Hydraulic Motor spec'ing a slight rant buyer beware

[fuchifarm]

I have been researching attachments for my SVL65 high flow machine. Every discount manufacturer USA made not chinese import stuff that I have come across CID, MTL, RUT etc are not properly specifying the hydraulic motors to what they advertise the capabilities of the attachment. This is just one example I came across today talking to MTL about a stump grinder.

They spec an Eaton 2000 series 160cc geroler motor for up to 32gpm high flow machines. All of Eatons disc valve gerolers are spec'd as 75lpm and 205bar continuous use. That equates to 20gpm and 2975psi. Intermittent use of 6s on 54s off is specified as 115lpm and 260bar. That equates to 30gpm and 3770psi. These manufacturers are using the intermittent use maximums to specify use on continuous duty applications. When I asked about it at MTL they said they tested it and it worked. My response was for how long will it work?

Most of these manufacturers can't even tell you which motors they are using other than the CC size. Eaton will deny any warranty claim on the motors as they are being used out of spec and good luck to the machine owner when you get contamination from a self destructed motor.
I haven't checked with any of the high dollar attachments to see what they do. I guess I will start exploring them next.

It sure appears to be a lawsuit waiting to happen for these small manufacturers.

 

[oldnslo]

What type of attachment? Brush hog - rotary mower, mulcher head, snow blower, etc. The higher dollar units of brush hogs or mulchers that I have seen use piston motors and will spin at much higher speeds so will take full rated flow.

 

[fuchifarm]

I've seen it on multiple types of attachments where they offer a non piston high flow motor. Anything advertised as flow rates over 20gpm is suspect in my mind now. Items I have looked at are rakes, cutters, grinders, tillers, and augers. I would assume the snow blowers are the same never looked at them. Usually they are advertised as standard flow 16-24gpm or high flows 20-30gpm etc. The standard flow will usually be a motor specd for 16to 20gpm continuous duty. The high flow version will be the same series motors just larger CC. Most of the major brand motors I have researched have the same maximum continuous use limits across most of the motor sizes in a series.

I did find a couple Char-lynn (now Eaton) geretol motors that will handle high flow without a case drain. The VIS 40 and 45 series and the HP30 series are designed for up to 4500psi and flows of 45gpm continuous use. So it is possible there are correctly spec'd designs out there I just keep finding in the discount markets out of spec motors and sales guys that will tell you that it will run perfectly on your machine.

 

[oldnslo]

I could be 100 % wrong in my thinking but geroler or geroter motors are usually considered low speed high torque motors and I do not view brush hog style cutters or grinders a low speed operation so would not consider them the proper motor for those applications. Post hole auger I doubt would ever be run continuous at full speed by most operators, tiller I would also put in low speed high torque category so there it would certainly depend on displacement vs equipment flow capacity.

I agree specs can be deceiving on attachments