HT20 big crash but no tooling involved, ripped hydraulic lines off

[dbramley]

Here is an interesting one. Was running the HT20 when huge bang and back end of the machine jumped off the ground. Hydraulic fluid running all over the place. The tool was far from the work piece. It appears maybe a bearing in the Hydraulic chuck actuator froze up and spun the hydraulic actuator ripping off the hydraulic lines???? It runs LX3 and when I replaced the lines and turned the hydraulics back on there were no alarms and was able to home the machine. But when I spin the chuck it wants to spin the entire hydraulic chuck actuator, any ideas?

Much appreciated!!!!

Dan

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[Jim Dawson]

You may be correct that the bearings failed. There should be a lever arm of some kind connected to the machine frame that is supposed to keep the chuck cylinder assembly from spinning with the spindle. Mine is just a fork that brackets one of the hydraulic fittings. Doesn't look original, more shop made to solve a problem.

[dbramley]

mine is the same "fork" that straddles the hydraulic fitting, when the bearing froze, I suspect, it all but ripped that bracket off.

[dbramley]

I am trying to get a grip on what spins and what does not when all is normal. If somebody is in their shop and has one spinning, could you shoot a quick video of the back of the spindle where chuck actuator is? I would really appreciate it. Maybe email it to me?

dsbfabrications@gmail.com

Thank You

[Jim Dawson]

I just happen to have some pictures of the back end of mine. And I can get a video later today.

Showing the anti-rotation arm on mine, the angle iron arm picture center. The finned housing is the chuck actuator. This was taken during my initial machine upgrade.



Showing under the chuck actuator. This was taken during my spindle servo upgrade.

[dbramley]

Thanks Jim, that looks way more ridged than original. Thanks for getting the video for me, It would be nice to know what to expect before I go tearing into it.

Dan

[Jim Dawson]

Here is a video I just shot. Turn down your volume, it's loud.

The only torque on the chuck actuator housing should be the rolling resistance of the bearings. Theoretically the hydraulic lines should be stiff enough to resist that torque, but that would not be a good design practice.

Basically everything between the coolant catcher and the disk brake is chuck actuator.

[dbramley]

Thanks a lot Jim!!! I am going to try to get a video and show you what I have, and see if have any further advice.

Dan

[dbramley]

Thanks Jim!!! I appreciate you taking the time to do that. Mine is a little different. I made a video to show you what I am up against. I an just not sure what is supposed to be spinning and what stays still, with housing. In the video I share some ideas. Again, thanks, and any advice is appreciated.

Dan

[Jim Dawson]

It looks like the bearings are a bit rough in the actuator. The aluminum housing where the lines connect should remain stationary, and everything forward of that should turn. Not sure where it comes apart at, maybe at the socket head cap screws towards the front. But I think there is no question that you are going to need to tear it down to find the problem.

[dbramley]

Thanks Jim, I am going to tear it down starting at the rear.