The convictions were secured following a four-and-a-half year investigation by the Driver and Vehicle Standards Agency and Lancashire Police.
The fraud was uncovered when DVSA examiners stopped a lorry near the M6 in Lancashire and found that the tachograph had been illegally modified.
Following an intelligence-led investigation and execution of search warrants, evidence was found that linked three men to the production, supply and fitting of tachograph interrupter devices to HGVs.
Darren Millington, 52, of Hinstock, Shropshire procured the devices; Stephen Young, 55, of Wolverhampton designed them; and Benjamin Hayton, 43, of Leyland, Lancashire helped in the design as well as fitting the devices for up to £1,500 each.
All three were convicted on 11 March following a five-week trial at Preston Crown Court. Each was convicted of conspiracy to falsify drivers’ records, and Millington and Young were also convicted of money laundering.
DVSA director of enforcement Marian Kitson said: “I’m incredibly proud of the hard work and dedication of my enforcement teams in bringing these men to justice and putting an end to this scheme.”
Hayton fitted at least one device to a vehicle operated by S Bamford International, of Preston. DVSA investigators found that two of the company’s drivers had falsely recorded rest periods more than 630 times in three months.
The two drivers were sentenced last year, with both receiving a suspended prison term and community order.
At separate public inquiries in front of a traffic commissioner, S Bamford lost his operator’s licence and the drivers lost their vocational driving licences.
UPDATED 8/4 17:15 with DVSA-supplied amendment on convictions