Antique equipment club

[alan802]

The hydraulic ovals were beasts. Fluid is easier to accel and decel than air (or was back then) and you could really crank them up past Precisions recommendations. But, many people overrode the saftey on the master print head. Dangerous. At Winterland one guy got his skull crushed. Died instantly. You need to respect hydraulics.

that is just terrible.  on a side note, that sort of thing really hurt the small plane industry in the 90's.  People wouldn't properly maintain their planes and they would crash and family would sue the manufacturer.  I am surprised it never happened that way with cars.

hydraulics are a totally different league than pneumatics.  You can briefly hold a gaunlet from indexing with your hands...servo will rip your arms off without realizing it did anything.

Even though servos are very strong comparably, aren't they (at least most newer machines) still fairly safe and are somewhat "smart" and will recognize an issue and stop itself?  Has anyone here with a servo had anything get lodged between the heads and pallets and what happened?  Reason I ask is I know our press can recognize an issue during the index and it shuts down the system and goes into free wheel mode.  During the last cold snap it got down to 23 degrees in the shop and our indexer was shutting down in mid index.  After a few minutes of thinking about what could be the problem I knew the issue had to be temp related and I remember Rick telling me that a few of his colder weather customers needed to change the servo bath oil to a lighter weight due to extreme cold temps.  I warmed up the servo area quickly with a space heater and problem went away.  If the system can detect that the oil is too thick and shuts down shouldn't it be able to feel something, anything in the way of causing unwanted stress on the servo and shut down?

I'm sure someone with more knowledge will chime in but based on what I saw with our servo system, I'd assume that it would notice a "head" lodged in the way and shut itself down before the head fell off, but I could be wrong and I don't intend on testing out my theory.

[mk162]

i am not so certain ours does that, but I really don't want to test it out.  I feel if it doesn't it will break something.

they should run like garage door openers.

[tonypep]

It would be pretty difficult with todays technogies to get caught in a servo or belt drive. That said, we had one of the first all over wing servo drive M&Rs at Harlequin. Two person load. They had weight sensitive safety mats to protect the loader closest to the first print head. Now one night I had a new guy who was all of 90 lbs soaking wet. Somehow he shifted his weight and fooled the sensor and he was literally picked up and sent over to the print head and nearly got himself printed. New meaning to an allover print I supppose.

[ScreenFoo]

I get the feeling the safety interlocks are indeed the key--I think the big issue with the index/servo thing is the momentum--it's one thing to hold the index still when it was already sitting still--how about slowing it down once it is moving at 3-4 feet per second?

As far as servos shutting down, they will (should) all be over-current protected, and should stop if enough load is on them to damage them, but if the momentum is already there, the motor can only attempt to reverse that momentum if it knows it is supposed to...

[ABuffington]

I have attached a diagram of our first press.  We used to print a ton of Van's t-shirts on these presses.
We designed their "Off the Wall" skateboard logo they still use til this day.
Before Rotary, older than dirt.

Al