41b Hydraulic issues

[futuresweets10]

I got a cat 416b backhoe and it had no hydraulic pump when I acquired it. (pump went out on previous owner). I purchased a new pump (aftermarket) and installed it...
I took the return line off the tank and bumped the ignition over a few times to help get the fluid started, then cranked it up. It took a second but fluid started flowing from the return line. I then turned the machine off and re-connected the line to the return of the tank. I got back on the machine and started to try the hydraulics out.

-The steering works great with no problem
-The outriggers go down and up with no problem, but once they hit the ground wont lift the weight of the machine
-The front arm will come down, but has to be worked ALOT to get up
-The front buket will not tilt at all (all the way down at the moment
-the back swing seems to work fine
-the back arm works on one cylinder but not the other
-the back bucket seems to move ok.

All of the hydraulics that dont move or move slowly can be pushed manually (someone holding the control and someone pushing on the bucket or arm)

At first I figured it was air in the lines, but now I dont know. With some of them, playing with them seems to make them work somewhat, but others it dosent help. its almost like the pump is working, but the pressure isnt high enough. Any adjustment on the pump pressure wise? Any other ideas? Thanks guys.

 

[futuresweets10]

Nobody has any insight???

 

[wdchyd]

When you installed the pump did you fill the case drain???? :confused2:

Did you clean tank and change filters?

There is adjustments on that pump (2 stage pressure compensator mounted on back plate)...I don't recommend adjusting without pressure guages and flow meter/load valve to monitor pressure and flow while running a simulated load and running the machine....

If I'm not mistaken from a previous thread that you started, you've inherited someone elses troubles....just throwing on a new/rebuilt/used pump is not a cure all....these piston pumps are not as easy a DIY if new to hydraulic troubleshooting....yes the pump could have been bad but the new/rebuilt one needs to have adjustments made to it to avoid same problems resurfacing....or worse crashing the replacement pump again....

Maybe you need hands on help from someone locally that is familiar with this machine and has proper technical specs to adjust/test this pump.....much better "Insight" Yes?

 

[futuresweets10]

When you installed the pump did you fill the case drain???? :confused2:

Did you clean tank and change filters?

There is adjustments on that pump (2 stage pressure compensator mounted on back plate)...I don't recommend adjusting without pressure guages and flow meter/load valve to monitor pressure and flow while running a simulated load and running the machine....

If I'm not mistaken from a previous thread that you started, you've inherited someone elses troubles....just throwing on a new/rebuilt/used pump is not a cure all....these piston pumps are not as easy a DIY if new to hydraulic troubleshooting....yes the pump could have been bad but the new/rebuilt one needs to have adjustments made to it to avoid same problems resurfacing....or worse crashing the replacement pump again....

Maybe you need hands on help from someone locally that is familiar with this machine and has proper technical specs to adjust/test this pump.....much better "Insight" Yes?

Pretty much the type of answer I was looking for, but not what I wanted to hear..... Yes, I inherited someone else's troubles. The old pump was decentigrated, so I know it was bad. I would love to find someone who I can pay to adjust the pump, but cant seem to find ANYONE. I am capable of adjusting it myself If I had the tools and knew the basics, but I dont know the basics. I know I need a pressure gauge and assume I need to hook it to the service port thats on the pump's pressure line, but have no clue about the "flow meter/load valve" you speak of.

BTW, I did fill the case drain, but it also has a line running from the case drain to the bottom on the tank that fills it from the tank. I also cleaned the tank (looked like brand new) and replaced the filters

 

[J_J]

Have you put a gage in the system to see if things are working? Install a hyd gage in the input hose on the first valve in the system after the pump. With all valves in neutral, should read little or no pressure. If a lever is activated, and all connections are good, then you should see high pressure. . If you have QD's, recheck the connection. Do you have to tie a lever back to get hyd to the back? Is your return hose from the BH connected properly? Did anybody mess with the relief valves?

 

[futuresweets10]

Have you put a gage in the system to see if things are working? Install a hyd gage in the input hose on the first valve in the system after the pump. With all valves in neutral, should read little or no pressure. If a lever is activated, and all connections are good, then you should see high pressure. . If you have QD's, recheck the connection. Do you have to tie a lever back to get hyd to the back? Is your return hose from the BH connected properly? Did anybody mess with the relief valves?

I have not hooked up a gauge yet, because I cant seem to locate one to purchase. There is a service port on pressure line right past the pump, would this port work the same as hooking it up where you described?

Ill be honest, Im kinda lost with your post, but im trying to follow it (my fault, not yours). I am fairly green when it comes to this stuff. If by QD's you mean quick disconnects, there are none. Also, what do you mean by tie a lever back to get hyd to the back? I do know that after the machine broke the previous owner had to loosen some of the lines to be able to get the implements up so it could be moved and worked on. (I assume only the lines going to the cylinders). The whole relief valve thing is new to me... Where would the relief valves be?

Bottom line..... All hoses should be hooked up properly and none of that should have been messed with. I am to "green" to know where or what relief valves are so I need a little schooling on that. I am going to try and find a pressure gauge today and try that.

 

[AKKAMAAN]

Nobody has any insight???

You have a variable displacement piston pump (axial). They are used on Constant pressure systems, usually with a feature called Unloaded. That means that pump drops to a lower stand+by pressure when there is no demand on flow. That demand usually comes from the directional valve, as a "signal" in a 1/4" hose.
There is a pressure compensator on the pump, looks like a smaller housing with one or two adjustable valves. Two valves, if this pump is made for this Constant Pressure Unloaded (with stand-by pressure). This mentioned 1/4" hose, from the control valve should be connected to the compensator. If not, pump will still deliver flow, but only a very low pressure, typically adjusted to some where between 300-600psi. This pressure is set by a spring. This is the stand-by pressure.
This stand-by pressure is enough to make cylinders move with no load, like swing and bucket curl etc...

The signal to the compensator, will add pressure (force) on the valve poppet, so total pump pressure will be stand-by plus system pressure. System pressure is set by a relief valve in the control valve.

If, eventually, your system is a Load Sensing system, it will work the same way as the Constant Pressure system, except that the pressure signal from the valve will be equal to the highest load pressure that for the moment is actuated by the control valve......

This is pretty complicated stuff if you have zero experience, but lets take everything from scratch. We need more info to be able to help.

Take some detailed photos on the pump, pressure compensator, control valve and the plumbing, and post.
Read the manual to determine what type of hydraulic system you have....if there are any schematics on the system available, please scan or take photo pix on them and post too.

 

[futuresweets10]

You have a variable displacement piston pump (axial). They are used on Constant pressure systems, usually with a feature called Unloaded. That means that pump drops to a lower stand+by pressure when there is no demand on flow. That demand usually comes from the directional valve, as a "signal" in a 1/4" hose.
There is a pressure compensator on the pump, looks like a smaller housing with one or two adjustable valves. Two valves, if this pump is made for this Constant Pressure Unloaded (with stand-by pressure). This mentioned 1/4" hose, from the control valve should be connected to the compensator. If not, pump will still deliver flow, but only a very low pressure, typically adjusted to some where between 300-600psi. This pressure is set by a spring. This is the stand-by pressure.
This stand-by pressure is enough to make cylinders move with no load, like swing and bucket curl etc...

The signal to the compensator, will add pressure (force) on the valve poppet, so total pump pressure will be stand-by plus system pressure. System pressure is set by a relief valve in the control valve.

If, eventually, your system is a Load Sensing system, it will work the same way as the Constant Pressure system, except that the pressure signal from the valve will be equal to the highest load pressure that for the moment is actuated by the control valve......

This is pretty complicated stuff if you have zero experience, but lets take everything from scratch. We need more info to be able to help.

Take some detailed photos on the pump, pressure compensator, control valve and the plumbing, and post.
Read the manual to determine what type of hydraulic system you have....if there are any schematics on the system available, please scan or take photo pix on them and post too.

There is a 1/4in hose that runs to the pump (on top) and the rest of the lines connect on the back. The other end of the 1/4in hose connects somewhere under the machine (to the one of the valve assemblys I assume?)

The two valves you speak of are on the back of the pump and not where the 1/4line goes in.
I am an auto tech by trade and have NEVER found anything that I couldn't figure out, so I know I am capable of doing this if I am pointed in the right direction. You seem to know your stuff, I look foward to hearing back from you and will get pics up ASAP

 

[AKKAMAAN]

There is a 1/4in hose that runs to the pump (on top) and the rest of the lines connect on the back. The other end of the 1/4in hose connects somewhere under the machine (to the one of the valve assemblys I assume?)

The two valves you speak of are on the back of the pump and not where the 1/4line goes in.
I am an auto tech by trade and have NEVER found anything that I couldn't figure out, so I know I am capable of doing this if I am pointed in the right direction. You seem to know your stuff, I look foward to hearing back from you and will get pics up ASAP

Well, at this moment I can only speak in general terms about this....there are thousands of varieties on this, and there is hundreds of different setups on these pumps....

So this hose might hook up on a different place on the pump....there is also another smaller hose connected to the pump casing, and its other end should be connected direct to tank (not through filter). It called case drain, and CAN NOT be restricted, kinked etc. Pressure in the case drain is a NO NO, just a little pressure will blow the shaft seal on the pump...

 

[futuresweets10]

Well, at this moment I can only speak in general terms about this....there are thousands of varieties on this, and there is hundreds of different setups on these pumps....

So this hose might hook up on a different place on the pump....there is also another smaller hose connected to the pump casing, and its other end should be connected direct to tank (not through filter). It called case drain, and CAN NOT be restricted, kinked etc. Pressure in the case drain is a NO NO, just a little pressure will blow the shaft seal on the pump...

Case drain is a 1/2in hose that runs directly from the bottom of the tank directly to the port on the pump. I will take pics later....