So I have tried all the things the service manuals express on to try and thus I end up coming to the tribal knowledge group that hangs out here.  I have in the past few days attempted to add a power steering kit to my 917 blower tractor along with the hydraulic lift (The designed Simplicity/A-C units for the 7100/900 series tractors).  So we are talking about installing the proper rock shaft and hydraulic cylinder for the hydraulic lift and then the hydraulic cylinder / steering column actuator for the hydraulic steering.

So have everything in and mounted, I can steer the tractor but there isn't any power assist and the lift shaft doesn't rotate either.  I did cycle the hydrostat system as stated in the manual to help remove any air along with adding about a quart and a half of fluid to the hydrostat to bring it to the top level of the fill tube.  My guess is I have some air trapped in the system as all of the items I added were most likely drained of any oil from their previous installed and working condition.

What is the trick to get this potential trapped air out of my system?  With the lift, I put a large crescent wrench on the lift arm and cycled it with the corresponding hydraulic lift lever.  I can get it to move in the correct direction as the lever would be sending it.  If I try to with the wrench apply a force opposite of the intended direction I have resistance as well as the neutral position of the hydraulic lever.  As for the steering, I saddled up and took the lawn tractor for a spin in the yard looking like a drunken sailor turning left and right numerous times, but no improvement.

Common sense would tell one to fill the cylinders/hydraulics with oil at assembly, but the design of the components, has all of the connections coming out on the bottom, thus making for a big potential mess at assemble.  It would be possible I guess to fill the two cylinders and hurry at an oily assembly.....so I thought I would put it out here for the unwritten wisdom of the forum.  Appreciate any thoughts or ideas, this is my blower tractor which I need to get back in action.

The Simplicity Large Frame Garden Tractors Service and Repair Manual covers it, but here is a good article about it as well:

https://simpletractors.com/forums/topic/65773-sundstrand-pressure-checking-recovered-article/" rel="nofollow - https://simpletractors.com/forums/topic/65773-sundstrand-pressure-checking-recovered-article/

Hope this helps