Distinction Bosch SB7 / SB23 OC / SB23 System

Here is a short guide on correctly identifying the Bosch hydraulic system of your tractor, across all tractor brands and models:

Bosch SB7

The Bosch SB7 system was used by various manufacturers from around 1960 into the 1990s in different generations.

Bosch number range:

  • Control units for rear hydraulics (old designation): Hy-SR10H...
  • Control units for rear hydraulics (new designation): 0 521 704 ...
  • Auxiliary control units (old designation): Hy-SRZ10H...
  • Auxiliary control units (new designation): 0 521 705 ...

Manufacturers that installed the system (list may be incomplete):

  • Fendt
  • MB Trac
  • Steyr
  • Porsche
  • Kramer
  • Deutz
  • Case IH (IHC)
  • Lindner
  • Schlüter
  • Güldner
  • Eicher

Flange system:

The earliest production years were delivered with three mounting studs (shown here as an example on a control unit):

Later production years were delivered with four mounting studs:

Bosch SB7 Endplatte Ansicht der Flanschseite

The additional holes between the holes for the mounting studs are for dowel pins; they serve to center the valve but were not always installed.

All valves with four mounting studs are downward compatible with the version with three mounting studs!

Note:

IHC often fitted SB9 valves in the last generations of tractors delivered with this system; here an additional return is integrated in the valve.

Please note that the SB9 system is not compatible with SB7 control units.

 

Bosch SB23 OC

The Bosch SB7 system was used by various manufacturers from around 1980 into the 2000s in different generations.

Bosch number range:

  • Auxiliary control units: 0 521 609 ...

Manufacturers that installed the system (list may be incomplete):

  • Case IH
  • Claas
  • Renault
  • Deutz
  • Steyr
  • MF
  • Zetor
  • Valtra
  • Valmet
  • Lindner

Flange system:

The system was always delivered with three mounting studs. Characteristic for the system is the symmetrical arrangement of the mounting studs and the supply bores:

Note!

With the original valves there is a right and a left version (depending on which side the valves are mounted). Replacement control units are usually made flexible for both versions by a replaceable sealing plate.

 

Bosch SB23 LS

The Bosch SB7 system was used by various manufacturers from around 1980 to the present in different generations.

Bosch number range:

  • Auxiliary control units (older designation): 0 521 610 ...
  • EHR control unit (older designation): 0 521 220 ...
  • Auxiliary control units & EHR control unit (new designation): R91700...

Manufacturers that installed/fit the system (list may be incomplete):

  • New Holland
  • Case IH
  • Claas
  • Fendt
  • Deutz
  • MF
  • Lindner
  • McCormick
  • Stey
  • Doppstadt
  • Landini
  • JCB

Flange system:

The system was always delivered with three mounting studs:

The two small holes in the area of the electrical unit supply the control with pilot pressure. The purely mechanical version of the SB23 LS system does not have these holes!

Note!

For the valves there is a right and a left version (depending on which side the valves are mounted).

The original valves had notches in the area of the mounting studs. If this surface has been machined flat, shims of 0.05mm must be fitted. These are intended to prevent clamping of the valve.