Volvo A40F articulated dumper

[Manfred]

Do you mean O rings installed on the piston shaft so that each shaft can not be pulled completely into the cylinder?

Yes at the piston shaft and the threaded rod.

Also is the Thor 2 BCD speed regulator ESC good enough or do you have better experience with another ESC type for parrallel CTI cylinders

The Thor is o.K.

Another option is this one. http://www.cti-modellbau.de/CTI-Schaltmodule/-154.html

With limit switches, you can limit the way and with this switch module you switch on minus the knob. If the limit switches are set correctly, the cylinder no longer drive fixed. I would recommend it but only with the O - try wrestling.

Manfred