Tomy Armatron

Marketed by Radio Shack

Now I'm straying off the topic of pinball... Although Armatron was marketed by Tandy and Radio Shack, it was developed by Tomy. Tomy is the same company responsible for Atomic Pinball and Astro Shooter. I was drawn to Armatron because it contains a crazy array of gears and mechanisms similar to the Tomy pinball toys. I vaguely remember Armatron from when I was a kid, but never had one.

As I looked around the Internet I found a few Armatron science projects that hinted at the toy's complexities, but no real detail. So I decided to hit eBay and get an Armatron of my own to take apart. I have no particular interest or knowledge in robotics. But every robot that I ever heard of employs some sort of individual servo mechanism for powering each joint of the robot. Not so with Armatron. Like the Tomy pinball games, the entire toy is powered by a single motor. All of the toy's functions are controlled by a complex array of mechanical transmissions and gear trains.

Shown above is the side of the box for a general overview of Armatron's operation. Click for larger image.

Shown above is an instruction manual for a detailed overview of Armatron's operation. Click for larger image.

This toy has so many moving parts it almost defies verbal explanation. Shown above is an overview of the base mechanisms. Each of the two joysticks can be moved up/down, left/right and clockwise/counter-clockwise for a total of six movements of the arm. Each of the six movements is bi-directional. Four of the six movements are bi-directional with two speeds in each direction. The joystick linkages (orange parts) control six transmissions (black and white parts). All the transmissions are powered by a single motor on the right. The gearing above the motor is for a timing mechanism described below. The gearing and shafting behind the transmissions connect the transmissions to a series of ring gears described below.

There are three sections to the transmission system: (1) a row of six black forward gears, (2) a row of six black reverse gears and (3) a row of six white indexing drums. The picture above shows the lower row of forward gears without the other two sections of the transmission. The picture also shows how the forward gears drive the output shafting.

The picture above shows how the upper row of six reverse gears mesh with the lower row of six forward gears.

The picture above shows three of the six indexing drums. The red arrow indicates an inner gear fixed to the main drive shaft. One of the outer black gears is for high-speed operation. The other outer black gear is for low-speed operation. Friction between the gears causes the entire drum to rotate about the shaft unless the drum's position is held by one of five indexing tabs. Green arrows indicate four of the five tabs distributed around the drum. The tabs determine which of the two gears on the drum engages the forward or reverse gear. The combinations are slow-forward, fast-forward, slow-reverse and fast-reverse. The fifth index is neutral where no gears are engaged. Note how the left drum is thinner and has only one outer gear. This corresponds to the claw movements, which have only one speed in forward and reverse.

The images above show how the up/down movement of the right joystick controls the indexing of the rightmost drum. This corresponds to the up/down motion of Armatron's shoulder joint.

This picture shows the gear covers back in place. The arm assembly fits into the round ring gear socket. Armatron can continuously rotate through a full 360 degrees. This is made possible by the stack of ring gears. Each movement is transmitted from the base to the arm via a ring gear. The orange and back barrel is a timer mechanism that cuts power to the arm after the allotted time has expired.

Here are all the ring gears layered back in the socket.

This shot shows the underside of the arm assembly that fits into the socket of ring gears.

I'm still in the process of adding to and refining this page. Check back for updates.

Shown above are patent drawings for Armatron. Click drawing for larger image.

There was also a Super Armatron and a Mobile Armatron. Super Armatron appears to be an updated marketing package that is otherwise identical to the original. Mobile Armatron appears to be an electrically actuated toy controlled by a tethered remote and really has nothing in common with the original Armatron.