Backhoe Hot Backhoe Hydraulics

RMulkey · Dec 23, 2000

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 · Dec 23, 2000

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 · Dec 23, 2000

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 · Dec 23, 2000

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 · Dec 24, 2000

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 · Dec 24, 2000

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 · Dec 24, 2000

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 · Dec 27, 2000

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 · Dec 27, 2000

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

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

RMulkey · Dec 29, 2000

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.