Hydraulic cooling system for LW7 Backhoe

Rich:

 I was thinking along the same lines of an oil cooler, but wanted to see if someone has already done and tested a system. I shoud have also asked, at the same time, about installing an in line filter since it came with no filter, only a strainer in the reservior tank.

Thanks

Blue Skies

LenBo

Bob:

That is a nice set up you made.  I'll have to go to the store and make one like it. Probably get the filter & housing at a auto store and the pipe & conections at a hardware store

The reservior tank came with the hoe. I just measured it and it is 7 gallon (looks smaller) and I take it that the PTO bolt on stock pump is 7 gallon.

The hydraulic oil I am using is ISO 46 (20W).

 I should have put a temp probe in the oil to know the exact temp.

What size bucket do you have on your LW-6 and what PTO pump are you using?

Thanks much!

LenBo

This BH issue is frustrating. The paperwork I got from the dealer listed AW32 for cold climates and 46 from warm climates. I live in Georgia where it is real hot durning the summer so I went with the ISO 46.

I spoke with the dealer and he said they have had all kinds of problems (problems like I am having) with that bolt on pump and he no longer sells them with the BH. He said they are going with another Chineese manufacture shaft PTO pump or plumbing the BH directly into the tractor hydraulics from the FEL. He said that work great.

I am going to get a Prince PTO, put an inline filter on, change to oil.

Where is a good place to get a Prince pump 7gpm? Also I guess I would need to take my return and pressure hoses off and have new fitting put on them to fit the pump. 

Thanks much

LenBo

Bob

Thanks

I am getting ready to order the pump and make the return line filter system like you have. The Prince web site also recomends putting a filter on the suction line. Should I get the 9GPM 3/4″ or 25GPM 1 1/4″ .

Thanks

Len

Thanks

I am on line with Surplus and will order just the suction filter.

I'll get back to you after I put the new pump on with the results.

Thanks again for all your help and information!!!!

LenBo

Hello all!

Well I got my Prince pump yesterday and started to make the fittings for it.  I went to two NAPA stores and the said they could not match it to my current hoses and did not have any fittings to make new hoses (they said the Prince pump had metric fitings – not so they didn't have a clue to the fitting size).  I live in SE Georgia in farm country and there isn't any real tractor shops for about 40 miles. Go figure! There is some small shops, but what I went through last night and today for cost and time I could have paid a shop from Atlanta to come out and set me up. I did not put a filter on the suction due to no one having fittings for the hose ( I purchased one from Surplus). My next attempt will be a filter on the return line like Bob did.

I had two different shops make me adapters for my factory hoses to fit the Prince Pump. One shop made an externsion for the high pressure side and another made the suction hose.  They made the suction hose the same size as the factory  5/8″ and I am thinking that is where my problem is.

I cleaned and pressurer washed the inside of the sump tank to make sure that all the rust was out of it, took out the PRV and cleaned it (there is a split white plastic spacer next to the “O” ring on the PRV, I take it that ring is split to be able to fit on the valve, if not do I need nother one?  Then hooked everything up and filled the tank with NAPA RO (10 weight) hydraulic fulid ( could not find anyone around here that had or heard of mulit vescosity AW32/46/68) I feel like I am living on Mars when it comes to parts and modifying/repairing this tractor in this area.

When I started the tractor up and engaged the PTO the BH jumped to life and the cylinders were working, but when I put the rpms up to 1,200-1,500 the pump started to “BUZZ” and the controls stopped working.

I am thinking that the return line is not big enough (5/8″) to produce the volume of suction needed and the pump is cavitating.

I most likey need to start all over and get at least a 1″ suction hose and make an adapter for the fitting in the reservoir  tank to remove the banjo fitting.

Any thoughts?

Thanks

LenBo

Changed the oil to AW32, reset the PRV to the factory setting ( when I took it out to clean and put it back in I needed to put it one more turn in), have the PTO set at 540, started it up and at 900rpms engine speed, dug a test hole and the BH worked 1,000% better than with the factory pto pump.  The Prince pump really makes a difference. The real test will be this weekend when I try to did out 5 stumps.

 I spoke to Prince tech support and they said not to run the pump more than 540rpms.  I guess when I put the engine speed up to 1,500 the pump was over working and started to make the bussing noise only when I moved any of the control levers.

I'll keep it at 900 – 1,000rpms while working with the BH.

Thanks

Well after putting a Prince HC PTO 7A pump (7gpm) on to see if the BH worked better I was impressed with the additional performance. However when I was trying to make the pump fit, I did not have the resources in my area to make up the proper suction/outlet hose so I modified the factory hose/fittings to allow the BH to work.  After taking the info from Bob Rooks and other members I was concerned that the factory suction set up was not good and would possibly damage the pump. I called Prince and a tech there said to use at least 1¼” line on the suction.  The tech manual for the pump states at least 1” and the pump came with a #16 SAE 1” barb for the intake. The high pressure outlet calls for at least ½” line.

I decided to make some modifications!

First I had to do a modification on the sump tank before I could get started. I removed the tank fitting that holds the in-tank filter and Banjo fitting and cut the center out with a cutting torch so that the male end of a 1¼” street 90 elbow would fit into it. I then welded it in the fitting.  Next I took a 1¼” npt hose barb and screwed it into the elbow, put that modified fitting back in the tank and connected 1.5’ of 1¼” suction hose, another 1¼” npt hose barb to connect the suction line filter rated at 25gpm flow with a 25 micron filter and a Filter Indicator Gauge to measure the vacuum on the filter to determine when it was getting dirty. Connected another 1¼” npt hose barb out of the filter to another 2.5’ of suction hose, then a 1¼” npt hose barb on the other end to connect into the #16 SAE fitting on the pump. With this setup the pump is almost like directly connected to the sump tank with plenty of fluid flow. I also put a digital temp gauge on my valve control panel with a remote sensor inside the return hose where it enters the reservoir tank. Wanted to see how hot the oil got from prolonged use.

Next I had to modify the outlet side of the pump. I connected the #12SAE fitting to the pump with 3’ of ¾” hose to a ¾” “T” with female swivels. On the top of the “T” I put a ¾” to ¼” adapter to put a 3,000psi gauge, on the other end of the “T” I used a ¾” to ½” adapter to connect to the line for the valve control. With the pressure gauge on the line I can adjust my PRV and know what my working pressure is.

Put everything on and filled up with NAPA AW32 hydraulic oil. Started it up and set my PRV at 2,000 – 2,100 psi and watched my pressure gauge while working. All hydraulic cylinders topped out at that psi when loaded. I took my machine to a friend’s property and started digging out some relativity big stumps this morning.

The BH that I have now after the modification is OUTSTANDING! I can’t believe how much difference it made; it’s not the same hoe.  It’s like I bought a $10,000 JD and put it on.  I only ran my tractor at 850 – 900 rpm’s (compared to 2,000 rpm’s with the old pump) and had real good control response and plenty of power in the hydraulic cylinders. Digging stumps and trying to rip the roots apart is probably the hardest workout a BH can get. The bucket & teeth made short work on ripping roots apart, the arm pulled well and the boom didn’t have a problem lifting  I ran the BH for six hours straight at full load digging out some big stumps with lots of roots (sweet gum, cedar) and the BH never slowed down or showed a lack of power. The hydraulic oil only went up to 118F degrees at the highest point. The outside temp was only in the low 70’s so I am sure the oil temp will go up when it gets in the 90’ around here.  I think with the new pump, extra large hoses and a big filter on the suction line worked like a cooler to dissipate any heat.

I just want to thank everyone for their input to assist me in making these modifications.  I was real disappointed with my factory LW-7, now I am real happy with my modified one.

List of parts for modification.

Bert:

It's like night and day. I don't know if you ahve had any problems with your LW-7, but mine is running 1,000% better. If you need any help for a modification like this contact me. Hopefully the hydraulic cylinders will hold out with all this new power or I'll be putting more posts on this site.

Thanks

Len

Bob:

Thanks for all your help. I guess if I have problems in the future they will be the piston seals. Ithought that the seals may have been a contributing factor to the lack of power in the beginning, but since I did the modification the BH is running GREAT. I suspect that if I start having problems again it will be the seals. Who sells a good set of urethane seals? I just may get them and change out before I have the problem in the middle of a project. I was thinking while I was implementing the modification that the next thing would be rebuilding the cylinders/piston seals or upgrading and purchasing bigger cylinders/piston depending oncost difference.  Since running the BH today the cylinders/pistons have plenty of power so I don't think it is necessary to buy bigger cylinders, but may have to rebuild the seals.

Thanks again for all your help!!!

Len

Thanks much!

I'll check with Afordable.

Just an update I have some pictures from this project. I still need to fabricate hose holders, but for now they are not in the way of any harm.

Prince pump connected to PTO. 1 1/4″ suction line & 3/4″ outlet line.

1 ¼ “ Street elbow with 1 ¼” NPT barb connection welded to sump tank flange.

1 ¼” connection to sump tank.

1 ¼” suction line with 25 micron filter/suction gauge and ¾” High pressure outlet line with pressure gauge.

This modification made my LW-7 BH a totally different machine. It works GREAT now.

Thanks

Len

Bob:

First of all thank you for inspiring me to make this modification.   If I didn’t do this and it didn’t work I would be looking for a new BH.  I did remove the in-tank suction filter when making the modification.

Prince Pump’s calls for a 150 micron suction filter for their pumps, but does not list the GPM flow rate on the suction filters. When I was researching parts for this project I went to Surplus Center and the only filters they have are a 10 micron return filter and a 25 micron suction filter in different GPM.

In my previous posts when I installed the new Prince pump with the factory suction & output lines, I had problems with the flow rate. The Prince PTO 7A pump calls for ½” output and 1” suction line. I decided to go with a bigger diameter  ¾” output line and a 1 ¼” suction line with a ZINGA Suction Filter:

25 GPM SUCTION LINE FILTER
New ZINGA. Spin-on type element. Ports 1 1/4″ NPT.

SPECIFICATIONS

• Suction Line Applications 25 Micron
• 25 GPM
• 5 PSI bypass
• 950 sq in filter area
• 5 1/3″ dia x 9 1/3″ long

This is a real big filter.

My pump is rated at 7 GPM and this suction filter is rated at 25 GPM so I did not think there will be any problems with the flow rate.  Before I did this modification I drained and flushed the entire system along with pressure washing the inside of the sump tank and then filling up with NAPA AW-32.

I ran my BH, as hard as I could, for over six hours one day and two hours today digging out stumps and the BH works GREAT. I think digging out stumps is the hardest workout for a BH. The suction filter gauge reads in the “Green” between “0” and “1” lb vacuum while at idle as well as under load.  I think it will be a long time before I ever need to change out this filter. See the picture – BH was running and the needle is between “0” and “1” lb.

This BH really operates GREAT now. Plenty of power and good control response.

Thanks again to all responding to this post for providing me with information and ideas for this modification.

Len

Bob:

Thank you for all you help. I am sure that I may be in need of your and other member's knowledge to fix or modify my machine.  I hope this project could help out other members with the same problem on a LW-7 BH.

I got to get some rest tonight. Will be turkey hunting in the morning and then  removing the BH and hooking my new 3 point post hole digger to start on another 500' of 5 rail fence.

Len

Bert:

Let me know if you have any additional questions when you start this project. I am glad that I don't need a snow blower, if we get a couple of inches everything shuts down here. I have fully stocked food/water source (bar) so we just stay home and make it a party untill the snow melts off the road.

Thanks

Len

John:

Sorry for the late response. I was pulling up the Ctoa web site several weeks ago and my NORTON protection for my laptop STOPED my system from this web site. It kept telling me that my computer was under attack from CTOA so I was off this site for a while.  I wouln't change anything in the mod-my BH still works 1000% better than the factory set up. The next mod on my LW7 will be to rebuild the cylinders (better seals) when I get a chance.  It still works fine, but the cylinders not hold a load up for a lenght of time, same as in the FEL.

I have read that the Chinese seals wear out fast.

 John if you haven't started the modification or need more info send me an email lsuchar@bellsouth and I'll give you my phone and maybe I can explain what i did.

Thanks

Len

John:

Great to hear you got it working. The guage will read zero or barely move until the filter starts to get dirty. Would like to hear how much better it works now.

Got your email from the “Friend” section of CTOA.

Thanks

Len

It may be a little bit more “jerky” due to more GPM hydraulic flow from the Prince pump. Just have to get used to the controls again.

Len