Constable David Williams, who examined the eight-wheeler tipper lorry, said four of the brake shoes were worn down to the rivets and all eight brake drums showed excessive wear.
He was giving evidence to the resumed inquest into the deaths of the six, including a mother and her two-year-old daughter, killed when the lorry and a BT van collided and ploughed into a sub-post office at Sowerby Bridge, West Yorkshire, on 6 September last year.
The Bradford deputy coroner, Mark Hinchliffe, said: 'It sounds like there wasn't one serviceable brake which you would regard as in an efficient and serviceable condition.'
PC Williams replied: 'That is correct. There may have been one or two giving some braking efficiency, but very little.'
The officer said he was quite certain the brakes would have shown excess wear when the lorry was serviced on 7 July, and could not have been assessed by an experienced mechanic as safe.
He believed the lorry driver, Derek Waterworth, 63, who died in the crash, may have been driving the vehicle with good foresight and good use of his gears and brakes.
PC Williams said the driver would have had little indication that anything was wrong until he had to make some form of heavy or emergency braking. He believed the driver had attempted to use a secondary braking system, used to park the vehicle, but the braking from this was insignificant.
The inquest was told that the BT Transit vehicle had no defects and medical tests for alcohol on both drivers proved negative.
Those who died were Ann Crossley, 32; her daughter, Karen, two; Beryl Rose, 46; Angela Rook, 28; Mr Waterworth and Peter Stott, 42, a BT engineer.
Mr Waterworth, of Bradford, died of crush injuries. The other victims died instantaneously from multiple injuries, apart from Mrs Rose, of Sowerby Bridge, who died from shock due to her injuries a few minutes after the accident.
A lollipop lady, Glenys Taylor, told the coroner she heard a noise like thunder. She turned and saw a lorry approaching very fast. It collided with the van, pushing it into the post office building.
The inquest resumes today.Reuse content