An electric tug was towing the trolley through the yard at JCB's headquarters in Rochester, Staffordshire on 16 October 2013. At the same time, a DHL employee was auditing incoming deliveries nearby.
Stafford Crown Court was told that the trolley fell on its side and struck the worker, pinning him to a stillage. He sustained fractures and internal injuries.
The Health and Safety Executive's (HSE) investigation found there was no system to segregate vehicles operating the warehouse from both DHL and JCB workers who were on foot.
JCB was fined £375,000 after pleading guilty to breaching ss 2(1) and 3(1) of the Health and Safety at Work Act. It was ordered to pay costs of £37,235.
DHL Services pleaded guilty to breaching s 2(1) of the same act and was fined £266,000 plus £23,370 costs.
HSE inspector David Brassington said after the hearing: "Both of these companies were well versed in transport risk management and both fell well below the required standard in ensuring that such risks were effectively managed in this area.
"These failings allowed a pedestrian worker into a busy area where vehicles were coming and going and as a result the worker sustained serious injuries from which he has still not recovered."