The man was injured by accident on "soft ground" near Okehampton in Devon, police said.
The man was with his 10-year-old daughter the time, officers said. There were no reports she was injured.
It is not known how extensively the man was injured, but Sgt Harry Tangye, of Devon and Cornwall Police, tweeted that the early signs were "good".
An air ambulance was called to the scene after the incident on Tuesday morning.

Georgina Callander, 18, was among 22 people who died in the suicide bombing at Manchester Arena on 22 May.
Hundreds attended the ceremony at Holy Trinity Church in Tarleton, Lancashire.
Attendees wore "a touch of yellow" at the request of her family, who thanked mourners for their "sympathy and support".
Parents Lesley and Simon, with brothers Daniel and Harry, laid flowers in the village before the funeral.
Shops were closed as a mark of respect as the funeral cortege made its way through.
Bishop John Goddard said the service was a chance to "put aside hatred and look to embrace love and hope".
A private burial service was held after the church ceremony.
Ms Callander was described as "beautiful" by friends who said on social media that she was one of the first people taken to hospital after the attack.
She was said to be a huge fan of 23-year-old Grande and was pictured with her in 2015.
The final song played at the service was the US singer's hit One Last Time, which has become an anthem for fans since the attack.
Grande performed an emotional rendition of the song at the One Manchester benefit concert on 4 June.

Staff in Jobcentres, banks, building societies and utility companies in England could also be trained to spot - and counsel - vulnerable people.
The ideas are raised in a consultation paper on suicide prevention.
The Samaritans said councils should have a mandatory responsibility to try to prevent suicides in their areas.
Some 4,400 people killed themselves in England in 2009.
Claire Wylie, head of policy and research at the Samaritans, told the BBC News website that many suicide attempts were made on impulse, so trying to restrict access to potentially lethal means was important.
"We know that people who are feeling suicidal are often very ambivalent about actually ending their lives," she said.
"If you can interrupt them at that moment you can prevent them going ahead."
Preventing deaths by jumping is a key aim of the consultation and it suggests a number of ways of doing that.
They include:
Overall, the number of suicides has steadily fallen in recent years, but the number of deaths on Britain's rail network had been rising until last year.
However, specialist training from Samaritans for rail staff was key to an 11% fall in 2010, according to the Rail Safety and Standards Board.
London Underground is also rolling out training to all of its staff after a pilot project at one station close to a psychiatric inpatient unit helped reduce suicides.
The government wants to see that sort of training given to a much wider range of people who come into contact with individuals who could be vulnerable because of their social or economic circumstances.
Jobcentre and benefit office staff, as well as employees in banks, building societies and utility firms are among those suggested in the consultation.
Ms Wylie said: "More training for all frontline staff is really important, but that needs investment and money is tight.
"In general, we really welcome the government's strategy, but there needs to be a lot more actual commitment to action.
"There's also an issue about local implementation because things like putting up signs and barriers depend on the individual local authority actually caring about suicide prevention.
"We would like to see a mandatory responsibility placed on local authorities to take this seriously."
The consultation closes on 11 October.
A man has been injured when he was run over by a JCB forklift handler vehicle in a field.
[NEXT_CONCEPT]
Streets of a village were decorated with pink and yellow ribbons for the funeral an Ariana Grande "superfan" killed in the Manchester terror attack.
[NEXT_CONCEPT]
Multi-storey car parks, bridges and tall buildings could be designed to make suicide more difficult, under government proposals to save lives.