A man's decision to put tyres and extra support beneath his ute before working on it has saved his life, after the jack slipped and he was crushed beneath the vehicle.

Emergency services were called to Waimaori Rd in Ruapuke, just south of Raglan in the Waikato, about 8.30am yesterday.

The 36-year-old man had been working on the axle of his vehicle when the jack slipped and the truck dropped on to his chest.

He had earlier put extra support material beneath the ute - tyres and planks of wood - as a safety precaution.

The extra padding meant most of the weight was not on the man and emergency services say the measure saved his life.

Westpac Waikato Air Ambulance pilot Loren Haisley said the ute owner had been by himself and if he had not taken the precaution, the outcome "probably would have been far more serious".

Mr Haisley said ambulance and helicopter staff were surprised to find the man had crawled from under the ute and into his house to alert neighbours and emergency services.

"When we got there, he was sitting up and breathing on his own while obviously not comfortable, but not screaming or anything like that," he said.

"When we took him to hospital I gave him a pat on the back [for his foresight] and wished him good luck."

Residents, including a nurse and a physicist, were able to help the man until emergency staff arrived.

A spokeswoman for Waikato Hospital said yesterday that the man was in a stable condition.