Understanding Leaf Chain Numbering: What Do LL, LH, AL, and BL Mean?
Leaf chains are specialized chains used in forklifts, lifting equipment, and material handling. Their design—multiple flat plates linked by pins—provides excellent fatigue strength. However, a confusing numbering system (AL, BL/LH, LL/EL) can hinder proper selection. Understanding numbering ensures safety, compatibility, and performance.
Leaf Chain Types
Light-duty, ANSI standard, aluminium or steel plates with a thinner design.
Heavy-duty, ANSI standard, extra-thick plates to match the next-size roller chain. Also referenced as LH in ISO standards.
LL/EL series Leaf Chain
ISO/British standard, light-duty, same as LL or EL/F series.
Decoding the Leaf Chain Part Number
A typical part number (e.g., BL844) indicates:
Series: AL, BL/LH, or LL/EL
Pitch code:
AL & BL: in 1/8″ units (e.g., “8” = 8/8 = 1″ pitch)
LL/LH: in 1/16″ units (e.g., “16” = 16/16 = 1″ pitch)
Lacing: two-digit code indicating outer × inner plates (e.g., “44” = 4×4)
Example:
AL1022 → AL series, 10/8″ = 1.25″ pitch, 2×2 lacing
LL1644 → LL series, 16/16″ = 1″ pitch, 4×4 lacing
Leaf Chain Lacing Patterns
Common lacing types include 2×2, 2×3, 3×4, 4×4, 4×6, 6×6, and 8×8.
The first number = outer plates;
The second = inner plates.
Identification Leaf Chain Step
Step 1: Measure the pitch (P) – center-to-center of pins.
Step 2: Measure pin diameter (A) and plate thickness (B).
Step 3: Use a chart to match measurements to series:
• AL Leaf Chain vs BL Leaf Chain, vs LL have distinct pin/plate dimension tables.
Step 4: Calculate part number:
• Identify series
• Convert pitch to code (x8 or x16)
• Record lacing pattern
• e.g. 1″ pitch, 6×6, 0.375″ pin → likely BL866.
Leaf Chain Size
Choosing the Right Leaf Chain
AL/LL: lighter, corrosion-resistant (especially aluminum), lower cost, but less strength.
BL/LH: built for higher load, shock, heavy cycles; heavier and costlier.
Choose AL for smoother, lighter lifts; BL for rugged, industrial use.
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As a professional chain supplier, we offer various industrial chain options: roller chains, conveyor chains, stainless steel chains, heavy-duty roller chains, double-pitch roller chains, roller chain attachments, etc.
