Speed Limiter

What an awful idea - limiting the amount of energy that children can expend!

But if you must - coat the central axis with teflon. Insulate this from the rest of the merry go round. Attach a commutator made of rabbit fur. Bulid a simple pendulum connected to the teflon. When the merry go round is turned, the rabbit fur rubbing on the teflon will build up a large static charge. At 30 rpm have the pendulum swing out and contact the merry go round, shocking all the children, and causing (momentary) loss of muscle control, throwing them all off.

I'd go for the old style revolving balls centrifugal governor, but connected to a friction brake. That way it can be hidden away from tampering hands and set to any desired rotational speed. (Also, the kids can still expend energy, they just won't go any faster!)

How about a centrifugal pump with a reservoir? Attach the impeller to the main shaft, the volute to the carriage, and put an orifice on the discharge of the pump. The faster they turn the harder it gets to turn. Different size orifice in combination with various viscosity of liquids should fine tune it.

Do what most of the ones here in Australia had, a circular sand pit around the periphery so when the "dizzy kids " fly off due to centrifigal force they land in the sand pit & in any case the kids parents should be keeping an eye on their children as often stupid older kids turn it fast when much younger kids are also on board, the younger ones just scream & hang on tighter.

The positioning of the hand rails right out to the outer periphery usually causes most injuries or sharp or steel edgings on the outer rim rather than the rotational speed . We call them "Razzle Dazzles" here.

Let the kids live a bit dangerous & have some fun without all the current over protectionism.

Australia is getting like the USA, our local councils are pulling down play areas for fears of litigation, some idiot wanting to sue the council for not fully overhead covering play areas 20 years ago maintaining that contrbuted to now having skin cancer.

Some litigation claims & court awards here are totally insane, we have lost the plot, what happened to being responsible for your own uttererly stupid actions or seeing that our kids don't do things that are beyond the norm or really endanger their safety.

Hi mate, I couldn't agree more, especially as I do a lot of health and safety at the moment. The denial of personal responsibility is becoming nuts here in the UK also, but it's driven by the insurance companies and organisations fear of litigation. The HSE here actually take a common sense approach, the problems I have are the usual 'we've always done it like that so were not changing now' paradigm!

You could use a magnetic coupling like this.

The way it works is that the plate is fixed and constructed of a conductive material. The magnet is attached to the merry go round and as it rotates it induces currents in the plate which will try and oppose the rotation. The faster you rotate the magnet the greater the opposing force.

Generally this force is only small and I havn't done the maths behind it but with the advent of rare super strong magnets of recent you may be able to get it to work.

like it! If was a kid I'd like it even more! Especially if I thought I had a chance to get a magnet that powerful!

Actually if you design it properly you can keep the magnetic field in a closed loop with very little leakage. The result is that you would hardly know it contained a magnet.

Although the antipodean solution (let them get on with it but avoid hidden dangers) sounds to be the most satisfactory, it's probably not an option. Failing that, I imagine you want to have zero resistance up to some speed, and then increase it rapidly. PlbMak's solution should fit - but given the restricted space you have for the govenor, you will probably need a sprung version. Once the balls come out far enough to contact a stationary rubbing strip, the forces should rise quite rapidly. Be careful that the mechanism is inaccessible to probing limbs, and that it can't bind suddenly - even if bits of crud fall in. Unless things have changed, your biggest risk is that the parks authorities won't maintain the thing properly.

It would be nice to combine the govener system with masu's eddy-current machine - but I fear cost difficulties.

N.B. The arrangement the kids would go for is the pump - provided that it sprayed water over everyone when the roundabout got really fast. But you'd probably be held responsible for the hygeine...