Sprinter front brakes?

My mates sprinter van was involved in a collision, when inspected it was found to have 1 front brake pad missing, prior to the accident 6 drivers had driven it with no complaints of braking issues, I said that it should have been pulling heavilly to one side but he told me he had an engineer look at it and was told the sprinters are fitted with a device that stops the pulling in the event of something like this happening, ?????
Can you shed any more light on it for me ,

Thanks Mick,