Large Round Baler

Overview

A large round baler is a trailed implement that gathers a cut and raked windrow of hay, straw, or silage, rolls it into a dense cylinder, binds it, and drops it in the field. The finished bale is 1.2 m wide and 0.9 to 1.8 m in diameter, weighing 300 to 900 kg according to crop type and moisture. The cylindrical shape sheds rain and is stable when stored outdoors, which is why round bales dominate forage handling on mid-size farms. The machine is towed by a tractor of 70 to 110 kW (95 to 150 hp) and driven through the PTO Drive Shaft at 1000 rpm. Field output runs 20 to 40 t/h at working speeds of 8 to 15 km/h, the limit being how fast crop can be fed without plugging the rotor.

Pickup and Feeding

The Pickup Unit is a 2.0 to 2.3 m wide reel carrying four Tine Bar rows of Pickup Spring Tine. As the reel turns, a fixed Pickup Cam Track at each end swings the bars so the tines sweep up at the windrow and retract before the crop reaches the Pickup Strip Guard strippers. A Windguard Roller presses the crop down so the flow stays even, and two Gauge Wheel units set pickup height above the stubble. Crop then passes into the Feed & Chopping Rotor, a tined drum that drives the material rearward across the Chopper Knife bank. The knives ride on the Drop Floor; each blade is held by a Knife Drawer spring that lets it trip over stones. With all 25 knives engaged the theoretical chop length is about 45 mm, which improves bale density and makes the forage easier to feed out later. If a slug of crop plugs the throat, the Drop Floor Cylinder lowers the floor to enlarge the gap and clear it without manual unblocking.

How the Bale Forms

This machine uses a variable Bale Chamber built from four endless Forming Belt running over a set of Belt Drive Roller and Belt Idler Roller. At the start of a bale the belts wrap a small loop against the Starter Roller, and the incoming crop is rolled into a tight core. As more crop enters, the bale grows and pushes the belts outward; the Belt Tension Arm swing back and the chamber expands smoothly to the chosen diameter. A fixed-chamber baler instead uses a ring of steel rollers or chains of constant size, so the core stays loose until the chamber fills. The variable belt design gives a dense core throughout and lets the operator pick any diameter on the In-Cab Display, which is its main advantage over fixed-chamber machines for hay and silage. Typical dry hay bales at 1.5 m diameter weigh 350 to 450 kg, while wet silage at the same size can reach 800 to 900 kg, so the operator drops the diameter for heavy silage to keep handling weight within the front loader rating.

Density and Binding

Bale density is set by the Bale Density System. Two Belt Tension Cylinder load the tension arms through a Density Control Valve, with a gas Hydraulic Accumulator cushioning the peaks and a Tension Spring as mechanical backup. Higher belt pressure makes a heavier, harder bale. When the Bale Shape Sensor on the tension arm reports the target diameter, the Net & Twine Wrap System starts. Net pays off the Net Roll Holder through the Net Wrap Roller, wraps the rotating bale two to three turns, and the Net Cutoff Knife cuts it. Twine binding using the Twine Feed Arm is available as a slower alternative. Once wrapped, the Tailgate swings up on its Tailgate Lift Cylinder, the bale rolls down the Bale Ejection Ramp, the gate closes, and the Tailgate Latch re-engages.

Driveline

Power enters through the Slip Clutch, a torque-limiting clutch that protects the drivetrain from shock loads. The Main Gearbox splits drive to the rotor and to the belt rollers through Roller Drive Chain loops on Drive Sprocket, each kept tight by a Chain Tensioner. A Driveline Flywheel stores inertia so the chopping rotor rides through dense slugs without stalling. The whole machine rolls on a single Axle Beam with two Road Wheel on flotation tires.

Materials

Frames and the Main Frame are welded box-section steel. The Rotor Shaft is 42CrMo4 alloy and the knives are boron steel for edge life. Forming belts are rubber-coated fabric ply, and the chamber Chamber Side Wall uses wear-resistant steel sheet against the abrasive crop.

Maintenance

Daily service is grease at the chain and roller Ball Bearing points, checking belt tracking, and inspecting the Chopper Knife edges. The Main Gearbox oil is changed each season, worn Roller Drive Chain and Drive Sprocket are replaced before they skip, and the net path is cleared of wrapped crop to keep the Net Cutoff Knife cutting cleanly.