Identifying a power steering gear

Identifying a Power Steering Gear

Hydrosteer regularly get asked all the time is how to go about identifying a power steering gear that is fitted to a vehicle.

Often we can identify a power steering gear fitted to a vehicle from the make, model and year.

It is normal for their to have been more than 1 power steering gear model used on a particular make and model. So there is nothing like 100% confirmation that we have the correct information.

To confirm we ideally need to identify the power steering gear from the part number stamped / fixed to it.  The style and location of this part number is not a consistent across the different steering gear brands.

What is consistent is they are always covered in grease, often positioned in the vehicle to make it difficult and typically pin punched in small characters so they are very hard to read.

There are 3 main brands of power steering gears which are fitted to North American and European trucks, R.H. Sheppard, TRW and ZF/Robert Bosch.

We have covered how to identify a R.H. Sheppard M100 or  M110 series power steering gear in an earlier blog.  As a reminder it is pin punched onto the machined surface which surrounds the output or sector shaft.

Click on the link below for a more in depth look at this,

TRW / Tas Steering Gears

Part Number on TRW Tas Steering Gear

TRW TAS series steering gears have the part number pin punched into a machined flat. The machined flat is typically located on the housing opposite to the input shaft.
These gear part numbers typically have a class of

TAS85020A or TAS85123A,

the second visible is the serial number.


ZF / Robert Bosch Steering Gears

ZF / Robert Bosch Steering Gear identification

ZF / Robert Bosch Steering gears have the part number on a small aluminium tag. The tag is fixed to the steering gear housing on also on the end opposite to the input shaft.
These steering gears have part numbers like


The equivalent Robert Bosch Part Number would be KS00 001 239, these are on a sticker fixed to the steering gear at present.

Robert Bosch are taking over the ZF range of power steering gear so overtime the ZF part numbers will be phased out and the Bosch numbers will become prevalent.



I hope that help the identification of your heavy vehicle power steering gear, Good Luck and drop us a line if you need any more help.












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