Large Square Baler

Overview

A large square baler turns a windrow of hay or straw into a dense, stackable rectangular bale tied with twine. Its value is handling efficiency: a square bale packs tightly on a truck or in a barn with no wasted space, weighs enough to make each handling cycle worthwhile, and holds its shape under stacking. The machine is a high-energy device built around a heavy ram that strikes many times a minute, and almost everything in it exists either to feed that ram a measured charge of crop or to manage the forces it creates.

Crop flows through the baler in a continuous chain. The Crop Pickup lifts the windrow off the field, the Feed System builds the loose crop into measured charges, and the Plunger drives each charge into the growing bale in the Bale Chamber. When the bale reaches the set length the Knotter System wraps and ties twine around it, and the bale slides out the back. The Driveline stores and meters the power for the plunger, the Frame and Running Gear carries the heavy machine, and the Control System let the operator set bale size and watch the process from the cab.

Pickup and feeding

The Crop Pickup is a Pickup Reel carrying dozens of sprung Pickup Tine fingers that comb the windrow off the stubble. A Cam Track swings each tine in to grab crop and out to release it past the Stripper Plate plates, a Windguard holds the windrow down for an even feed, and Gauge Wheel wheels set the height. From there the Feed System takes over. Rotating Packer Fork forks stuff crop into the Pre-compression Chamber, and when a Charge Sensor reads that the charge has reached the right density, the Stuffer Fork loads the whole charge up into the bale chamber in time with the plunger. Machines fitted with a Cutter Rotor and Knife Bank chop the crop to a shorter length, which makes a denser bale that feeds out more cleanly.

The plunger and bale chamber

The Plunger is the heart of the machine. A heavy Plunger Head reciprocates in the chamber tens of times a minute, each stroke driven by a Connecting Rod on the Crank Bearing crankpin. As it advances, the Plunger Knife shears the new charge from the feed throat, and Plunger Roller rollers and Plunger Slide slides keep the heavy head running true against many tonnes of side load. The plunger packs each charge against the column of crop already in the Bale Chamber, whose Chamber Rail rails and hydraulic Density Door doors squeeze the sides. A Density Cylinder sets how hard the doors press, which is what fixes bale density, and a Roller Floor reduces drag as the long bale creeps toward the Discharge Chute. A Length Star Wheel star wheel driven by the moving bale measures its length and trips the tie cycle at the set point.

Tying with the knotter

The Knotter System is the most intricate mechanism on the baler and the part that most defines a clean job. As a bale finishes, the Twine Needle needles swing up on the Needle Yoke, carrying twine from the Twine Box through the packed crop to the Knotter Unit units waiting above. Each unit uses a rotating Bill Hook to form a loop while a notched Twine Disc grips the twine ends, then a Knife Arm cuts the twine free, leaving a finished double-knot band. A Knotter Fan blows chaff off the knotters so they keep tying reliably through a long day. Several bands are tied at once across the width of the bale so it holds its shape under handling.

Driveline, frame, and controls

Because the plunger strike is so powerful and so intermittent, the Driveline is built around a heavy Flywheel that stores energy between strokes and gives the tractor a steady load instead of a hammering one. A PTO Shaft feeds the flywheel through a Shear Clutch, and a Main Gearbox reduces speed to turn the Crankshaft that drives the plunger. The whole machine rides on a Frame and Running Gear with a Tandem Axle bogie on Ball Bearing hub bearings and a Drawbar Hitch to the tractor drawbar. From the cab the Control System tie it together: a Cab Monitor shows bale count, length, and density, while a Baler Controller times the stuffer, knotters, and doors, reading a Moisture Sensor and Load Sensor sensors. Large square balers run in large hay and straw operations where the dense, uniform bales they make pay back their cost in storage and transport savings, working at field rates of fifteen to thirty tonnes an hour behind a high power tractor.