Belt Length Acronyms (La, LE, Ld, Lp, Lw and Li)

What do these belt length acronyms mean?

We’re putting it here as a quick reference.

  • La: Outer (circumference) length1 
  • LE: Effective length2 
  • Ld: Datum length3 
  • Lp: Pitch length3, 4 
  • Lw: Working length3 
  • Li: Inner (circumference) length1 

Certain conditions: 

1 No belt stretch / tension applied 

2 Length relative to the effective outside diameter of a sheave with belt stretch / tension applied 

3 Length at the pitch diameter of the sheaves used with belt stretch / tension applied 

4 Technically defined as “any circumferential line which keeps the same length when the belt is bent perpendicularly to its base” (ISO 1081:2013) 

 Here’s a more detailed explanation of belt lengths, according to the GatesFacts Technical Information Library.