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Hydraulic Drives

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  • Rayfield Simon
    The attached Acrobat file contains some interesting mods to the hydraulic drive. I am unsure of what has happened here, the performance of my
    Message 1 of 8 , Feb 28, 2001
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      The attached Acrobat file contains some interesting mods to the hydraulic
      drive.

      <<Untitled.PDF>>
      I am unsure of what has happened here, the performance of my engine with a
      fixed 2-bladed prop is faultless (apart from usual prop walk problems).
      2000rpm engine speed gives around 6 knots, I normally run at 1800rpm, the
      engine goes all day quite happily at that. I do not really want to run my
      engine at a higher rpm if it is not necessary and what about fuel
      consumption?

      Dediou
      #42
    • galljj35
      I recently had some hoses replaced on the hydraulic drive - the two leading to/from the dennison unit. Now, I seem to have lost low end power in the system.
      Message 2 of 8 , Oct 1, 2013
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        I recently had some hoses replaced on the hydraulic drive - the two leading to/from the dennison unit.


        Now, I seem to have lost low end power in the system.  Before the replacement, the prop would immediately bite, and provide decent acceleration.  Well, some acceleration.  Now, the "bite" is gone, and it seems like the system takes a while to get to 5 knots - whereas before it would get there almost immediately.

        I've got the yard checking on the ISO on the fluid they used - I seem to recall that the system used to be run with an ISO 68 weight oil.

        Is it at all possible that they connected the hoses reversed as to how they should have been installed ?  I don't know, but presume different lengths of hose would almost make this impossible.  Also, I don't know how the system is constructed - but it seems that the shift simply runs a multi-position valve that directs the fluid either clockwise or counter clockwise through the system - and that the impeller on the drive unit is tuned to operate in forward gear - and would sacrifice some in reverse. if the hoses were reversed, it would lead to poor forward speed.

        If anyone has thoughts on this, it'd be appreciated.

        john
      • John Stothart
        Hi John, I have a diagram of the hydraulic system from my original Nich 35 Green Book but it s in Devon and I m in Mallorca until Sunday. I will look it out
        Message 3 of 8 , Oct 1, 2013
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          Hi John,
          I have a diagram of the hydraulic system from my original Nich 35 Green Book but it's in Devon and I'm in Mallorca until Sunday. I will look it out when I get home.
          Regards,
          John



          On 1 Oct 2013, at 19:13, <gall.john.j@...> wrote:

           

          I recently had some hoses replaced on the hydraulic drive - the two leading to/from the dennison unit.


          Now, I seem to have lost low end power in the system.  Before the replacement, the prop would immediately bite, and provide decent acceleration.  Well, some acceleration.  Now, the "bite" is gone, and it seems like the system takes a while to get to 5 knots - whereas before it would get there almost immediately.

          I've got the yard checking on the ISO on the fluid they used - I seem to recall that the system used to be run with an ISO 68 weight oil.

          Is it at all possible that they connected the hoses reversed as to how they should have been installed ?  I don't know, but presume different lengths of hose would almost make this impossible.  Also, I don't know how the system is constructed - but it seems that the shift simply runs a multi-position valve tha t directs the fluid either clockwise or counter clockwise through the system - and that the impeller on the drive unit is tuned to operate in forward gear - and would sacrifice some in reverse. if the hoses were reversed, it would lead to poor forward speed.

          If anyone has thoughts on this, it'd be appreciated.

          john

        • ralpharnesen
          Hi John, My father-in-law put a right hand prop on a left hand gear box and had poor performance till he ran aground and destroyed the gearbox. It was then he
          Message 4 of 8 , Oct 1, 2013
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            Hi John, My father-in-law put a right hand prop on a left hand gear box and had poor performance till he ran aground and destroyed the gearbox. It was then he found out about the mistake. Your idea about the hoses being switched could be the problem or not. My hydraulic system doesn't get much power out of the motor, I have used 32 hydraulic oil, would that make it less efficient? I noticed somewhere about using automatic transmission oil, anyone know the right fluid?
             
            Ralph
            Argonaut of Rhu  
            -----Original Message-----
            From: gall.john.j <gall.john.j@...>
            To: campernicholson <campernicholson@yahoogroups.com>
            Sent: Tue, 1 Oct 2013 18:13
            Subject: [campernicholson] Hydraulic Drives

             
            I recently had some hoses replaced on the hydraulic drive - the two leading to/from the dennison unit.

            Now, I seem to have lost low end power in the system.  Before the replacement, the prop would immediately bite, and provide decent acceleration.  Well, some acceleration.  Now, the "bite" is gone, and it seems like the system takes a while to get to 5 knots - whereas before it would get there almost immediately.

            I've got the yard checking on the ISO on the fluid they used - I seem to recall that the system used to be run with an ISO 68 weight oil.

            Is it at all possible that they connected the hoses reversed as to how they should have been installed ?  I don't know, but presume different lengths of hose would almost make this impossible.  Also, I don't know how the system is constructed - but it seems that the shift simply runs a multi-position v alve that directs the fluid either clockwise or counter clockwise through the system - and that the impeller on the drive unit is tuned to operate in forward gear - and would sacrifice some in reverse. if the hoses were reversed, it would lead to poor forward speed.

            If anyone has thoughts on this, it'd be appreciated.

            john
          • JIM TEIPEN
            John, The hydraulic oil that I ve had since I serviced the hydraulics on my boat several years is ISO 32. I can t recall how I chose this particular oil, but
            Message 5 of 8 , Oct 1, 2013
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              John, 

              The hydraulic oil that I've had since I serviced the hydraulics on my boat several years is ISO 32.  I can't recall how I chose this particular oil, but it probably was on the advice of the hydraulic shop where I had some hose replacements made.   It's worked fine all this time.  

              Regarding the hose order, you are correct that the switch changes the direction of oil flow through the drive, thereby controlling the direction of the shaft rotation.   I was told by the hydraulics expert  that I could change from left to right hand rotation simply by reversing the two hoses on the shaft drive unit, I was fitting a new prop as well, so I had that option at the time.    In your case however, it seems like if the yard switched hoses somehow, the forward/reverse shifting would be the exact opposite of what you are experiencing. 

              Jim
              Alegria 
              CN 35-68


              To: campernicholson@yahoogroups.com
              From: gall.john.j@...
              Date: Tue, 1 Oct 2013 10:13:52 -0700
              Subject: [campernicholson] Hydraulic Drives

               
              I recently had some hoses replaced on the hydraulic drive - the two leading to/from the dennison unit.


              Now, I seem to have lost low end power in the system.  Before the replacement, the prop would immediately bite, and provide decent acceleration.  Well, some acceleration.  Now, the "bite" is gone, and it seems like the system takes a while to get to 5 knots - whereas before it would get there almost immediately.

              I've got the yard checking on the ISO on the fluid they used - I seem to recall that the system used to be run with an ISO 68 weight oil.

              Is it at all possible that they connected the hoses reversed as to how they should have been installed ?  I don't know, but presume different lengths of hose would almost make this impossible.  Also, I don't know how the system is constructed - but it seems that the shift simply runs a multi-position valve that directs the fluid either clockwise or counter clockwise through the system - and that the impeller on the drive unit is tuned to operate in forward gear - and would sacrifice some in reverse. if the hoses were reversed, it would lead to poor forward speed.

              If anyone has thoughts on this, it'd be appreciated.

              john

            • Albert Boyce
              John There is a pressure relief valve on the directional control valve near the hose connections. If you have a pressure gauge fitted in the system you can see
              Message 6 of 8 , Oct 1, 2013
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                John

                There is a pressure relief valve on the directional control valve near the hose connections. If you have a pressure gauge fitted in the system you can see when the pressure relief valve kicks in (sort of like a governor that protects the system from a dangerous pressure build up).  If the setting is too low the system will not develop the designed pressure which i think is about 2000 psi and there will be a consequent loss of power. Although its kind of difficult to change  the setting accidentally, It's possible that the pressure relief valve was accidentally set to a lower setting or was damaged so that it is tripping at a lower pressure than it should. You may want to try increasing the setting on the pressure relief valve.    Probably don't want to do that if you dont have a pressure gauge fitted in the system.  

                Albert Boyce 
                443 831 1860

                Sent from my iPhone 

                On Oct 1, 2013, at 2:02 PM, John Stothart <john.stothart@...> wrote:

                 

                Hi John,
                I have a diagram of the hydraulic system from my original Nich 35 Green Book but it's in Devon and I'm in Mallorca until Sunday. I will look it out when I get home.
                Regards,
                John



                On 1 Oct 2013, at 19:13, <gall.john.j@...> wrote:

                 

                I recently had some hoses replaced on the hydraulic drive - the two leading to/from the dennison unit.


                Now, I seem to have lost low end power in the system.  Before the replacement, the prop would immediately bite, and provide decent acceleration.  Well, some acceleration.  Now, the "bite" is gone, and it seems like the system takes a while to get to 5 knots - whereas before it would get there almost immediately.

                I've got the yard checking on the ISO on the fluid they used - I seem to recall that the system used to be run with an ISO 68 weight oil.

                Is it at all possible that they connected the hoses reversed as to how they should have been installed ?  I don't know, but presume different lengths of hose would almost make this impossible.  Also, I don't know how the system is constructed - but it seems that the shift simply runs a multi-position valve tha t directs the fluid either clockwise or counter clockwise through the system - and that the impeller on the drive unit is tuned to operate in forward gear - and would sacrifice some in reverse. if the hoses were reversed, it would lead to poor forward speed.

                If anyone has thoughts on this, it'd be appreciated.

                john

              • Graham Norbury
                John, Things to check:- - Were the right size hoses used? Too small a hose (or fitting) inside diameter will unduly restrict the flow and cause the relief
                Message 7 of 8 , Oct 1, 2013
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                  John,

                  Things to check:-
                  - Were the right size hoses used?  Too small a hose (or fitting) inside diameter will unduly restrict the flow and cause the relief valve to open prematurely.
                  - Is the filter blocked?
                  - Is there air stuck somewhere in the system?  Air cavitates at the pump and is compressible.  Both cause loss of driving force.
                  - Does the reservoir have sufficient fluid in it?
                  - Was the correct ISO viscosity fluid used?
                  - Is the relief valve partially stuck open?  Dislodged dirt can cause ball check valves not to reseat properly.

                  Good luck
                  Graham

                  On 10/1/2013 1:13 PM, gall.john.j@... wrote:
                   

                  I recently had some hoses replaced on the hydraulic drive - the two leading to/from the dennison unit.


                  Now, I seem to have lost low end power in the system.  Before the replacement, the prop would immediately bite, and provide decent acceleration.  Well, some acceleration.  Now, the "bite" is gone, and it seems like the system takes a while to get to 5 knots - whereas before it would get there almost immediately.

                  I've got the yard checking on the ISO on the fluid they used - I seem to recall that the system used to be run with an ISO 68 weight oil.

                  Is it at all possible that they connected the hoses reversed as to how they should have been installed ?  I don't know, but presume different lengths of hose would almost make this impossible.  Also, I don't know how the system is constructed - but it seems that the shift simply runs a multi-position valve that directs the fluid either clockwise or counter clockwise through the system - and that the impeller on the drive unit is tuned to operate in forward gear - and would sacrifice some in reverse. if the hoses were reversed, it would lead to poor forward speed.

                  If anyone has thoughts on this, it'd be appreciated.

                  john

                • bob lemmer
                  John We recently took out boat from Falmouth to Largs and, as luck would have it, after rounding Lands End we had very little wind and ended up motoring for 60
                  Message 8 of 8 , Oct 2, 2013
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                    John

                     

                    We recently took out boat from Falmouth to Largs and, as luck would have it, after rounding Lands End we had very little wind and ended up motoring for 60 out of the total 72 hours. As a result when we arrived at Largs our Hydraulic Tank was indicating that it needed a little top up. The manual indicated that the correct fluid was Shell Tellus 32. I contacted Shell who said that they had not made that for some years; after some research they came back and said the correct modern equivalent was Shell Tellus S2M68. Apparantly, the S2M bit is important because there is more than one variant of Tellus 68 and this is the marine version.

                     

                    The bad news is that it only comes in 20L drums at approx UKP 45.00 per drum.

                     

                    Hope this helps.

                     

                    Regards

                     

                    Bob Lemmer

                     

                    35/2

                     


                    From: campernicholson@yahoogroups.com [mailto:campernicholson@yahoogroups.com] On Behalf Of John Stothart
                    Sent: 01 October 2013 19:03
                    To: campernicholson@yahoogroups.com
                    Subject: Re: [campernicholson] Hydraulic Drives

                     

                     

                    Hi John,

                    I have a diagram of the hydraulic system from my original Nich 35 Green Book but it's in Devon and I'm in Mallorca until Sunday. I will look it out when I get home.

                    Regards,

                    John

                     


                    On 1 Oct 2013, at 19:13, <gall.john.j@...> wrote:

                     

                    I recently had some hoses replaced on the hydraulic drive - the two leading to/from the dennison unit.

                     

                    Now, I seem to have lost low end power in the system.  Before the replacement, the prop would immediately bite, and provide decent acceleration.  Well, some acceleration.  Now, the "bite" is gone, and it seems like the system takes a while to get to 5 knots - whereas before it would get there almost immediately.

                     

                    I've got the yard checking on the ISO on the fluid they used - I seem to recall that the system used to be run with an ISO 68 weight oil.

                     

                    Is it at all possible that they connected the hoses reversed as to how they should have been installed ?  I don't know, but presume different lengths of hose would almost make this impossible.  Also, I don't know how the system is constructed - but it seems that the shift simply runs a multi-position valve tha t directs the fluid either clockwise or counter clockwise through the system - and that the impeller on the drive unit is tuned to operate in forward gear - and would sacrifice some in reverse. if the hoses were reversed, it would lead to poor forward speed.

                     

                    If anyone has thoughts on this, it'd be appreciated.

                     

                    john

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