Hydrostatic Diesel Utility Scooter

[Andi]

Sorry to disappoint no such animal yet, but I'm considering it. I've build a few custom all aluminum utility trailers as well as customized some tools and equipment. I've always thought my next step should be to build a motorized vehicle. Since I worked with a lot of diesel powered hydraulic equipment, I have come to the conclusion that a hydrostatic vehicle would be kind of cool, combining that with my new passion I think it has to be a scooter.

I have enough aluminum U-channel for the frame and to give it that utility look I thought to use checker plate sheeting for the skirt and rear side panels. Definitely has to have a flat floor, with the fuel tank in the floor and partially up the inside of the front skirt, maybe even a small recess area in the floor/fuel tank for the battery. I worked out a front and rear swing arm kind of suspension using a single airbag and shock absorber each. The hydraulic oil reservoir will be in part of the upper frame, by encasing the U-channel.

At the heart of it I'm going to use a YANMAR L100AE air cooled diesel
providing a continuous output rating of 9 hp at 3600 rpm, which I will likely match up with a White KP 101 series hydrostatic pump, 0.62 cu in/rev (10 cc/rev) and 1425 psi max continous.

I have researched the hydraulic formulas, but am by no means an expert in design, so I was hoping for some help with matching up the hydraulics. I think the pump is a good match for the engine power and speed but I'm struggling a bit to find a suitable wheel motor. I require a shaft speed of around 1500 rpm and with the White pump I can only go up to 1425 psi continuous. I've looked at the Sauer Danfoss OMP Series 25, 32 and 40; the Van Ruden vane motor model 10 or the Anchor Lamina model A-27 or A-32, but will likely have to add a bearing support with the motor mount at the output shaft on the swing arm, to be able to handle the side load.

By no means a first, but I think interesting nonetheless. I have read of quite a few diesel motorcycles often with a CVT or gearbox using the same or similar engine some even running on Biodiesel. There even already is a Hydrostatic Motorcyle out in Minnesota, following is a link if anybody is interested: www.hydraulicinnovations.com/

What do you think? Any help would be appreciated?

Andi

[Aaron]

This is really cool Andi... Riker140 and I are discussing a compressed air powered scoot currently. Dave Riker is an honest to god engineer with 78 years of life experience.. I know he could help some. He drops equations and formulas on me that make my janitors mind really hurt. His spelling is awful (so is mine) but we chat every evening I'll ask Dave tomorrow what he thinks.

[Andi]

That would be awesome, I'm trying to understand the relationship between pressure and flow a bit better, what happens under load, going up a steep incline or moving with heavy cargo. I know speed is flow and torque is pressure and I also understand that the output hp of the engine will be the same hp at the rear wheel shaft of the motor, minus any inefficiencies in between the system. As there is no physical gear ratio, how do you get enough force to start moving and at the same time enough top speed without shifting gears? Its obviously possible, but I don't quite understand how the oil flow and available pressure provide the wheel motor with enough force to move from a stand still to a potential say 60 mph, what do I have to look for in a motor? Also what happens to the wheel motor if oil flow is reduced drastically, by slowing the rpm of the diesel engine and zeroing the angle of the swash plate on the pump.

I guess I would have to have some bypass system in between the pump and motor that allows free wheeling, by maybe simply allowing the motor to get a supply of oil from the reservoir tank and returning it back to the same tank, sort of like pulling the clutch lever on a geared motorcycle.

Many questions I know.

Andi

Andi

[Andi]

Btw, I have read something about a compressed air hybrid vehicle out of France and I think there also was an India and Italy joint venture, where basically a little van was outfitted with an air motor where the engine would have been and it simply had a large tank to hold extremely high air pressure. I think they had enough air for an average of about 200 km (120 miles) travel distance on the test vehicle. Sounds interesting.

Andi

[earlwb]

That would be really neat to build that.
Go for it. it would look good.
I have thought about building a Cushman like scooter using a vertical diesel industrial engine too.
Maybe one of these days I'll get the time to do it.

[natefromogden]

Ok, somebody hit me with a clue bat. I understand that hydraulic drive is good for heavy equipment and moving heavy loads at low speeds but what would be the advantage for a 2-wheeled vehicle? Particularly since we are seeing the implementation of fairly high-tech variators, (ie. Burgmans) that are still relatively light and simple and maintenance free except for belt replacement every couple years.

My neighbor uses a riding mower with hydro drive andd even from 2 houses away I can hear the drive running over the engine sounds. Why would that be a benefit on a scooter or motorcycle?

[earlwb]

Because it is there. Because it can be done. Because it would be fun to do it. Because one can do it. Cost doesn't really have anything to do with it.
Basically it is a hydraulic version of a CVT unit.

[Deleted]

All the hydraulic drive motors I've seen are variable displacement (tilting plate type). That's what allows changes in "ratio" and also allows idling.

Cool thing about this is that you could also easily have a reverse gear. ;D

[Andi]

earlwb said:

Because it is there. Because it can be done. Because it would be fun to do it. Because one can do it. Cost doesn't really have anything to do with it.
Basically it is a hydraulic version of a CVT unit.

Thanks earlwb, I couldn't have put it better myself.

Its mans never ending quest to do something different out of the ordinary, learn something in the process, maybe make it better and perhaps even come up with the latest revolutionary idea. Now don't get me wrong I'm not aiming for the last part and my idea is not new, in fact it has recently gotten some attention as an option for hybrid vehicle technology using regenerative braking technology and with very favorable results, but it would be fun to do and certainly beats sitting on the couch watching TV ...... at least in my book.

Andi