963B Slow Boom Raise During Travel

[631G]

Have a new one for the HEF team. We have a 963B that is slow to raise the boom once at operating temperature, but only while traveling. When the machine is park the boom cycle time is within spec. We have also replaced the implement pump thinking that was the culprit but still have the issue. Pressures also are checking out while stationary. Anyone seen this before?

Serial number: 9BL00974

 

[Nige]

Is it something that is getting worse over time..?
Does engine RPM (while travelling) have anything to do with it..? Low(er) engine RPM could produce the symptoms you are describing.

 

[631G]

Is it something that is getting worse over time..?
Does engine RPM (while travelling) have anything to do with it..? Low(er) engine RPM could produce the symptoms you are describing.

Nige,
No, not that we can tell does the engine pull down while traveling beyond what would be expected to be seen when engaging the travel motors. However, there is not a functioning tach on the machine at the moment so this evaluation is based on hearing alone.

Do you think this could be a seal problem possibly a valve spool. We’ve gotten ahold of a cat manual and there is a low and high flow valve that is actuated based on how much you move the control that I’m thinking could be the next candidate to look at. Have you had anything like that give out before?

 

[Nige]

You need CMark, our resident track loader man. I don't think he's seen this thread. Drop him a PM if he doesn't jump in.

A thought. You say that you have checked implement system pressures while stationary. Have you checked them with the machine moving..?

 

[Cmark]

Fact 1. Unlike the 343 and 953, the 963 and 973 have a pilot controlled implement system.
Fact 2. The transmission and implement hydraulic systems do not interact with each other in any way except that they are both driven by the engine, at engine speed.

The implements hydraulics are slowing. This sounds like a flow problem, not a pressure problem. Bearing these in mind, given that the implement hydraulics are slowing down when warm and travelling, the slowing must be related to engine RPM slowing under transmission load. Also bearing in mind the implement pump is new, it is less likely to be the problem, which leaves the pilot system suspect.

What am I driving at? Check the pilot pressure.

 

[631G]

Fact 1. Unlike the 343 and 953, the 963 and 973 have a pilot controlled implement system.
Fact 2. The transmission and implement hydraulic systems do not interact with each other in any way except that they are both driven by the engine, at engine speed.

The implements hydraulics are slowing. This sounds like a flow problem, not a pressure problem. Bearing these in mind, given that the implement hydraulics are slowing down when warm and travelling, the slowing must be related to engine RPM slowing under transmission load. Also bearing in mind the implement pump is new, it is less likely to be the problem, which leaves the pilot system suspect.

What am I driving at? Check the pilot pressure.

Cmark,

Just wanted to follow up on this loader. We have pulled it back into the shop again to start looking at this issue once again. Things have let off a little since the summer building season with a little bit of a wet spell here. We lost our staff mechanic and have been in search for a replacement but so far no luck. This was one of his open ended items he left us with when we packed it in unfortunately. We'll be checking the pilot pressures and get back with you to close the loop on the advice you gave. Also I've spoken with the operators who have most recently ran the machine and all report that the engine is not pulling down RPM's when the boom begins to slow which again is pointing to something other than the implement pump. One operator told us that when he previously owned a company with his brother that they had a hose begin to come apart on the inside and it began to operate as a one way valve where the lining of the hose would flap down when fluid moved past it. You seen anything like that before?

Apologies for the delay in getting follow ups out on this and some of my other posts. All the help I've received has been much appreciated.

Thanks,
631G

 

[Nige]

One operator told us that when he previously owned a company with his brother that they had a hose begin to come apart on the inside and it began to operate as a one way valve where the lining of the hose would flap down when fluid moved past it. You seen anything like that before?

It's probably a lot more common in all types of machine that you might imagine. Gives people nightmares when trying to diagnose problems. Just bear the possibility in mind while troubleshooting.

 

[Welder Dave]

I think if it was a collapsing hose problem would be slower all the time not just when travelling but stranger things have happened.

 

[631G]

It's probably a lot more common in all types of machine that you might imagine. Gives people nightmares when trying to diagnose problems. Just bear the possibility in mind while troubleshooting.

The owner decided enough is enough, loaded it on the lowboy this evening and its off to a independent mechanic...

 

[631G]

Well, we have our answer. Our previous mechanic replaced the wrong hydraulic pump. Despite his insistence that he changed the implement pump he actually changed the pilot pump. On an upside, I now know more about a 963B than I thought I ever would.

Thanks for all the help, even though he didn’t listen when I told him what you guys had said. I guess some guys just can’t take advice.

Thanks,
631G

 

[Nige]

When you say "previous mechanic" I take it that he is no longer in your employ..?

EDIT: Sorry - asked and answered in your post above.

 

[631G]

When you say "previous mechanic" I take it that he is no longer in your employ..?

Yes, he definitely is no longer drawing a salary from us. And never will again if he wants to come back. He quit, and maybe this is why. This is one of those head scratching moments where you just ask yourself “Really, I mean REALLY! That was the problem?! The exact thing I told you to fix!”
We’ve gotten the impression that most of the things he touched never got completely repaired. I am generally one of those guys who knows what I don’t know, and isn’t afraid to ask or find people who do. He on the other hand was more of a “I got this, now let me work” type of guy and so we get BS like this. Unbelievable... makes me more angry the more I type.

Thanks,
631G