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I tried to put a steering knob on my 1985 JD 318 that I recently purchased. I love this tractor! I don't understand why I can't place a steering knob on it though. I installed the knob at the 2:00 O' Clock position with the wheels going in a straight line. Took it for a little drive and the steering knob ended up poking me in the gut (6:00 O' Clock) while I was going in a straight line. Put the knob back at 2:00 O' Clock and it ended up at some other random point after a little drive. Then I noticed that the deer on the center of the steering wheel never ended up in the same place twice while going straight.

What the hey!
 

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Is the steering is driven by hydraulics?
 

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Jimmy, Yes. The 318 had power steering.

BC, Either EXTREMELY loose front end parts or bad steering control valve. Lift/jack & support to both front tires off of ground. Watch hydraulic cylinder on right side of tractor and push/pull tire...to simulate a turn left or right. If little or no movement before hydraulic cylinder wants to move, bad steering control valve...located at bottom of steering column. Bob
 

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The above posts are correct -- the hydraulic power steering does not provide a deterministic mechanical coupling of the steering wheel position to the direction of the front wheels. Even a brand new tractor would not provide a repeatable position considering over-travel of the wheel at the steering stops, starting and stopping the hydro pump, movement of the steering wheel when the engine is not running, etc. Here is the hydraulic schematic diagram, and the theory of operation for this tractor's steering system:

5-port PS on 318 -  hydraulic schematic.JPG

View attachment power steering theory of operation from 318 Tm1590.pdf
 

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Discussion Starter #7
I was thinking the steering knob was going to give me a "feel" for direction. Since it's physical position on the steering wheel would always be relative, I can't use that aspect of the steering knob.

Question for the folks using a steering knob on their 318, do you get used to the knob stopping at a random position? Just trying to wrap my head around this. I was ready for the funny farm after about 5 minutes of using it. :laugh:
 

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I was thinking the steering knob was going to give me a "feel" for direction. Since it's physical position on the steering wheel would always be relative, I can't use that aspect of the steering knob.

Question for the folks using a steering knob on their 318, do you get used to the knob stopping at a random position? Just trying to wrap my head around this. I was ready for the funny farm after about 5 minutes of using it.
I went though the same thing when I put a knob on my old 445, and its the same way on my new 1025r.

Yes, you get used to it. I don't even notice it anymore. I just jump on and go, don't pay attention to position of knob relative to tires.

Sent from my SM-G960U using Tapatalk
 

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I went though the same thing when I put a knob on my old 445, and its the same way on my new 1025r.

Yes, you get used to it. I don't even notice it anymore. I just jump on and go, don't pay attention to position of knob relative to tires.

Sent from my SM-G960U using Tapatalk[/QUOTE

Thank you! I was hoping someone would say something like this.
 

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Agreed that you will get used to it!:)
 

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This is a great site! I thought I was going to be the only one with questions like this. So, now that I have discovered that the behavior of my 318 steering is normal by not maintaining the steering wheel position to the direction of the wheels, does anyone have suggestions on which steering wheel knob to buy?
 

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Joe, This IS a great site with ALL good people in here. You may get a lot more answers than needed because people use different reasoning for their thoughts/ideas. But we're all here to help!

As far as which knob to buy, that's like asking what car, Chevy Ford, Chrysler, Toyota, Honda, etc. YOUR tractor, YOU are the one to look at it, and YOU are the one to use it. Get the one that appeals to YOU! It's not a major expense where you'll have to re-mortgage your home, and they all do the same thing, attach to steering wheel and rotate! Some look better than others, but that's a personal opinion...like are blondes or brunettes better looking. ? Bob
 

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What happens with the PS when driven by a hydrostatic system, once you reach the mechanical limit of the steering (the "stop" down at the axle pivots) and continue a steering input, you run up against a relief valve, It allows the steering wheel to continue turning, while the wheels don't go any further. So, when you straighten up the wheels, the steering wheel isn't necessarily in the same position. It's not all that noticeable to me on my 318, but I noticed it all the time on my X748. The 2520 must use a slightly different system, an independent hydraulic loop to the steering cylinder, I suppose, because once the steering cylinder reaches its travel limit, the steering wheel won't turn further, like in a car.
 
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