Parker/ TRW / Ross HGA Hydraguide Model Identification

In Uncategorized by MWS Staff

HGA Model Number Explanation


Parker TRW Ross Hydraguide Series Steering Control Units (SCU) have a unique model number assigned to each SCU.  This part number is stamped into the top end cover.  Please see attached PDF, or take a look at our photo for a visual description.

The top end cover is attached to the main body by (4) four attaching bolts. This cover houses the input shaft seals.  The main input shaft protrudes from this cover.  The HGA part number is stamped into the metal with a die, often by hand. The number is under the surface.  Generally the number follows a three digit letter sequence “HGA” followed by five numeric digits.

For an example, it might look like HGA08122 236 16

BUT wait there are more digits?  Sometimes there will be a date code after the model code.  So in the above EXAMPLE 236 16, stands for the 236th day 2016.

So back to the example HGA08122– we have a HGA08 displacement, open center with a pinhole shaft.  We can explain options further with a phone call or an email.

OR you could have an example of HGA08122-A1-2750….Which calls out a steering column.  Please call us so we can provide pricing and availability


SO what if the HGA does not have a part number?  After you have scrapped paint, cleaned rust off and removed any brackets you still can’t find a part number. Don’t worry.  We can still help you.  Just give us a call.  We will need to know some information to be able to provide parts, an entire unit or one of our amazing aftermarket replacement units


  • How many ports?
  • What type of input shaft? See attached PDF
  • What is the height of the gerotor can, #51 in the attached PDF diagram.
  • Open Center or Closed Center Hydraulics?
  • What is the application? or call us @ 1.800.237.5048