hydraulic steering questions

[Jsta_Rebel]

Originally Posted by Dave852

Maybe the op does not have a pump at all but one of those bolt on the wheel type autopilots?

Bingo.. and here's where the problem lies. Two incompatible systems.

[Celestialsailor]

My Hallberg Rassy came with an older style Vetus helm pump. I could not find specs or prints on it. I replaced it with a new style Vetus pump of a totally different design. That was a pain. In hindsight, I should have dug into the old pump as I found later, one of the check valves was without a retaining spring. That pump had 3/4 of a turn before the rudder moved. Not good and I'm not sure the spring was the problem.
But I can tell you, both the old and new pump had what id called creep. In other words, you go hard over (ram full extended) and with moderate pressure the wheel would move very slowly. The steel ball valve held against the steel seat by the steel spring, is not a perfect seal. Tiny amounts of hydraulic fluid can and will bypass. This is why most if not all Windvane manufacturers recommend a separate windvane with it'sown rudder like the Hydravane. I have worked around this problem on my boat with a tiller and wheel. The tiller being directly on the rudder post. I use a hydraulic bypass valve to accomplish this. My electronis autopilot is an Autohelm 3000 MkII. It works fine uo to a point of sea state.
You have the EV system which I think is a separate electric pump. I'm wondering if you need check valves in the system to stop feedback to the helm pump?

[tkeithlu]

Does your pump have pressure relief bypass valves on it?

[lucseawalker]

Right now I have no autopilot electric hydraulic pump at all ... but might put one after I solve the steering system ...
First I have to find out for sure if it is the pump or the cylinder that causes the possible turning after maximum HO and what I read so far seem to indicate it is the pump ...
On the schematic I have of the pump, it is hard to see if there is a pressure relief valve ... I hope I can speak with someone at Vetus tomorrow to find out .. if it is, I worry for nothing ... it was designed so all along. Perhaps I can then somehow, set that pressure a little higher ???

[lucseawalker]

I just called Vetus in Holland and spoke with a technician who indicated that when the helm is HO .. if more than 60 Bar of force is applied, then the relief valves in the pump will protect the system by circulating the oil inside the pump. That is a crucial info to know I will now test pump and cylinder individually, then put everything back on our boat with brand new AW 32 hydraulic oil I was very lucky to find in the small town today and then see how it all goes ... Will the helm offer enough resistance when turned HO or will it continue to turn too easily. If the latter was the case, apparently there is not much to be able to do to repair the pump ... so I will have to replace the pump then ... I will keep you posted ... I just called Vetus in Holland and spoke with a technician who indicated that when the helm is HO .. if more than 60 Bar of force is applied, then the relief valves in the pump will protect the system by circulating the oil inside the pump. That is a crucial info to know I will now test pump and cylinder individually, then put everything back on our boat with brand new AW 32 hydraulic oil I was very lucky to find in the small town today and then see how it all goes ... Will the helm offer enough resistance when turned HO or will it continue to turn too easily. If the latter was the case, apparently there is not much to be able to do to repair the pump ... so I will have to replace the pump then ... I will keep you posted ...

[DeepFrz]

Maybe all the pump needs is a new ball and spring. Possibly the ball seat if that's replaceable.

[Celestialsailor]

Usually the ball seat is machined into the pump body itself. You must be thinking when they use to Engineer and manufacture items that were replaceable. that might have been 40 years ago though.

[lucseawalker]

We finished testing pump and cylinder today with another pump & cylinder on a friend's boat and we discovered that my cylinder (1980!) is doing very well but my problem is the pump. The relief valve must open at very low pressure.
So I will buy another pump, a bigger one that will give me less than 3 turns HO to HO so my autopilot will be happy with it and both my problems will be solved. I just dread the fitting of the new pump (from a different manufacturer since Vetus has no pumps big enough anyway) as far as connections and housing size ...

If I did not have the issue with my autopilot, I might try to see if i could fix the pump relief valve issue but since a new bigger pump will also solve my autopilot compatibility issue, I will go that route!

Thanks everyone for your ideas ... I will return in a few weeks after I get the pump shipped to me here in the Philippines and have finished installing it ... hopefully with a very good ending!

[lucseawalker]

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 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

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 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

[DeepFrz]

It would be so easy to replace the balls and springs and rebuild the pump and then try it out and see if your autopilot works. I think your autopilot may be struggling because of the leaking valve.

that might have been 40 years ago though.

Yep, seems like only yesterday.

[tkeithlu]

Skipping over a bunch of technical stuff to get back to your pump relief valve opening too easily. From very messy experience (I hate taking a bath in hydraulic oil) I can tell you that the tiniest bit of trash between the ball and its seat can rob you of your steering. Do clean the system and reload with clean oil before you dump what might be a perfectly good pump.