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I just found this post as I begin working on my 1963 B61T power steering and I thought I would jump in here. 
My B61T has a small belt driven pump mounted high up on the left side of the engine.  The two hydraulic pump lines run to and from a proportioning valve that is the link between the pitman arm and the steering knuckle.  Two more hydraulic lines from the the proportioning valve run to and from the power assist cylinder that runs parallel to and on the back side of the front axle.  I don't have any power assist in the steering at this time and I suspect the hydraulic pump isn't doing any work.  I will confirm that when my hydraulic test kit arrives this Friday.  There is a noticeable leak in the proportioning valve so I expect to rebuild that soon.  Has anyone seen this setup?  Neither my Mack service manual nor my Mack parts book shows any power steering options.  The only nod to power steering is the mention of ST-A (Hydraulic Steering Fluid) "Use Type "A" Suffix "A" Automatic Transmission Fluid" in the lubricants section of the manuals .  I'm  hoping to find Mack part numbers when I remove the proportioning valve this weekend.    


Sounds like garrison power assist steering

6bf39367a7706362601d0a5ecd80ccfb.jpg

Clean the grease off of the control valve, drag link, you may find a part number

99f0732c9aece1792141862db1700ff0.jpg

If you pm me your email address I can send you the manuals that I have

Does it turn to the right with power assist?

Depending on where you are located you may be able to get it to work by changing the fluid

Good news is that garrison is still in business and located in Southern California

Bad news is that the valves quite often are not rebuildable due to wear.
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4 hours ago, HugeHugh said:

I just found this post as I begin working on my 1963 B61T power steering and I thought I would jump in here. 

My B61T has a small belt driven pump mounted high up on the left side of the engine.  The two hydraulic pump lines run to and from a proportioning valve that is the link between the pitman arm and the steering knuckle.  Two more hydraulic lines from the the proportioning valve run to and from the power assist cylinder that runs parallel to and on the back side of the front axle.  I don't have any power assist in the steering at this time and I suspect the hydraulic pump isn't doing any work.  I will confirm that when my hydraulic test kit arrives this Friday.  There is a noticeable leak in the proportioning valve so I expect to rebuild that soon.  Has anyone seen this setup?  Neither my Mack service manual nor my Mack parts book shows any power steering options.  The only nod to power steering is the mention of ST-A (Hydraulic Steering Fluid) "Use Type "A" Suffix "A" Automatic Transmission Fluid" in the lubricants section of the manuals .  I'm  hoping to find Mack part numbers when I remove the proportioning valve this weekend.    

My B Mixer has that set up. It's a Garrison Hydraulic Assist. All the parts are available from Garrison in California and from Steering Re-builders and Truck Parts in Texas.  For both Ross and Shepard boxes.

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After I cleaned off the dirt, I found a Garrison 2001-10-x0 as the power assist steering valve.  The Garrison rep says no metal parts are available for the valve.  The pump is an Eaton "U" model pump with cylindrical steel vanes.  The pressure relief poppet was installed backwards in the pump and that is why the power assist steering wasn't working.  There is leak in the steering valve that I need to evaluate but the power assist is functioning.  I will check with Steering Re-builders and Truck Parts in Cleveland, TX to see what they offer.  Anyone familiar with Garrison know what the two numbers below the model number designate.  My valve has 5  72.  Do you think that is a manufacture date of May 1972?  

garrison_2001-10-x0_value.jpg

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Mine is stamped 12 74 and it is on a 1975 truck

I have always assumed that the numbers were the build date

Your valve looks different from mine, can you post a picture of the entire valve

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I just got my paperwork from the Mack museum yesterday, it only took them 3 months, and the steering is listed as garrison

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The slave on my B is 6-61 date of manufacture of my B mixer is 9-61.

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