Identification: Machine S.N. # 3XM02247 First off there is confusion about this machine whether it is a 320A or 320L between the owner and the CAT dealer. Problems: This machine is owned by a friend of mine and it is having a problem with the thumb circuit bleeding off making it hard to grip and handle large rocks that are on a job that he is doing now. The thumb cylinder has been rebuilt recently according to owner. He has had a mechanic troubleshoot it and he determined that the thumb circuit relief cartridge was bad. The problem is that they cannot get the same relief cartridge that is installed in the machine from CAT. The P.N. on the cartridge that is in the machine is 51055-4 GN 94 N. The P.N. for the cartridge according to the Machine S.N. is 107-7033 from the CAT Dealer. I was told by the owner of the machine that the 2 parts Do Not Look alike but I cannot confirm that. My thought on this is that they may look different but work the same provided they fit. I would appreciate help on identifying the machine correctly, any additional troubleshooting advice and information on the part numbers that I have provided.
Machine S/N 3XM02247 is a Japanese-built 320 excavator. The Serial Number index document SEBF9451 shows it to be neither a 320-A or 320L, just a basic 320. (I think that the equivalent 320L had a 4JM-Serial Number prefix.) SIS2.0 shows it to be a 320-A but I do not believe that. I imagine that's where the dealer is getting their position from. That does not appear to be a Caterpillar Part Number. Certainly the format does not look like an OEM P/N to me. The poossibility exists that if the thumb lines were added after the machine was originally built the valve may not even be an OEM part. In fact a search online for "51055-4" threw up a valve Part Number manufactured by Husco. The 3XM machine was never intended for export outside Japan, but obviously over the years a few of them escaped captivity. The problem is that there is no parts information in the online system regarding it. My guess is that the dealer used the "World" equivalent 8LK-prefix machine to get their 107-7033 Part Number for the valve. TBH I would not 100% trust that way of working. My recommendation would be to get hold of an OEM Parts Manual. See below. You can search online for one or download a copy from the Cat Pubs web site.
None of the machines I appraised over the years actually showed that they were A models. When the B models came out everyone just called the first round A models. The L models usually denoted something different with the track frames. What I observed was that the L models had seven rollers instead of six. It also might mean the L had different spacing on the roller and the frame were a little longer. Nige can probably check that. I don't know if Cat or any other factory installed thumbs in that time frame. The dealers in those days kept that option for themselves. If the machine is gray market the thumb could have come from PSM, Balderson, HPF or even ESCO if it was sourced in the northwest. The tubes would have been custom made, and the control setups sourced aftermarket. Control handles might be pistol grips that were common in those days but could be rocker switches on the top. Thumb control was usually on the right side joy stick.There was usually an aluminum block with the cartridges installed in the top and the block mounted at the base of the boom. The cartridges were cross over reliefs and usually set at 2,100 PSI. There were three or four places that sold the cartridges in those day but I think the most likely to have what you need is Spencer Fluid Power in Kent. The number I have for them is 253 796-1100. Good Luck
Thank you very much for your quick replay and great information. I am sending the owner of the machine all the information that is be provided.
Thank you very much for your quick replay and great information. I am sending the owner of the machine all the information that is be provided.