More torque for my Power trac?

[stray]

I started working on this set up before but at the time I didn稚 have much use for it. I recently have had a couple of jobs where I could have used more pulling power. Just a bit more torque would have made the difference. I know this set up will be controversial and could cause damage to wheel motors if (pushed too hard) but I知 willing to take that risk. If one is considering changing all four motors it wouldn稚 be much of a risk anyway. It will be nice to hear thoughts, comments and experiences of what flow, pump volume and pressure changes might take place. Wonder if it will help power or will the pump not have enough volume or the motor enough power to make a difference.
Four valve a few fittings and some hoses and it can be tried. In my case most of the time I would leave the PT in normal mode and in the few cases where I need that little more power I could switch the valves and use the torque mode. I have broken one wheel motor with the wheels reversed and going all out and then some to move a load of rock 3 times the weight of what I should have been moving. I still reverse the wheels at times but I am a little more careful.
Anyway comment and criticism welcome.

 

[stray]

Or maybe this Quick disconnect set up would take less room?????

 

[woodlandfarms]

First, I need you to help me lay out a schematic for my PT, You did a great job, I assume you are using something like a drawing program or do you have a special program with all the pictures for connectors?

So, are you adding another pump? or are you plumbing a T connector, like a second output, to each side of the pump?

I would think that the hoses to the motors, the hose size would have to be increased either way...

What about, instead of adding to the 4 wheels, you divert the flow from the rear to the front wheels. Meaning make the tractor 2 wheel drive for those extra special moments.

 

[MossRoad]

From what I see, in one position, two motors will be in series with each other and in the other position, two motors will be in parallel with each other? Is that correct?

If so, when in parallel and one motor encounters an obstacle, its mate will get all the flow. Conversely, if one motor is on ice and spins, it will get all the flow and its mate will get nothing. It could take all the flow from all 3 other motors, couldn't it?

 

[J_J]

You can not usually get something for nothing. So. if you want more torque, go with larger wheel motors like someone else did. I believe he said the torque improved, but the speed will decrease somewhat. You could go with smaller diameter tires, but stronger wheels. There again you will decrease speed, and gain torque. You will lose some height from the bottom of the PT to ground. The wheel motors are rated at so much HP. and that is what you have to work to with. As with all the PT's, more power means bigger engines, bigger tires, bigger pumps, etc. If you have the room, use a larger engine, and larger pump, and either get larger wheel motors, or perhaps a two speed wheel motor. If you look at hydraulic motors in the catalog, you will see if you go with more cu in, the speed of the motor will decrease. You might even get by with the same engine, and larger pump, but you can not use all; your hydraulics at the same time. You will run out of HP.

 

[SnowRidge]

From what I see, in one position, two motors will be in series with each other and in the other position, two motors will be in parallel with each other? Is that correct?

If so, when in parallel and one motor encounters an obstacle, its mate will get all the flow. Conversely, if one motor is on ice and spins, it will get all the flow and its mate will get nothing. It could take all the flow from all 3 other motors, couldn't it?

And that is the rub. The "limited slip' feature of the series connected motors is lost.

Still, it would be interesting to hook them up in parallel and see what happens.

 

[ponytug]

Wouldn't rather have a flow matching device, to ensure that F/R, and R/L all got equal volumes of fluid for your high torque/traction issues? Clearly, not a feature you want enabled at all times because you'd scuff the heck out of most surfaces, but it would be akin to locking a differential.

All the best,

Peter

 

[woodlandfarms]

Not that this makes a hill of beans, but on my 1850, A hose goes to the front wheel, and then a hose goes to the back wheel, and then a hose goes back to the pump. - Same on the other side. I am still trying to track down the relief hoses and where they all go to...

 

[MossRoad]

I also wonder if you locked the wheel motors together and tried to turn, what the side loads on the wheel motor shafts would be.

 

[SnowRidge]

Not that this makes a hill of beans, but on my 1850, A hose goes to the front wheel, and then a hose goes to the back wheel, and then a hose goes back to the pump. - Same on the other side. I am still trying to track down the relief hoses and where they all go to...

Case drains?

 

[J_J]

Not that this makes a hill of beans, but on my 1850, A hose goes to the front wheel, and then a hose goes to the back wheel, and then a hose goes back to the pump. - Same on the other side. I am still trying to track down the relief hoses and where they all go to...

Carl,

There are no relief hoses on the wheel motors. You have pressurized fluid going to the motors, and used fluid going back to the input of the pump. You maybe referring to the case drains on the wheel motors, as Snowridge mentioned. I believe all case drains go back to the pump case drain and then the fluid goes from the pump case drain to the cooler. Some of the wheel motors used on PT's do not have case drains. On my 1445, all the case drains are collected in a manifold and one line goes to the pump case.

 

[woodlandfarms]

yeah, sorry, case drains. I have been sketching out rough aproximations of what I think my hydraulics does as it looks like PT will never get me a schematic. I now have a the basics down, except for how the cooling system ties in.

 

[stray]

With the present or factory set up. If both right wheels or both left wheels were say off the ground the two wheels off the ground would just tend to spin and the pt would put little power to the ground. Actually both the right side and left are powered form the same port coming out of there hyd motor. The back wheels if in the air won't spin freely because each side are in a serious with its prospective front (fluid goes through one side motor then straight to the second on the same side).
Now with the set up I am purposing if the back wheels were off the ground then they would tend to spin losing power to the front. So while using this set up some traction needs to be on all four. This set up would be good carrying normal loads up steep hills going forward. If backing up a hill with a normal load I feel the back wheel s would tend to spin. Also this mode would not be for getting unstuck.
What I am looking for this to be is a cheap way to occasionally traverse up steep hills with normal loads. A usable lower gear as long as most of the traction will not be lost to any wheels. It won’t be a miracle cure to have a lower gear in all situations. If it were I guess Power trac would already be doing it.

 

[ponytug]

Since the PT has a variable volume pump, eanbling you to have high power at low pump volumes, I think that what you are asking for is better traction. Wouldn't chains be an easier solution?

All the best,
Peter

 

[J_J]

Does this make any sense?

If you put all motors in series, the motors will all run at the same speed w/ different torque - turning will be hard. If you put two motors in parallel, it will be like a differential - both motors will have the same torque, but different speeds. If you put the front two motors in parallel, and the back two as well, and then place both sets in series, you'll have the equiv. of a 4wd truck.

 

[SnowRidge]

On the 400 series machines, each side has the front and rear wheel motors in series. The two series coupled sides are in parallel.

It works well.

 

[stray]

Thats right Snowridge and maybe you can better explain about the slower speed setup. I don't know how else to explain it. Maybe just studying the drawing and thinking about the flows would help.

 

[stray]

Ok guys, first I want to thank you all for helping me work through this. It has helped me to come up with a cheap fix for the spinning of the rear wheels. I will place a fixed orifice in the places indicated in the drawing. (Size of the orifice yet to be determined). This will allow only a limited amount of fluid t o go to the rear wheels and leave the desired torque to the front. So now if either one or both of the rear wheels loose traction the front would still pull. A pipe coupling just after the quick disconnect with a setscrew threaded into it will be very cheap and effective. I can then drill different size holes in the set screws until the best size orifice is found. Because hoses for the normal speed will not be used when operating in the original set up the orifices will not be a factor then. Now thoughts on this but please study the drawing. Come on guys it is a little work but I feel were getting close to coming up with a cheap fix for the PT痴 hill climbing ability. (Lack of that is)
Possibly later on, if this works well, then one could replace the disconnects with solenoid valves and switch back and forth at ones leisure. How about that? Doesn稚 anyone else think that would be useful or am I the only one who has had climbing issues?

 

[woodlandfarms]

First, Stray, how do you make these diagrams? Just photoshop or do you have a dedicated program?

I have many questions about what you are doing, but am so uneducated about Hydrualics I am going to stay out. The only thing I wonder is are you going to increase the heat you have by restricting the oil flow?

 

[KentT]

Stray,

I've been intruiged (sp?) by this idea since you first posted your thoughts about a "two speed" system by using valves to switch between serial and parallel plumbing circuits. I certainly had hill climbing issues, but ended up replacing all the wheel motors with larger displacement ones...

In fact, I was ready to try your earlier design -- until I researched the White RS 200 series wheel motors (used on the old 425s and 422s) a bit more. They're simply not designed to handle doubling the pressure, which is what would theoretically happen by changing the circuit to increase the torque.

They're only rated for 2250 PSI, peak, and itermittent at 1750 PSI. I'm afraid that that the first time you put a heavy load on the wheel motors that you'd blow the seals when the pressure rose above the 2250 PSI peak rating...

Model 200
Displacement CC [cu in] 205 [12.5]
Max Speed RPM Cont 300
Max Speed RPM Inter 370
Max Flow lpm [gal/min] Cont 61 [16]
Max Flow lpm [gal/min] Inter 76 [20]
Max Torque Nm [lb-in] Cont 297 [2640]
Max Torque Nm [lb-in] Inter 345 [3050]
Max Pressure bar [psi] Cont 103 [1500]
Max Pressure bar [psi Inter 121 [1750]
Max Pressure bar [psi Peak 155 [2250]

http://whitedriveproducts.com/pdf/catalog/2008/RScatalog.pdf