Yeah but av seen it happen so I will agree to dis-agree I guess.
The problem is not as prevalent on the newer P&H Centurion machines as the ABSS kicks in. This is automatic and most of the time the operator won't even notice but we know as its logged. On these machines here it's all controlled via a 'Linear Resolver' which measures backward boom movement, its not a switch at all more like a linear transducer if anything, The whole range is from 0 to 1 degree and the Stage 1 & 2 events are programmed per customer request. Stage 2 brake set 'No reference ABSS' on these shovels is 0.5 degree I think.
Never seen brakes set during limits. It normally shuts the direction function down and goes into Proving.
Been a while since I done any Product training on these shovels.
All operations and shovels are different, here the lower limit is set with the bail lower down. This allows maintinence to work on the bail during coffee breaks without shutting the limits down. I recently replaced a Rope retainer boss on a 72yrd equalizer. The operator simply lowered the bail vertical for my convenience.
And don't get hairy, the info is for anyone interested, please feel free to add info that I missed?
What I am saying, is that you have seen something else, and are misinterpreting it as a boom jack. You cannot create enough force to overcome the weight of the boom, and cause it to lift with only the weight of the stick, bail bar and bucket flipping down and up. You have to lift the boom to get a boom jack, and that's not possible by bouncing the stick in the air.
We run A, B and C series machines with both Avtron and Centurion control systems, and it just doesn't happen like you're saying. I'm well aware that the resolver measures the boom movement, but, unlike what you are saying, the resolver does not set a 30 second shutdown. So any 30 second shutdown that initiates will be from a shock or jarring event tripping another sensor somewhere.
I'm in no way getting "hairy" as you claim, I'm simply trying to make sure the correct information is there for those who want it.
Only time I've had it give me a boom jack from something like that is when the limits are set wrong and the brakes lock up when you try to crowd in to far when cleaning the floor or something. Then I have had it boom jack. Ours are A models.
That's exactly what I'm saying Desertwheeler. That's a normal boom jack, where the stick is out too far, and lifts the boom. Wether it's from skipping the bucket off the floor, crowding too far, or ramping the boom with a brake locked crowd, the boom has to be lifted to get a boom jack.
(But highly unlikely)