Dbothe
New Member
Greetings, this is my first post.
I am having trouble with the pilot controls on my Terex HR16 excavator.
I have found the information on this forum most helpful, And I am Thankful you are here!
My excavator machine: Terex HR16. Year 2003
Pump installed : Kayaba PSVD2-18e-3.
Appears to be original pump, but the parts list says it should be Rexroth.
I do know about 400 serial numbers later Terex started putting KYB pumps on this machine.
Machine serial # is 358/3633
symptoms:
The operator said the joystick functions were lost suddenly, over the coarse of about 5 seconds. No odd noises reported. All functions lost were joysticks only.
Now, Tiny amount of function on joysticks, then dead after 4 seconds.
Tracks work fine, pedal controlled
Dozer blade fine, pedal controlled
Aux thumb fine, pedal controlled
At full throttle the joysticks running the boom and bucket work for 4 seconds with almost no power, ie: the bucket will lift 1 inch off ground and that’s it, then nothing, I can lower it.
Also I have tested the shut off near the seat (which locks out the joysticks) and cleaned it and it is open and clear and doesn’t seem to be the issue.
This unit has almost no electronics, most everything is hydraulic. Including joysticks.
I have gear to test pressures.
There are 4 flow hoses coming from pump. Three of them power equipment. These all test fine, they are running three different valve banks. I believe, this type of pump is a single cylinder, dual flow pump, with another variable flow gear pump at the end of the unit. And another small gear pump, internal, that powers the pilot controls. That small gear pump that powers the pilot controls, is not variable, and has an internal pressure Release valve maintaining a certain psi. (I think) On a sidenote, I find this pump to be absolutely fascinating. A real work of engineering art!
So when I pressure test the fourth hose coming off the pump. It is reading 200 psi at full throttle. This hose powers the joysticks, I have deadheaded this hose,(carefully!) and the pressure gauge, as I said reads 200 psi. The specification that I can find from Terex, states that the pilot pressure should be 406 PSI.
further..there is an accumulator in the pilot controls hydraulic circuit. I thought, and maybe still think it could be the problem so I ordered this part and it will be here this week.
Yesterday while preparing for the new accumulator, I was disassembling the hoses and discovered a small piece of metal stuck in the check valve near the accumulator. It was about 1/4” long and polished shiny on one side. This is a happy/sad moment. I proceed to clean out the check valve, blow out the hoses, put it all back together, thinking this cracked-open check valve could be the problem! It wasn’t. Same symptoms. So now with this new piece of evidence, the shard of metal, and knowing that the only place it could’ve come from is the main pump, the pilot controls pressure hose. I am assuming, that this small gear pump inside the main pump has failed. But I’m trying to imagine in my brain, why it still reads 200 psi? (Charge pressure??) So my question to the world here today is, does anybody have the specifications of my pump? So can can know if it should read 200 psi. Kayaba has been no help to me, yet. Terex was purchased by Yanmar and is now under the jurisdiction of Vermeer. My local Vermeer store has been trying to help me. But of course at first they didn’t even know that my machine falls under their umbrella. Yet, they are being most helpful! But so far, they have been unable to find any info on this pump.
Does this sound like a bad pump problem? If so can I rebuild this pump, just the part of the pump that seem problematic? Does anyone know of a replacement pump that would work on my machine? Is it possible there are small clogged screens in the joysticks themselves?
Is there any testing i can do to further diagnose?
Any info you guys have to help me with this puzzle will be greatly appreciated!! Big thanks in advance!
I am having trouble with the pilot controls on my Terex HR16 excavator.
I have found the information on this forum most helpful, And I am Thankful you are here!
My excavator machine: Terex HR16. Year 2003
Pump installed : Kayaba PSVD2-18e-3.
Appears to be original pump, but the parts list says it should be Rexroth.
I do know about 400 serial numbers later Terex started putting KYB pumps on this machine.
Machine serial # is 358/3633
symptoms:
The operator said the joystick functions were lost suddenly, over the coarse of about 5 seconds. No odd noises reported. All functions lost were joysticks only.
Now, Tiny amount of function on joysticks, then dead after 4 seconds.
Tracks work fine, pedal controlled
Dozer blade fine, pedal controlled
Aux thumb fine, pedal controlled
At full throttle the joysticks running the boom and bucket work for 4 seconds with almost no power, ie: the bucket will lift 1 inch off ground and that’s it, then nothing, I can lower it.
Also I have tested the shut off near the seat (which locks out the joysticks) and cleaned it and it is open and clear and doesn’t seem to be the issue.
This unit has almost no electronics, most everything is hydraulic. Including joysticks.
I have gear to test pressures.
There are 4 flow hoses coming from pump. Three of them power equipment. These all test fine, they are running three different valve banks. I believe, this type of pump is a single cylinder, dual flow pump, with another variable flow gear pump at the end of the unit. And another small gear pump, internal, that powers the pilot controls. That small gear pump that powers the pilot controls, is not variable, and has an internal pressure Release valve maintaining a certain psi. (I think) On a sidenote, I find this pump to be absolutely fascinating. A real work of engineering art!
So when I pressure test the fourth hose coming off the pump. It is reading 200 psi at full throttle. This hose powers the joysticks, I have deadheaded this hose,(carefully!) and the pressure gauge, as I said reads 200 psi. The specification that I can find from Terex, states that the pilot pressure should be 406 PSI.
further..there is an accumulator in the pilot controls hydraulic circuit. I thought, and maybe still think it could be the problem so I ordered this part and it will be here this week.
Yesterday while preparing for the new accumulator, I was disassembling the hoses and discovered a small piece of metal stuck in the check valve near the accumulator. It was about 1/4” long and polished shiny on one side. This is a happy/sad moment. I proceed to clean out the check valve, blow out the hoses, put it all back together, thinking this cracked-open check valve could be the problem! It wasn’t. Same symptoms. So now with this new piece of evidence, the shard of metal, and knowing that the only place it could’ve come from is the main pump, the pilot controls pressure hose. I am assuming, that this small gear pump inside the main pump has failed. But I’m trying to imagine in my brain, why it still reads 200 psi? (Charge pressure??) So my question to the world here today is, does anybody have the specifications of my pump? So can can know if it should read 200 psi. Kayaba has been no help to me, yet. Terex was purchased by Yanmar and is now under the jurisdiction of Vermeer. My local Vermeer store has been trying to help me. But of course at first they didn’t even know that my machine falls under their umbrella. Yet, they are being most helpful! But so far, they have been unable to find any info on this pump.
Does this sound like a bad pump problem? If so can I rebuild this pump, just the part of the pump that seem problematic? Does anyone know of a replacement pump that would work on my machine? Is it possible there are small clogged screens in the joysticks themselves?
Is there any testing i can do to further diagnose?
Any info you guys have to help me with this puzzle will be greatly appreciated!! Big thanks in advance!