Backhoe Hot Backhoe Hydraulics

[RMulkey]

I have a question on how hot should hydraulics get on my Backhoe? I have a Woods 9000 Sub frame backhoe with the PTO driven hydraulic pump. Today I was working the unit pretty hard, digging 6'x12" trenches for about 2 hours when a rod seal started leaking on the boom cylinder. The cylinder was so hot I could not touch it. The local hydraulic repair shop says that when the packing seals start leaking, it is the first sign of working the machine too hard or letting it get too hot. I have used the unit less than 80 hours total. The hydraulic pump and resivior on the backhoe does not have a oil cooler that I can find.

Second question: Does the tractor hydraulics have a oil cooler on a Kubota L4310? Would I be better off using the Power Beyond tractor hydraulics for the backhoe to help keep the oil cool?

Any advice would be appreciated.

 

[TomG]

I use tractor hydraulics for my hoe. The gpm and pressure specs are well within recommended ranges for the hoe. I suspect that most PTO hydraulic pumps have greater capacities than compact tractor hydraulics, so the PTO pump may be the better choice.

In terms of heat, cylinders too hot to touch are definitely too hot. The oil will over-heat if the hoe is stalled a lot. You should be able to hear a pressure relief valve open. Same thing could happen on some 3ph hoe setups which use tractor hydraulics. The hoe mount locks down the 3ph, but the 3ph lever could inadvertently be in a raise position. In that case, the system pressure relief valve would be heard. I've heard of flow restricting valves installed in some hoe setups to slow down certain operations. I guess that could heat the oil, if a restricted flow operation was used heavily, but I doubt that's the problem. I'd ease up on the demands a bit and try to avoid stalling the hoe. If you're new to backhoes, you might re-read the manual for digging techniques. Maintaining the bucket at a good digging angle, avoiding dragging full buckets, and avoiding 'long-range' digging and lifting all reduce demands on the hoe.

 

[Keoke]

The size (gallons of hyd fluid) of your sump has a lot to do with the working temp of the fluid. My guess is that a tractor sump (trans case) holds a lot more fluid then the portable hyd. tank that came with the PTO pump setup. If you are going to work the hoe hard you may want to think about a larger tank or a heat exchanger for your unit.
Happy Holidays,
george

 

[Jag]

Sorry, I can not say what the problem could be. I have worked several backhoes and then my Kutota B4690 this last summer in the hotest part, ran one ditch through clay about 75 yards long 16"x 24" deep and never had a cylinder get more than comfortable warm.

 

[patton]

A rule of thumb for operating hydraulics w/o a cooler is that the tank capacity, in gallons, should equal the flow rate in GPM. This assumes the tank is exposed, and not in high ambiant heat conditions. This also assumes normal working conditions (ie. most, or all, of the energy is used to do work, not expended in a pressure relief valve.)

Pat

 

[RMulkey]

I am deffinitely new to backhoe operation. It sounds like I am stalling the BH too much, lifting the relief valve, and this is the source of the excessive heat. The PTO pump is ~10GPM @2500PSI. The tank on the backhoe is 10 Gal. The whole unit is from Woods, so I assumed I was doing something wrong. In the future, I will take smaller bites to keep the bucket moving at all times while digging and see if it helps. Thanks for the great advice. I bought the book "Backhoe Loader Handbook" by Reinar Christian. It's pretty good for someone like me who knows nothing, but did not discuss how to tell if you are working the machine too hard Or mention the potential overheating caused by stalling the BH and lifting the relief valve. Chalk up the cost of rebuilding the first cylinder to operator training... Thanks again.

 

[Keoke]

For zero worth, I think Pat is right on with the excess heat coming from the high friction relief valve blowoff causes.
How was that book by Christian on backhoe operation?
Where did you get it, was it expensive?

Happy Holidays,
george

 

[RMulkey]

I bought the book from Amazon.com about a year ago. I think it was ~$20. It is about 160 pages of mostly text with some line drawings and pictures. It is OK, but could use some more pictures. I would kill for a video of how to use a BH. The book will deffintely put you to sleep at night. It covers all the basics pretty well and some advanced topics like hopping trenches. It was great for me because I knew nothing about backhoe other than how to hire a person to come do work for me... I would recomend it if you have nothing else to learn from (like me).

FYI// I should get my rebuilt boom cylinder back tomorrow. I'll let you all know how things go with my new operational methods...

 

[Thomas]

RMulkey,
Books and video do help also watching a good operator and hands on...just take time.




Thomas..NH /w3tcompact/icons/wink.gif

 

[RMulkey]

Here is the final findings on the leaking boom cylinder. There is good news and not so good news:

Good News: It does not look like operator error (that's me) ruined the seal. The seal failed because the rod had paint on it extending far enough into the cylinder to rub on the seal whenever the cylinder was contracted. It eventually wore out the rod seal.

The not so Good News: Cost me $95 to get the cylinder rod seal replaced and learn that the paint on the cylinder from the factory caused the failure. The Backhoe is 2 months out of warranty.

To be fair to Woods and the dealer, I did not take the bad cylinder back to the backhoe dealer for the repair. My local hydraulic shop was faster and I was on vacation (I spend my vacations on the tractor when I can).

I have checked the other cylinders and found one more that has the same paint issue. This was quicky fixed with a dab of paint remover.

Thanks everbody for the helpfull hints. I used the BH today with the new operation mode. The heat was much lower but still hot to the touch. I can leave my hand on the cylinder for a couple of seconds before it is too hot. This still sounds a lot hotter than some of you are experiencing.

 

[jgh]

1/7

One other quick note. Have you contacted Woods's tech support guys? Go to http://www.woodsonline.com site for the 800 # and give em a call. They seem really helpful.

J

 

[hayden]

I really think you've got something wrong if it's getting that hot. You shouldn't have to baby the hoe. Running at full tilt/pressure should not be a problem. Are you sure your reservoir is full and have you changed the filter? Are you sure eveything is plumbed correctly? If, for example, the fluid return is going right to the pump intake rather than circulating through the tank to disapate heat, that would cause what you are seeing.

Can you test the fluid in the reservoir to see if it's hot too? Maybe just feel the side of the tank. Are all the cyls hot or just some of them.

 

[RMulkey]

Hayden,

Thanks. I have felt the temperature of the tank, hoses, all the cylinders, and PTO pump. Everything gets hot. A fluid and filter change did not help.

It takes about 1>1.5 hours of working, digging 6' deep by 12" wide trenches to get to the hot temperature. The hoe came from Woods pre assembled and the dealer did the final setup. It seems to dig great. This is really the first time I have worked the hoe so hard and for so long. Usually I am digging some shallow short trenches or just planting something.

I checked the fluid pickup in the tank to make sure it was clean. The high pressure hose is routed to the joystick controls. The low pressure return is routed to first to the filter and then the tank return. The return hose does not feed directly back into the pump (I had the same thought).

I guess I will call Woods tomorrow to see what they think. The dealer did not have any sugestions beyond what I have already tried.

 

[hayden]

Well, you've already checked everything I can think of. A call to woods sounds like a good idea. Maybe it's OK after all.

Good luck,

Peter

 

[TomG]

Early on in this thread somebody mentioned a desirable ratio between gpm flow and reservoir capacity. I hadn't thought of that issue, but it seems like it might be a good idea to revisit.