Power steering question

[cranetruck]

Question for you 5-ton guys, if you put the front wheels off the ground, how hard is it to turn the steering wheel without the engine/pwr steering running?

I'm trying to find out what's "normal". My 8x8 with two axle steering is extremely hard to turn and the ball joints are very tight, just can't believe it's supposed to be that way. (My truck hasn't been driven yet) I can't imagine that it would be possible to keep going straight if the caster effect of the wheels has to fight this.

I have one of the tie rod ends off, but can't find any spec on the torque required to turn the ball in the socket (mine is like 50-70 ft-lb)....


Thanks,

 

[M543A2]

I can try it for you on a normal 5 ton, but the steering on it is probably not as complicated as on your 8x8. Do you want me to run the experiment for you anyway on my five ton tractor? I could give you some information like what force reading I get on a pull scale at the outer end of a steering wheel spoke. Also, all of my trucks have been used, so the parts might not be as tight as new.
Regards Marti

 

[cranetruck]

Yes Marti, thanks, that would be great.
The more info the better, the 8x8 may have two steering axles, but the principle is the same and all factors effecting the alignment apply.

My friend Frank in Tulsa, OK says that his xm757 "drifts" on the road. His joints are also very tight. IMHO the tightness of the tie rod ends and the other ball joints is the cause of this.

 

[M543A2]

Bjorn:
OK, will do. It may be this evening or tomorrow. There are the two types of PS, the newer version with the assist cylinder and the older version with the huge Ross unit on the frame rail. Which one do you want me to test, or both?
Thanks Marti

 

[M543A2]

Bjorn:
Another thought. When we had complaints of this at the shop, we would check axle tilt. Adding wedges between the axle spring perch and spring pack at the rear to angle the axle king pin alignment reference the road surface more did the trick. The top of the axle is rotated back to the rear more by the wedges, causing more positive steering due to more caster angle. These small wedges are commercially available. There should be specs somewhere showing what angle the axle should have. This won't be an easy job with the large parts involves, but it may be the answer. I will still get the info for you.
Regards Marti

 

[cranetruck]

Appreciate your help! The alignment may be a problem too, since the right front tire is worn unevenly, but that will have to wait, gotto fix the ball joints first. I was almost afraid of breaking something when turning the steering wheel the first time (both front axles on blocks).
The system consists of a Ross gear and a Vickers hydraulic cylinder as shown below. As you can see with all joints stiff the problem is multiplied by 13, that's a lot of torque to fight. Actually 11, the idler arm and the joint at the cylinder are lubed joints.

 

[Knucklehead]

Bjorn, I just tested Kerri, my blue M52A2. With a scale on the outmost edge of the steering wheel spoke here are my results.

Both tires in the air=4.3 lbs. pull.

One tire in the air= 4.75 lbs. pull

Both tires on the ground, no jack support, = 10.75 lbs.pull

I made a full revolution of the steering wheel in both directions to obtain these results. I am sorry it took so long but cold damp weather kills this crippled old fool.

 

[Elwenil]

If I remember correctly, in my conversations with Tom on his Expansible Van 8x8, he said his was a handful to keep in the road. When I asked about the 45 MPH top speed he said that was all it had in it, and I really wouldn't want to go any faster since it was sort of hard to drive.

 

[cranetruck]

Thanks Knucklehead, beautiful, this forum really is a great resource!
I'm now positive that the handling problem can be traced to the ball joints.

 

[M543A2]

Bjorn:
My M543A2, both wheels off the ground, with the steering assist cylinder like your illustration shows, takes 5 to 6 pounds pull at the rim of the steering wheel. I used a steady pull, going one half turn of the wheel, keeping the pull scale as tangent to the wheel as I could. I maintain a regular PM/lube schedule on the trucks, so everything should be properly lubricated. The truck steers down the road at 55 MPH with no problems whatsoever.
If yours turns as hard as you found with all wheels in the air, you definitely have something binding up. My suggestion about the caster angle will not help in that case.
Do the joints have grease fittings on them? If not, I have drilled and tapped ones on an M135 for grease fittings. Maybe that cannot be done on yours.
If I can get any more info for you, please let me know.
Regards Marti

 

[cranetruck]

Thanks for your help Marti! Another confirmation that I'm on the right track.

I began the thread with this: http://steelsoldiers.com/index.php?name=PNphpBB2&file=viewtopic&t=8407&start=60

but separated this question from the main body of things for a more specific answer and got it. You guys are the best!

Marti, as you can see from reading the longer thread, the options are now down to buying new replacements for the tie rod ends or, if possible, excercise the joints until they loosen up (I'm working on that).


Thanks again,

 

[jasonjc]

Bjorn you mite try to get Bruce to give you an ide on the steering on his hemtt is. That mite be beter being an 8X8 also. Just a thought.

 

[M543A2]

Bjorn:
I have heated joints with a torch and then put them in cold automatic transmission oil. As the part cools, it draws the oil into the joint. If possible, work the joint as it cools under the oil. ATF's high detergent content really floats the crud out of stuff when you work it during and after immersing it in this way. You don't want to get them red hot which will damage the joint, just 200 or so degrees. The heat on the outer socket also usually loosens the tolerances so there is more room for oil to penetrate.
Good luck! Marti

 

[JDToumanian]

Marti, those joints have plastic (Delrin) inserts with a dry lubricant impregnated cloth liner... An unusual design. The other thread on this topic (link in Bjorn's post a few back) had a cut-away view of one of them, and design information from an original publication. I'm sure they could be heated some without damage, but knowing when to stop would be the trick, and you wouldn't know if the joint had in fact been melted.

Jon

 

[cranetruck]

I agree with you Jon.
Suppose I could cook one on the stove in oil and then move it into a bath of cold oil.
A digital thermometer to keep track of temps.
Then again, soaking in different penetrants for two weeks didn't accomplish a thing.

Wonder if the joints got tight during their time in service. They served from 1969 to about 1980 something....

 

[M543A2]

Good point, Jon. I missed the cutaway view. My engineering information shows Delrin, depending on formulation, having a melt-flow point of 345 to 374 degrees Fahrenheit. This is why I suggested 200 degrees F.
We can still investigate if they can be drilled in a strategic point for a grease fitting. The cutaway should give one an idea of where this might be. When drilling into things like this where I do not want shavings to get into it, I keep the drill tip coated with heavy grease, only drilling a short distance at a time, retracting the drill to clean off the shavings and grease, adding new grease, and so on. I do the same with a tap.
Regards Marti

 

[cranetruck]

Marti, the image below shows the cap drilled. I used a greased bit like you suggested. After two weeks of soaking one in CLP and a second soaking in "Heat Valve Lubricant" (GM), there is no change to speak of, both still require 50 to 70 ft-lb to turn.

The penetrants have yet to exit on the "bottom", they are very tight indeed. Really don't think grease will do any good at all, without grease channels.