Hydrostatic ATV

[kdlklm]

Gotcha.

Keep in mind though that even 15 mph is going to be stretching it. In that Power Trac clip, they made it clear that they had no "attachments" available for it....such as a blade mount/three point/etc. Sounds (to me) like they made all the compromises they could in order for it to attain an "ATV-competitive" top speed, (and 14-16 mph isn't really competitive anyway), and sort of abandoned the notion that it's suitable for real work.

On another forum I frequent, one of the topics frequently discussed are issues with lawn and garden tractors. Breakdowns and lack of reliability are common discussions. The overwhelming majority of "issues" are experienced by the operators that are continuously asking too much of the machines. A good rule of thumb, is to consider what attachments the tractor manufacturer offers for a particular model. Lots of these guys buy a tractor and then build their own trailer, (that's too big), to pull around behind it, or they hook up to a large spike aerator, (and then add a bunch of weight to the tractor for traction), and try to drag it around. They can go right to the manufacturer's website or sales brochure and see that all that's listed for accessories for their model is a light-duty yard cart, and somehow that doesn't register.

In Power Trac's situation, I think the fact that they don't offer attachments is very telling. It certainly "looks like" it could be a real workhorse, but....

I definitely see your point, but I am looking at 10 to 15 hp more. Which should give me more torque at speeds of 15 mph, I also plan on having a high and low range. It's just a matter of figuring out which pumps and motors to accomplish what I want.

 

[kdlklm]

Search for the Ventrac series 300 they have done something also like you want.

that is the first time I've ever seen that machine, I like it. But it doesn't meet my needs. It's only rated for 400 pounds, which a power chair user is in the 600 pound range. And I also need to be able to use a joystick to drive. I don't think I'd want the motor in front of me like that. But it looks good.

 

[kdlklm]

I'm looking for some input on opinions about what would be the best articulating joint. I wanted to be able to go left and right but also be able to rotate. It needs to be as compact as possible and relatively maintenance free. There's many ways that it can be done but what do you think is the best.

 

[Iplayfarmer]

I'm looking for some input on opinions about what would be the best articulating joint. I wanted to be able to go left and right but also be able to rotate. It needs to be as compact as possible and relatively maintenance free. There's many ways that it can be done but what do you think is the best.

A simple U-joint would work if you were okay with up and down movement as well. You could do something as simple as a trailer ball and hitch.

If you want to exclude up and down movement, it complicates things; but only a bit.

 

[David Devuono]

You need to look at how the transfercase\transmission in a Unimog attaches to the front and rear axle. That joint (similiar to a Birfield Joint in Solid Axle Toyota and Suzuki Samurai. If it was not for the Panhard Rod on a Unimog Axle, it would move sideways as well as up and down. This joint is the only thing supporting fore and aft movement on the Unimog axles and contains the single U-Joint. Unlike normal vehicles that have two U-joints on a drive shaft. Anyway in this picture I am holding the outer socket that bolts to the transmission front output shaft, and you can see the ball that is part of the torque tube that locates the front axle. Lots of jeepers are trashing Unimogs just for the front portal axles and you might be surprised to find a cheap front torque tube in the USA. It I was you, I would take the easy route and just build a strong Joint for Left and Right steering and then Pivot the front axle like a farm tractor. That way you have steering and some articulation?

 

[evo803]

This is what I did to solve the problem. I have hydro axles that are belt driven so the centerline of pivoting had to incorporate a jackshaft for the drive belts. You need to be precise or else the belt length will change to much for a tensioner to compensate for when turning and twisting. My links were made from cat 1 toplinks.

 

[kdlklm]

here is a blueprint of what I've been working on. The unique circumstance this machine s that it can't have a front axle, because the front-end needs to be able to lower down. The machine is for a wheelchair user. I've got a close-up of the articulating joint, I'm not quite finished yet, I need to add something so that it can only rotate a certain amount. It goes left and right and allows the joint to rotate in the center.

 

[kdlklm]

I added a overhang plate, to allow the hitch the only rotate a certain amount. This should prevent it from rotating too much when turning on uneven ground. I plan on using 1.75 inch shaft pins so it should be plenty strong enough. It will take quite a lot of weight, a person in a power wheelchair is anywhere from 500 to 600 pounds. the steel plate is all quarter inch. And all the bearings are very heavy duty and large. The hydraulic ram mounts have to be added yet for the articulating steering. But I have to sort out the hydraulics yet.

 

[evo803]

Depending on weight distribution over the axles and the balance point will decide how much added stress will be on that center joint. There will be a significant amount of force and the front piece of that articulation joint that is u-shaped looks vulnerable. I would bend this out of 1/2" plate IMHO.

To limit rotation I would incorporate stops onto the rear portion of the pivot so it stops the u-shaped piece from rotating more than 10-15 degrees.

Could you post some more design photos?

 

[kdlklm]

those are good suggestions, and I incorporated it into the new photos. I added bolts to the top to make the rotation adjustable. I also beefed up some of the steel. Let me know what you think.

 

[kdlklm]

Here are a few update photos of the 3-D design. Subaru was kind enough to send me a full-blown 3-D model of their engine, perfectly to scale with every possible detail. The file is so huge my computer could barely open it. I couldn't find any 3-D files of engines in the 30 hp range, and none of the companies except Subaru were willing to send me a file. I don't think I'm planning on using a Subaru engine, but it is very close to the size that I'm looking for. I think I'm going to use a Kawasaki with a digital fuel injection.

I think I've decided to go without a front-end kneeling system. And just go with the foldout 48 inch ramp. It is about a 1 foot incline, which is a little bit steep but not too bad. I couldn't come up with an idea that I feel would be strong enough to have the front wheels move up and down to lower and raise the front-end. I would love to get some input if someone had a creative idea.

 

[Iplayfarmer]

I couldn't come up with an idea that I feel would be strong enough to have the front wheels move up and down to lower and raise the front-end. I would love to get some input if someone had a creative idea.

Build a swing arm that the wheels are attached to. Now have hydraulics raise and lower the "seat" inside the footprint of the swing arm.

They have skid loader trailers that the whole bed drops down to ground level. If that system can hold a skid loader, you should have no problem holding a mobility scooter or powered wheel chair.

 

[kdlklm]

That's a very interesting idea, i will have to look into that. It might be complex but interesting. would you happen to have any photos of an example, for exactly what you're talking about.

I found the following website which is good a good example of what I'm sure you're talking about.

http://www.lift-a-load.com/index.html

 

[Iplayfarmer]

That's a very interesting idea, i will have to look into that. It might be complex but interesting. would you happen to have any photos of an example, for exactly what you're talking about.

I found the following website which is good a good example of what I'm sure you're talking about.

Lift-a-Load Elevating Platform Trailers and Lo Riser Inclining Platform Trailers by The Advance Metalworking Co., Inc.

Those look like the skid steer trailers I've seen.

Here are some simple drawings of the swing arm concept I'm talking about...

 

[kdlklm]

I tried a little bit of a different approach, I wanted to incorporate the fold up ramp into a fully automated system, to reduce the amount hydraulics. The pieces for the foldout ramp are a little crude yet, but now that I've got the ratios right, I will start to incorporate better pieces. Does the system look strong enough, I used a thrust bearing between the mainframe at the wheel motor mount, there is 1.75 inch shaft holding it together. Let me know what you think.

 

[kdlklm]

It looks like I might have to go with a two pump configuration, for the hydraulic system. What is a typical set up, for running two pumps off one motor.

 

[aczlan]

It looks like I might have to go with a two pump configuration, for the hydraulic system. What is a typical set up, for running two pumps off one motor.

A double pump could work or a chain/belt driving two pumps.

Aaron Z

 

[kdlklm]

Essentially a double pump is just two pumps piggybacked. Is that correct.

 

[kdlklm]

I've also been considering changing my design to a similar machine as the photo attached. But I can't seem to find a track that will be long enough for my needs. I think one for a skid steer would be way overkill. My machine will be about 80 inches long. So the track would have to be very close to that. Because if I do go the track system, I will just have two tracks. It will help make the hydraulic systems less complicated.

All the ATV track systems are designed for the four-wheel system. Any suggestions.

 

[kubotakid USA]

I've also been considering changing my design to a similar machine as the photo attached. But I can't seem to find a track that will be long enough for my needs. I think one for a skid steer would be way overkill. My machine will be about 80 inches long. So the track would have to be very close to that. Because if I do go the track system, I will just have two tracks. It will help make the hydraulic systems less complicated.

All the ATV track systems are designed for the four-wheel system. Any suggestions.

kdlklm,.. I was surfing along and came across this post, I knew right away, we had talked over on hyd/pnu , Ive never shared and ideas with you, But have enjoyed reading this post, If you remember, I have three friends in wheel chairs, so, Iam Very intrested in building a prototype, and seeing these guys try it out! Iam leaning twards a zero turn chassie, It offers excellent mobility, and reasonably cheap to build, But Iam also looking at the 4x4, articulated, model that you posted a pic of, IMO, I would build it using (1) hydrostatic pump,..With 4 wheel motors, If you use a wheel motor with a (case drain) , you can run multipul motors, in series, and your speed will not change, The oil goes threw 1 motor,. then to the next, and so on, Very simple, You might need a flow valve or two, but I know It works and works good, as I have a small road grader set up this way, Than I would piggy back a small hyd pump for steering and hyd lift/attachments, Theres a real sharp guy over on hyd/pnumatics, kevinj, He might be able to help with the Pump/motor specs, :thumbsup: I love these kind of projects, and will help what i can, Eric