Hi; I recently purchased a gently used 950 wheel loader #73J4494. I have a service manual for the machine and a retired NC Cat engineer helping me. The machine is not able to turn as far to the right as it should, though we can turn it to the left with room to spare. We've adjusted the follow up linkage to spec, and have ascertained that either the pitman arm is bent (it doesn't look damaged) or the cog in the steering control box is off a tooth, whether that means it sheared a woodruff key or jumped or however it happened. The linkage appears to need to be shortened as far as it allows in order to get the limited steering we do have to the right, lengthening it to the 7.5" on center limits the steering further. Basically, bringing it to spec made it worse, and while shortening the adjustment helps, it's as short as it gets. With the follow up linkage disconnected, we get 3 full rotations of the wheel. I cannot find in any service manual or from any local operator the proper number of rotations of the wheel - and without knowing that information it's difficult to proceed with further troubleshooting save tearing the steering box apart to try to check for ourselves. Does anyone have any information that might help or know anyone with a similar machine I can contact? I've contacted NC here in Anchorage and their research guys haven't gotten back to me, I imagine they are having difficulty finding this answer as well. Thanks! -Chance.
There was a problem with the larger loaders with the whole control station moving I believe causing a similar issue. Perhaps someone else will chime in. We owned 73J3713 many years ago. Was a Japanese sourced 950 if I remember correctly.
No experience with 950 Cats but one thing we did find with the 966C's and 988A's was if someone tried towing a dead machine and was not very careful to work the steering wheel to keep up with even small pivoting of the machine while being towed the arm the follow up linkage was connected to would get bent. It does not take very much of a bend to cause you to not be able to center up steering, not something you would notice just looking at it by eye. The fact you seem to say you have more than enough turning to the left also leads me to think this is what has happened. The proper fix would be to replace this arm with a new one or a known good used one. That said at risk of being told "DON"T DO IT!" more than once when we had this problem we "fixed" it by the same method that caused the problem. What i'm saying is if it won't turn far enough to the right with engine running a few careful nudges to the right with engine off might tweak it back to where you can get it to adjust properly in both directions. There are only a few people I would trust doing this proceedure as too many are like the "Bull in a china store" and would make matters much worse. The arm that gets tweaked is the part in red above. Looking in SIS it looks like the part number for this part is 6K8534 and shows as being available in Morton for $1,173.62 And a side note when searching on line for that 6K8534 it shows up under the assets of "UGANDA NATIONAL ROADS AUTHORITY"! so if anyone has connections that way.....
I appreciate it guys - the pitman arm (5 in red) in the service drawing above being bent was indeed our first consideration. It's a joy being in Alaska and not having anything to compare this to, and to spend $1600 after shipping and a months wait time to realize we have sourced the wrong solution is really the issue. At the same time, re-torquing the arm to the correct position also could cause a problem where there isn't one - if the pitman arm isn't bent, and it's the gear in the steering box that's off a tooth causing a lack of rotation or the receiving part had sheered a woodruff key, then we've got a bigger problem than we started with. If I can find out how many rotations the steering gear is supposed to allow with the pitman arm disconnected, then I can eliminate the steering gear from the equation and order or try to re-bend the pitman arm as described. I can't find it but I'm assuming there are specs for that steering gear somewhere (or in someone's head). Thanks again
Well if no luck finding anyone with spec's and no one with a 950 or 966C, which I am thinking has the same steering box, can chime in with steering turns lock to lock. One could possibly open the box up with it in the machine and see the gears and confirm they are in right. Actually did check and the two gears inside the box are the same part number for the 950 and 966C steering box. Another look at the steering box below, the green cover looks like it would not be too bad to remove by it's self. The adjuster in the middle is just a thrust button on the inside. Book says to run it in till it touches and back off 1/8 turn so should not be anything to get excited about. Thing is unless someone has had this apart in the past there would be no way for the box to jump a tooth. One thing for when you get this figured out is I would suggest removing the steering column from the box by taking the bolts out that go through the flange in blue near the top of the picture and clean and lube the splines as they can sometimes get stiff and sticky and cause hard steering.