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Reversing Gears at High Rate of Forward Speed?

Discussion in 'Technical Discussion' started by Capt Bill11, Jan 17, 2010.

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  1. 61c40

    61c40 Member

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    You'er right about the big direct units although the last one I saw was on a opposed quad 6-71 with a single output
  2. Marmot

    Marmot Senior Member

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    Ah, sounds like you might be a kindred spirit. Were those engines on one of the small landing craft, an LCI or something like that? I think I know the bearing you mean, it was about 2 feet by 2 feet, had kind of a straddle type mount/sump and a circular inspection port on top?

    I used to have a tug with a direct reversible Enterprise that used a Kingsbury GF thrust bearing but that boat was WW2 vintage.
  3. geriksen

    geriksen Senior Member

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    I have a theory for you guys on this one......
    We had a guy run over his own anchor line. He got it caught in both props and throttled up to try and get free. When he did that it literally "winched" both shafts together and pulled both struts loose. It actually pulled one up through the bottom of the hull. I got a late night call as the boat was going down quick and we did an emergency haul out and saved it. We still have one propshaft (bent) in the shop that still has that anchor line wound up on it tight as a drum. If your charter customers did this, I can see it causing this damage without a ding on the props. If the struts on the boat were strong enough the engine mounts could be the next weak link in the chain.
    Btw, we repaired the boat and it is still running fine.
  4. Capt Bill11

    Capt Bill11 Senior Member

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    Thanks for moving it. And sorry for getting off track on the other thread.
  5. Capt Bill11

    Capt Bill11 Senior Member

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    It's possible. But the charterer claimed he never hit anything. And there was no indications on any of the underwater gear or bottom that they touched anything. And remember, this is a boat where the keel sticks down below the props.

    As to the bent shaft, the engine was running and in gear when this happened. And the shaft also cracked the shaft log/tube as it fell off it's mounts.
  6. Capt Bill11

    Capt Bill11 Senior Member

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    No damage to the prop or rudders. And the transmissions to shaft couplings had "Drivesavers" on them. The Drivesaver on that engine was not completely torn apart as it should have been if he had hit something with the prop that could cause the mounts to fail. In fact the Drivesavers should prevent that kind of damage in the event of a prop strike. And I have seen them do just that in the passed.

    The engine mounts and grade 8 mounting bolts are not the original ones. And the likely hood of all failing at once would be astronomical.

    I can see perhaps one failing but even that would not take out the rest. Also these are the softer type mounts that a bit of give to them. In fact I have seen one mount fail on these type of engines before and the engine/boat was running fine sitting on the three remaining ones.
  7. Capt Bill11

    Capt Bill11 Senior Member

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    Well, then please explain how this could all happen while the engine was in forward with out the prop hitting anything?
  8. Capt Bill11

    Capt Bill11 Senior Member

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    I agree. And we had a charterer do just that with a tow line. But there was damage to both sides in that case. And in this case the major damage was only to the stbd engine.

    Although the port transmission failed not to long after this happened. And on close inspection there were indications that the port engine had shifted on it's engine mount to the rear farther than normal.
  9. Marmot

    Marmot Senior Member

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    Not having been there or having looked at the parts, I can't tell you anything other than there is much more to the story than going astern.
  10. Capt Bill11

    Capt Bill11 Senior Member

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    He had that option. In fact I suggested he get his own surveyor to look the damage over. He never took it.

    Also the bolts were not over torqued to correct alignment issues. There were no on going alignment issues with this boat. My personal boat at the time.

    The shame of it is, he had agreed to cover all the out of pocket costs for parts and supplies to repair the damage as long as I did the majority of the work myself. Which I did. He even signed a paper to that effect of his own accord. In fact that was his idea of how to best settle this without having to go to court. Then he reneged and would not even return my calls. And as I stated before, once he was before the judge (well on the phone with, because he would not come down to appear in person) his story changed in many ways.
  11. Capt Bill11

    Capt Bill11 Senior Member

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    I don't disagree. But I could only go by the "facts" as told to me by the charterer and what I saw at the time.

    He would never once even entertain the idea that he had shifted the engine into reverse. Even as I said, after I found the transmission to be in reverse when I arrive on the scene.
  12. Marmot

    Marmot Senior Member

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    And what kind of shift control was used? Was it a Morse cable? What direction did the actuator lever on the gearbox move to select astern?

    And who is to say that in the confusion caused by the engine and shaft banging madly around the driver didn't try shifting to see if that would stop whatever was going on?

    The position of the gear selector lever is probably the last thing that indicates anything about that incident.
  13. Capt Bill11

    Capt Bill11 Senior Member

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    Morse cables. And the engine falling backward would not pull the cable in such a way as to put the transmission into reverse. In fact it could do the opposite.

    "And who is to say that in the confusion caused by the engine and shaft banging madly around the driver didn't try shifting to see if that would stop whatever was going on?"

    Don't disagree. But the charterer was adamant that he had never gone into reverse. Only chopped the throttles and gone into neutral.

    Again, based on the layout of the controls, I think he "chopped" the gears. :)
  14. captainJJ

    captainJJ New Member

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    Reversing Gears at High Rate of forward speed

    Impresive photos looks like its trying to be a land rover puling something out of a ditch, didnt know the old ford had so much torque, would have thought gearbox would have suffered before mounts:eek:
  15. Henning

    Henning Senior Member

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    Nothing should have suffered.
  16. Captd13

    Captd13 New Member

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    Thank God I have the pleasure of Rolls Royce ASD Z drives. I can take my 98 ft Edward J. ***** at full ahead (13 kt) to stop and start astern in the length of the vessel. She shakes an ungodly amount, but when you need it it is a life saver. We have twin EMD 12 cyl. turbo charged. fantastic for the power needed to stop on a dime
  17. cdg

    cdg Member

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    This may be the wrong thread but......... can anyone tell me what happened to me today:
    1. we were manoeuvring happily from our pier.... port wing station controls (electronic controls back to sender in engine room which drives morse cables to transmission boxes about 2m away) port fwd/starbd reverse to shimmy over.
    2. ease port to neutral, and starbd to neutral - starbd does not respond.... we move fwd at 1kn (which seems v quick in tight marina with wharf ahead hoving into view). Intermittent alarm sound at port station.
    3. toggle starbd control back to reverse, back to neutral. no response.
    4. proceed quietly (!) to the bridge , press 'come to me' button, wait precious seconds for controls to come to bridge throttle station,... arrest fwd mvmt (just in time to save their wharf and our dignity..... ahem)
    5. bridge controls worked fine
    6. repeat performance end of day.... when starbd engine actually shut down to stop fwd motion (berth on port engine and bow thruster - fun). Bridge throttle control alarm sound.
    7. problem solve:
    - morse cables driving selector OK
    - no morse cable damage
    - all throttle stations (5) tested - apparently gears selected OK (couldnt tell as engines off)
    - cable tension seemed OK (but may have been a little tight - so loosened off a bit)
    - next day repeat checks - this time engines on) - all OK.

    We're running ZF Mathers Controls Micro Commanders (and of course ZF transmissions)

    Now, I never mind an absence of system failure. I love that. But when I have one (apparently) and I can't find/prove the problem later.... I hate that.

    Your thoughts?
    - user error (if so what) ?
    - what would cause the alarm to sound: is it saying "Warning: no comms here" or is it saying "Warning: the gear lever has moved but the transmission has not responded as you directed"... or something else.

    Thank you all in advance :)
    Campbell
  18. Capt Bill11

    Capt Bill11 Senior Member

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    Sounds like a communications failure with the Mathers. Time to call in a skilled service tech I'd say.
  19. NYCAP123

    NYCAP123 Senior Member

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    The alarm confuses me. However, taking that out of the equation for a moment (before calling in the service person) I'd first check that the control handle isn't slipping. Had that happen to me last year with manual controls. My mind went everywhere, and I felt like a fool when the tech came aboard and immediately found it to be the set screw backed out. The second thing I'd check is that the cable is secured before the linkage. A few times I've had them jump out of the clip, and learned to cable-tie them in place. When out of the clip sometimes they work and sometimes they don't.

    Now back to the alarm. That leads me to what Capt. Bill surmised, and it's beyond my capabilities to diagnose. So if not one of what I mentioned, I'd call in the tech as it sounds like an electronic error.
  20. Capt J

    Capt J Senior Member

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    Change the control head. The zf mathers micro commander controls are not very susceptible to a wet location and they usually fail intermittently like that, then start doing it more often. The control head is not that expensive $700 maybe and can be changed pretty easily. The fact you're getting an intermittent alarm there tells me it's an issue with the station. The only other thing it could be, would be the wiring connections and when you pull the control head out, you'll be able to inspect them, as micro commanders utilize very small wires.