New Prince PTO pump vs. new gearbox

Hi Len,

The filter usually goes on the return line just before it enters the tank. That way it intercepts foreign matter floating around in the system and prevents recirculation and accumulation of this gunk in your tank. A fine mesh strainer should be fitted to your suction line which stops any foreign material before it can damage your pump. These are usually internally mounted and accessed for cleaning by removal of a coverplate at the base of the reservoir however they are available as an inline component as well.

Something you might like to consider is forgetting the pto pump altogether and running your backhoe off the tractor hydraulics. I have done this mod to my dozer by tapping into the 3pt linkage feed and installing a selector valve which either lifts my linkage or directs flow to the hydraulic couplings. Works really well for my backhoe. In your situation it might even work out cheaper than replacing the gearbox. Can post some pics and skematics if you decide to go that way. 

Good luck finding adaptors. Cut and crimp new fittings. When all else fails I get the shop to braze a standard hydraulic thread onto the chinese fitting. 

did you figure out where the oil went?

Len, that is exactly how I plumbed my Prince pump. There is no need to install a relief valve because there is one built into the LW6 valve stack. I used it to power my LW6 also, but since that’s gone now I use it to power the laser grader.
Since you’re installing a suction side filter be sure to also install a vacuum gauge in the filter head so you can monitor the filter condition. They sell them at Surplus Center for around $10 with markings.

Yes and yes. The suction side filter is equivalent to a 60 mesh screen. Get them at Surplus Center (best price). The Prince pump is more than adequate for the LW6. In fact you will find that you will have to run at reduced r/m.

I run a high capacity suction filter, has 1″ NPT in & out. I bushed down to 3/4″ NPT.
Can’t show pic from phone.

You can see the setup on my FB page.

I can better reply when I get to my ‘puter tomorrow.

1) A return line filter isn't really necessary with a suction filter, but it wouldn't hurt anything. I have a tendency to get anal and overdo things a bit but I like to know what's going on. Here is a pic of the return line filter I installed on my LW6. The pressure gauge measures filter restriction and there is an oil temp thermometer.

2) Both ports on the Prince pump are SAE O-ring, straight thread. You will need adapters if you are going to use tapered pipe. There are lots of different adapters available. In my case, I have quick disconnects on the suction and pressure sides mounted on schedule 80 90°elbows. This facilitated removing and reinstalling the pump. Sorry, no pic yet.

3) On the return lines you can use anything you want as there is minimal to no pressure involved. The pressure side will require schedule 80 pipe, and JIC fittings.

So now I am curious to know the reasons why you guys prefer to run PTO pumps and bear the cost of maintaining two separate hydraulic systems, especially when your tractor already has hydraulic couplings plumbed so all you really need to do is buy mating couplings and possibly lengthen the feed and return hoses?

Speaking for myself, my LW6 came as a self contained unit, which I think most do, with it's own reservoir and pump. After blowing several pump seals I decided to install the prince pump and use the dozer's left saddlebag reservoir. That system worked well but then I started blowing cup seals in the LW6. The LW6 rapidly fell out of favor with me so I sold it and bought a LiTW BH7600 (equivalent to a LW7 sizewize) and plumbed it identically. That system worked well for me too until I decided I needed more versatility and power, so I sold the LiTW and bought an excavator with a hydraulic thumb and dozer blade. It has four different buckets (with quick-change) and a root rake.

Make sure the couplings on the rear of your tractor (and the tractor's hydraulic pump) have the capabilities and capacity for running a back hoe.

Suction filter restriction indicator (vacuum gauge). High pressure fittings are not required in this circuit. Schedule 40 pipe and fittings may be used.

You can see the Prince PTO pump buried underneath the quick hitches hydraulic top link. This is now set up to run the laser grader.

This is an older pic with a test gauge, but it's still basically plumbed the  same way, with a few refinements.

Just for information in case anyone out there reading this is not aware that their dozer also has a high speed PTO, it is located behind the rectangular cover plate directly above the low speed PTO shaft. The hydraulic pump off the LW-6 backhoe bolts straight on. Probably same arrangement on the tractors, can anyone confirm?

Yes. That PTO runs at engine speed. It is a tang drive.

The splined shaft below it turns at 540 or 720 (1,000 on some) r/m at 1,750 engine r/m. These speeds are requirements for certain implements.

Yes, this is the same configuration on most wheelies.