Starcompressor - Star

BOCK CO2 StarCO2ompressor HR40:

Naturally innovative

The BOCK StarCO2mpressor vehicle compressor is the new generation of mobile CO2 compressors for bus and train air conditioning. The innovative drive concept in combination with a heat pump offers new opportunities for electric bus air conditioning. In contrast to synthetic refrigerants, electric buses can be heated even at low outside temperatures of up to -20°C.

CO2 compressor and heat pump or:

Why is the Bock HR40 a star?

The cylinders are arranged in a star configuration around the crankshaft, resulting in a compact system design that is perfectly matched to the natural refrigerant CO2 (R744).Co2 Leaflet

The result for the user: Energy saving and range increase.
  • No need to use fuel-driven auxiliary heaters
  • 40 % more vehicle range
Secured competitive advantages for manufacturers and transport companies: Economically and ecologically sustainable investment

Busworld Innovation Award Label 2019

  • Welded, robust steel housing
  • Specially adapted oil management
  • High running smoothness
  • Practical suitability proven in field tests
  • Radial piston technology innovatively developed for mobile CO2 applications
  • Winner of the Busworld Innovation Award 

Cooling Application

  • Bus and Railroad (vehicles)
  • Mobile Cooling / Transportation

Co2 compressor HR40


BOCK HR40 StarCO2mpressor
 Logo StarCO2mpressor 4c

StarCO2mpressor - Product highlights and things to know

All advantages at one click

StarCO2mpressor: More mobility with the climate-neutral refrigerant R744 for functional and ecological advantages in bus and train air conditioning.
  • Climate-neutral: no ozone depletion potential (ODP = 0) 
  • The lowest global warming potential (GWP = 1)
  • Efficient operation of heat pumps down to an outside temperature of -20 °C
  • Meets the criteria of the "Blue Angel" eco-label
  • Meets the requirements of many national subsidy programmes
  • CO2 air-conditioning: award criterion in the hybrid bus
  • Funding from the German Federal Ministry for the Environment,
  • Nature Conservation and Nuclear Safety (BMUB)
RaRadial reciprocating piston technology, specially developed for mobile CO2 applications:
  • Space-saving roof installation in electric buses and trains
  • Low overall height, low weight
  • Increased efficiency for air cooling and heating
  • Complete climate control: heat pump function - even at outside temperatures of -20 °C
  • Achieve plus 20 % efficiency with combined heat pump solution
  • Pioneering solution: state-of-the-art efficiency in air conditioning and heating
  • Eliminates the need for auxiliary heating
  • Increases vehicle range by up to 40%.
The BOCK StarCo2mpressor is state of the art!
  • Four-cylinder radial reciprocating compressor HR40
  • Max. permissible overpressure: 150 bar/100 bar (HD/ND)
  • Weight: 83 kg
  • Height: approx. 220 mm, total length: 600 mm
  • Max. permissible inclination: 22° continuous operation, 30° short term
  • Pipe connection with flange connection, optional soldering socket
  • Displacement at 50 Hz / 2,900 1/min: 7.3 m3/h
  • Capacity cooling1/heating2: 7 - 35 kW / 5 - 28 kW



Bock Co2 Verdichter Kältemittel R744






BOCK CO2 Verdichter - StarCO2mpressor

CO2 is a natural refrigerant, environmentally friendly, inexpensive, compare it with fluorinated refrigerants. It is colourless, non-flammable and non-toxic. CO2 is the basis for determining the CO2 equivalent of refrigerants.

R744 has a GWP value of 1 and is excluded from the so-called "Phase-Down-Zenario" (F-Gas-Regulation). From a weight of 5 tonnes CO2 equivalent, the leak test of a refrigeration system is mandatory. Therefore, the leak test is not required for refrigeration systems with R744 below a charge of 5 tonnes. If CO2 is released into the environment during service work, there is no need for costly refrigerant recovery.

Demanding factors are the high operating pressure of the refrigerant, the low critical point, dry ice formation when the temperature falls below the triple point and the very high standstill pressures. The requirements and component selection of the refrigeration system must be considered accordingly.

It's good to have an expert on hand here, or even a whole tool. Feel free to ask our experienced cooling experts in the field of CO2 or find out more about our BOCKCO2Tool and get an activation at:

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