Support Structure

Function

Each sub-assembly of the support structure performs an alignment-critical function: trunnion pedestals control the roller-centre spacing and height; the thrust-roller bracket controls drum axial position to within 5–10 mm; and hood-support legs maintain the chute centreline height to within a few millimetres for seal clearance. Incorrectly dimensioned or deformed support structure elements produce misaligned contact between rollers and riding rings — resulting in the characteristic barrel or taper wear pattern on the ring face — excess end-thrust, or binding of the drum seal. For mobile plants, the support structure incorporates transport tie-down provisions and may use pin-and-clevis or bolted-splice connections to allow rapid field assembly.

Construction & quality

Fabricated from IS 2062 Gr B / ASTM A36 structural steel using hollow sections (SHS/RHS) and channel sections for secondary members, and plate-welded box sections for heavy-load pedestals. Trunnion bearing housing mounting faces are milled flat to ±0.3 mm and provided with elongated slots for roller-centre adjustment. Height setting uses precision-machined steel shim packs or M36/M42 jackscrews with lock nuts. All structural welds match the full-penetration and continuous fillet-weld standard of the main base frame. Surface preparation and finish: Sa 2.5 blast, epoxy primer 75 µm DFT, polyurethane topcoat 50 µm DFT in plant-standard colour.

When to replace

• Visible deformation or buckling of a pedestal column from mechanical overload or impact
• Elongated bolt holes in trunnion mounting pads from chronic vibration indicating loose fastening
• Corrosion at hollow-section seams in coastal environments causing internal wall section loss
• Differential settlement of individual support legs visible as a riding-ring tilt measured by dial gauge
• Cracking at gusset-to-base-plate welds on trunnion pedestals under fatigue from unbalanced drum loading