Live Swivels

https://www.surpluscenter.com/Hydraulics/Hydraulic-Adapters-Fittings/Live-Swivels/NPT-Female-to-NPT-Female---Straight/1-2-NPTF-x-1-2-NPTF-Live-Swivel-Coupling-LV5000-08-08-9-LV5000-8-8.axd

Rotary Unions in 360 Excavator

• A specialized rotary union is used, not just a simple live swivel - [1]
• Explanation from hydraulics and pneumatics - [2]
• In real life: Infinite spin is attained. From Reddit thread - [3] -

Backhoe vs Excavator

• Backhoe spins 200 degrees, excavator a full 360 degrees. [4]

Shopping

• $1500 for 1/2: rotary union [5]. But what about the female socket part?