two black, one black with white stripe. I'm connecting to arduino uno. I cannot find a reference to identify the wires.

 

 

I'm connecting to arduino uno

Given that the device shown seems to be a hand-cranked high voltage generator, connecting it to an Arduino via those wires directly (if that's what you intend) seems a recipe for disaster.

 

It's a high current Radio Control servo, so I wouldn't try supplying it with power from the Arduino directly. According to the datasheet it takes from 6.to 8.4V, and has a stall current of 2.8A at 6V, 3.5A at 7.4V.
As for connections, I'd hazard a guess that the white striped wire is the signal wire, the middle one the positive supply (that's usual on servos), and the remaining outside black is 0V.
So you need to connect the 0V and supply wires to a good, high current supply, and connect another wire from the 0V supply to an Arduino GND, along with the servo signal wire.

https://www.chd.hk/Product_Detail.aspx?id=203

 

There are two styles where the center wire could be positive or negative.
Firstly, check to see if the connector is keyed. The signal wire is always on the edge with the key except for Airtronics.





Hobby Servo Tutorial - SparkFun Learn

Indentifying servo wiring - Using Arduino / Project Guidance - Arduino Forum