Hydraulic gear pump/motor as a steering pump?

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    Hydraulic gear pump/motor as a steering pump?

    Considering putting hydraulic steering on my boat and real marine hydraulic steering systems are ridiculously expensive for what they are. Units for 150hp+ non-power steering sterndrives are less common and even more expensive ($1000+). It's not a power steering system, just a helm pump and a cylinder at the tiller. I can't see any reason that a small displacement hydraulic motor or bi-directional gear pump wouldn't work at the helm, and a small steering cylinder at the tiller. Even buying new I'd be at less than half the cost of marine stuff and have heavier duty parts. The left over money could be used elsewhere, possibly add an autopilot (most require hydraulic steering)

    #2
    Originally posted by larboc View Post
    Considering putting hydraulic steering on my boat and real marine hydraulic steering systems are ridiculously expensive for what they are. Units for 150hp+ non-power steering sterndrives are less common and even more expensive ($1000+). It's not a power steering system, just a helm pump and a cylinder at the tiller. I can't see any reason that a small displacement hydraulic motor or bi-directional gear pump wouldn't work at the helm, and a small steering cylinder at the tiller. Even buying new I'd be at less than half the cost of marine stuff and have heavier duty parts. The left over money could be used elsewhere, possibly add an autopilot (most require hydraulic steering)
    I've had a couple wacky situations where I wanted to use a hydraulic motor and a hand wheel to drive a cylinder or another hydraulic motor. I never got around to building anything but I could never come up with a good reason it wouldn't work for human driven input speeds.
    Last edited by arse_sidewards; 05-27-2020, 08:41 AM.

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      #3
      When I was a GSE tech most of the ramp trucks and a lot of GSE in general had a hydro pump driven by the motor. I suspect high rpm may be an issue with cavitation or heat but it all worked great on The equipment we serviced.

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        #4
        Definitely possible, What kinda boat/motor?

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          #5
          Originally posted by crisbee1 View Post
          Definitely possible, What kinda boat/motor?
          22' fiberglass cabin cruiser, 188hp mercruiser. The hull likes to wander when trolling, not much keel to it, it's extremely sensitive to any play in the stern drive's steering. I put a new NFB rack and cable in which helped, but there is still enough play in the cable steering to make it a PITA to keep it going in a straight line.

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            #6
            what about using an ardupilot and a motor to give you automatic steering and course correction?
            Penguins can't fly, I can't fly, therefore I am a penguin.

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              #7
              Why not a power steering pump?

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                #8
                Originally posted by crisbee1 View Post
                Why not a power steering pump?
                Every PS pump I've taken apart looked to me like they would only work in one direction. I think the vanes are pressure balanced from the output so I think you'd only be able to turn one direction.

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                  #9
                  I must have missed why it needs to run backwards.

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                    #10
                    Originally posted by larboc View Post

                    Every PS pump I've taken apart looked to me like they would only work in one direction. I think the vanes are pressure balanced from the output so I think you'd only be able to turn one direction.
                    Nah thats why you use a rotary valve.

                    If thats your thought on ps pump the hydro pump is the same thing...they are the same thing.

                    Your looking for hydrostatic which is $$$ which uses a pump and a swash plate to change the direction...but not backwards...just out of a different port.

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                      #11
                      Originally posted by crisbee1 View Post
                      I must have missed why it needs to run backwards.
                      I think you missed that it isn't a power steering system, only a human powered steering wheel pump that connects to a cylinder. The only thing turning the pump is a steering wheel attached to the shaft.

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                        #12
                        Originally posted by A_G View Post

                        Nah thats why you use a rotary valve.

                        If thats your thought on ps pump the hydro pump is the same thing...they are the same thing.

                        Your looking for hydrostatic which is $$$ which uses a pump and a swash plate to change the direction...but not backwards...just out of a different port.
                        Not really, have you ever had the vane pump part of a saginaw p-pump apart? It relies on the output pressure to seal the vanes so if you went make a left hand turn, the fluid would just bypass the vanes. Simple bi-directional gear motor/pumps I've had apart done't care, but I'm not sure if the lobes would result in pulsing or dead spots in the wheel.

                        Hydrostatic pump wouldn't make any sense since it's all going to be hand powered.

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                          #13
                          so a 12volt column power steering motor out of a junkyard car would work. I had a 1992 22 ft Maxum sc, I didn't troll with it however at no wake speed and a little chop it wandered a lot.

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                            #14
                            https://www.youtube.com/watch?v=-nA6wo9PXls

                            Penguins can't fly, I can't fly, therefore I am a penguin.

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                              #15
                              Originally posted by larboc View Post

                              Not really, have you ever had the vane pump part of a saginaw p-pump apart? It relies on the output pressure to seal the vanes so if you went make a left hand turn, the fluid would just bypass the vanes. Simple bi-directional gear motor/pumps I've had apart done't care, but I'm not sure if the lobes would result in pulsing or dead spots in the wheel.

                              Hydrostatic pump wouldn't make any sense since it's all going to be hand powered.
                              Ok so wait are you talking about hooking up the pump to your steering wheel and providing pressure with your arms?



                              Thats way it reads to me

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