Cold Bin Gate and Actuator

Function

Accurate gate positioning directly controls aggregate grading proportions delivered to the dryer, which in turn determines the final mix grading sent to the mixer. A sticking, worn, or inaccurate gate introduces feed rate variation that causes under- or over-heating in the drum and produces aggregate grading errors in the finished batch. Actuator response time and gate wear-clearance both affect the speed and accuracy with which the control system's feed-forward and feedback loops can correct feed deviations and maintain target aggregate temperature.

Construction & quality

Gate slide plate: mild steel or AR300 plate, 10–16 mm thick, operating in a machined guide channel. Side seals: grease-purged UHMWPE or brass strips preventing aggregate fines from migrating into the guide and causing binding. Actuator options: (a) electric gear motor with integral spring-set brake, 0.18–0.75 kW, IP55 minimum, 24 V DC or 3-phase 400 V to plant specification; (b) double-acting pneumatic cylinder, 50–100 mm bore, with NAMUR-mount solenoid valve block, IP65. Position feedback: multi-turn rotary encoder on motor gearbox output, or draw-wire transducer on gate stem — both providing 0–10 V or 4–20 mA analogue output to the PLC. Actuator housing: powder-coated carbon steel or die-cast aluminium.

When to replace

• Gate slide plate binding or requiring excess actuator current to move at normal speed
• Visible wear groove along gate plate edge allowing aggregate bypass when gate is nominally closed
• Position sensor reading diverging from actual gate opening — calibration offset exceeding ±5 mm
• Electric actuator motor tripping thermal overload relay under normal operating load
• Aggregate leakage under the closed gate affecting conveyor belt calibration accuracy