Grasso RC311 compound compressor

I am having problems with a grasso RC311 compressor. I think the High pressure head should load as soon as there is oil pressure, with this compressor there is a long delay. I have fitted a pressure gauge to the line feeding the loading piston and get no pressure untill it loads then I get over 200 psi and every thing works ok. I have stripped and checked all the oil pump including the control pistons. There is oil pressure at start up imediately for the crank shaft (2.5 bar) so I can,t figure out why I can,t get pressure for the loading gear? Any body got any ideas?

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Originally Posted by aupanner

I am having problems with a grasso RC311 compressor. I think the High pressure head should load as soon as there is oil pressure, with this compressor there is a long delay. I have fitted a pressure gauge to the line feeding the loading piston and get no pressure untill it loads then I get over 200 psi and every thing works ok. I have stripped and checked all the oil pump including the control pistons. There is oil pressure at start up imediately for the crank shaft (2.5 bar) so I can,t figure out why I can,t get pressure for the loading gear? Any body got any ideas?

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Aupanner
There is an inbuilt hydraulic time delay (within the oil pump) which is a piston with a small "bleed orifice".
This ensures a 3 minute time delay approx. I think?
This also ensures that the compressor does not start loaded!
There are 2 different pistons available with 2 sizes of orifice which is fitted is dependant upon the age of the compressor.
Also relevant is the fact that when servicing the unloading pistons and seals.
It has been known for some engineers to fit a return spring to the H.P. Head, when 1 is not fitted!
I will search my archive and post more if you deem it
Necessary.
Incidentally I did not realise that they did a compound 3 cylinder machine?
They say you learn something every day!
Grizzly

Thanks for the reply, it puts my mind at rest because when it loads it runs great. It is a 4 cylinder (RC 311) the C stands for compound the 3 is for 3 primary cylinders and 1 is for High pressure cylinder. thanks again.
Regards Gordon.

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Originally Posted by aupanner

Thanks for the reply, it puts my mind at rest because when it loads it runs great. It is a 4 cylinder (RC 311) the C stands for compound the 3 is for 3 primary cylinders and 1 is for High pressure cylinder. thanks again.
Regards Gordon.

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Gordon.
RC (recip comp)
3 1 = 3xlp 1xhp
11 = Grasso recip series 11
therefore a 4cyl compound =
RC31.11
Whereas a RC3.11
Is a 3 Cylinder recip series 11. (working on some today )
At least that's how they explained it at the factory in Holland, many moons ago!
They haven't changed the was they designate their compressors, as far as I know.
Hence my initial confusion.
Anyhow thanks for the acknowledgement many people don't even bother to reply!
If I can be of further assistance don't hesitate to ask!
Grizzly AKA. Steve.

Grizzly,
A good note, the propriety answers.

grizzly,

Better late than never many thanks for the info.

regards,