520H Power Steering Modification

[JoeM 8,963]

Straight from the back burner, I have been tinkering with this 520H. I bought an orbital steering valve from 19richie66 and decides to modify the 520 to power steering. 

I seen a thread a while ago were someone added steering to a 518. Figured that would be a nice side project if I came across a reasonably priced steering valve. 

 

I wanted to keep it looking the same and tucked in the column. It was a little tricky with a mix of face seal and jic piping. Picked up some face seal fitting from MMC and silver soldered to the steel pipe.  

 

For now it is on ice, next will be the front axle mod to accept the steering cylinder. 

 

Absolutely don't need a 520H with power steering but I like to build things and keeps me out of the Mrs. cross-hairs. 

 

Used the c120 and old deck belt to test run.

 

front view

 

 

 

 

[ebinmaine 74,709]

Interesting concept. 

I've mentally tossed about the idea of using a steering quickener from a race car - but reversed. 

Twice the steering wheel turns but with half the effort.....

 

 

[peter lena 9,479]

@JoeM   like it !  for me experimentation  is a regular thing , don,t have any hydro anything  , but can relate to the piping set up . like trying  to improve / remove repetitive issues . your side view pictures , did it for me , often refer to roller stooling around  a set up , while  trying  something  , makes it much easier, like to  change over  a plow and frame set up , that way , 2 milk crates  hold the frame / plow  at   close to original set up height  , yet you are  free ,  to  swap out  and detail linkage rods , improve  functional detailing, once swapped  out  improved , you can easily  make it  effortlessly  swing  and move , the swing quadrant  squeeze lever , runs the entire show . grand son is slotting  a golf ball size , palm grip metal push / pull point  , he builds welds truck frames  . stay at it , pete    

[JoeM 8,963]

32 minutes ago, ebinmaine said:

a steering quickener from a race car - but reversed

years ago, I kicked that around myself. 

In the end I was thinking if the fan gear would hold up and moved on.

[Handy Don 14,758]

The 518 conversion was in the UK. As part of the project, the member replaced the lower steering shaft and the tie rods with a solid bar linking the spindles. The hydraulic power steering cylinder moved the bar. 

Turns out the different linkage configuration didn’t have a proper Ackerman geometry and so steering was easy but cornering caused tire scuffing and wander. 

 

[JoeM 8,963]

Testing vid

 

[Pullstart 68,324]

@Bow_Extreme Matt, did you have the 520H power steering prototype of many years past?

[Bow_Extreme 580]

On 11/8/2025 at 11:13 AM, Pullstart said:

@Bow_Extreme Matt, did you have the 520H power steering prototype of many years past?

 

It’s still here.

[Bow_Extreme 580]

On 11/8/2025 at 7:32 AM, JoeM said:

Testing vid

 

Nice job on this!  

[JoeM 8,963]

On 11/7/2025 at 5:13 PM, Handy Don said:

Turns out the different linkage configuration didn’t have a proper Ackerman geometry and so steering was easy but cornering caused tire scuffing and wander.

HD good catch!

I went back and searched for the PS thread and found it was done by @Damien Walker. He wrote an excellent PDF with updates. The steering geometry was solved by adding these plates to the arms on both sides. This will save me from cipher'n the problem myself. 

 

Damien also sited the number of turns lock to lock. I have about 3 1/2 turns lock to lock. I may replace the cylinder with a smaller lift cylinder from a 520H. It should get me below 2. Damien says he used a 1 inch cylinder and it worked good plus the steering was still easy. 

 

 

[Blue Chips 245]

On 11/7/2025 at 5:13 PM, Handy Don said:

Turns out the different linkage configuration didn’t have a proper Ackerman geometry and so steering was easy but cornering caused tire scuffing and wander. 

 

I encountered a similar Ackermann geometry issue on my1953 Ford NAA (Golden Jubilee) tractor. After resetting the front axle to a wider track width (to match the widened rear track width) and resetting the toe-in to the correct amount, it steered easily and tracked perfectly when driving in a straight line, but the sharper the turn, the more the wheels scuffed and dug in, since the radii inscribed by the left and right wheels were no longer concentric with each other. I could see no way to correct the geometry without custom alterations, so I'm planning to change the front track width back to standard width. The main reason I widened the front track width to match the rear was so that I could mow very close to obstacles with the front tires, knowing that the rear tires would also clear the obstacles. I'll just have to be more careful when going by obstacles after I change the front back to standard width.

 

 

Edited Monday at 02:24 PM by Blue Chips

[Handy Don 14,758]

19 minutes ago, Blue Chips said:

I encountered a similar Ackermann geometry issue on my1953 Ford NAA (Golden Jubilee) tractor

As noted in the couple of previous posts, your issue might be remediable by relatively simple changes. Lots of tractors were designed to have adjustable front tracks and included alternate positions for attaching the tie rods to the central steering actuator and the spindles to maintain good steering geometry.

The math for it is standard 11th grade trigonometry combined with carefully accurate measurements. The best explanation I’ve seen online is this one  

[Blue Chips 245]

4 hours ago, Handy Don said:

As noted in the couple of previous posts, your issue might be remediable by relatively simple changes. Lots of tractors were designed to have adjustable front tracks and included alternate positions for attaching the tie rods to the central steering actuator and the spindles to maintain good steering geometry.

 

The math is no problem. And yes, the NAA front axle was designed to be adjustable to several different widths, ranging from 48 to 76 inches IIRC. However, I have several shop/service/owner manuals for it, and I have not seen any mention of any steering adjustments to be made after changing the width other than adjusting the tie rods (aka, drag links) for toe-in. Here is a LINK to an owner's manual (see pages 27-30). From my readings and from other owners, the general consensus seems to be that for agricultural use, it wasn't considered very important if the wheels scuffed the ground on sharp turns in soft soil, but if you were using the tractor primarily on hard/paved/smooth surfaces, such as for mowing lawns, it would be a much bigger factor, and you would probably want to leave it set to the standard width.

 

NOTE that the spindle arms only have one attach point for the tie rod end and can only be attached to the spindles in one position, as they are keyed to the spindles.

 

Likewise, the two sector shaft arms (pitman arms) also have only one attach point each for the tie rod end, and the splines were cut in a way that only allows one position on the sector shaft.

 

IF I modified the splines to allow different positions of the pitman arms on the sector shafts, I might have a little to play with regarding changing the relative turning radii of the inside and outside wheels on sharp turns. I don't know if it would be enough, and it's not a high priority, so it will probably never happen.

 

Now that I'm no longer bush hogging about 20 acres of fields (since we sold our other property), I only use the tractor for a once-a-year first mowing/de-weeding of about an acre of grass and cutting down encroaching shrubs around the edges, and I don't want to tear things up too much, so it's going back to a standard width.

 

 

Edited Monday at 07:49 PM by Blue Chips