[Granathe]

Hi,

I have something that i find quite strange on my 120P, if i activate either open or close solenoid valve for the chuck there is a considerable amount of air leaking from the silencers on the solenoid valve's (it will empty my 150L compressor tank in 20min) if i open or close the tail stock valves there is no air leak,

is this correct?

should they leak?
should the solenoid valve for closing the chuck be activated the whole time or just during the closing process? i would say it should be activated the whole time to prevent loss of gripping force when turning due minor air leaks?

have i wired something wrong?

Br/ Victor

[Diesel_Pilot]

The pneumatic drawbar actuators rotary union is lubricated by oil in the air so there is always pressure to the chuck. Loss of pressure should not release the chuck because there is a safety valve in the actuator. Bad seals in the chuck would still cause loss of grip, but hold long enough to stop after the error. Whether or not the valve should leak depends on the type, some have seals some don't. You can look up the Bosch part number to check this, but I think they should not leak.

[Granathe]

Ok. i would be interesting to see how the signal works from the original TM02 controller if the valve is constant active when the chuck is closed. You mentioned that it should hold long enough to stop after the error, are there any sensor to set of an alarm in case of air pressure failure inside the actuator?

[Diesel_Pilot]

The 120P manuals show a pressure switch between chuck valves and actuator. If pressure fails here, machine errors and stops. This indicates the machine would have pressure to the chuck at all times. My 325 is setup the same way and does leak air at the union. And my valve exhausts leak, but I think they shouldn't. If you haven't found the Yahoo emco_turn_120 group we have a lot of documentation.

Look up the Rohm manuals for LVS actuators. S indicates "safety" and this is a valve in the actuator that keeps pressure in the cylinder after pressure leading to the union is removed. In reality, it should hold for a very long time if not indefinitely, but depends on the condition of the seals. It also talks about lubrication. Now, I remember in the manual that said for applications where air is turned off, it must be applied for 10 sec every 10 min to maintain clamping force. So you can disconnect air after actuation. Safety relies on proper maintenance of the actuator and design of the pneumatic system, there is no way to measure pressure within the actuator.