The hydraulic system is considered to be the “blond circulation” of a concrete pump. It ensures reliable and metered movements of the transfer tube, mixer shaft and placing boom. Therefore, it’s a crucial maintenance step. In the video below, the Putzmeister America team shows step-by-step how to change the hydraulic loop filter:
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Instructions to Change The Hydraulic Loop Filter
Changing the hydraulic loop filter on your Putzmeister Pump is a real easy process to do. We’re going to demonstrate step by step how we do this. Step one will be to drain the chamber that houses the filter. There is a drain port down at the bottom of the cover. We remove the drain port and then there is a quick coupler drain hose that is used to drain into a bucket. This way we don’t have oil making a mess on the floor. As I close the quick coupler, it opens the damper and allows oil to flow through out of the filter chamber. We open the drain plug and remove the drain plug so that we can vent the chamber.
And now we are draining the primary chamber of the filter canister. While it is draining, I can start to remove the cover plugs.
With my cover plugs removed, the chamber has already drained out completely, so I can remove my hose, my quick coupler hose.
I have to remove the vent plugs from both chambers. This is one filter but it has two chambers in it. Now we remove the cover to give us access to the filter. You just pull towards you slightly. You will get a small splash, so put a pad underneath it. On the cover, there is an O ring for a seal and then a bar here that we align our filter with. At this point, we set this aside. The filter is inside here. I reach in, and grab the filter and pull it towards me and let the filter drain into the bucket. The only part of this that will be reused is the cap on the end. It’s a camlock, just put it on the new filter and you’re ready to reinstall. You want to take a clean rag and wipe everything down inside the filter housing and on the filter.
Now, it is important to note the notch in the top of the filter. This notch must line up with the notch inside the cap, the steel rod inside the cap. And so, we must make sure they align when we put it back together. Clean, new filter. Make sure out notch is horizontal. Just give it a light tap in. The cover has been cleaned. A little bit of light oil around the O ring so that it’ll seal. Align the notch. Give it a tap.
Now we reinstall all four bolts. The O ring creates the seal for this cover, so please don’t use a 10-foot breaker bar to over torque the bolts. This is an aluminum housing. I snug the bolts down to torque in a cross pattern. Opposite corners and then opposite corners. So, I don’t accidentally distort the cover. My cover for my check valve is closed. My four bolts are back on and tight. Now, if we were to just stop here and run our concrete pump, we would cavitate the hydraulic pumps. Standard Putzmeister old school filters were self-flooding filters, which meant when you push the filter in, it opened the tank. And then it would then proceed to fill the filter chamber all by itself. But this filter is not that style. This filter we have to prefill. If you do not, you will destroy your hydraulic pumps.
The suction filter adds oil to the closed loop circuit. It is a true suction filter that is in the tank, so there will be oil come out of here when we open it up. When I pull the filter out, there is a damper inside the tank that is going to close off the tank so that we don’t drain the whole tank. So, to remove the suction filter, we loosen the nuts all the way to the end. You don’t need to remove them. Now, when I pull the filter straight back towards me, it will close the damper. I twist, and remove the filter. To change the filter, the filter is screwed into the handle. So, we replace the handle. Clean and lubricate the O rings and then reinstall in the reverse step. We want to make sure that the area around the O ring sealing surface is clean. So, take a soft, clean cloth and wipe any particulate debris off of this surface.
Reinstall a new filter cartridge and now we reverse to reinstall the filter. When I enter it, right now I’m hitting the plunger in the tank, I’ll give it a good rap and twist and tighten the nuts down. That successfully changes the suction filter on this type of Putzmeister.
Once again, the cover is sealed by the O ring and not by the torque of these nuts. So, snug them down good, but do not use a breaker bar to over torque them. This filter is self-flooding and what that means is when we push the filter canister back in, the oil from the tank floods the chamber thus prefilling the filter. There is no need to prime this filter. We use a clean oil source to refill the chamber.
You absolutely must do this. If you do not, you will destroy your hydraulic pumps. I try to fill both chambers a little at a time. As it fills up, you’re just looking to make sure that all the air bubbles have vented out of the chamber.
This is not a time to be in a hurry. Once we get it full, we let it set for a few minutes to let all of the remaining air come out of the filter. Now that we’ve ensured that the filter is completely filled, we make sure our plugs and caps are clean and then we reinstall them in the ports they came out of. Same again with the large plug. We want to make sure that the seal is clean and then reinstall.