Wa 500-6 series Komatsu Steering Problem

[Lewis12]

:Banghead The steering issue on this loader is that when you press down on the brake pedal and hold it there, and then you turn the steering wheel. The steering wheel will turn freely, but the front tires will not turn in any direction. Unless you let go of the brake pedal you can turn the steering wheel. Has anyone seen this issue.

 

[Lewis12]

Am going to look into the relief valve at the steering valve. If you let go of the brake pedal the tires will turn either way.

 

[DK88]

Sounds normal..

 

[BuMach]

check the presure relieve valve of the steering system, might be that you dont have enough pressure to steer it against the brakes.
I don't have enough experience with those bigger komatsu's to tell you if it would be normal that when you apply the brakes that you can't steer..
i know smaller loaders (until 30 tons) will do.

 

[DK88]

With brakes applied it will steer only maybe 10 degrees each way and then it will lock up, completely normal.
What's the pressure? Put frame lock bar in and plug a gauge on the steering cylinder.

 

[Lewis12]

Yes the steering wheel will turn in complete circles but the wheels will not turn either way when the brakes are applied at the same time. Just release your brake foot then your wheels will steer either way. Now am told the komatsu guy gunna take a look at it. Will post what he finds once he takes a look at it.

 

[posthoorn]

and? found out anything regarding the steering issue?

 

[Lewis12]

Steering pump and ppc pump that mounts to steering pump were both replaced and it still does the same thing. I think the problem is in the steering control valve that's the only thing left pretty much. But operator using it like this anyway

 

[DK88]

What's the steering relief pressure?

 

[Jim D]

Leaking head seal on one of the steering cylinders?

Had that happen on a smaller loader, and the loader steered and worked ok, but you could turn the steering wheel around and around against a load, like 'turning' the bucket sideways against something immovable. (The real problem was that highwaying you slowly wound the wheel to the right, with each back and forth steering correction)

 

[kshansen]

Leaking head seal on one of the steering cylinders?

Had that happen on a smaller loader, and the loader steered and worked ok, but you could turn the steering wheel around and around against a load, like 'turning' the bucket sideways against something immovable. (The real problem was that highwaying you slowly wound the wheel to the right, with each back and forth steering correction)

Head seal? Maybe it's just a terminology problem but to my way of thinking a "head seal" leaking would be seen as oil coming out where head is attached to the barrel or around the ram itself. I would be thinking bad piston seals on one or both cylinders. But the one thing I see missing here is any mention of when this problem started. Did it work fine Monday morning then around 9:00 am it all of a sudden started doing this? Or is this a new operator who just got in a loader for the first time this morning and has no experience running anything bigger than a riding lawn mower?

Just working on first cup of decaf this morning so I might be rambling on a little. But a couple things I would be checking as someone else said what are the pressures at the cylinder with frames locked? Next I might want to leave frames locked and disconnect the lines from the cylinders and connect a couple gauges to the hoses from the control valve and see what pressures you get that way. If it was low when hooked to the cylinders but right where it should be with the cylinders unhooked then you know the problem is in the cylinder(s).

I would like to know what made the "dealer" decide to replace the pump. Ideally hooking a flow meter to the pump would be a way to prove the pump was good or bad.

Has anyone removed and cut open the filters to see what if anything is in them?

If this was a year ago I could check out how the WA600 at work steered with brakes locked, but I'm retire so that is not an option. However seem to recall most of the loaders of that size we had would steer, a little hard and slow, with brakes applied. I do recall the one time I roaded a loader, 966D I remember that the steering wheel did slowly work it's way around while making corrections going down the road, that was a brand new loader with almost no hours on it and was used for many years with never a problem. So I would say that is normal.

 

[DK88]

remember those have valves on the top of te front frame that cut the oil flow to the amp valve to avoid the hard jamming of the steering, usually ifthey stick they will only turn one way but it could be a case of not quite enough cut off to make full pressure.. just a thought.

 

[Jim D]

kshansen, yes, piston seal. Sometimes hear 'piston head', meaning rod head... the head on the rod...

What I saw was a bad seal on one piston. The machine still worked ok.

 

[Jim D]

I do recall the one time I roaded a loader, 966D I remember that the steering wheel did slowly work it's way around while making corrections going down the road, that was a brand new loader with almost no hours on it and was used for many years with never a problem. So I would say that is normal.

I have a small machine, built with only one steering cylinder (on one side), so there's piston displacement turning one way and piston displacement minus rod displacement turning the other way. The steering wheel winding around while driving is normal, and it is very annoying.