It's a 1.6 L. 1981 non turbo. I had read that they make 52 HP but I can't remember what rpm it is.

I agree on not being able to hit 20 mph from a dead stop with a load. I thank that a fellow could get good enough to shift on the fly. Although mabey not.

You can shift a sychro transmission without the clutch if you back off the gas so the engine speed is close to where you need for the next gear. I never managed to get it to work down shifting. A hydraulic motor is more fixed in it's speed than a gas engine. The hydraulics doesn't have a flywheel or coast down in speed when you throttle back. It goes to the new speed when you adjust the flow control and it stays there not wanting to drift faster or slower.

You could make a lot of expensive sounds trying to shift.

My tracked dumper is hydrostatic, essentially what you are trying to do, but it has a variable displacement pump, which is more efficient. It has a two speed gearbox where you stop it to shift gears and start again in the next gear. The hydrostatic drive can control from zero to full speed in either gear. Flat out in high gear is about 4 mph. The 10 hp diesel has to be at full throttle pretty much all the time for it to move. Maybe 3/4 throttle if it is empty but it bogs a bit. Loaded GVW is about 4000 pounds. With a full load it is at it's limit climbing my driveway.

If you run your 1.6l diesel at full rpm (which you can't continuously) so you have 52 hp, then you have 5 times the power of my dumper. You hope to go 5 times faster and move at least twice the weight and you have a less efficient hydrostatic drive.

You would get more useable power from the engine with a conventional drive system with a clutch, (that's way they build them that way) and it would be much more driveable because you have a clutch. You still may need more horsepower.

The calculations are complex so the easiest thing is to compare with other similar vehicles, like I did with the dumper.

You need to figure out how much your machine is going to weigh, both empty and full.

Chris

For the simplicity of the machine I would love to say with a clutch.

But this engine's factory clutch is total different setup than a normal clutch.

I have to agree with cj...I have an email that I will try to share here about hydraulic efficiency.
Hello again Michael,

Do you know when NOT to use hydraulics?

As a fluid power consultant advising clients
in a diverse range of industries, it's an issue
I deal with a lot.

One recent client, the designer of a three-wheeled vehicle,
approached me to design a hydraulic drive. He wanted
to power at least two-wheels, ideally three.

To keep cost to a minimum, the machine designer
asked me to consider gear pumps and motors.
A gear pump or motor in good condition is 85 percent
efficient.

So a gear pump driving a gear motor has a best-case
efficiency of 0.85 x 0.85 = 0.72. That's 72 percent -
not considering losses through valves and conductors.

But say a gear-type flow divider was included to achieve
multi-wheel drive. The theoretical efficiency would now
be 0.85 x 0.85 x 0.85 = 0.61. That's 61 percent,
not including losses through valves and conductors.

Compare this with a chain drive in good condition,
which is 97 to 98 percent efficient. This explains
why you don't see any hydraulic bicycles around!

In this application where the available input power
was limited by space and weight, the question I had
to ask my client was: Can you afford to lose
40 to 50 percent of available input power to heat?

In his case, the answer was no.

Contrast this example with another client for whom
I'm advising on the design of a 6,000 ton press.
Regardless of efficiency, hydraulic power transmission
is really his only option.

But this is also a relatively efficient use of hydraulics.
One of the reasons for this is the efficiency of a
hydraulic cylinder approaches 100 percent.

And because it's a high-pressure application, piston pumps
are essential. The overall efficiency of an axial
piston pump in good condition is 92 percent. So the
theoretical efficiency of the press hydraulic circuit
is 0.92 x 1.00 = 0.92 or 92 percent - not including losses
through valves and conductors.

A significant, 'built-in' inefficiency in this application
however, is the compressibility of the hydraulic fluid -
the subject of your next hydraulics email in few days time.

Yours for better hydraulics knowledge,

Brendan Casey
Author of 'Insider Secrets to Hydraulics';
'Preventing Hydraulic Failures' and
'Advanced Hydraulic Control'.
http://www.hydraulicsupermarket.com/books.html
=======================================

Well I guess I don't no what to do now.

Ya'll say not to use a hydraulic drive so now what do I do?

I can't use a factory vw clutch?

Guess I need to do some thanking.

I don't mean to say to not use hydraulic drive.....I think we just want you to be aware of possible limitations. With a hydraulic motor turning the transmission I think it would be as Cj said, quite difficult to shift as you're mobile. That being said, it likely won't have the power to start from a standstill in top gear...empty maybe, I can't say for sure.
Not at all trying to shoot down any ideas, trying to help so you end up with a project you are happy with.
Couple questions, do you have the VW clutch assembly? bell housing and or transmission? Is there any chance of using a VW tranny in front of the one you have (I realize from the pics that they don't currently line up)
Another thought, it would be a bit of work maybe but how about if you had a clutch assembly that fit's your existing tranny and drive that with a hydraulic motor.
You could also go with your original thoughts and maybe sacrifice the higher speed. There is no doubt that you can make this thing have lots of torque, it's just getting any speed out of it.
Hope some of this helps.

maybe you could us a centrifugal clutch to let you shaft.

Lincoln, I no everyone is tryin to help and I REALLY appriciate everyone's help.

I have the vw clutch still. I cut the tranny up cause I though I could use the main shaft and chain drive down to a jack shaft going to the 3 speed tranny.

I would rather use the hydraulic drive. I believe in my mind that it would be a good setup.

Would a piston pump like this work?

http://www.surpluscenter.com/item.asp?item=9-8239-L&catname=hydraulic

And this motor?

http://www.surpluscenter.com/item.asp?item=9-9425&catname=hydraulic

Hey Dustin,

If you put that pump and motor together the pump will be able to take 18.6 horsepower (intermitant, even less for continuous) and you will get about 12.1 horsepower out of the pump (intermitant, not continuous). If you had a bigger pump you could get up to 16 horsepower out of the motor. I used an online calculator for this and it was set for 65% efficiency for the motor. You might get slightly higher efficiency but by the time you consider piping losses it is probably good to stay with the 65% factor. If you got 85% you still couldn't drive your machine. Also, that motor can only give you 800 rpm going into the input of the transmission. Just guessing at numbers, if it was a car with a 4 cylinder engine it would probably turn the input shaft at 3000 rpm for 60 mph in high gear (on the highway) That means about 15 mph with 750 rpm going in. Your reasults would vary depending on tire size and rear end gear ratio's. Do all those rear ends you've got have the same gear ratio?

I imagine you are finding this discouraging at this point but it is really the way to build something. Fiqure it out right to the end first. Then start building. Otherwise you risk having an expensive problem further down the road.

Chris

Hey Dustin,

Here is a link for calculating power for a vehicle

power for vehicle

Chris

Lots of cool projects that I miss by not coming by more often. I'm interested in how the Rabbit motor works out for you. I have one in a car (with 500k km on it) that I got that I'm keeping in "inventory" for the right project.

On the hydraulic drive, it seems that it shines when you need to convenience or control. There's a reason why the "hydrostatic" drive is the norm, the variable displacement pump coupled to the motor is the simplest and lowest loss. The VD pump gives you speed and direction control with no other valves, so although the pumps seem more expensive at the outset, I suspect that if you add up the costs of all the eliminated valves and hoses they become a lot more cost effective.

I'm still waiting (unless I missed it too) for Matt to get his MatTrac going with the VD pump. Will give some great real world experience on projects of this size.

My suggestion is that if you go with hydraulic drive, get a good big VD pump. You can always throttle it down (reduce the flow) if the motor starts to bog, something that can't be done with a fixed pump. That's the way I plan to go when/if/whenever I get a project on the go.

Looking forward to seeing more.

cheers,
Andrew

I would love nothing more than to have a variable displacement pump. However the only ones that I have found are either way to small or way to expensive.

How about a combine hydrostatic pump? Sunstrand 23 or Eaton 48

Some swathers used 2 hydrostatic drives, one on each front wheel.

There is an old combine junk yard within 30 miles from my house. I'll have to check them out in the next couple of weeks.

F350ca, I no this is gonna be a dumb question, but what's a swather?

Guess its a self propelled mower with a pickup head that brings the crop into a swath or row for the combine to pick up or in the case of hay to bail. Not a farmer but from what I understand if you cut the crop before its totally dry and leave it in the swath it will dry before combining or bailing. If the crop is dry you can straight combine where you cut and combine in one operation.
The swathers operate with two driven wheels at the front and a castor or castor wheels at the back. To steer them you vary the speed of the driving wheels with respect to each other, like a zero turn mower. Some used variable pulleys to regulate speed but some used two hydrostatic transmissions. Nice compact units, input shaft and output shaft on the same axis with a lever controlling the output speed and direction.
http://www.eaton.com/Eaton/ProductsServices/ProductsbyCategory/Hydraulics/Transmissions/PCT_261208

Some hydro pumps turn the wrong way for coupling to the back of an engine. I am not sure which combine to tell you to look at.
Red, yellow, some green used the same pumps. (pretty close?) Maybe, 1640 or 1660 IH TR70 or TR75 NH.
I haven't asked how much a hydro system costs but I was behind a guy at the salvage yard that asked and was told $500 for pump and motor. I got a new Eaton hydro pump from ebay for $250 but that was a nickle on the dollar deal.

I looked at a hydostatic pump on surplus centers website. According to Cjmac they wouldn't be nearly enough for what I want to do.

E718. I'm glad you gave me a couple of model numbers. Now I can tell the junk yard about what I'm lookin for.

Well I just got done weighing this chunky gal and if I did it right she weighs in at around 2500 lbs.

I used scales for a go kart that hat 4 seprate pads. I assume I just add all 6 wheels together.