User manual for that servo:
http://www.crustcrawler.com/motors/RX28/docs/RX28_Manual.pdf
That servo is not a standard R/C type servo, but rather one that uses serial communication to command the servo(s) attached to a serial bus via a serial protocol that includes a servo device ID, such that several servos can share a common "daisy-chained" bus that supplies data and power to the servos. It is no way compatible with the arduino standard servo library so cannot be used as you have proposed wiring to a arduino. I suspect that these are really just 5 volt servos that have built in +5 vdc voltage regulators inside the servos.