Vehicle compressors for mobile cooling - FK series

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FK series - Vehicle compressors for mobile cooling

Leading Through Tradition and Innovation
Decades of innovation for bus, rail, and transport cooling. The FK40, a reliable symbol of quality, leads a constantly evolving series meeting diverse refrigerant and application demands.

Features and benefits of vehicle compressors for mobile cooling

Lightweight, compact, robust, powerful, wide speed range

Decades of expertise: the FK series compressors are the product of extensive experience and innovation.

Versatile applications: designed for bus and rail air conditioning, as well as transport refrigeration, they excel in various settings.

Proven reliability: the FK40, with a rich history, consistently meets high-quality standards, ensuring efficient cooling.

Continuous adaptation: the entire series evolves to meet new refrigerant requirements and diverse application needs, symbolizing ongoing innovation.

Available for R134a, R513A, R1234yf as well as R452A, R404A, R407C

  • Wear-resistant and durable power unit
  • Forged aluminium connecting rods for maximum stability and robustness
  • Two easily visible sight glasses
  • Integrated oil collection system with large storage volume
  • Special valve plate systems for bus and transport cooling
  • Demand-oriented capacity regulation possible
  • Product range with 2-, 4- and 6-cylinder reciprocating compressors
  • Ribbed surface optimizing heat dissipation

With the most powerful version FK40/755, we offer customers 15 % more power with the same external dimensions. BOCK® vehicle compressors are equipped with the K valve plate system as standard.

They are ideally suited for bus air conditioning with increased cooling power requirements in city-, intercity and articulated buses or in areas with very warm ambient temperatures.

Unique FK valve plate system specially developed for air- conditioning

  • Valve plate made of aluminium
  • Working valves made of high-quality, impact-resistant spring steel
  • Extremely robust and reliable in the face of speed and pressure fluctuations as well as exposure to liquids
  • Long service life due to loosely guided annular discs which prevent bending and torsional forces
  • Highest operational safety and efficiency

For air conditioning and normal cooling.

  • For universal use in mobile applications
  • Lamellas clamped on one side, which are exposed to bending and torsional forces; therefore limited load-bearing capacity at high speed and exposure to liquids
  • Specially adapted version for low temperature cooling
  • Valve plate TK design for low evaporating temperatures, based on the N-valve plate basic concept with torsionally stiff lamellas
  • With additional measures for delivery rate optimization at low evaporating temperatures
  • Piston crowns provided with grooves in the suction lamella contour: for further damage space minimization and increased performance in the low-temperature range
  • Increased efficiency and performance in the low temperature cooling range

Special K1 housing – Applications for Euro 6

Due to special requirements by customers, there is a demand for additional fastening options on the compressor housing – particularly where there is little installation space available, as is the case in many Euro 6 buses. This has been achieved by means of the K1 special housing, which creates a higher level of stability thanks to the compressor being fastened directly to the vehicle motor.

Special features of the K1 housing:

  • Optimized housing
  • With intermediate flange 46 mm for suction and pressure shut-off valve
  • Available models FKX40/470 K1, 560 K1, 655 K1 and 755 K1
  • 6-cylinder compressor series FK50 with K1 housing with additional mounting points on request

Looking for spare parts?

BOCKSHOP Spare parts catalog


The online spare parts catalog allows you to find the right spare parts and accessories for BOCK compressors and units with just a few clicks. 



Type Name Language Valid for Updated Download File type
Brochure BOCK FK Compressors English Multiple 06 Oct, 2023 2.6 MB .pdf


Compressor selection tools - VAP

The VAP tool is ideal for finding the appropriate compressors for mobile applications. By inputting the required refrigerating capacity and operating conditions, the tool will display compatible components right away. In the VAP tools you will also find additional details about the suggested compressors.

Related applications


Join the CO₂ Technology Training at our Training Center in Frickenhausen

On-site CO₂ Basic training with the tour of the training application, available in English and in German.

Gain a good awareness knowledge about CO₂ technology and register to one of our face-to-face courses. A complete transcritical supermarket cooling system, incl. heat recovery, air conditioning, parallel compression and ejector is available at our training center in Frickenhausen.