CMP Trailer ZPI
The Trailer ZPI (Zone Position Indicator), later sometimes called Trailer, AA Radar No4 Mk 1, was a medium-range radar system that composed part of the Radiolocation (Radar) Unit GL III(c). It was used for early warning and passed information to a nearby Accurate Position Finder (APF) for target tracking. Once deployed, the horizontal boom on the top of the mast would rotate to scan for targets in all directions.
The trailer itself was a drop-frame trailer with turntable steering and Warner electric brakes, dual 9.00-20 tyres front and rear and had a laden weight of nearly 7 tons.
- Bart Vanderveen, "Wheels & Tracks" magazine No.5.