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Hydraulic steering questions

Discussion in 'Technical Discussion' started by lucseawalker, Jan 21, 2017.

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  1. bobhorn, Jan 24, 2017
    #21
    bobhorn

    bobhorn Member

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    Does the autopilot pump not operate directly on the steering cylinder? I don't understand how the wheel turns HO to HO affect the autopilot pump?
  2. Capt J, Jan 24, 2017
    #22
    Capt J

    Capt J Senior Member

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    I find this to be true also. I also don't think the autopilot would have to do 5 turns lock to lock to maintain a heading in 98% of situations....1.5 turns in each direction should be sufficient.

    ANYWAYS, I'd recommend changing the steering ram also to the matching one of the helm you're putting on. If you go with a 3 turn (lock to lock) with a ram designed for 5 turns, the faster speed and pressure on the old ram will probably start blowing seals sooner or later. Perhaps not.
  3. lucseawalker, Jan 24, 2017
    #23
    lucseawalker

    lucseawalker New Member

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    Yes, there is a set key so that is not the issue ... Tnx
  4. lucseawalker, Jan 24, 2017
    #24
    lucseawalker

    lucseawalker New Member

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    Yes, that would be nice .. but I tried all the settings and nothing seems to do the job ... and the manual states that the wheel autopilot works on helm with 1 to 3.5 turns ...
  5. lucseawalker, Jan 24, 2017
    #25
    lucseawalker

    lucseawalker New Member

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    No, the autopilot is connected to the wheel with a belt. A possible option indeed would be the replace that belt system on the wheel by a hydraulic pump and I am considering that solution. But since it seems that my actual pump is deficient, then I can replace it by a bigger pump that will give me less than 3.5 turns .. and Bingo, the actual wheel belt system should work .. famous last words !
  6. lucseawalker, Jan 24, 2017
    #26
    lucseawalker

    lucseawalker New Member

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    Good point, I guess the rams and pumps are designed to work in diffrent combination so I hope there won't be such issue ...

    I am thinking that if the pump works in regular sea conditions, I should perhaps keep it and just install an hydraulic pump on the autopilot ... In case of heavy seas, I could always use the autopilot pump to control the rudder if the helm slips ...

    I am waiting now to hear from HyDrive about sending me one of their pumps ...
  7. Bamboo, Jan 25, 2017
    #27
    Bamboo

    Bamboo Senior Member

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    Can you post a pic of that section of the manual? I've never seen nor heard of marine steering with 1 turn lock to lock.
  8. lucseawalker, Jan 26, 2017
    #28
    lucseawalker

    lucseawalker New Member

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    Here is the scan ...


    extract manual EV100.jpg
    Last edited by a moderator: Jan 26, 2017
  9. lucseawalker, Jan 26, 2017
    #29
    lucseawalker

    lucseawalker New Member

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    I did some thinking today and came the the following plan:

    Based on my calculations of the torque of my rudder (see attached plan), I should be able to downsize my steering cylinder from the actual 200cc that gives me around 1000 Nm of maximum torque to a MTC52 that gives me a 510 Max torque.
    If my calculations are correct, my torque is around 329 Nm so the 510Nm of the smaller cylinder should be ok.
    My speed can be up to 10 Kts .. but mostly between 4-8Kts.
    Are my calculations correct or am I missing something???

    If I am correct then I can get a smaller pump HTP42R (Vetus does not make the MTP 53 like I have now (not working well!) ... and that should give me 2,5 turns HO to HO , what my wheel autopilot will like .. :)

    I thus replace my entire Vetus hydraulic steering system but do not need to do anything as far as my autopilot goes :)

    rudder drawing.jpg
    Last edited by a moderator: Jan 26, 2017
  10. Capt Fred, Jan 26, 2017
    #30
    Capt Fred

    Capt Fred Senior Member

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    I would not rely on the autopilot to control the rudder in high seas and pretty sure your system, as is, will not control the rudder in high seas with out a lot of slipping(bypassing). Since you are willing to replace the pump why not try to modify the pump. My guess is the the small ss balls mentioned in the beginning of this thread are the relief valves. I would experiment with some springs that will add a small amount of force to increase the pump output pressure. In example a 4 oz spring pressure against the ss ball that sits over a .020 diameter seat would create about 745 PSI or 50 bar pressure. You can experiment to get a spring that feels right. I would think the autopilot would work as Capt J suggest but it could be improved by changing the drive sprocket diameter.
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