LDS Hydraulic Pump Powering a Hmmwv Hydraulic Winch

[Lieutenant Dan]

Ok so I picked up a hmmwv hydraulic winch a few weeks ago and mounted it on my deuce. I bought a LDS power steering pump (vickers vtm42). I got it mounted today and all hooked up. The pump whines around 1200 to 1500 rpm. The winch works great under no load. Once the engine reaches that rpm it starts making the god awful noise. I pulled it apart to check for irregular gear wear as I've read on two different types of timing gears. All was fine. I also pulled the pump apart again to make sure everything was fine on the inside since I flipped the rotation of the pump to left hand drive instead of right. All was fine there too.

The pump is plumbed with a 1 gallon reservoir above the suction port. The suction lines are 1/2" hose with 1/2" npt fittings on the ends. The pump has a 3/4" inlet. The outlet is 6 jic and I used 3/8" lines to the winch valve and to the cooler back to the tank.

I haven't put the winch under a load yet and I also didn't bleed the system but after about 30 seconds of the engine running the winch started to work. I did notice the tank oil was quite foamy.

My pump is rated for 5 gpm and 2000 psi which might be a bit high but should be OK for now.

So I don't understand why it's whining. Is it just air in the system? Is something wrong? Is my tank to small? Is the suction line to small? I've read in the tm that the winch valve has a 3.5 gpm restrictor in it so is that creating to much pressure at at 1200 to 1500 rpm and going through the internal relief valve of the pump? It's really frustrating now and I'm ready to lose my cool. Any help would be greatly appreciated!

 

[Jeepsinker]

It is just air. The fluid gets foamy because the pump is cavitating. If you go through this a couple more times and it doesn't clear up then you need a bigger tank. That tank is awfully small for what you are doing with it. I would think more like 3-4 gallons or even 5 would be best. Remember, the more fluid in the system, the cooler it will run under a load as well.

 

[welldigger]

You need a bigger reservoir for sure. That being said I wonder if the bypass is opening. The only other thing that comes to mind is the pump starving for oil.

 

[rustystud]

Cavitating for sure. Let it set for a day to get the foam to settle, then recheck the level.

 

[Lieutenant Dan]

Here's what it sounds like.

LDS Hydraulic Pump Whine: http://youtu.be/1NrG_plEimE

I worked the winch this morning. I hooked to a tree and drug the truck across the yard. It works good. Two things I noticed. The pump is almost quiet now at idle. But the sound is still there at about 1250 to 1500 rpm. It seems to quiet down some when I use the winch during the sound.

 

[Jeepsinker]

Ok Dan, the foam has settled now and that is why most of the whine is gone. It is still whining at more throttle because the reservoir is too small. That pump is pulling fluid from the tank and circulating it back, then picking it up again before it has a chance for any bubbles to settle out. Cavitation destroys hydraulic pumps and motors. You need to see about finding and mounting a bigger tank buddy. You might have to mount it somewhere else instead of underhood.

 

[Lieutenant Dan]

You think that is definitely cavitation?

How does waterloo get away with a smaller tank then I'm running or is it because it's power steering? What if I went bigger on the suction hose?

 

[Jeepsinker]

He gets away with it because of two things. # 1: the fluid has a longer path to travel before it goes back to the tank ( notice when you use your winch things quiet down, that's because you lengthen the fluid path temporarily), this allows the whole system more capacity and opportunity for cavities to settle before recirculation.
#2: The system is powering a hydraulic solenoid instead of a motor. Solenoids tend not to cavitate fluid during their operation as a motor might.
The Saginaw box may also have a built in bypass that flows higher volume, but I can't say so for sure.

 

[Jeepsinker]

If you went with bigger suction hose it would get worse. Ever notice the little whirlpool that happens when you drain a bathtub? That is what is happening in your tank, and why it is sucking air. How do you stop the whirlpool in the tub? Notice it only starts when the fluid (water) gets low... You have to add more fluid capacity.

 

[Keith_J]

Depth of reservoir is a factor as is return and supply port geometry. You could add capacity and depth to see if this helps but vortex breaker plates would offer benefit too.

 

[Lieutenant Dan]

It seems like I have alot more hose then the waterloo kit. Maybe not suction hose but the lines to the winch then cooler then back to the tank are definitely longer. I'll have to see what I can get for a bigger tank.

 

[Jeepsinker]

Tractor supply carries small capacity hydraulic tanks, 3-5 gal sizes. Or you could just use an old air compressor tank if you can find a small compressor that the motor crapped out on. You'd have to do some mods to it in order to plumb the lines in. Easy if you can weld.

 

[m16ty]

What is the GPM of the pump? What is the GPM of the winch?

It would also help if your suction and return lines were as far away from one another as possible.

Another solution that may help would be to just install a "tee" in the bottom of the tank and have the suction and return hoses tied into it. It will be harder to get the system bled initially but it should help with sucking air after it's bled. You'll basically have a closed system with the tank just being used for make up oil and fluid expansion. The down side to this is that your system will run hotter because the tank won't work as a heat sink as well. You may be ok though but I'd want to watch the temps at first to see how it's going to work. Probably not the best solution but it would be the easiest to try. All you'd need is a tee and a plug to plug one of the holes in the tank.

I'm not a big fan of a pump running all the time when it's not needed. A PTO driven pump would be a better setup but since you've already got this pump, I'm sure you can make it work.

 

[Lieutenant Dan]

The pump is 5 gpm and the winch says in the tm that it has a 3.5 gpm restrictor in the valve body.

The plan is to run it like this for a little and add on power steering.

 

[Jeepsinker]

That isn't a bad idea to run it the same way the HMMWV does. You just need a bigger tank or one better designed is all.if you had a tank that was deeper but narrower, with the intake fitting on the very bottom and the return on or very near the top you might get away with the one gallon size. But then it still comes back to fluid temperature. Your cooler may drop the fluid temp by anywhere from 20-60*, but it probably won't be enough to keep up. The cooler your fluid temp is, the longer the pump and winch motor, and even the fluid itself will last. Maybe just jump up to a better designed 2 gallon tank. Can you fab a new tank to fit?

 

[Lieutenant Dan]

I could modify this tank yes. I don't really want to make or buy a new tank but the more I look at it I might go with the 5 gallon from tsc. I'd like to plumb in auxiliary ports somewhere. I don't know what I'd use them for but it would be nice to have. Plus I'll never rule out another one of these winches in the rear of the truck.

The problem with the 5 gallon tank is where to put it.

 

[Lieutenant Dan]

Besides this tank having the ports farther apart I'm not sure how it's much different.......

 

[Lieutenant Dan]

I forgot to post the second video.... you can definitely hear the pump is much quieter at idle after working the winch.

LDS Hydraulic Pump Whine 2: http://youtu.be/F-Zkt4W3OeE

 

[red]

Your fittings are too close. When the fluid is being returned to the tank the hot oil is pushing the cooler oil away from the suction port.

Notice how the ports are far away from each other with the tsc tank? It prevents that issue. Modify your tank to have the fittings on opposite ends of the length and you should be able to get away with your tank.

 

[m16ty]

The pump is 5 gpm and the winch says in the tm that it has a 3.5 gpm restrictor in the valve body.

That may be your problem. You're trying to push 5 gpm into a 3.5 gpm winch. It just depends what they are calling a "restrictor". If it's just a restriction in the system, it will cause you problems trying to push 5 gpm into it. If it's some other valve that will just divert anything above 3.5 gpm back to the discharge, it shouldn't cause problems.

Is there a way to remove this "restrictor"? I can't figure why it would be there other than trying to keep the winch from running too fast.