passing through the chassis, but the rear trailing arms extend rearwards and downwards and the hub centre is lower than the axle centre. This difference in design together with the lower depth of the chassis rails on Sevel's special camper chassis does mean that the difference in load height is less than one might at first think.