Definition: Transport refrigeration unit powered directly by the vehicle’s main engine via a mechanically-driven compressor (PTO – Power Take-Off). No separate refrigeration engine.
How It Works:
- Compressor driven by vehicle engine via belt or PTO shaft
- Only operates when vehicle engine running
- When parked, battery-powered standby unit or shore power required
Advantages:
- Lower initial cost (no refrigeration engine)
- Less maintenance (one engine instead of two)
- Lower weight (fuel efficiency benefit)
- No refrigeration engine fuel consumption
Disadvantages:
- Cannot cool when vehicle engine off (idle restrictions problematic)
- Increased load on vehicle engine
- Requires standby power for extended stops
- Not suitable for operations with long parking periods
Best Applications: Short-haul distribution, continuous operation routes, urban delivery with frequent stops
Related Terms: PTO, TRU, Standby Unit, Shore Power