Good afternoon
This is a random post but i suffered a serious back injury at work & now pretty much immobile for rest of my life so had to say goodbye to ever driving a truck again & because i have a non HGV solicitor he struggles on specifics when the company fires an answer back,the company in question states i neglected to lower the double decker suspension to the floor,i know thats not possible but when he wants my reply i cant even guess, does anyone happen to know how many inches (roughly) does the ride height suspension lower the trailer at the back,also,the rough weight of the roller shutter door on the double decker trailer
Firstly you need a specialist industry solicitor, where you find one i don’t know, hopefully your union solicitor is up to the job.
For technical specs, you must be able to find out the make and model and year of the trailer in question, the company should provide this information, then contact the trailer maker for full specifications and if possible a video of the specific trailer in operation so the solicitor you find that’s more appropriate can see exactly how the vehicle operates and what both you and the company are talking about.
Just a general note, the company may well be liable but they will know that you are probably by now suffering financial hardship, their side will probably make derisory offers once you have a concrete case hoping that you’ll accept a low offer because you might be accrueing debts and starting to panic, do your best to hang on for as long as it takes, which might well be a year or two down the line.
An old friend of mine was in similar position with long term injuries though he was able to resume lorry driving, they tried to time him out into accept a low payout, what they didn’t bargain for is that he’s possibly the most obstinate man (after my dad and my son, naturally it skipped a generation 
) and solvent financially for an extended period, hence he beat them at their own game.
If this claim is because the shutter tensioning failed suddenly then the actual weight will be relevant. Otherwise I would say the actual weight of the shutter is probably irrelevant whether it is a roller shutter or an "up and over " type, since it will be counterbalanced or tensioned by powerful spring(s) so that the effort to raise it is acceptable. Find out the make and model of shutter fitted to the trailer and speak to the shutter manufacturer. JR, Hendersons and Dover are all makes of vehicle shutters . They should be able to tell you the specified range for the effort required to raise it and its actual weight. That said the effort to roll it up or to park it in the roof will exceed its actual weight if the tensioning has completely failed. In those circumsatnces I would very much doubt that you could lift a double decker shutter at all.
Its a pity the UK doesn’t have workers compensation, Because you can bet it will be a long wait before going to trial.
But in the mean time I suggest as has been said already that you get a experienced lawyer who has a good track record in Trucking Accidents and Health and Safety at Work etc. Act 1974. And be warned your company will try every trick in the book to prove it was your fault.
Also as has been mentioned talk to your Union !!
Good Look
Would be interesting to know how an injury was caused?