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Typically, however, the ratios are not used to design a level of torque; they are
used to create a saw with the optimum blade speed (blade Shaft RPM) for you.
The major factors are:
♦ diameter of blade(s) you commonly use, and
♦ cutting conditions you work under
We can also tailor the Blade Shaft RPM (blade speed) by adjusting the “primary”
ratio between the engine and the Blade Shaft. By selecting a Blade Shaft sheave
and Engine sheave, a multitude of additional ratios (and Blade Shaft speeds) are
possible. The following Sheave sets are available as standard kits:
Engine
Sheave Blade Shaft
Sheave Engine
Spacer* Ratio Blade
Shaft
RPM
Engine
RPM MERCURY
Kit #
3.6 4.75 .75 1.32 : 1 2121 2800 18600
3.6 5.0 .5 1.38 : 1 2028 2800 18601
3.6 5.3 .375 1.47 : 1 1904 2800 18602
4.1 4.2 .75 1.02 : 1 2735 2800 18608
4.1 4.4 .5 1.07 : 1 2609 2800 18607
4.1 4.5 .5 1.10 : 1 2545 2800 18604
4.1 4.75 .375 1.16 : 1 2413 2800 18603
4.1 5.0 .375 1.22 : 1 2295 2800 18605