• Eliminates the need for all non-operational idling
  • Provides heating, air conditioning, and electrical power
  • Air compression and main engine coolant circulation
  • Leave lights and communications on when parked for added safety
  • Reduces fuel and maintenance costs


Product Details

Product Details

Customer installations show that, when it comes to comfort, convenience and - most importantly - value the WillisAPU is a wise investment. It is a revolutionary technology, yet it is a concept that has been proven in the aviation industry for over forty (40) years. What differentiates the WillisAPU from a simple truck generator is that the WillisAPU provides for all of the power support requirements for systems typically installed on a heavy duty Class 8 truck, except pulling the load.


Features Benefits & Details
Integrated Alternator, Heat Exchanger and Air Conditioning Compressor
  • Provides heating, air conditioning, and electricity to the cab and sleeper.
  • Eliminates cold starts by maintaining engine temperature.
  • Eliminates the need for parked idling, which shortens life of truck engine.
  • Maintains a comfortable living atmosphere for better driver rest.
  • WillisAPU HVAC utilizes truck heater cores, controls blowers and ducting so that none of the premium cab and sleeper space is taken away by APU components.
  • 150 Amp alternator gives total back up to truck electrical system.
Uses industry-proven Kubota
3-cylinder engine to run the APU
  • Uses about an average pint per hour diesel fuel in normal heating mode; and an average of over one quart per hour of diesel fuel during air-conditioning mode, as compared to 1.0 to 1.2 gallons/hour when idling the main tractor engine.
  • Emits less pollutants than an idling big bore engine, which facilitates compliance with pollution regulation.
  • Superior noise attenuation, which helps drivers sleep and rest better.
  • Keeps noise levels down around truck stops and along highways.
Electrical Monitoring System
  • Monitors engine temperature and battery voltage for extended parking.
Uses the best brand name, off-the-shelf heavy-duty truck parts available
  • Reliability and reputation of industry proven components.
  • Quality is remembered long after the price is forgotten.
Integrated Air Compressor Options
  • Provides a complete back-up air source through its integral air compressor for the truck's primary and secondary air systems.
  • Keeps trailer level constant at loading docks.



Fully integrated into truck Systems
No additional heater or A/C controls
No storage space lost in sleeper cab
Microprocessor based solid state electronics with VFD Display

Operation Modes: Off Mode - All APU functions are turned off
Manual Mode -

Provides automatic glow plug operation for cold APU start; While truck is in motion, APU can be started to provide back up heating, cooling, dc power (alternator) and air-pressure (with air- compressor option) to avoid emergency stop and expensive road service

Auto Mode -

Normal operation mode; Starts and stops with “Park Brake”;
with an air-compressor option, auto-starts APU if air pressure drops below 80 PSI

Monitor Mode - For extended parking mode; Auto-starts APU to maintain battery voltage above12.2V, and truck engine temperature above 55°F
A/C Capacity: 28,000 – 38,000 BTU (Truck Model Dependent)
Heating: 25,000 BTU (Truck Model Dependent)
Engine: Kubota (3) cylinder D 722, 18.8 HP
Fuel Consumption: Average 1/5 of a gallon per hour for 50/50 duty cycle between heating and air-conditioning. About one pint per hour average during normal heating mode and over one quart per hour average during normal air-conditioning mode. The outside ambient temp, electrical load, and APU engine rpm setting have influence on fuel consumption.
Alternator: Leece-Neville, 150 Amps
Heat Exchanger: Cast Aluminum Free Flow (No cleaning required)
Frame mounts: Cast Aluminum 356T6
Transmission Housing: Cast Aluminum 356T6
Housing: Diamond Plate Aluminum
Air Comp (Optional) : Meritor WABCO 12 CFM
110V Power (Optional) : Tundra CM 2000 Inverter
Steps: Required/Optional depending on mounting location.


Weight in Pounds
Total Base APU Installed


Comfortable Heating even at extreme cold conditions: The Willis APU heats the coolant with a cast aluminum heat exchanger on the exhaust designed exclusively for this system. From the Heat Exchanger the pre-heated coolant is pumped through the APU engine, directly through the heater cores and then to the truck engine keeping it warm. This allows the heater cores the benefit of using the highest BTU’s available in the system. With the truck engine in operation, heated coolant is circulated through the APU engine keeping it warm. The microprocessor control provides for a high RPM mode to provide more BTU’s for extreme cold conditions.

Best Cooling even at 100+ degrees: The exclusive Willis APU fan drive system provides plentiful airflow across the trucks large condenser and radiator, giving the same capacity to air condition the truck cab and sleeper as the OEM. The integration into the truck system has the benefit of using the OEM HVAC controls and ducting. With the exception of one other manufacturer, all other systems are stand-alone and only cool the sleeper cab, and they are not capable of adequate cooling in 100 degree plus temperatures.

Most DC Power: 150A Alternator, higher output than any one else

Never a cold start: Keeps the tractor and APU engines coolant and oil at temperatures higher than any one else for easy start even at the most adverse weather condition. Test results have shown crank case temperatures at +70 degrees F. with test cell ambient temperature at –20 degrees F. (Nevada Automotive Test Center)

Best Solid State Electronic Control with many safe, useful and unique features: Microprocessor control. Exclusive features include “MANUAL” for cold starting using automatic timing of glow plug, “AUTO” for automatic starting and shut–down of the APU with the park brake when the truck is in operation, “MONITOR” for monitoring engine temperature and battery voltage when the truck is parked for an extended period with “auto start” to maintain required parameters and “UTILITY” providing time keeper for recording operating hours, service intervals, clock setting, pre-start time and “High” and “Low” RPM settings. “Low” is for fuel savings and noise level, and “High” for extra heat output and high electrical loads. Safe automatic shut down of APU for low oil pressure or high coolant temperature. Willis APU has Industry’s best fluorescent display.

Most Powerful, Quieter and Smoother APU: Powered by a three (3) cylinder 18.8 Horse Power Kubota D-722 engine makes it smoother and more powerful by nature of design versus the two (2) cylinder or single cylinder engines used by the competition. Low and high RPM settings are used depending on power requirements, which also contribute to lower noise levels and fuel consumption.

115V AC Power – Optional 2000 Watts of continuous power using industry’s best inverter from Tundra fully wired with convenient outlets for safe operation

Exclusive Options from Willis APU only:

Air-Compressor - The Air-compressor option provides automatic backup to the truck air system. It can work in parallel with the truck compressor to overcome a major leak or independent if the truck compressor fails. Trailers will be kept at the proper level at loading docks and air is available for tire inflation or air tools. When used as designed the APU is pre trip started to warm the engine and build air supply saving the truck engine from cold starts and idle time to build air.

Rock Solid Drive System – Modular design allows quick access to the enclosed drive system, which has been engineered, for long life and low maintenance. Drive belt is kept at proper tension with an automatic belt tensioner. Extensive engineering and testing was conducted by Litens Corporation to achieve a smooth drive system.

Highest Quality – A close look and overall evaluation of our product will reveal the in-depth thought, engineering and careful development of this unit. High quality aluminum castings (356T6) are used for frame mounting, drive housings and heat exchanger. Coolant hoses are custom molded, and allow for efficient and unrestricted coolant flow. The design, manufacturing, selling and service processes are being documented to comply with the latest Trucking Industry Quality system TS16949, ISO9001: 2000.