I drive a 'welfare' vehicle based on a 2.8 ducato.
Problem with having 4 rear wheels is when you want to reverse, one set of wheels is being forced to follow a line they do not want to go - hence why most buses & coaches with tri-axles tend to have rear wheel steering as well.
Only done 33k & this is what going backwards round corners does...

Only one reason for this--poor design. A proper trailing axle set up won't do this. You will usually have sideways creep, but no twisting with a fixed trail axle. If it is set up with steering it should castor steer a few degrees only, and should be fitted with a lock pin for reversing.

Is this an al-ko tandem torsion setup? Torsion bars are broken if so I'd say. The tyres should slip long before that kind of movement. Breakages usually due to lack of lubrication.


http://www.al-ko.co.uk/chassis-maintenance2.htm

find your local al-ko service centre here:

http://classic.multimap.com/clients/places.cgi?client=alko

Not my bus so I have no idea what's under there.
However, it is serviced every 6 weeks - no idea what that involves though.
latest news is - the huge box section chassis has ripped on 3 sides, a major job & it will be going to a specialist chassis company in the new year. I'm told it's going to be a big job as they may have to take the floor up!
It has, however, thrown up a huge problem for my bosses as their whole fleet of low floor buses have been recalled for inspection & another two have been found with fractures - so far!
seemingly, a large number of these buses were made & the company ended up going bust - I'm guessing from the p1ss poor design problems.
The chassis company has had loads of these buses in, all around similar age/mileage (4/5 years).
but i often thought this would be a problem as you can always see where i had been reversing due to the scuffs from those dragged wheels.

All the same, I thought it worth mentioning just in case anyone else out there was driving a similar setup (and I know that quite a few councils bought the same vehicles.)

Update. We now have 3 low floor ducatto tri-axle welfare buses sitting in the compound waiting for???

The company that was to do the remedial work on the chassis has gone bust, Oxfordshire has a number of these vehicles with identical problems, most have been fixed but it's a long, complicated (and expensive) process.