In Iron, Forged in Fire Part 1, the Earth Movers are used for an archaeological dig to uncover information on the Makluan Rings, Howard Stark rejects Obadiah Stane's plans to weaponize the Earth Movers because his isn't a company that destroys lives. After the plane crash, however, Stane went with his plan to weaponize the Earth Movers in Iron, Forged in Fire Part 2 and succeded. Stane demonstrates the three Earth Movers to potential buyers, and when Iron Man shows up, Obadiah tests the modified Earth Movers on him. Iron Man discovered that the laser arrays are going to overload and they could take out the testing grounds and all of upstate New York. Iron Man overpowers the first one. He flies into the power core of the second one and absorbs all of the energy, which nearly overwhelmed his systems, and projects it powerful unibeam that destroys the final one.
The first Earth Movers had powerful lasers on its base which are used only for tunneling into the ground for archeaological or disaster relief purposes.
After Obadiah Stane had modified the Earth Movers, they had laser cannons in its center that could burn through really strong walls and destroy tanks in seconds. They also had four extra laser cannons close to the top and gatling lasers on the sides of the top of the machine.