When starting the machine, 33HR which used in ratchet self sequencer keep sending pulses indicates that the rotor is turning. is it normal?

 

Elshaer,

If I understand the description, no; it's not normal for 33HR to toggle <b>AFTER</b> the shaft has broken away from zero speed.

For most Frame 5s, a "bump" from the ratchet mechanism is required to help the starting means (via the torque converter) to break the shaft away from zero speed. So, sometimes, 33HR may toggle during initial starting, but not usually after L14HR drops out (which indicates the shaft is no longer at "rest (zero speed)).

So, it would seem there is something amiss with the ratchet permissive logic or the ratchet self-sequencer (which is driven by the Speedtronic--which should stop "driving" the self-sequencer after the shaft starts turning), or the solenoid output (relay) to the self-sequencer has failed in the energized state (which does happen, but not usually).

Please write back to clarify the description if I misunderstood it, and to let us know how the problem was resolved.

 

When starting the machine, the ratchet will run continuously until the shaft breaks away from rest. This is perfectly normal and is to assist the Starting Means to break the shaft away.

 

Bob Johnston brings up a very good point I hadn't considered because I'm still not clear about the problem description. During starting the ratchet is run continuously (no 3-minute wait between cycles) in an attempt to provide that little "bump" necessary to help the starting means (through the torque converter) break the turbine shaft away from zero speed.

The starting means clutch (usually a jaw clutch, but sometimes a SSS (Synchronizing, Self-Shifting) clutch is used) is supposed to be engaged, and there is usually a limit switch, 33CS or 33CS-1, to indicate that the clutch is closed. However, there is usually a manual valve (sorry I can't recall the valve number, VM-something or other) which must be in the proper position to port hydraulic ratchet pressure to the starting clutch rams to engage the clutch (if it's the typical jaw clutch) and actuate 33CS.

So, if the unit has a jaw clutch and the manual valve is in the wrong position then when the unit is started the jaw clutch will not engage and the ratchet will operate continuously and the unit will never break away from zero speed--which is the part of the problem description which is not clear. Did the unit break away from zero speed during starting and the ratchet continue to operate? Or, did the unit not break away from zero speed during starting and the ratchet operates continuously?

There is still another possibility for a problem even if the manual valve is in the wrong position and that is if the torque converter is not working properly or is in dire need of refurbishment, and/or the diesel starting means is not providing sufficient torque to help break the shaft away from zero speed even with the assistance of the ratchet, then it's conceivable that the ratchet would run continuously and the unit would not break away from zero speed.

So, the original poster needs to clarify the problem description. Does the unit break away from zero speed during starting, and does 33HR continue to toggle (not likely)? Or, does the unit not break away from zero speed during starting and the unit ratchet continuously trying to help break the shaft away from zero speed?

If the latter is the case, then someone needs to review the Starting Means P&ID and determine if there is a manual valve in the hydraulic tubing to the jaw clutch and if so, if the manual valve is in the proper position and if the jaw clutch is engaged/engaging or not during starting.

If the jaw clutch is engaged during starting, then the problem is either the torque converter is worn or is not working properly or some solenoid valve associated with the torque converter is not working properly or some manual valve associated with the torque converter is not in the proper position--again, all such valves (solenoid-operated and/or manual) are shown on the Starting Means P&ID. Or, the starting means (electric motor or diesel engine) is not providing sufficient torque to the torque converter to break the shaft away from zero speed.

One more question which I should have asked: <b>When did this problem start?</b> After a maintenance outage? After some work was done in the area of the Accessory Gear Box?

It would also be helpful to know if anyone has actually observed the shaft being rotated (approximately 1/8th of a revolution) during the start attempt (presuming the shaft is not breaking away from zero speed during starting). If it is not, and the jaw clutch is engaged (as proven by manual observation and the actuation of 33CS), then it's possible there is a problem with the ratchet mechanism--but not likely, since 33HR is seemingly changing state continuously.

The typical logic for the ratchet mechanism is as follows: 33HR should close (and make L33HRF go to a logic "1") at the END of the forward stroke of the ratchet mechanism. So, as the shaft rotates through approximately 1/8th of a revolution and then stops, 33HR should change state and remain closed (L33HRF should remain a logic "1") during the entire retraction stroke. Then the ratchet mechanism will another forward stroke for a few seconds (to keep the jaw clutch halves engaged) and 33HR will change state (open--making L33HRF go to a logic "0") and then the ratchet mechanism will stop for approximately 3 minutes.

During starting, there is no 3-minute wait between ratchet operations--the unit is ratcheted continuously trying to break the shaft away from zero speed. So, 33HR will be closed for the duration of the retraction stroke (when the shaft is not being rotated) and will be open during the 1/8th revolution of the forward stroke. If 33HR is toggling faster than every 20 or 30 seconds or so, then it would seem there is a problem with the ratchet mechanism or with 33HR. Again, this would be obvious if someone were observing the shaft during the start attempt. If the ratchet is operating normally and being rotated approximately 1/8th of a revolution, then pausing, then rotating 1/8th of a revolution before pausing again, and so one, and the shaft is not breaking away from zero speed then 33HR and the ratchet mechanism is working properly. But, if the shaft just barely moves and 33HR changes state and then then changes state again very quickly and the shaft barely moves before 33HR changes state again, then there is some problem with the ratchet mechanism or with 33HR. But, it's necessary for someone to be observing the shaft during starting to determine what is--or isn't--happening.

Usually, if the shaft does not break away from zero speed after some time there will be a process alarm to indicate "Failure to Break Away." Which is another question for the original poster: Are there any Process Alarms (or Diagnostic Alarms) being annunciated during the starting?

So, there are a lot of questions to be answered by the original poster to clarify the problem resolution. And, one of the most important is: Has anyone observed the shaft being rotated by the ratchet during starting?

And, there a lot of possible causes for the ratchet to continue to operate, causing 33HR to toggle periodically, if the shaft is not breaking away from zero speed during starting.

Lastly, if the unit has a SSS clutch between the starting means and the Accessory Gear/turbine shaft, it would be very unusual for the SSS clutch not to engage (as indicated by the change of state of 33CS)--but stranger things have happened. Usually, a slight rotation of the drive side of a SSS clutch is all that's required to engage it. If the SSS clutch is not engaging, then the problem might be the SSS clutch. Which, again, if anyone has actually observed the shaft rotating during starting would most likely eliminate the SSS clutch as the problem.

It is sincerely hoped the original poster will write back to clarify the problem description and provide more details about the problem.

Thanks to Bob Johnston for jogging the memory (no pun intended!).