Every time the cool-down is made, the 20CS-1 gets energized. HR starts and Develops pressure of 45 bar. 33CS is also showing true but no ratcheting.

To add to all this the clutch is not dis-engaging at all, even if oil is drained out or HR is stopped. the hydraulic pistons have also been taken out and checked. How to dis-engage it??

We have cleaned the filter and also checked the PRV in line of HR discharge. what is the pressure developed by HR pump during normal operation?

 

Dear Arindam,

It looks like the strength of springs in the two hydraulic rams have weakened. Please have a look or replace them.

Normally, during cool down cycles. There are two things that hold the jaw clutch engaged: the shape of the jaw and the remaining oil in the hydraulic rams. It is possible to manually disengage the clutch by draining the oil using the manual valve. When the oil is drained the springs in the rams should push the jaw clutch backward to disengage.

Please try.

Best Regards,
KevinBuBu

 

Arindam,

First, the teeth of most jaw clutches are designed such that they are tapered and will not allow easy disengagement when the ratchet pump is shut off and there is no hydraulic ratchet pressure.

Second, what is the state of L33HRF? Both when the hydraulic ratchet pump is running and when it's not?

Third, it would seem the hydraulic ratchet pressure is low. There are <b>MANY</b> threads here on control.com about ratchet troubles.... One or two likely have typical hydraulic ratchet system pressures. But most turbines do not have pressure gauges installed by the factory on the ratchet system so it's difficult to say what the pressure is during normal operation for a particular machine. Did you install a gauge on the system at your site for troubleshooting purposes?

Is this a new unit or has ratcheting been working properly and just developed a problem, say after a maintenance outage?

If the unit is equipped with VM-2 it should be possible to put it in the "test" position and operate the ratchet and see, first, if the clutch halves disengage during a retraction stroke (when L33HRF is a logic "1"), and second if the driving side will turn during a forward stroke (when L33HRF is a logic "0"). If it does, then something mechanical is preventing the shaft from turning when VME-2 is in the normal position, or the hydraulic ratchet pressure is insufficient.

Please write back with the results of your efforts and the requested information if you need more assistance.