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Bucket Elevator
Brief description
A continuous vertical conveyor mechanism designed to elevate bulk loose materials (grain, flour, coal, gravel, or crushed ore) using a series of open buckets attached to a continuous loop of belt or chain moving between upper and lower sprockets or pulleys enclosed in a protective casing.
Use / Function
- Primary Use: Vertical transport of bulk agricultural crops (wheat, corn, seeds) into storage silos and processing mills.
- Secondary Uses: Lifting coal, cement, limestone, or crushed mineral ores in chemical plants, foundries, and mining operations.
- Scale: From small farm mill elevators to industrial bulk handling terminals.
Operating principle
- Continuous Loop: An endless belt (made of heavy rubberized fabric or leather) or double strand of steel roller chain loops over a driven top head pulley and a bottom boot pulley.
- Scooping/Scoop Feeding: As buckets pass around the bottom boot pulley submerged in a boot hopper, they scoop up incoming loose material.
- Vertical Elevation: The moving belt or chain carries the filled buckets vertically upward inside a tall housing tube.
- Centrifugal Discharge: As buckets loop over the top head pulley at speed, centrifugal force throws the material outward into a discharge chute.
How to create it
- Build the Head and Boot Sections: Construct a lower boot casing with a material inlet hopper and an upper head casing with a discharge spout from timber or sheet metal.
- Mount Shafts and Pulleys: Install a top drive shaft with a crowned pulley/sprocket on bearings at the head, and a sliding tension shaft at the boot.
- Assemble the Loop Belt or Chain: Splice a heavy multi-ply canvas, rubber, or leather belt (or double roller chain strand) to fit the center distance tightly.
- Attach Buckets: Fasten deep metal or stiffened canvas buckets uniformly along the outer face of the belt using flat countersunk elevator bolts.
- Install Casing and Drive Mechanism: Enclose the ascending and descending legs in twin wooden or sheet metal casings to contain dust, and connect the top shaft to a reduction gear or pulley system.
Materials needed
- Buckets: Pressed Steel, Iron sheet, or rigid molded composite.
- Belt / Chain: Multi-ply Fabric, heavy Leather, or forged steel chain.
- Drive Pulleys & Shafts: Cast Iron or Steel shafts and sprockets.
- Enclosure Structure: Structural Wood or Steel sheet housing.
- Power Coupling: Drive Rope or belt pulleys.
Variants and improvements
- Centrifugal Discharge Elevator: High-speed bucket loop where centrifugal force clears buckets at the head discharge spout.
- Continuous Bucket Elevator: Slower-moving loop where buckets are placed side by side with no gap; as one bucket turns over the head pulley, its back acts as a chute for the following bucket (ideal for fragile or coarse materials).
- Positive Discharge Elevator: Buckets are inverted over a secondary idler sprocket at the head to ensure sticky or damp materials dump completely.
Limits and risks
- Dust Explosion Hazard: Fine agricultural or coal dust inside enclosed elevator casings can ignite explosively from friction sparks or static electricity; explosion relief vents are critical.
- Belt Slippage & Jamming: Overshed material in the boot can jam the lower pulley or cause belt slippage on the head pulley.
- Bucket Rollback: If power fails while fully loaded, gravity will pull the heavy ascending leg down backward; a mechanical ratchet backstop is required on the head shaft.