Understanding Leaf Chain Numbering: What Do LL, LH, AL, and BL Mean?
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- Issue Time
- Jun 18,2025
Summary
Understanding leaf chain numbering helps you make a proper selection.
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.
CTS® | Professional Chain Manufacturer
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.