Discharge Gate Rubber Seal

Function

A sound discharge gate seal maintains batch integrity by preventing premature material loss during mixing, avoids mortar contamination of components below the trough, and reduces material waste and cleaning burden per cycle. It contributes to dust and noise containment within the mixing zone during operation. Seal degradation allows paste to bypass the gate edge, leading to drip-contamination of the receiving skip, bucket, or truck below and causing progressive abrasive erosion of the gate frame face — a structural repair that costs far more than timely seal replacement.

Construction & quality

Seals are moulded in 60–70 Shore A natural rubber or SBR compound selected for resistance to repeated compression set under alkaline concrete slurry, pH 10–13. The profile is a D-section or hollow-bulb extrusion, vulcanised and joined to form a continuous perimeter frame; extruded strip is supplied as an alternative for site-fitting to existing channel grooves. Cross-section dimensions are held to ±0.5 mm to ensure consistent gate compression. Moulded corner inserts are supplied where the gate frame requires 90° bends without fold-cracking. The moulded surface is clean and flash-free to ensure full contact along the sealing face.

When to replace

• Fresh concrete or mortar dripping from the mixer with discharge gate confirmed closed
• Visible cracks, splits, or surface hardening along the rubber bead
• Gate closing pressure or stroke reading abnormal on PLC (gate not fully seating)
• Permanent compression set flattening the seal profile so it no longer rebounds
• Paste accumulation in gate frame channels indicating bypass around the seal face