Hydraulic motors for dummys ?

[CompoSimmonite]

I have a design brewing (just in my head at present) for an off road mobility scooter that will tackle even large rocks. I'll be honest and admit it'll be a rip off of some aspect of the Swincar e-Spider
The e-Spider uses hub motors at each of the four corners. I'm thinking that hydraulic motors might be a suitable alternative for my design.
My knowledge of hydraulic motors is NIL so hopefully somebody might be able to either advise or shoot my idea down in flames

Torque will be a requirement - can such motors provide that ? Speed not important so walking pace adequate for clear sections and snails pace over rocks.
I'm assuming that a pump can be powered at a constant rpm so flow, and thus speed, can be regulated by valves. Is this right or am I thinking a load of rubbish ?
How do you compare hydraulic pump and motor power to electric ? ie say the design wanted 500 watts of electric at each wheel so do you need a similar hydraulic motor or does the flow rate / pressure dictate power ?

I'm sure I've got loads more questions so thanks for any advice, opinions, ridicule etc

This is the Swincar e-Spider that has given me the inspiration -
https://www.swincar.net/product-1.html

 

[winchman]

Hydraulic motors are very compact and can supply massive torque, I suspect cost and the power pack to run it may be an issue

 

[slim_boy_fat]

How about something along these lines? I'm not suggesting this particular one but link it just to give you an idea of what might be suitable for the purposes you outline. [I used to drive one of those machines ]

https://www.eastern-triangle.com/to...-3150-3250d-3100-3200-3050-greensmaster-mower

 

[8ob]

I have a design brewing (just in my head at present) for an off road mobility scooter that will tackle even large rocks. I'll be honest and admit it'll be a rip off of some aspect of the Swincar e-Spider
The e-Spider uses hub motors at each of the four corners. I'm thinking that hydraulic motors might be a suitable alternative for my design.
My knowledge of hydraulic motors is NIL so hopefully somebody might be able to either advise or shoot my idea down in flames

Torque will be a requirement - can such motors provide that ? Speed not important so walking pace adequate for clear sections and snails pace over rocks.
I'm assuming that a pump can be powered at a constant rpm so flow, and thus speed, can be regulated by valves. Is this right or am I thinking a load of rubbish ?
How do you compare hydraulic pump and motor power to electric ? ie say the design wanted 500 watts of electric at each wheel so do you need a similar hydraulic motor or does the flow rate / pressure dictate power ?

I'm sure I've got loads more questions so thanks for any advice, opinions, ridicule etc

This is the Swincar e-Spider that has given me the inspiration -
https://www.swincar.net/product-1.html

It’s not a good idea to throttle down or regulate pumped hydraulic flow or pressure to regulate speed, it just turns energy into wasted heat and in some circumstances cook or foam the oil. Better to size the drive motors correctly and use a variable output pump, basically it varies the flow but not the pressure so you can have a controlled slow start with maximum torque and increase speed with flow.

Hope this makes sense.

Bob

 

[knighty]

I think hydraulics will be too inefficient and kill your batteries?

you can get electric bike wheels with motors built into the hubs - you can get geared ones which are made for higher torque and lower speed, they might work well for you?

what kind of wheel size are you looking at? - a bike motor made for a 26inch wheel but fitted into a 13 inch wheel will be even more torky?

 

[pressbrake1]

It’s not a good idea to throttle down or regulate pumped hydraulic flow or pressure to regulate speed, it just turns energy into wasted heat and in some circumstances cook or foam the oil. Better to size the drive motors correctly and use a variable output pump, basically it varies the flow but not the pressure so you can have a controlled slow start with maximum torque and increase speed with flow.

Hope this makes sense.

Bob

And it stops oil starvation to the furthest pump/ under highest load

 

[500e]

Look under swash plate pump, "advantages", did a boat outdrive, constant speed motor & the pump to control speed.
Did a 26 ft sailing boat auxiliary motor once ! it was a learning curve & heavy-ish,
Primary drive motor ( single cyl Robin diesel), SW pump, pipe work, oil tank, filter, misc valve blocks then final drive motor, all for max 82% efficiency.
Final drive on the boat was a hyd motor enclosed in a teardrop waterproof housing with outrigger bearings driving the prop it worked well but not a paying job the reason to do it was throwing a Thirsty 80Lbs petrol outboard away so vapour risk gone & less weight cantilevered out over stern, the Robin would get across the channel with about 2gallons of fuel, the OB would have required 20\30+.
We took it to the South of France & used 3gallons for the trip there & back motored most of the way back from Aber Wrac'h to Falmouth due to no wind

 

[8ob]

I reckon a peerless hydraulic mower transaxle would tick a few boxes for the OP`s application , gives the variable hydraulic drive, gears and reverse, just need to spin the small pulley behind the fan with a leccy or petrol motor.

 

[500e]

Strange picture @8ob clicked to enlarge went to Escort agency tried a couple of times different results

 

[500e]

Went to enlarge pic, that took me to a machinery Co, clicked on a breakdown of a machine then this, had to run virus prog to get rid of adverts & possibly key logger

 

[knighty]

clicking it works fine for me, must be a problem your end?

 

[8ob]

Strange picture @8ob clicked to enlarge went to Escort agency tried a couple of times different results

Thats odd, pic was dragged and dropped from google images

Bob

 

[outofthefire]

Individually powered wheels using a hydraulic motor can be brilliant if you know the science (sadly i've never known enough). I've been watching them for years, I first saw them on Ian Drysdale's 2x2x2 motorbike in the 90's. Hydraulic motored vehicles excel offroad and you get shedloads more bang for your buck engine wise, the Swincar e-Spider is a great example, but I like this defender

my absolute favourite so far though is the green rock dawg

 

[sako243]

We looked into converting Dad's Argo to hydrostatic (off a petrol engine) and without investing in high efficiency pumps etc we were looking at about 50-75% efficiency which would be a killer for batteries if going that way.

If you're going battery powered then I'd stick with electric motors. If not then I'd be tempted to stick a generator unit on the back and still go electric motors. That way you'd be into the 90% efficiency area.

If that's a concern at all?