We've been resurrecting a slightly abandoned 1988 Link-Belt LS4300 CII excavator (same as Case 9040 and Sumitomo H300) that had major electrical problems. The machine runs perfectly but we've had to tear out a nightmare of bypass wiring that had been amateurishly installed to replace the original controller. I've made up a new console panel with 12 fused toggle switches, 11 of which are assigned to each of the known 11 solenoid valves. We haven't been able to get pilot control of anything yet and suspect that one valve next to the hydraulic tank has a shorted coil as it blows a 10 amp fuse. That coil is held onto the armature core with a plastic nut. The coil has the identifying number: SKU6D/G24. The shuttle valve will shift position when a strong magnet is held next to the core with the magnet coil removed, so we don't need anything other than a replacement coil. Anyone out there that might have a suggestion for finding the coil? The armature core has an O.D. of 19.5 mm and is a slip fit into the coil bore. Thanks, -Tom
One other issue we encountered was that the throttle control motor was bad. We took it apart and found the internal motor and gear unit were beyond repair. John C on this forum suggested using a boat throttle cable assembly with suitable mounting bracket(s) to control throttle, but we already had installed a center off momentary toggle switch on the new operator control panel and it seemed a shame to not use it. I went online looking for a 24 volt linear actuator and found what looks like the perfect choice on Amazon for around $50. It has a 2" travel and plenty of force to handle the throttle job. The only possible negative might be that the speed is too fast. If that is the case I'll put a large resistor in series with the 24 volt supply to reduce current to the point that it works reasonably. I think this will elegantly resolve yet another of the few problems we've been facing with this beast!
High idle is controlled by injection pump. You might consider a rheostat so you will have off on and speed control . Bob
Thanks Bob. I'll bench test the actuator and determine what size resistor to use , if any. The toggle switch that was originally going to be used for the original throttle motor provides for throttle up or down depending on which way you push it, so it will work fine for the new setup as the actuator motor only requires two wires which we already have in place back at the engine. You reverse polarity of the motor power tho change direction of travel. Center position of the switch is off. I really appreciate the help I've received from folks on this forum!
The original control panel had a switch for idle 1 or idle 2, so was/is that electrically controlled at the injector pump? I didn't notice if any wiring went to the pump when I was on top and removing the old throttle motor.
Happy to say that I have the new coil on it's way from Dallas and will be here in the morning. I sourced it through my local Case Construction dealer as a Case 9040B part rather than Link-Belt LS4300 CII or Sumitomo H300. According to my earlier respondent they're essentially the same machine except for paint.
Sad to correct the earlier post because the coil that we ordered was for a later valve than ours. We ended up having to buy a complete valve assembly (with coil) as coils only are no longer available. And so it goes with keeping big iron on the job!
Hello Iowahill. I am pretty new at this excavator stuff.. I also bought a linkbelt Ls4300C11 and was told it is the same machine as the case 9050, I am not sure though....
View attachment 206460 View attachment 206460 It was remarked to me earlier on this forum that the Case and Sumitomo brands were essentially the same as the Link-Belt LS 4300 CII which is built by Sumitomo, but I found out in ordering parts that isn't necessarily true. I've been using Shafer Equipment in Sparks NV and Bejac in Rancho Cordova CA as my LBX parts sources. I'm thinking that having the Serial number of your machine is absolutely essential as the basic platform is individually configured according to the specific application (excavator, log handler, etc), and that is critical when doing work and/or service on the hydraulics including pumps, valves, pilot control, and cylinders. We were fortunate to get all the manuals with our machine which I have been scanning as backups. Without those and (in my case) enlarging the electrical and hydraulic schematics the task of understanding how to troubleshoot problems might exceed one's capabilities. I've also had benefit of a couple of service managers familiar with the older Link-Belt machines which really helped. The smaller of our two parts manuals has a "Key List" which is the guide to the various parts assemblies. It's a vital document that will save a lot of time and frustration. Our machine had the original computer control removed and bypassed, effectively keeping the beast in Emergency Bypass mode. If you study the electrical wiring schematic you can see how this switch eliminates the controller with loss of some non-essential operations i.e. Bare Bones. We've replaced much of the wiring using color-coded and bonded 16-gauge 4-conductor trailer wire to make identification of solenoid wiring simpler, installed a new custom made aluminum control panel that uses a 5-amp fused switch for each of the 10 solenoids we've identified, replaced the key switch, installed a master solenoid kill switch, and are presently waiting on a couple of adjustable voltage controllers, one for the new throttle actuator that I designed to replace the original inoperable throttle motor and the other to give me a degree of control over the very important proportional control solenoid valve. My equipment partner and I got into this machine dirt cheap and so far it hasn't disappointed in any way. Motor and hydraulics is strong, the undercarriage is fair to good, and with replacement of a couple of pilot and pressure hoses we should soon be moving material with the 2+ yard bucket. If you've never worked on an excavator before there's a lot to learn, especially with safety in mind when working with massive weight and hydraulic pressures in excess of 5000 psi. That's where familiarizing yourself with the manuals is most important. Having some hands-on experience with other heavy equipment, especially hydraulic equipment is a real plus. Good luck with your new baby, all 35+tons of it!
The original operator control panel was broken and junk. So I laid out this replacement that has a 5-amp fused switch feeding each of 10 solenoids on our machine. That's also a new key switch, new Hobbs, and battery readout and condition monitor. Installation of a couple of adjustable voltage controllers for the new throttle actuator that replaces the original throttle motor and the other to give more precise control of the proportional control solenoid valve is in progress. I also replaced the original fuse panel with a 12-fuse marine fuse panel.
Iowahill, Thanks for the great information., I do have a shop manual, operators/maintenace manual, and the parts book which has the key sheet specific for my machine. I have no mechanical experience so am having to hire someone to do everything. So far we have replaced the 4 top rollers, the H link to bucket, 4 main Hyd hoses that attach to boom,new seals in the delivery flow valves on Isuzu motor.New idler wheel, had bucket cylinder repacked, new ignition switch and now getting ready to rebuild rotary joint seal. The computer controller on mine was taken out also so it is working on bare bones, also like yours the throttle motor had been removed. As soon as it warms up enough that my mechanic can fix the rotary joint, i am going to move it to my house and maybe we can start working on the wiring and fix a throttle control similar to what you are doing. Your control panel looks great and will give us something to strive for when we get to that point. The people on this forum are fantastic and have already given me good advise, I am searching the forum on excavators to get any information that is similar to our task at the time. i always check the first 2 or 3 pages and then return to my search, which started at the oldest pages of this forum. So glad to have you here, thanks again to you and all the people on this forum..
One early suggestion solving the throttle question was to use a boat throttle cable and make a bracket to hold the cable housing at the injector pump. I decided instead to use a 24 volt linear actuator that I bought on Amazon for about $50. Making up a mounting bracket was a simple job that bolts right on the motor pedestal. The travel is 4" with speed that is manageable and has more than enough power to overcome the pump lever spring when going for higher rpm's. I think the previous owner was operating at fixed throttle with the original frozen throttle motor and used the manual cutoff cable to kill the motor. In our case I use a center off DPDT momentary switch to control and reverse the two motor leads to increase or kill the motor with that switch. I have a couple of voltage controllers on order that will give me speed control on the actuator to make fine tuning for a given job better. Ask 10 guys for a solution and you'll get 10 different approaches. That's one of the great benefits of this forum and the folks who contribute. That's how we learn!
Your control panel looks great, My nephew is an electrician but i am not sure if we will be able to figure this out. he knows nothing about excavators so i am sure we will have to get the excavator mechanic involved. Let us know how it works when you put it to work..I have confidence in you!!
The bypass wiring is pretty simple in the most basic form, so if you can find and see the color code of each wire as noted in the electrical schematic then it should be straightforward. I had large prints made for the electrical and the hydraulic drawings which made the job much easier for my old eyes, and we ended up just running new wire to the solenoids. Only six were necessary as (in our case) the other four were for the bucket quick change hydraulics and two others that are plumbed but we haven't identified their function yet. If this is something you need or want to do I can PM a brief write-up and punch list of what you need to do to get the machine into manual or by-pass mode. Identifying the solenoid locations and specific function was the hardest part for us until we got help from a local LBX service manager who identified each after I sent photos of the pump and control valve locations. I get the impression that maybe no two machines are configured identically, and that each is assembled from a basic platform with whatever options the purchaser would order. Semi-custom so to speak. Regards, -Tom
Thank you so much Tom, that is very kind of you and i really appreciate your offer. It would be great to have any of the info you can give me. The wiring is so raty looking, i dont know how it is even working. Thank You, Ramona
The LinkBelt C2 machines are the same as the Case 9000 series. The LinkBelt Q machines are the same as the Case 9000B series. All built by Sumitomo.
Many thanks for the updated info. The Case dealer I had gone to was referencing the 9000B as he thought that was the line that most closely matched the date of our machine which is 1989 or 1990.
Thank you Excavator, It is good knowing the machines that are not compatible, as this can be overwhelming when looking for parts, especially for a newbe. Thanks again.
Stick with LBX dealers for parts unless you're certain that a crossover part will work. Bejac in CA and Shafer in NV have been 100% for my needs. BUT... get prices first! In the case of our Swing solenoid valve there was a $450 difference between the quoted highest and lowest price.
Thanks Iowa Hill, 450 is a big difference in price and i am on a budget as most people here. This started off as a project to dig crystals with the nieces and nephews so they could have a fun hobby. It has turned into a bigger project than we expected. Do you happen to know if the 4300c2 when started went automatically into low travel mode.
I'd have to refer to the Operators Manual to confirm but I believe I read that it does in ByPass mode which is what we've permanently wired our beast for. Since travel and other functions are controlled by the engine speed I would hazard a guess that the original speed control was a function of of the controller UNLESS in ByPass mode.
Thanks Iowahill, when you wired your beast for the bypass mode, do different functions work on different size amp fuses?
The fuses for each solenoid are only there to protect the wiring should a short occur somewhere, and don't have anything to do with function. The solenoids pull +/- 1 amp and we are using 5 amp fuses. The Operators Manual describes what functions are default when in By-pass mode and that's how our machine behaves. We presently don't have enough pilot pressure to get full operation. That pressure is tested at the port under the cab and above the frame. We're only seeing around 50 psi when we should be seeing more like 600. I'm headed up the hill tomorrow with a replacement pilot filter and a test tee that I can put inline after the pilot pump and before the filter to confirm whether or not the filter is clogged in case that's the problem. As the pump #1 and #2 pressures hit around 5000 psi we assume that the pilot pump section is okay too. So another possibility IF the pre-filter pressure is low might be that the pressure relief valve on the side of the pump may be dumping to the tank because of a piece of debris or dirt keeping the spring loaded pintle open. If that's the case I'll open the pressure adjustment screw all the way, then close it down to see if I can pick up the required pressure. The pressure hose off the relief valve to the filter is a #8 compression fitting, so I picked up a tee that has male and female #8 fittings and a female pipe port for my gauge.
CORRECTION: The pilot hose fittings off the relief valve and beyond are #6 compression, NOT #8. We found that out yesterday after heading up the mountain to test and diagnose our pilot pressure drop only to find we didn't have the correct plumbing. I picked up a #6 compression tee as well as a couple of #8 to #6 reducers so that I now have two test tees, the smaller one with a male 1/2" quick connect test port that we will keep on the pilot line coming off the pump relief valve so that we can monitor pressure before the filter and check valve. Talk about peeling the layers of an onion!
Correction to my correction! The fittings are British Standard (BST), NOT #6! Japanese JIS fittings constitute the majority of the rest. I'm starting to have a very diverse variety of various types as I've been trying to diagnose a significant low pilot pressure issue.
i have a case9040 with a bad swing gearbox runs great no cylinders leaking good undercarriage thinking of cutting it up for scrap or selling it whole maybe part it out