IN ACTION: One of the six High Mobility Engineering Excavators.

The army today unveiled its latest piece of kit, new $800,000 fully-armoured combat tractors.

The six US-made 16-tonne green machines - capable of 90 kmh - were put through their paces ripping around a paddock at Trentham today.

Officially named JCB High Mobility Engineering Excavators, or HMEEs, they are designed to operate with and support a deployment of armoured vehicles - clearing roads and removing obstacles.

Lieutenant Colonel Rian McKinstry said the new tractors will allow operators to be protected from enemy fire, while clearing routes, building fortifications, or doing road works in dangerous areas.

The army has bought six of the vehicles, at a cost of $4.7 million. The cost included spare parts.