Knee Movement Troubleshooting

Knee Movement

• Check Power to Carriage HPU

• Safety Valve active on console, does it open/close the safety valve? (usually a visible vibration when toggled)

• The RMCTools “Event Log” page, and “Plot” Trending can reveal a lot of troubleshooting Information to assist diagnosis. RMC project file should be located in D:\Cleereman\Files\Linear Carriage 4k.rmcproj

List of parts that can cause knee position/movement issues.

• • Valve

  • Probe

  • Probe to Carriage junction box cable

  • Carriage Junction box to Cabinet Cable (Across pantograph)

  • Magnet inside the Cylinder (this is what the probe sense as the knee moves)

  • Gibs that guide/brace the knee movement on the base, these being too tight, or too loose can cause excess friction restriction movement, or allow too much movement, or the knee to twist and bind.

Runaways

Use RMCTools on optimizer PC on the system with the issue. Monitor for errors on the knee plots, event log is also helpful. This will help determine the root cause of the runaway.

Knees moved while in the saw

• WISP(wood in saw protection)protection enabled? Ensure set values make sense and are accurate. If WISP is disabled the operator can input commands that cause moves while in the cut.

• Was there a runaway? Or was this a bad movement instruction?

• Band mill Offset? There was previously a bug that caused this, Update PLC program. (if they cut deeper, triggering the cutline switch and backed off for some reason, and then took a more shallow cut the band mill offset was moving the knees to the deeper cut position plus the offset which may be passed the saw.)

• Verify the knees moved, and not just the dogs, could be a dog movement or air valve issue.

 Knee Oscillation

• Check the Valve RMC connector, have them unplug/replug the connector. Ensure there is no oil or debris contamination in the connector. It should be clean.

• Knee fluctuations around the intended position, turning down knee acceleration, or pgain usually fixes the issue, at least temporarily if there is a part issue that is continually degrading.

• Usually caused by one knee having movement issues, but symptoms may be seen on several knees as they try to move together. Isolate each one by disabling the others and testing them one at a time until finding the problem Knee. RMC tools may also shower a higher magnitude of movement in the problem knee.

  • If you can isolate the issue to a single knee, try moving parts to see if the problem follows, Valve, Probe, Cable etc.

No Transducer

Probe to RMC communication failure.

• Check for loose wires/connection. Disconnect/reconnect probe connector (could be seated incorrectly causing spotty connection)

• Check Cable across pantograph for any wear/pinches/exposed wires.

• Swap malfunctioning probe with one from a functioning knee to see if problem follows.

• Replace Cable across pantograph

• Replace Cable between probe and Carriage junction box.

Out of Control Knee Movement

• Check knee valve control cable length and connections a short/wear, it could be receiving voltage to move the knee at the valve when it should not.

• Simulate cutting up a log with the carriage empty to try and find the steps to cause the issue to happen, this will help pinpoint the cause of the problem. (Disable scanning, Take saw off)

• Check each knee for probe signal issues, if a probe signal is lost/disrupted it can cause a bad knee position on the RMC to register and then send voltage for this knee to move to the position it should be from the incorrect position registered. This can result in all knees moving some to follow before a runaway occurs.

Knee will not move

• When installing valves, if either the valve is put on 180, or the receiver is rotated during the change, and the valve is put on and bolted in (will bolt either way) the knees will not function.

• Check that voltage is being sent out, electrical meter between the Out and Common wire for the servo in the setworks cabinet, or the carriage servo/probe junction box to verify the signal is getting to the valve.

• Bad/loose connector. The cable from the carriage junction box to the valve may be loose or dirty/contaminated with oil. Disconnecting, cleaning, and reconnecting the connector may solve the issue. If not replace the cable.

• Check for any physical obstructions, or that the knee has not locked up due to damage. You will be able to hear the hydraulics still “trying” to move.