Dear sir,

We have 6 frame - 6 gas turbine in which 2 machines are newly commissioned but within span of 8 months our 1 newly commissioned unit subjected to problem of hydraulic oil. MHOP is not able to develop sufficient pressure means AHOP started. it happens 3 times.

then we replace the coupling of MHOP (BOwex coupling) with new one and started the m/c. Machine started but within 3 months again failure of teeth of bowex coupling. then we again replace it but after 3 months again same problem.

so please give ur suggestion and feel free to ask any data.
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When couplings repeatedly fail it's a pretty sure sign there is either an alignment problem or an excessive load.

I have seen improperly configured hydraulic system relief valves (being incorrectly used as pressure regulators) cause excessive load on Aux. Hyd. Pump motors. Also,incorrect valve settings on hydraulic accumulators can cause excessive load.

Typically the same pumps and couplings are used for both Hyd. pumps. It's entirely possible there is some mechanical problem with the Main Hyd. pump. (They have been known to fail....

 

Dear,

is it possible you can send me your Hydraulic Oil System drawing so that we can comment.

my email address is [email protected]

 

> When couplings repeatedly fail it's a pretty sure sign there is either an
> alignment problem or an excessive load.

> I have seen improperly configured

i support the above diagnosis. it can be any of the following.

1, improper alignment.coupling failure,

2, wrong installation of gear pump,

3, starvation of pump,not getting enough oil @suction.

4, relief valves not stetted properly,immature opening ,there by releasing all oil in the circuit.

 

Hi,

Inspect Aux gearbox; check no# 4 shaft and bearing any damages and also check oil feed hole any blockage, this issue cause for frequently coupling failure.

 

yep, as stated by chikkham, check the alignment of AGB #4 bearing. We had 2 quill shafts break about 2 weeks apart.

 

Did either of these broken quill shafts cause the coupling between the Accessory Gear Box Main Hydraulic Pump Output Shaft and the Main Hydraulic Pump input shaft to fail?

Did either of these broken quill shafts cause the Main Hydraulic Pump to be incapable of producing sufficient Hydraulic Pressure, resulting in the starting of the Aux. Hyd. Pump?

 

Thanks for your valuable comment. but i think for avoiding the alignment problem M.s- Flender provides flexible coupling (bowex).
Is it possible to do the alignment without dismantling other shaft??
what is expected maintenance time for performing this job??

 

Every time we found coupling teeth damaged towards Acc. gear box side not towards MHOP side.

 

There is a limit to the amount of misalignment a flexible coupling can "absorb."

However, a problem with the accessory gear box output shaft could also be the problem. There's probably little which can be done to determine if a problem with the shaft is causing the couplings to fail without a shutdown to open the accessory gear box.

Please write back to let us know what you find.

 

Thanks for your valuable comment, but every time we found teeth damage of Bowex coupling towards AGB side and axial float is also very high 1.73 mm and backlash is 0.25 mm.

then it is suggested to replace Bearing support or holder (P/n- 9673D004C2, 465) and replace Brg. of MHOP.

but i am not very much confidence about that this is route cause of problem and coupling would not fail again.