Hello All... Looking for hydraulic system description/schematic for my Cat 315bl. Assembling / Rebuilding a final drive unit and simply trying to understand the hydraulic system as it pertains to the drive unit. PN 148-4570. During the dis-assembly and cleaning process I noted a small (3/16"+/-) port that leads into the gear housing from the hydraulic motor bolting flange. I do not have a hydraulic schematic or flow diagram to understand what the function is of that port. why it is connected to the gear box side. Relief valve port? But why into the gear box side. There are 4 O rings that can be seen to seal up the ports, one of those is the one that leads to the gear box side. Any help on this would be great. Nick
The port noted is the one that goes over to the gearbox side of the housing. Orientation is at the 6 Oclock position or basically pretty much on the bottom when installed. What is the purpose of having gear oil coming over to the hydraulic motor? Initially I thought perhaps it was a relief port, although venting into the gear box certainly did not make sense either, and after considering the position it is in, I am thinking its to lube something in the motor?? The next closest port to that one, is the one that supplies oil to the brake piston. Might it have a function with that process? At 180 degrees out from those is the two that supply control oil to the swash plate pistons under the plate. The issue that has me inside this was the failure on the gearbox side. While the unit is out, simply resealing it and installing new bearings at the same time. Simply curious as to what that crossover ports function is? I have read about hydraulic oil making its way to the gearbox side, but thought I understood it to mean the shaft seal between the motor side and the gear side failed? Is my interpretation correct on that? However, also read a post on here about the brake piston o rings failing and that having the ability to push the hydraulic oil over to the gear side as well. Might this be the port that happens through if that type of failure occurs? Thanks..
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Just a wag, but perhaps it's a brake release port?
Thanks for the info Nige, expect that it will be very helpful. I will get to reading and see what I can learn about the hydraulic circuitry. I will update the post and share what I find out. Presently have 90 % the parts in from Cat for the rebuild of the final drive - missing just the 2 planetary gears that were not in the USA. Word from the local Cat parts folks is 2 weeks out on those, seems they are en route on a ship headed this way. Thanks Again.. Nick
Howdy Huntoon, Not sure what that port is intended for going from the motor flange to the gear side. In looking at the motor housing, there is no matching port- o ring seals to a flat surface with no port route. Beats me at this point.