Pump is a 2006 Reed. One problem is when pump is engaged after warms up it will pump one cylinder fast and other will pump real slow, taking 5 time as long or more to complete stroke on that side.doesnt do it 100% of the time. I’m assuming this is in control block not hydr pumps tandem 125’s. It’s at a hydraulic shop now. Any input welcome.

a competitor got excited to buy a used T-A nice pump but has the exact same quirk in the stroking.

guess its been through three shops without a proper dianostic. my wild guess could be a blockage in the control block, but iam really interested in the outcome.

Reed Concrete Pump Cycling Issue Analysis

This uneven cycling issue on your 2006 Reed pump is something I've seen discussed by experienced operators. Your assessment that it's likely in the control block rather than the hydraulic pumps is probably correct, especially since:

1. The problem only appears after the pump warms up
2. It doesn't occur 100% of the time
3. The significant difference in cycle speeds (one side 5x slower)

Likely Causes

Control Block Issues

• Check valves: A leaking or sticking check valve in the slave loop could cause this exact symptom. Since it only happens when warm, it points to thermal expansion affecting valve tolerances.
• Proximity sensors: Incorrect proximity sensor location can cause short stroking, which might present as a slow cycle on one side.
• Shift valves: The differential relief valves that control the crossover between cylinders may be sticking when hot.

Less Likely But Possible

• Damaged seals: While you mentioned it's at a hydraulic shop now, make sure they check the piston seals for damage.
• Hydraulic oil contamination: Particulates might be circulating through the system and intermittently blocking flow.
• Sequence valves: The control system sequence valves might need adjustment.

Recommendations

Since your pump is already at a hydraulic shop, make sure they specifically:

1. Inspect all check valves in the slave loop circuit
2. Verify proximity sensor placement and function
3. Check pressure settings on both sides of the hydraulic circuit
4. Look for thermal expansion issues in the control block

This issue is relatively common on concrete pumps with some age, and usually fixable once the specific component in the control block is identified.