TL;DR
Drop door hydraulic faults prevent batch discharge and can cause compound to degrade in the chamber. Check hydraulic pressure, door seal, and door latch solenoid before forcing the door open.
What you might see
- drop door does not open on command at batch discharge
- drop door hydraulic pressure alarm
- door latch solenoid clicks but door does not release
- compound sticking in the chamber from delayed discharge
Likely causes
Drop door hydraulic cylinder pressure low from a circuit leak or pump fault
Door latch solenoid valve coil failed preventing latch release
Compound buildup on the door seal preventing it from seating and re-opening
Door guide rails worn causing mechanical binding
Required tools
- Multimeter for solenoid coil check
- Replacement solenoid coil (if needed)
- Hydraulic pressure gauge
- Solvent or scraper for compound cleaning
- LOTO kit for drive and hydraulics
Safety first
- Lock out the mixer drive and hydraulics before any work near the drop door latch or cylinder.
- Ensure the discharge chute is clear before any drop door test cycle. Hot compound falling into a blocked chute creates a fire risk.
Procedure
- 1
Attempt a manual drop door open command from the machine control. Note whether the solenoid click is audible and whether the door moves at all.
- 2
Check the hydraulic pressure at the drop door circuit gauge. Compare to the specification.[1]
Warning: The drop door hydraulic system operates at high pressure. Do not loosen fittings while the circuit is pressurized. - 3
Lock out the mixer drive and hydraulic systems before manually inspecting the door latch mechanism.
Warning: The drop door opens to a discharge chute. Hot compound at temperatures above 120 C can fall if the door opens unexpectedly. Ensure the discharge area is clear before any latch work. - 4
Inspect the latch solenoid coil for continuity with a multimeter. Replace the coil if open circuit.[1]
- 5
Inspect the door seal and door guide rails for compound buildup. Clean the rails and seal with approved solvent or scraper.
- 6
After repairs, cycle the door 5 times manually before returning to production to confirm consistent operation.
Sources
Farrel-Pomini Farrel BR / F-Series Rubber Banbury Mixer general technical documentation, Farrel-Pomini
Farrel-Pomini Banbury mixer drop door hydraulic system maintenance documentation (general)
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