In {HEAD ~ another embodiment}, {TAIL ~ two separate systems} are installed, one on each side of the trailer 
In { HEAD ~ another embodiment } , { TAIL ~ two separate systems } are installed , one on each side of the trailer
OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH