His employer and the pump supplier have now been fined a total of £7,000 for the incident.
The 37-year-old man, who does not wish to be named, had been working with another employee for O'Neill Concrete Pumping Ltd to pump concrete into a garden in Wrockwardine, Telford, on 27 February 2010.
When the job was finished he went to clean the hopper and lifted the automatic locking hopper grille. As he did, the swinging tube, which is part of the pumping mechanism, moved and trapped his right hand, crushing his fingers. He was taken to hospital and needed extensive surgery - three fingers and part of his thumb had to be amputated.
During the subsequent Health & Safety Executive (HSE) prosecution, Telford Magistrates' Court heard that there were defects with the concrete pump that Transcrete (GB) Ltd had supplied to O'Neill Concrete Pumping.
Following the incident prohibition notices were immediately served on two truck-mounted concrete pumps owned and used by O'Neill Concrete Pumping due to the failure of the interlocking system on the hopper.
The HSE found that O'Neill had failed to ensure that effective measures were taken to prevent access to dangerous parts of the hopper of the lorry-mounted concrete pump and that Transcrete had failed to ensure that it was designed to be safe when it was being cleaned or maintained.
O'Neill Concrete Pumping Ltd, of Wellington Road, Bilston, West Midlands, pleaded guilty to breaching Section 2(1) of the Health and Safety at Work etc Act 1974 and was fined £3,000 with costs of £2,000.
Transcrete (GB) Ltd, of Pool Lane, Winterley, Sandbach, Cheshire, pleaded guilty to breaching Section 6(1) of the Health and Safety at Work etc Act 1974 for failing to ensure the concrete pump supplied was safe between 1 January 2004 and 31 December 2006. It was fined £4,000 with costs of £2,000.
Speaking after the hearing, HSE inspector Guy Dale said: "The employee will see his injuries every day and have to change the way he lives for the rest of his life. A safe, compliant machine and simple safety checks would have meant the incident would never have occurred.
"Both the supplier and user of the machine had a duty to ensure they were safe and that the critical parts were assessed and the appropriate measures were taken."