Extract from Neil Thompson's
I.Mech.E Professional Review Report
(section B1.1.6)
Shows the secondary suspension leveling valve rod
and bent bracket.
Excessive roll of trailer cars when fully loaded
caused the bracket to bend, this increased air bag
inflation when the car returned to the Ievel.
Greater air bag inflation increased the tendency of
the car to roll.
Events continued during a run until the suspension
height was such that the air bag vented continually
BREL design team visited site and in view of the
evidence decided that anti-roll bars were to be
fitted.