Emergency Stop Failure

[Gary Prentice]

One of our staff managed to roll a stumpgrinder this week. Of concern is his claims that both the emergency stop button and the ignition failed to stop the machine.

 

On being manually 'righted' the emergency stop worked! Testing in the workshop shows that both the ignition and the ES are working correctly. This machine is wired so that the fuel solenoid is closed (or opened- I'm not certain exactly which way it works) when it receives current. Is it possible that due to the position of the solenoid, it could stick in its working position?

 

Any one else had the same problem or experience?

[Le Sanglier]

What machine is it?

[Gary Prentice]

I knew someone would ask? Off the top of my head I couldn't say. I get lost with all we have, I know it runs a water cooled lombardini derv engine, think its a FSI or something

[treequip]

The solenoid should be open when energised, it pretty much has to be otherwise it would drain the battery when not in use.

 

The orientation should be irelevant howeve it is possible that if the coil field is weak it MAY not opperate properly if it were sudenly asked to pull the actuator uphil but this is an unlikley scenario, as a rule coils work or they dont.

 

You can test this by removing the solenoid and testing its opertion in various orientations.

[Gary Prentice]

Sounds like a plan:thumbup1:

 

Excusing my electrical ignorance, but could/would a low battery charge level have any affect on the coil? We had a faulty rectifier on it last year and the voltage dropped sufficiently for the electro-magnetic clutch to slip, so I wonder if the solenoid would act similarly.

[treequip]

Sounds like a plan:thumbup1:

 

Excusing my electrical ignorance, but could/would a low battery charge level have any affect on the coil? We had a faulty rectifier on it last year and the voltage dropped sufficiently for the electro-magnetic clutch to slip, so I wonder if the solenoid would act similarly.

 

The solenoid is a coil and a magnet, the voltage through the coil creates a magnetic field, the field of the coil and magnet are polarised to oppose each other which causes the magnet to move when the coil is energised thus operating whatever action it is attached to.

 

low voltage will casue problems but not usually huge, as an example I have a 24 volt tipper pump unit, (motor and solenoid) it works fine on 12 volt but the pump isn't as fast and the solenoid is a bit weaker but it still works

 

The short answer is that the voltage would have to be on the bones of its backside for the coil not to energise.

[Gary Prentice]

Ok Thanks Andy

[Craig.]

The stop solenoid should need power to open to let the fuel through to injection pump and let engine run, as treequip said. If the voltage dropped low enough the solenoid wound shut stopping the engine.

Perhaps when it turned over it carryed on running on oil fumes if the engine oil got into the breather/air filter while on its side?

If every thing checks out Ok, may be it was just good old operator error, it was`nt me boss it was the machine:001_rolleyes:

[Gary Prentice]

The stop solenoid should need power to open to let the fuel through to injection pump and let engine run, as treequip said. If the voltage dropped low enough the solenoid wound shut stopping the engine.

Perhaps when it turned over it carryed on running on oil fumes if the engine oil got into the breather/air filter while on its side?

 

That's a possibility, it was reported to be smoking heavily

 

If every thing checks out Ok, may be it was just good old operator error, it was`nt me boss it was the machine:001_rolleyes:

 

The thought had crossed my mind:001_rolleyes:, I'll try re-orientating the solenoid whilst testing the emergency stop. Obviously I'm not happy to let it go out if there's a fault.

 

I'll check the air filter too. Any idea how long it could run on fumes for? Its a bit worrying that all the safety features to stop the engine could be made useless due to the oil in the filter though. No real way round that except don't roll it over.

[treequip]

Its unlikely it was eating its own fumes, if that happens its usually because the crank case is pressurising, does the breather even go to the air intake? That’s an emission’s thing and a lot of small engines (particularly older ones) don’t.

 

The smoke is also not conclusive, all 4 strokes smoke if you put em on their side.