Cat 426 Boom wont lift a load unless i start to swing.

[aschumann28]

Ok so I got a new Tranny in my Backhoe and its been working great so now to tackle the next problem. The main boom is slow to lift and when it has a full bucket it wont lift at all. But i learned this weekend that if I start to swing the boom while lifting it does the job. I can swing left or right, as soon as the stick moves to open the swing valves i get the hyd power to lift the boom. Is the problem in the joystick manifold.any comments is appreciated. Thanks

 

[Bob/Ont]

Try lifting the boom and working each other circuit and see if they will make the boom come to life. If any other circuit will it's the resolver valve for the boom.
Later Bob

 

[aschumann28]

I will try that this afternoon when i get back to my property.

 

[aschumann28]

So I warmed up the hydros and after I got the fluid warm I tried like you said and the boom would only come to life when I would swing. It did not do any good when I tried the other functions. I was going to check the resolver valve this weekend. Could it be something else? Thanks

 

[Mobiltech]

It could actually be a resolver in the swing too . Usually when you have a signal resolver problem it ends up being the one valve that works that has the bad resolver.

 

[Cmark]

It could actually be a resolver in the swing too . Usually when you have a signal resolver problem it ends up being the one valve that works that has the bad resolver.

I would go so far as to say it fault probably is in the resolver for the swing spool.

The reason is as each function operates, it tries to build pressure in the resolver network, but the pressure is lost through the bad resolver. When the function with the bad resolver is operated, it is able to build pressure in the network against all the other good resolvers.

There was a thread on this a while ago. I'll try and find it.

Edit. This one has a bit of yak about resolvers. https://www.heavyequipmentforums.com/showthread.php?25733-Cat-924G-hydraulic-problem