Another Motorgrader

[DRohacek]

I'm thinking of welding a bung into the bottom of the rear cover to draw oil from to the pump mounted behind the rear hydro sending it to a 5 spool valve and returning it through the oil cooler then into the top of the trans through the top cover.

[DRohacek]

https://www.vevor.com/products/5-spo...xoC6rUQAvD_BwE

[sawdustdad]

Originally Posted by DRohacek

I'm thinking of welding a bung into the bottom of the rear cover to draw oil from to the pump mounted behind the rear hydro sending it to a 5 spool valve and returning it through the oil cooler then into the top of the trans through the top cover.

That's a good idea. I installed bulkhead fittings into the axle cover--pump suction (with a dip tube on the underside), relief valve return and motor return. Your valve has an integral relief valve, so you'll only need one return. Perhaps a fill port as well. You'll need a return for the front axle drive pump, too, I guess. And maybe a relief valve for that, too. Depends on what you set up is.

I have 5 hydraulic functions--left and right blade height, blade skew, blade angle and blade locking pin. I have a 2 twin spool valves for the first four functions, and I use the tractor's original lift spool valve for the locking pin cylinder. I've thought about needing another for a ripper, but I've run out of spools, so I'd have to add another.

I only mention this to point out the need to determine ahead of time all the various functions you need and to plan ahead with spool valve capacity.

I wish I had considered a float function. Right now, blade position is fixed by the cylinders. It would be nice, in some situations, to let the blade just float and follow the terrain. Or, as with many front end loaders, the joystick has a float position that puts some moderate down force but allows the bucket to follow the terrain. That would be a nice feature if you could manage it. There are some joystick (for FEL) that have float, don't know about the multiple spool type that you posted.

[Ambush]

You fellas have access to some very affordable hydraulic components. And like sawdustdad said, these are toys, not production machines.

Definitely a float valve would be an asset on the blade height cylinders. I could be wrong, but I believe you could add one after the tractor's original valve.

Just operating the cylinders on the grader won't cause much heat. A bigger issue with using the axle housing as the reservoir would be, IMO, the fluctuation in fluid level. You've got several cylinders in the system and each one has a volume differential between the two sides. Depending on rod diameter the difference can be quite substantial. The difference between having all (or most) cylinders extended or retracted at the same time would be fairly extreme in the small axle reservoir. There would be times of underfill and times of over fill.

To hydraulic drive the front would absolutely require a separate pump, motor and reservoir. And would be near impossible to synchronize.

If I was intent on having a front drive, I'd change the rear drives over as well. I'd remove the hydro drives. Take two salvage motor shaft/pinions and mount a motor to each. Drive those motors through a three port flow divider with a separate pump direct mounted to the engine. Figure the difference in the driven gear ratios between the rears and the donor front drive and get a motor to suit that.

I think a better investment in time and engineering would be a walking axle.

[DRohacek]

Ambush I think you are correct about a separate pump and reservoir. I have thought about using the transmission for a reservoir but definitely don't want to starve it at any time or cause the external pump to cavitate.

I know that synchronizing this will be a challenge but I am going to attempt it. I think it needs to be pretty close but it will be working in dirt and gravel so I think there is room for a small amount of leeway. Today I have mounted the Case tractor speed control and linked it to the control lever for the rears. The case valve moves less distance than the hydro plates so I needed to hook the Case control closer to the pivot point so that it would move the correct amount when the others move farther. Not sure how clear I am making this.

Finding a place to mount the control and be able to hook to the dash lever of the hydro was a challenge to say the least. Getting it in position and mounted was like putting 10 pounds of sand in a 5 pound bag. The pictures may not show everything that I am trying to explain but I did the best I could with them.

[DRohacek]

Figuring out the seat placement and steering wheel placement is in progress. Right now it's still in mock up to see what works best for me. After I am happy with the seat placement I will build the bulkhead behind the seat. I'm going to have to be creative with the exhaust routing as it is way close to the seat. I will insulate the bulkhead with header wrap material and some high temperature batting that I have.

[DRohacek]

You fellas have access to some very affordable hydraulic components. And like sawdustdad said, these are toys, not production machines.

Definitely a float valve would be an asset on the blade height cylinders. I could be wrong, but I believe you could add one after the tractor's original valve.


I had thought about float but at this point I am going without it.
At this point I can raise and lower the blade, tip it right or left(up or down), angle it left or right, skew it to the right and angle it to cut a ditch or up to grade a bank.
The blade can roll forward also to make the cut less aggressive and more of a finishing step.

[DRohacek]

I haven't made any decent pictures of the progress lately. I am very busy with work right now and haven't had much time to spend in the garage. I am having knee surgery next Tuesday so I'm not sure how that's going to work with playing in the garage. I had ordered a bi-rotational hydraulic pump but when it came I didn't like that it had 4 ports and an additional drain hole. The pump was bigger in size than I expected which was going to make it more difficult to get it in place where I want it. I want to mount it behind the rear hydro much like Frank did on his tandem tractor build. This pump was too big to sit in the cavity. One good thing though, I sent a message to the folks I bought it from and told them it was exactly what I ordered but I was wrong with what I ordered. They said no problem, send it back for a credit and even paid the shipping for the return!! Like who does that??? So I will definitely buy a smaller pump from them.
I think I am going to try to get things buttoned up and running with just the two rears so I can test everything before I start redoing it to hook in the front drive axle. I think I need to sort everything out before I set up the extra hydraulic system. I'm still trying to decide if I will use the rear hydro for a reservoir or put on a separate tank. Space is starting to be a premium so I'm leaning towards using the rear for the reservoir. I am also running an inline oil cooler. More pictures soon.

[DRohacek]

Purchased some of the hydraulic hoses today. Man those guys don't play. the two power steering hoses are 153 inches long. $100.00 each
The 5 spool valve is all BSPP thread which needs to be changed to JIC 6 12 of those @ 8.45 ea. A few more fittings and one 24 inch hose and $297.00 later out the door I went. This is about half what I need yet!

[CADplans]

Powering the front axle will be eazy-peazy,,,

Simply design the drive of the pump/hydraulic motor to be a little too fast(10-15%) at working speed.
The front axle has to be designed for a single speed, or else the pump will need to be variable displacement
(VD means BIG $$$$ ,, and hard to operate considering the 10 other levers you will already be trying to move correctly,, )

The trick will be to use a VERY low pressure, so that the excess flow will simply go past the pressure relief valve .

You can get the power you want by using a large hydraulic motor, and matching pump.

The pressure has to be low (less than 650 psi) so as to not heat the hydraulic oil too much.
So, you need to buy a hydraulic motor that will give the speed and torque you want when operated at 650 psi.

Now you know the pump size (displacement in cubic inches per revolution)

The pump that you select will simply be sized to give the flow needed to rotate the hydraulic motor at the correct speed.

There is no other spec for a single stage gear pump, only the GPM at engine speed.
I do not know of a pump that is not rated for the pressure that you will be using, so GPM is the only spec for the single stage gear pump.

(The higher the pressure, the greater the heating of oil as it goes past the relief valve)

I simply explained the drive system that was used on an early rear wheel assist conversion for a two wheel drive combine,,
that was used to convert the 2WD combine to 4WD at the lowest possible cost.

I read about it somewhere,, but, that was the "pre-internet" era,,