Hi my name is Joe

I am a carpenter and builder and recently I have bought a cheap pump I'm slowly going through the thing and learning it's in a working. 

I have fully serviced it including new filters and all fluids I have come across an issue where at the end of a stroke the S tube overextends past before swinging back the other way I also have an issue where once its wings the other way it doesn't completely align with the second material cylinder it's about the thickness of the wall out please any pointers would be greatly appreciated I have attached a photo and a few videos the videos show the sequence from three different points of view ,one of the S tube 1 of the material cylinders and one of the pressure gauge

I have gone through and made sure the material cylinders aren't bottoming out and The Adjustment screws on the rear roughly in the same position it seems to be pausing while the ram behind the hopper is compressing that extra little bit before swinging back the other way

Thanks again

S-Tube Alignment Issues

Based on your description, you're experiencing two main problems with your concrete pump's S-tube:

1. Overextension before swinging - The S-tube is moving too far at the end of the stroke before shifting
2. Misalignment with the second material cylinder - The S-tube isn't properly aligning when it shifts

Here are some troubleshooting steps to address these issues:

Check S-Tube Adjustment

The S-tube should be properly adjusted to align perfectly with both material cylinders. According to maintenance guidelines:

• Castle nut tightness: The nut on the S-tube should be as tight as possible without hampering the shift movement
• Bell crank alignment: Ensure the bell crank is properly mounted and aligned with the S-tube

Verify Hydraulic System Components

Your symptoms suggest potential issues with the hydraulic shift circuit:

• Accumulator pressure: Verify the accumulator pressure is within specs (must be ZERO during maintenance)
• Shift cylinder function: The hydraulic switching cylinders (plunger cylinders) control the S-tube movement and might need adjustment
• Solenoid valve operation: Check that the solenoid directional valve is functioning properly

Proximity Sensor Adjustment

The misalignment could be caused by incorrect proximity sensor location:

• Proximity sensors signal when to shift the S-tube
• If they're not positioned correctly, the shift timing will be off

Check for Mechanical Issues

• Spline shaft wear: Dry stroking can cause premature wear on the spline shaft
• Yoke bolts: Keep the two bolts going through the yoke tight to extend S-tube life
• Mechanical stops: Verify any mechanical stops or limiters are properly adjusted

Operating Recommendations

• Try slowing your volume down and place the pump into "soft shift" mode if available
• This can help prevent spline damage and might improve alignment

If these steps don't resolve the issue, I'd recommend contacting a service technician. The Alliance Service Department can provide specific guidance for your model.

Would you be able to share those videos or photos you mentioned? That would help provide more specific advice for your situation.

Thanks for getting back to me.

I will go through the steps and see what I can do. 

Here is a link to a video of the issue. Ive taken a video of behind hopper. Then behind material cylinders.

https://youtube.com/shorts/muFXK06W22c?si=9iXmFGM8DsvTiE4c

Let us know how it goes