Bitzer smashed conrods

[Drew]

Hello all,

if a six cylinder bitzer semi hermetic compressor smashes two conrods and looses the two big ends off the shaft would we expect the oil failure to trip due to lack of oil pressure?

thanks.

[HVACRsaurus]

Ouch.

Yes... But... Consider the delay, a machine can still smash itself up pretty good in 90 seconds. Maybe if fragments got jammed in the crankshaft oil hole it could be enough to keep the oil pressure from activating.

[Drew]

Say the holes aren't blocked would the loss in pressure be enough to trip the oil failure. Therefore less than 9psig difference. ( I think?) . The client says that it was still running and that he turned if off, I would have thought it should have tripped on oil failure and shut down?

[Drew]

Good point though!

[HVACRsaurus]

Hard to say for sure if the oil pump would have enough flow to keep the oil pressure up like that, perhaps if the switch was a bit tired or out of adjustment..

Testing the operation of the particular switch & control circuit would be advisable, maybe operate the motor starter with the motor leads disconnected & put it through its paces.

[Peter_1]

The oil pump runs on the crankshaft, so if the conrods brake, then the pump still can run and provide the nccesaary pressure.

[cadwaladr]

the overload should have tripped,would check that its set for the correct amps and not set on auto reset!

[Drew]

The big ends also came off shaft so oil would have been spraying into sump? Oil pressure should have dropped and compressor should have tripped on lack of oil pressure.i understand that the pump can still provide oil down shaft but the pressure should drop and trip .

[cadwaladr]

but there is a delay built into the switch,and it can destroy itself in that time which it did.

[THE DUDE]

You would be correct in expecting a Functioning Oil Failure to trip.

[Drew]

It would be the same as a worn compressor, pump running and delivering oil, but due to worn big ends the pressure difference created by the pump would be low and the oil failure should react.
The oil pressure switch can react to worn compressor, low oil, foamy diluted oil, faulty oil pump or blocked oil filter. I recon two big ends missing would equate to the same as worn compressor?

[Peter_1]

What are 'the big ends'?

[mikeref]

Bottom half of the connecting rods bolted to the crank Peter.