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Oct 3, 2023
Anyone have some experience with trouble shooting/fixing this alarm on a HST210SS?
Think we have narrowed it down to a hydraulic oil leak on the brake.
We are hoping that trying to find the leak, fixing it then bleeding it will sort the issue out.

But if anyone has any tips or tricks in regards to bleeding and or finding high likelihood places for a leak I'm all ears. Never had to take one apart and do any of this myself before.

I'm not familiar with the SS but, yours has hydraulic oil for the brake? Except for one application, I believe they are all pneumatic. Do you hear the air valve cycling when you try to jog the table? Does it reengage when you stop?
From what I can tell it is air actuated but the brake itself has a line with brake fluid in it.
If you look at the Haas Brake bleed procedure there is a line coming out of the brake (its somewhat impossible to see in their pictures. But I've included some of ours.)

But yes I can hear the air valve cycling.
Does the brake engage when stopped? It wont even let us get past trying to jog it (it just gives the above alarm.)

My limited understanding of the system is the plunger with the spring in the pictures below is meant to be 3/8 away from the block for the locked position.

Ive tired talking to our supplier of Haas, but they are saying they wont even send out a Tech to look at it. Haas has told them that any issues with 4th axis units need to be sent to a faculty in the USA.

So finding information of any kind to fix it ourselves has been nigh impossible, we just get told to ship it out.


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Based on reading the repair process, there is a pressure switch in there that is looking for clamp / unclamp state of the brake. If the pressure switch doesn't respond, it errors out because it can't tell if it's dragging the brake or not. I'd say you already solved your problem. Fix the leak, bleed the bubbles out and it should be back in business.

It's also funny that the program they include in the bleeding procedure is the G-code equivalent of bleeding brakes (pump the pedal, hold, bleed the bubbles, close, repeat).
So we are trying to bleed the system. But we cant run the brake bleeding program without zeroing the a axis.......
Also tried todo it manually but without success.

Anyone with a assembly diagram or a way to run the brake bleed program without having the a axis zeroed?
They are original. But show no signs of wear. The unit is just over a year old.

So we found the leak, replaced it and refilled it with hydraulic fluid.
Have now come to the conclusion that the system isn't pressurizing correctly. (it sucks oil in when bleeding and has some pressure when burping) but the brake is still on. (we try to move the 4th in jog with the safety's off. We can see the servo moving but the main cylinder it drives wont move.)

Went full grimsmo and took the whole thing apart, have potentially found the issue in the master cylinder. Looks like the seals are shot causing pressure in the line that blew (the leak we found in one of the lines had a massive hole in it. but looked like it blew from internal pressure)

I have a picture of the potential offending seals and unit.

Anyone have similar experience's with the HRT210SS?

We just cut Aluminum, but we are a production shop. So its pretty much used on a daily basis. Wear and tear??? A year of use seems really low to me.


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