Hydraulic Temp

[Bud605]

Ive notice while using the backhoe that when I happen to touch one of the cylinders the temp is fairly warm. It wont burn you but you wouldn't want to keep your hand on it very long. Is there anything to do? Filters are all less than 50 hours, changed all when I bought machine.
Thanks in advance.

 

[Roadworthy]

Normally when running hydraulics they do build up some heat. That's why you should let your tractor warm for a bit before actually using it - to warm the fluid. If you left your tractor in the sun here today you wouldn't want to touch the cylinders even if it wasn't running!! I think it's gonna warm up tomorrow though.

 

[William1]

After a few hours of digging with my little BZ25D, the hydraulics get hot enough that they feel like they'd burn me. I've never done a temp check as they do not seem that hot, but I'd not be surprised if they were over 200 degrees F.

 

[Dave_eng]

Ive notice while using the backhoe that when I happen to touch one of the cylinders the temp is fairly warm. It wont burn you but you wouldn't want to keep your hand on it very long. Is there anything to do? Filters are all less than 50 hours, changed all when I bought machine.
Thanks in advance.

You need some reassurance and a reference. Surfaces at 130F are too hot to touch.

The cooling system of most vehicles is designed to run at 200+ F hence the need for a rad cap with a pressure rating to prevent boiling..

An automotive automatic transmission used to be cooled by a coil in the radiator so it needs to be much hotter than 200+ F to reject heat to the rad coolant.

Modern engine and hydraulic systems are designed to run at high temperatures. Kubota recommends running an engine at a high idle for up to 30 minutes in cold weather so the hydraulics warm up. Running too cold is far more destructive than the temperatures you are seeing.

Dave

 

[Bud605]

Thanks Dave!

 

[NWAZL3560]

I've been using my BH77 for a couple of hours every day for the last few days and the boom cylinder does get pretty hot. It's only 2 years old with 190 hours and serviced by the Dealer at 50 hrs. So I guess this is normal.

 

[SidecarFlip]

My temp indicator is the backside of my hand. If I can put the backside of my hand on a 'hot' part and keep it there for 10 seconds, far as I'm concerned the fluid temp is fine.

 

[baronetm]

All the components in the hydraulic system are designed to dissipate the heat generated from pressurizing and moving oil. The operating temperature of most industrial hydraulic system I worked on ran in the temperature range of 120-140 degrees F. These were also using tube or plate heat exchangers to cool the oil using a chilled water process with cooling towers, similar to a radiator to remove heat. A rule of thumb we used was if you can hold your hand on it for about 3-5 seconds it is running within spec's. We always attempted to cool the oil to an optimum 120 degrees but ambient temperature and wet bulb temperature effect how much we could cool our process water, hence higher oil temperatures, on hot summer days an oil temp of 160 degrees plus F was not unknown.

That being said if your are moving oil over a pressure relief valve a hydraulic system will generate excessive heat and possibly over heat the oil quickly, if you are running your implements to the point they will not lift or dig you my be at the relief setting, squealing is a sign of high pressure oil going over a relief valve. If this is done intermittently the system should dissipate the extra heat with no issue.

If a hydraulic systems oil temperature gets in the 180-200 plus degree range for a significant period of time the life cycle of your oil will be cut significantly and damage to components is inevitable over time. Oil that has been at this high temperature many times in my experience has a burnt smell to it and a very dark in color.

The cylinders on my L3901 with a BH77 hoe get warm to touch on a hot summers day but nothing that concerns me, even at minus 10 they are warm enough in a few minutes so snow will melt off them and they feel warm but not hot to touch. I look at the heat generated as lost HP or work and lift capacity, just a law of physics.

So the short answer, the higher the ambient temperature and humidity the warmer your hydraulic system will be. All this is dependent on not having any mechanical issues.

Attached is a link to a hydraulic web site with more specific information on hydraulic oil.

Controlling Hydraulic Oil Temperatures

Every hydraulic system generates a certain amount of heat, but if the system is running higher than 140 degrees, it is too hot. Find out how this can be prevented.

www.machinerylubrication.com