Distinction Bosch SB7 / SB23 OC / SB23 System

Here is a small guide regarding the correct identification of the Bosch hydraulic system of your tractor, covering all tractor brands and types:

Bosch SB7

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

Bosch number range:

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

Manufacturers who installed the system (list may not be complete):

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

Flange system:

The first production years were delivered with three studs (shown here as an example on a control valve):

Later production years were then delivered with four studs:

Bosch SB7 Endplatte Ansicht der Flanschseite

The additional holes between the stud holes are for dowel pins, which serve to center the valve, but were not always installed.

All valves with four studs are backward compatible with the version with three studs!

Note:

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

 

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 valves: 0 521 609 ...

Manufacturers who installed the system (list may not be complete):

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

Flange system:

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

Note!

For the original valves, there is a right and a left version (depending on which side the valves are mounted). The replacement control valves are usually flexible for both versions through a replaceable sealing plate.

 

Bosch SB23 LS

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

Bosch number range:

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

Manufacturers who installed the system (list may not be complete):

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

Flange system:

The system was always delivered with three studs:

The two small holes in the area of the electrical unit serve to 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 studs. If this surface has been machined flat, 0.05mm thick shims must be added. These are intended to prevent the valve from binding.