A caravan trailer which Russell Stuart Russell was towing also had defects and he was uninsured.
The offences came to light after the 54-year-old was unable to stop the Russell’s International Circus lorry in time as traffic ahead slowed.
It ploughed into the back of a Peugeot car which, in turn, was forced into a BMW in front, being driven by Russell’s wife.
The incident happened on the A47 at Scarning in Norfolk on October 11 last year.
Prosecuting, Josephine Jones told King’s Lynn Magistrates’ Court on Monday that Russell, 54, of Harris Boulevard, Mablethorpe, held a provisional licence and was driving unsupervised and with no L-plates.
Miss Jones said a vehicle examination of the Foden lorry by police revealed a “long-standing” issue with a disc brake which was rusty.
The caravan’s brakes were also defective.
“The HGV brakes had a negative effect on the caravan and the caravan had a negative effect on the HGV,” she added.
Russell pleaded guilty to driving without due care and attention, using a motor vehicle/trailer likely to cause danger of injury, driving otherwise in accordance with a licence and having no insurance.
Mitigating, David Chapple said his client was a showman who ran the circus and the lorry was part of it.
“As a business which relies very much on vehicles moving between A and B, the business itself employs its own mechanic,” he said.
“It’s his business and ultimately his responsibility. He had obviously no reason to believe that there was going to be a problem.
“The last thing he would have wanted to do was be in a vehicle like that travelling behind his wife.”
Mr Chapple added Russell thought he was entitled to drive on his Bahraini driving licence and was insured.
“Following this incident and enquiries, he rapidly became aware that the insurers would not have insured the vehicles,” he said.
For having no insurance, Russell was disqualified from driving for six months and fined £487. For driving without due care and attention he was fined £250.
There were no separate penalties for the other offences but his licence will be endorsed. He was also ordered to pay £85 costs and £48 victim surcharge.
Chairman of the magistrates’ bench, Ian Engall, told him: “Looking at the photographs of this vehicle you are a very, very lucky man.
“There could have been some serious consequences to this, and you could have been facing some far more serious charges.”