It is noticeable that the torque is pretty even , with little belt flapping , until the button is used , and then the engine is effectively a big single . McLarens would seem to have got their bore sizes well proportioned to produce such even torque .

The answer is that it wouldn't. Nowhere near as quick.

The governors could not put the engine in mid gear as young Mr Searle did, nor would it have permanently shut the regulator. Both of which as seen stopped the engine PDQ.

A governor would simply have effectively closed the regulator until the speed dropped to a pre determined level. Then opened it again.

Some big mill engines had a special fitting.
 

Most governors on large mill engines were belt driven.After a few misadventures in early years when belts came off and engines ran away to destruction a special fitting was added to many. The name Musgrave comes to mind here. It was apparently a giant clockwork motor geared to rapidly close a stop valve on the main supply to the engine, It was triggered by breakage of the belt driving the governors and/ or by various other emergency stop handles strategically placed. I believe that later devices were electrically driven. Hope this is of interest David Powell.

The interesting thing about some governors is they don't fail safe.

Thanks very much to steamshovel for passing on his detailed knowledge of belt drives, which seems to confirm my own observations of the video in my earlier post - belt resonance, then belt slippage, followed by belt loss.

I also reflected that a big engine might be expected to generate 300 amps at 110 volts (typical fairground loads). That's about 55 hp, call it 65 BHP to cover belt and dynamo losses. My earlier post estimated power from what others have said to be about double that. Don't expect to overload anything by a factor of 2 without some risk to life and limb.

As to governors.
1 They should be used as a first line of defence against the engine racing away.
2 Once the load starts to slow the engine from it's governed speed, the test should be stopped - a simple way to estimate excessive overloading.
3 Governors do not eliminate the need for someone on the footplate to shut down manually in case of problems.

As to general safety:
1 Barriers in this instance were not adequate to the rear of the demo. and would provide no protection from flying debris.
2 The coal team were definitely in danger, but perhaps were not made aware of the danger.
3 A maximum loading must be estimated before testing starts based on the lower of engine NHP x some agreed factor OR belt width x some agreed power per inch width.
4 There seems to be a case for a "referee / safety marshall" to oversee such tests and tell others when to stop.

I'm really not against dyno testing done in a controlled and safe manner. Nor am I a safety saint - I have had too many of my own self induced stupid moments but have been lucky.

I had a p.m. this morning from another member which reads "I was there to witness it and the whole spectacle left a number of us feeling like we had witnessed a car accident or similar, it was an unpleasant experience............"

Is that how we want rallies to be?

Martin

insurance
 

does the NTEC club third party insurance cover you for this sort of thing ?

Many Pickering governors had a spring loaded trip device to close the governor in the event of a mishap . This was often attached to a cord which ran to wherever it could be reached by those using the machinery . Known in the States , I believe , as ' The Sawyers Lever ' . The ratchet parts are often to be seen on governors .
A refinement of this was a weighted pulley on a swinging arm . The pulley ran on the back of the governor pulley , and if that belt broke or malfunctioned , then the pulley dropped and a lever from its arm tripped the ratchet and closed the governor . Very effective , and a good reason to use a Pickering .

No, under the present laws any claim would be against the engines RTA insurance.

In second video the Sledge did move quite a bit, aside from that there seems to have been quite a bit of shake as the legs supporting the Dynamometer didn't seem to be braced.. As no one was injured maybe a case of learn from the incident.

I wouldn't like to rely on that. I agree that since Vnuk the fact that the test didn't take place on a road is irrelevant but if, and I stress if, a case like this came to court any engine owner would have to convince a judge that the test was 'use of a vehicle which was consistent with the normal function of that vehicle'. This of course in the light also of any restriction on cover contained in the Certificate of Motor Insurance.