Backhoe Pressure Gauge on HW/JW/LW-03 Backhoe

[RonMar]

I don't know... Let me think on that a bit. There appears to be two of you interested now. I don't want to do this a bunch of times, so if anyone is interested, now would be the time to speak up...

As for the filter, that appears to be pretty easy with a cartridge and base and some hose barbs as it is the low pressure side of the valve just flowing back to the resovoir. There also appears to be enough room inside the control cabinet to place the filter assembly, just below the valve. My stock Jinma pump label says 10ML/Revolution and at a 2000 RPM max pump RPM, that is a maximum flow of 20,000 ML/MIN or 5.28 gallons/MIN. I think one of these smaller 7GPM, 3/8" 10 micron filters would fit in the space quite nicely. Surplus Center Item Detail
I use one of these on the tractor main hydraulics which is a little over 5GPM also, plugged into the rear ports to filter that system when I am not using the 3PH. Sort of a maintenance filter as I have to remove it to use the 3PH lift function. With the right combination of hose barbs and elbows, the stock return hose looks long enough to incorporate this type filter inside the control cabinet with just a few dollars in filter and fittings.

 

[Red55]

Ron- Thanks I just ordered the filter assembly from the surplus center. (ouch shipping is almost as much as unit) Would you be so kind to direct me to right fittings for 3/8npt (9-7291) return line filter. I would like to splice it into the return line. Yes they love me down at the plumbing supply house I know what I want but don't know what ya call it Thats the only reason why I like the big box stores you can keep looking until you find what works or fits. And the more I read about these Chinese fittings the more frustated I get because I know nothing about hydraulics. Thanks again Ed

 

[RonMar]

Whoa... I thought I said I am going to do this, but I have NOT done it yet. I haven't even ordered the filter assembly for it...

As an estimate I would say it will require two 3/8" 90 degree street elbows and two 3/8" hose barbs as the 1-10-16 MPA(single braid, 10MM, 2320PSI ?) metric return hose looks to be very similar to a 3/8" line. Certainly close enough to accept a 3/8" hosebarb in this low pressure application.

Tell you what, I am home sick today, but tomorrow I will stop and get a few fittings on my way home from work. Then I will disassemble my tractor maintenance filter that uses this 3/8 filter cartrige assembly and install it in the backhoe(shouldn't take very long). Then I can tell you exactly what fittings are required and post a pic or two of the installation.

 

[Bob Rooks]

RonMar,
I would advise installing one of these gauges because the volumetric capacity of the 3/8" filter is so small (it could fill up and go to by-pass in a heartbeat, that's why I went with the 3/4" unit).

Surplus Center Item Detail

 

[Red55]

Sorry Ron- I thought you were talking about milling the connector for pressure gauge.(thinking about it. . ) Regular plumbing fittings aren't too much of an a problem cause there available locally. My problem was what type of fitting do I need to get to attach the hose to (after I cut it) I remember someone (think Bob Rooks) mentioned #12 aeroquip reusable fittings. Checked their site and it reinforced how little I know about hydraulics And please accepted my apology. More importantly I hope you're feeling better. -Ed

 

[RonMar]

RonMar,
I would advise installing one of these gauges because the volumetric capacity of the 3/8" filter is so small (it could fill up and go to by-pass in a heartbeat, that's why I went with the 3/4" unit).

Surplus Center Item Detail

That is a good idea Bob and could easilly be added with the addition of a "T" on the inlet side of the filter in place of an elbow. They don't spec the pressure on that gauge you linked to, but since the relief in these cartriges is around 18 PSI, just about any low pressure gauge that is oil compatible would do. Once the pressure gets up in the teens, it is time to replace the cartridge. Another tool I have found usefull is my hand or an infared temp sensor. Once the oil is warm, a filter that is bypassing will be colder than the filter boss, as it won't have much warm oil flowing thru it.

Thanks Ed, just a bad cold. I think a plain 3/8" hose barb will work in this case as it is very low pressure(you shouldn't see over 18PSI). 3/8" is .375" I believe the hoses on mine are 10MM(stamped 1-10-16 MPA) 10MM is .394", so the hose ID should only be .019" larger than the 3/8" hose. Since hose barbs are oversized to have the hose stretch over it, I bet it will work OK, just slightly looser than 3/8" ID hose would be.

 

[Bob Rooks]

This is a closer look at my setup. I ultimately went with a 60# glycerine-filled stainless steel gauge because of the high pressure fluctuations when operating the hoe, and the outdoor environment.
I also installed a thermometer to monitor the oil temperature, which will reach 160°F when using the hoe "hot 'n heavy". It is also an indicator of a low hydraulic oil level, where the oil doesn't spend enough time in residence in the reservoir to cool.

Hope you're feeling better.

 

[RonMar]

I like the temp gauge, that is cool. I use the rule of thumb, or at least I used to... If I can't hold my thumb on the banjo fitting on the return line to the resovoir for a count of 5, then it is probably too hot(around 150F). It is also pretty easy to just shoot it with the IR thermometer. Isn't technology wonderfull

I found a small 0-30 PSI gauge and a 3/8-1/8 pipe bushing in one of my bins to go with this filter. So I will probably need a 3/8" female-male-female "T", a 3/8" street elbow and two 3/8" hose barbs to put this thing in place tomorrow.

 

[Amez]

Thanks for the info.I found that my backhoe tank would overflow no matter how low I dropped the fluid.The oil returning from the cylinders seemed to pressurise the tank , forcing fluid up the submerged fill tube, I had to install a filtered breather to make it work.

I have no problems with lifting power for the boom.I have lifted rocks that were almost too big in size to balance on the bucket. That is why I am curious about my relief pressure(too high?)

 

[RonMar]

OK, Anyone who is interested in an adapter for checking the pressure of the HW/JW/LW-03 series of backhoe, send me a Private Message with your E-mail address and we can talk particulars. They will cost exactly what it costs me to produce and ship them, so I would prefer to do this only once