Well that's not nearly as much fun.
Since to purpose of this barge is to transport the electric car from one island to another for grocery shopping I'm set on using it for the power source.
Hydraulic motor sizing - weird project
- Thread starter cmaas
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Well that's not nearly as much fun.
Since to purpose of this barge is to transport the electric car from one island to another for grocery shopping I'm set on using it for the power source.
MossRoad
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MossRoad
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:thumbsup:
Good point. I hope to stay on the gravel or pavement. In theory the casters don't need any weight on them though. The drive wheels are doing all the steering. Of course I don't want this thing doing a nose dive going down hill so there will be enough weight on the casters to avoid that, I hope.
There are a lot of ways to skin this cat for sure.
Two things to keep in mind: The wheels need to retract out of the water so I'm not dragging them around; If I don't steer with the separate motors on the drive wheels I'd need to set the rear wheels up to steer. That can be done - like tie them to the sterndrive - but it is a new element to deal with.
Good point about the traction. I will have the torque - otherwise I'm not going anywhere - so I figure it's a matter of choosing the right tires and weight distribution.
MossRoad
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You could use the front steering axle off of a 4wd pickup or Jeep and power that with 1 reversible hydraulic motor.
Then you'd only need to power 1 variable volume hydraulic pump to provide infinite speed control in both forward and reverse to that reversible motor on the steering axle.
You power that VVpump with the spinning rollers from the drive wheels of the electric car set at a specific speed and cruise control set.
That takes care of your ground drive and steering.
If you want to go with one hydraulic motor on each drive wheel instead of the above mentioned, then you'd have to figure out how to steer them. You could do either two VVP's, one for each motor, or some valving arrangement.
Either way, the pumps and motors to provide that kind of torque and power will be expensive if you can't salvage them from something else.
With a hydraulic motor, you could power a manual transmission and get gear reduction to a differential.
Man, there's all kinds of what if's in how you could go at it! :laughing:
Anyhow, good luck with your project. Sounds fun. :thumbsup:
Then you'd only need to power 1 variable volume hydraulic pump to provide infinite speed control in both forward and reverse to that reversible motor on the steering axle.
You power that VVpump with the spinning rollers from the drive wheels of the electric car set at a specific speed and cruise control set.
That takes care of your ground drive and steering.
If you want to go with one hydraulic motor on each drive wheel instead of the above mentioned, then you'd have to figure out how to steer them. You could do either two VVP's, one for each motor, or some valving arrangement.
Either way, the pumps and motors to provide that kind of torque and power will be expensive if you can't salvage them from something else.
With a hydraulic motor, you could power a manual transmission and get gear reduction to a differential.
Man, there's all kinds of what if's in how you could go at it! :laughing:
Anyhow, good luck with your project. Sounds fun. :thumbsup:
oldnslo
Super Member
Cmaas,
On the counterbalance question. Each motor will require two one on each work port. These valves free flow in indirection and are piloted open in the other or restrict flow when pilot signal is lost. I.e. going down hill.
On your design I presume the tires and motor will be under water especially when launching and landing. Will they also be in the water while traveling on the water? Is this salt water or fresh water. Not to beat a horse to death but you might want to check into the rules on hydraulics used in submersible applications in your area for any special requirements on oils, seal requirements, etc.
If using open loop system yes you can run multiple functions off one pump. If running full speed majority of the time a simple fixed displacement pump is the most economical. If running at slower speeds or doing turns on a frequent basis a variable volume load sense pump would create the least amount of heat and waste the least energy.
110 percent agree on the devil is in the details and if you size something incorrectly or miscalculate traction could be an expensive learning curve. Any good reputable hydraulic shops in your area the tspecialize in mobile equipment? They could potentially provide some ideas for you also.
On the counterbalance question. Each motor will require two one on each work port. These valves free flow in indirection and are piloted open in the other or restrict flow when pilot signal is lost. I.e. going down hill.
On your design I presume the tires and motor will be under water especially when launching and landing. Will they also be in the water while traveling on the water? Is this salt water or fresh water. Not to beat a horse to death but you might want to check into the rules on hydraulics used in submersible applications in your area for any special requirements on oils, seal requirements, etc.
If using open loop system yes you can run multiple functions off one pump. If running full speed majority of the time a simple fixed displacement pump is the most economical. If running at slower speeds or doing turns on a frequent basis a variable volume load sense pump would create the least amount of heat and waste the least energy.
110 percent agree on the devil is in the details and if you size something incorrectly or miscalculate traction could be an expensive learning curve. Any good reputable hydraulic shops in your area the tspecialize in mobile equipment? They could potentially provide some ideas for you also.
4570Man
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You really wouldn’t even need the transmission or clutch. The car already has those functions. If the rollers the car sits on were direct drive to the raft wheels it would be simple and work fine.
Thanks again. I really appreciate your giving this some thought.
The tires and wheels are under salt water when launching/retrieving. Otherwise they are on pivoting legs that retract. Except for the high pressure this is the same as outboards and sterndrives relying on seals to keep the oil out of the water, and vice versa, but I take your point and will check into it. Metal corrosion is a constant battle in this environment. I try to keep trailers outboards etc. rinsed off but steel components can have a very limited life here. Even galvanized.
I've got the name of a hydraulic shop in Seattle that does a lot of work on commercial fish boats. I need to find a knowledgeable place for mobile equipment but there's not a lot of ag stuff in this area. I wanted to get some basic knowledge (which you are helping to give me) before I contacted a hydraulics shop. Didn't want to sound like a complete idiot!
Re. traction, weight etc. A lot of what I can do to work on this design is learned empirically. Like mimicking the load weight and traction using my little tractor in 2wd towing a loaded trailer on the 23% hill that my amphibious barge needs to climb. I can compare that to the torque and speed numbers my engineering student calculates and see how the real matches the theoretical.
I may end up putting bigger tires on the drive wheels and will definitely make them as wide as I can get. But bigger diameter means more torque needed at the wheel. Other comments on this post are making me think I should increase the weight those drive wheels carry by moving the wheels back some to carry more load.
I couldn't figure out a way to make those drive wheels (1) on a differential that I could retract out of the water (2) keep that diff, and the cv joints it would need, from rotting in the salt water, (3) Connect a direct drive to those wheels and the sterndrive (propeller) that moves the barge.
I figured that since I need hydraulic cylinders to lift wheels and ramps anyway I might as well size it up to run a couple of motors.
Earlier design ideas had direct chain drive but that meant only one drive wheel which I'm pretty sure won't get me up the hill.
It's all a matter of trade offs and compromises. In the end I just hope to have something that works okay, doesn't take forever to build and doesn't cost more that three times what I estimate.
