Excavator Toy

During the construction of the excavator, I did not document all stages of the build, and I had no intention of writing instructions for its creation. The demonstration of its operation is provided in the attached video, along with a few construction details below.

Supplies

Drive

The vehicle is moved by two motors salvaged from a damaged children's toy car. Initially, the plan was to use one motor, but it didn't have enough power. Currently, even two motors don't always suffice. The motors drive separate axles to which wheels are rigidly attached. The whole system rotates on ball bearings.

Step 1:

Excavator Arms

I crafted the arms, like most of the frame, from thin-walled profiles to keep the overall weight low. The movement of the arms is controlled by small motors salvaged from car door mechanisms (specifically from a Mercedes).

These motors have several advantages. The movement of the screw is translated into the rotation of a gear, making the gear rotations relatively slow, but it's very difficult to stop it. Importantly, once the gear is stopped, it won't move until the motor moves again. In my case, I translated the gear movement to a 4mm flat bar, on which I cut teeth consistent with those on the gear. I framed the entire mechanism in a metal guide and limited the movement with screws at the ends. The system is strong enough to dig holes in the sand.

The shovel itself is made from cut, heated, and bent PVC pipe, reinforced on the sides with thin sheet metal. Since it's a toy for a small child, control had to be minimized (2 switches – one for each hand). Therefore, the folding movement of the shovel results from the crosswise arrangement of the profiles of the second arm.

Step 2:

Power Supply Diagram

I'm not an electrician, so please forgive the simplicity of the diagram.

Electricity from the battery is transferred to the gas pedal, which I made from a switch salvaged from a screwdriver. Here, the amount of current is adjustable and passes through 3 simple double-pole switches: one is responsible for the direction of movement, and one each for the movement direction of each of the two excavator arms.