Agricultural Chains for Baler

The heaviest chain position on the machine — transmits the full PTO torque to the plunger crank that compresses material into the bale chamber. This chain sees enormous torque spikes every time the plunger encounters a dense slug of hay. ANSI 100 SP or ANSI 120 double-strand heavy-duty chain is the engineering minimum for this position.

Drives the pickup rotor that lifts hay from the windrow and the augurs that feed it into the bale chamber. These chains run at higher speed than the plunger drive but at lower torque. ANSI 60 or ANSI 80 single-strand is the typical specification, with heavy-duty variants where the pickup must handle stemmy or bunched hay.

The knotter on a square baler is a precision timing mechanism. The chain that drives it must maintain phase accuracy to ensure the knot is tied at precisely the correct moment in the plunger cycle. This is a low-load but high-precision position — any chain slack introduces timing error that causes knot failures.

Round baler belt tension chains and the bale ejection drive use chain to coordinate bale wrap and ejection. These are lower-load positions but must be dimensionally stable to maintain the geometric accuracy of the bale wrap sequence.

Australian summer hay — particularly lucerne cut in December and January — is extremely dry at the time of baling and forms high-density slugs in the bale chamber when windrowed unevenly. The impact load when a slug enters the plunger chamber can be 3–5 times the continuous plunger chain load. Standard ANSI 100 chain side plates crack at the connecting link holes under these repeated shock loads; SP-series reinforced side plates with shot-peening are the required specification.

Dry Australian hay generates fine leaf-particle dust that penetrates chain joints and acts as an abrasive compound. Plunger drive chains in typical Australian hay conditions need more frequent lubrication than the manufacturer’s standard interval, and dry-film lubricant or heavy EP oil (rather than light mineral oil) is recommended to maintain film integrity against the abrasive dust environment.

Hay baling in paddocks with variable windrow density involves many start-stop cycles as the tractor slows or the pickup encounters gaps in the windrow. These deceleration-acceleration cycles impose fatigue loads on the plunger drive chain connecting links — the point where fatigue cracking most commonly initiates. Replace connecting link cotters every season regardless of apparent condition.

Inspect connecting links on all chain positions. Check plunger chain tension — sag should be within the OEM specification, typically 10–15 mm at mid-span. Apply lubricant to all chains.

Measure plunger drive and pickup chain elongation. Replace plunger chain at 1.5%, pickup at 2.0%, knotter at 1.0%. Inspect all sprockets for tooth hook wear and replace any showing visible cracking.

Remove all chains. Clean and inspect rollers and side plates for fatigue cracks, particularly at connecting link holes and at the innerplates. Store with a rust-prevention coat. Document elongation measurements to plan pre-season replacements.