"Ron(UK)" wrote in message
...
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)


Thanks a lot Ron, that's how I thought it worked but still cannot quite
understand how it accomplishes this but it seems that there is too much
resistance on the wheels most of the time so it ends up spinning when it
shouldn't, I can get it to go forward and back a little but then it seems to
get stuck in a spinning motion even though there is no obstacle, I thought
it might be the joins in the wooden floor but it does the same thing on a
smooth table. Anyhow thanks for your confirmation on how it works, this
makes me confident that i least understand that part right. I will post a
reply when I get time to take it apart and look at it, hopefully it is not
just wear and tear that cannot be fixed, the rest of the mechanical
mechanism is in very good order, I have another of these robots and it seems
to have the same problem so it looks like wear and tear, which maybe a bad
thing for me.