Grain Bag Extractor

Overview

A Grain Bag Extractor empties silo bags, the long polyethylene tubes that farms use to store grain in the field. After harvest grain is sealed into bags up to 500 ft long lying directly on the ground. When the grain is sold or moved, the extractor reverses that process: it straddles the filled bag, opens it, draws the grain out, lifts it into a waiting truck, and reels up the spent plastic film so the field is left clean. The machine is towed and powered by a farm tractor, taking rotary power through the PTO Driveline and running its own hydraulics from that same input. A single operator on the tractor advances the machine along the bag while the truck pulls alongside the discharge spout.

The complete machine breaks into eight subsystems: the Pickup Head, the Cross Collecting Auger, the Discharge Auger, the Bag Winder, the Driveline, the Hydraulic System, the Chassis, and the Grain Loss Sweep. Grain flows forward to rear and then upward through the first three; the others move the machine, power it, and keep losses low.

Grain pickup

At the front the Pickup Head does the digging. The Bag Slitting Knife slits the top seam of the bag a few feet ahead of the head, and a slow-turning Pickup Drum fitted with flexible Rubber Drum Paddle flaps rolls the exposed grain rearward onto the Pickup Pan. Rubber paddles are used instead of steel so the drum can sweep grain off the bag floor without tearing the plastic, because the film still has to be rolled up intact afterward. Two Sweep Auger units, one from each side, then draw the grain inward toward the center. Each sweep auger is a short Sweep Flighting wound on a shaft and carried on a Hanger Bearing. Pickup height is set by the Ground Gauge Skid shoes, which ride the field and keep the drum from gouging into the soil.

Conveying and discharge

Grain collected by the head drops into the Cross Collecting Auger, a wide horizontal auger running in a steel Cross Auger Trough. Its Cross Auger Flighting carries grain laterally to the Feed Throat, the casting where the horizontal flow turns vertical. A replaceable Abrasion Trough Liner of UHMW plastic protects the trough floor, since grain moving at this rate is abrasive and the trough would otherwise wear thin.

From the feed throat the Discharge Auger lifts the grain. It is a long enclosed tube auger with high-pitch Discharge Flighting inside the Discharge Auger Tube, driven at the top by the Upper Auger Gearbox. At full output it elevates grain to a Discharge Spout roughly 14 ft off the ground, high enough to clear the side of a grain truck or trailer. The spout folds on its Spout Fold Hinge for transport, driven by the Spout Fold Cylinder, and an adjustable Spout Deflector Hood aims the falling stream into the box so the operator can fill front to back without spilling.

Bag winding

As the machine creeps forward it leaves an empty plastic tube behind it, which must be gathered up rather than left in the field. The Bag Winder handles this. A Bag Pinch Roller pair grips the film and feeds it onto the Bag Winder Drum, where it wraps into a tight roll. The drum has its own Winder Drive Motor, an Orbital Hydraulic Motor driving through a Winder Drive Chain, so winding speed can be matched to ground speed independently of the augers. Winding torque rises as the roll grows, and the Winder Pivot Arm lets the drum swing out to follow the bag. A full roll of used film is dropped off at the end of the run for collection.

Drive train

Everything mechanical is powered through the Driveline. Tractor power enters at the PTO Driveline, a telescoping shaft with universal joints at each end that tolerate the angle and length changes between tractor and implement. The Main Gearbox turns the input through a right angle and splits it to the cross auger and to the Chain Drive Case units, which drive the pickup drum and sweep augers by enclosed roller chain. A Slip Clutch sits in the line as a torque limiter: if a rock or a wad of plastic jams an auger, the clutch slips rather than letting the driveline or a gearbox break.

Hydraulics, chassis, and cleanup

The Hydraulic System run off a gearbox-mounted Hydraulic Pump, so the machine needs no hydraulic hookup to the tractor beyond the PTO. The Control Valve Bank bank routes oil to the Lift Cylinder units that raise the head, to the spout fold cylinder, and to the winder motor, with a Return Line Filter cleaning the return flow. The whole works rides on the Chassis, a frame that spans over the bag and rolls on two Transport Wheel assemblies, hitched to the tractor at the Drawbar Hitch. Behind the pickup, the Grain Loss Sweep uses a Cleanup Brush and a Grain Pan to recover grain that escaped the head, returning it to the cross auger. On a 600 t/h machine even a small percentage left behind is many bushels per bag, so the cleanup sweep pays for itself across a season.