trigon wrote:
Thanks, the toy i am talking about is even simpler than that, I have
described it further in a reply to my original post. There are no
electronics involved in the bump and go mechanism. Sorry I did not describe
this as a toy in my original post.


These kind of toys usually have a simple mechanism driven by a single
motor, it`s not easy to describe tho. Usually, a vertical motor drives a
pair of wheels in a free turning cage. It`s a kind of differential -
imagine the solid back axle of an old car with the prop shaft vertical.

The whole toy balances on these wheels, stabilised by a couple of
protrusions on the underside of the toy. Because of the design of the
bottom of the toy, when there`s little resistance, the robot moves
forwards, but if it is stopped by an obstacle, the resistance on the
wheels causes the the cage to be spun by the motor, thus steering the
toy in a different direction - Imagine how a dodgem (bumper) car works
except the steering wheel is turned by the motor when the driving wheels
are obstructed.

So, I think the chances are either one of the wheels is loose on it`s
shaft, or the cage is somehow jammed. Maybe you can post a link to a
photograph of the underside?

Ron(UK) (Old Toy Collector)