[Nikola]

Hi everyone!
I have a problem when for some reason my H400 turn's hydraulic's off (weak eletricity power) I get NMI servo alarm. In that moment Y-axis starts falling down to the end of way causing collision between the tool and workpiece. Shouldn't there be any brake to stop it in that case? Just to mention that hydraulic is used as counter balance. Havent found any check valve to support it in hydraulic circuit diagram.
Any idea?

[botha.y]

Well usually the vertical motor would have a brake on it, activated when 0V. So maybe a 24V short?

[Night Shift Wiz]

Well usually the vertical motor would have a brake on it, activated when 0V. So maybe a 24V short?

Technically, the brake is activated (clamped) by springs and deactivated with a 24V coil pulling the brake pads open. Either it's still getting 24V when you get the alarm or the brake is worn, oily, or stuck in the open position.

[underthetire]

Or...
There is no brake, and it's a hydraulic counter balance Y axis, and he's loosing pressure before the machine can alarm to shut off the solenoid.

[Night Shift Wiz]

Or...
There is no brake, and it's a hydraulic counter balance Y axis, and he's loosing pressure before the machine can alarm to shut off the solenoid.

I can see them cutting corners on the newer Mazaks. However, our older ones all have brakes and hydraulic counterbalances. Plus, if it's just a loss of pressure, the servo would hold it in place until it alarmed out. Odds are it has a brake.

[Night Shift Wiz]

It's also possible that the brake quit working ages ago, probably even caused a few servo overload alarms at first which the operator/mechanic just reset. After a few days or weeks of moving with the brake engaged it finally wore down to where it won't hold the axis up anymore. As long as you never power the machine down you would never know it.

[Nikola]

hm.. It makes sense wiz. I'll check about servo break with my electrician later. We bought the machine before few months ago and I've seen that they haven't serviced it like they should. I'll tell you what we found out.
Thank's!

[Zamet]

[IMG]D:\Замета Ю.Л\Оборудование\Митсу Сейко\img_0740.jpg[/IMG]

[Zamet]

Я решил проблему механическим путём. Изготовил раму, повесил груз около 200 кг на цепь. Прекрасно.

[machinist360]

Same thing happened to me but I think you are talking about X axis. The 24 volt supply to the brake doesn't turn off at the same time the servo drive de-energizes servo. My fix was to unplug brake from one servo drive and plug into the one next to it (cost $0.00). I can post pictures if your still having trouble. Just ran across this post....