|LEGO → TECHNIC|
The excavator features controlled steering, a rotating cab and a pneumatic arm. The knob on the top of the model can control either rotate the cab or control the steering, depending on its height. One of the pneumatic pistons controls the angle of the arm, and the other controls the scoop. This means the arm cannot bend in the middle. The pistons are powered by hand using the model's pump, and the direction the pistons move is controlled by the switches on the back of the model.
The alternate model is a truck with a rotating crane arm.