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Load Sense

partsandservice

Senior Member
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Feb 14, 2011
Messages
846
Location
Georgia
I posted a similar thread in the wheel loader section, but got no response. I am working on a JD 544j. The steering system is not activating the pump. When in a bind the steering is weak but will kick in if you work a lift function at same time. I have found the steering compensator valve and removed the cartridge . The cartridge does not look like it could be disassembled and the orings are good. A small line comes from the steering valve and goes to the compensator block, also a small line goes from the steering motor to the main control valve. So my question is , how can I determine where I am loosing the load sense signal from the steering valve without replacing parts?
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AndrewC

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Feb 2, 2013
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458
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Miles away
Did you put a gauge at the load sense connector and see what its actually doing? Have you changed the steer valve yet?
 

partsandservice

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Feb 14, 2011
Messages
846
Location
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I have not changed any parts yet. I had a gauge on the load sense connected on the pump compensator. When ever I work a load function I have 2500 psi when function reaches end of travel. When steering I only have 500 psi, when machine is rolling steering is fine. When the steering gets in a bind I can move a lift function and the load sense pressure goes up and it steers fine. I am not discounting the steer Cly. Idea I just have trouble wrapping my head around how a blown piston packing could create this problem . I had a similar situation with a track buncher. Tracks would hardly move, unless working a boom function at the same time, turns out it was leaking the load signal in the swivel. I guess I should make up some tee fittings and check if the steering valve is even sending and how much. I will still check the steer Cly for bypass.
 

AndrewC

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Check your steer cyls by dead heading and pulling the opposite line to see leakage, but we do change a lot of steer valves they wear out and usually start to steer on their own. The ls signal is only going to be the effort to steer so if a cyl was leaking your ls will drop off.

Just another thought to eliminate all ls checks in control valve would to be cap the ls line at the orbital valve and stroke functions on the boom and see if creating a ls signal from the other function will allow the steering to work. If t doesn't then we know it is in the steer circuit ie. cyls or valve.

Could you let me know what s/n your working with just to confirm a couple other things.
 

cutting edge

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Mar 27, 2010
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upper canuckistan
you've got a bad ls check valve in the main control valve. the seat will he pounded out. maybe Andrew c can pull up a parts page for you,he should know what I'm talking about.
 

willie59

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Dec 21, 2008
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Knoxville TN
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Service Manager
I'm not familiar with a 544J hyd circuit, but many functions like this, steering orbit valve that has a load sensing port, use a shuttle valve to send a load sense signal from the A and B output ports. A faulty shuttle valve would cause this problem if that's what the system uses. Just a thought.
 

Mobiltech

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Jan 14, 2014
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Sask.
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Self employed Heavy duty mechanic
you've got a bad ls check valve in the main control valve. the seat will he pounded out. maybe Andrew c can pull up a parts page for you,he should know what I'm talking about.

I agree on this. In a load sensing system its usually the component that works good that is the one that has a check valve problem. The main control is dumping the signal created by the steering .
 

partsandservice

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Feb 14, 2011
Messages
846
Location
Georgia
I could not find the check valve on the parts break down. The load sense line from steering valve goes into end section. I did see check valves in the spool sections are these what you speak of? AndrewC, 544j serial number 604168. thanks Keith
 

AndrewC

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Feb 2, 2013
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Miles away
The one in the outlet is the steer load sense for the steering. I cant find a good picture of it though. Find anything else?
 

chester8420

New Member
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Apr 6, 2021
Messages
4
Location
31091
Did anyone figure this one out? I have a 544J doing the exact same thing.... Weak or no steering pressure sometimes, and working a different hydraulic function restores full steering power.
 

grandpa

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Oct 15, 2009
Messages
1,979
Location
northern minnesota
you've got a bad ls check valve in the main control valve. the seat will he pounded out. maybe Andrew c can pull up a parts page for you,he should know what I'm talking about.
I've run into this as well. The washer the check valve seats on gets pounded out and sticks in the bore not allowing it to open up.
 

partsandservice

Senior Member
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Feb 14, 2011
Messages
846
Location
Georgia
It has been many years but i recall that the load sense hose from the steering valve was collapsed internally. Never saw it, just started replacing related hoses out if desperation .
 

chester8420

New Member
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Apr 6, 2021
Messages
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Location
31091
I am going to take a look at the machine tomorrow to familiarize myself with the hydraulic manifolds. I scoured through the JD online parts catalog for an hour or so trying to figure out how everything looks. Grandpa, would you happen to know where specific check valves are located, and/or what they might be called in the parts catalog? Sorry for my ignorance, but I just bought this machine. Thank you.
 

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grandpa

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Oct 15, 2009
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northern minnesota
Mine happened to be on snowplow controls, but the check was located right where the main pressure came into the control bank. On mine you pull the check valve out, and it comes out in a cartridge. Then dissassemble the valve and look in the bottom where the plunger seats. I was very lucky on mine, thinking the seat was part of the casting until I was blowing it out with air when the thing came loose and fell out. All I did was lapp the washer back smooth and it fixed it. The previous owner [governmental] had two new pumps put on to no avail.
 
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chester8420

New Member
Joined
Apr 6, 2021
Messages
4
Location
31091
Well I had my local dealer take a look at my 544J that has weak steering. They said it was losing the steering loadsense signal in the main loader control valve. The mechanic said he would get me a quote to rebuild it. I got the quote emailed to me... $6100
 
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