Gearbox Efficiency vs Input Speed

For most gearbox models, efficiency varies across rpm.  However, most vendors state a single rated efficiency for all speeds.  This is sufficient in most cases when the efficiency varies slightly across the entire speed range.  However, some gearboxes see their efficiency vary significantly throughout the speed range.  The efficiency vs input speed curve is used to calculate the proper efficiency at the specific speed.  Hence, all performance calculations are more accurate, and require no estimation or adjustment by the user.

If the selected gearbox uses the Efficiency Formula, and the formula also uses the [T] variable, then the T2 torque input is also shown in the Gearbox Efficiency form.

Efficiency 7 Point Curve & Efficiency Formula

Since v2, the gearbox efficiency has been specified in the database using a 7 point curve (Input Speed, Efficiency). The efficiency points curve is typically published at gearbox rated torque [T2N]. The 7 point curve is sufficienctly accurate for most gearboxes.

The Efficiency Formula [Eff_Frml] added in v4.6, allows for gearbox efficiency based on the variables Input Speed [n] and Output Torque [T]. The formula can be up to 500 characters. The formula is optional, and if not specified, the efficiency points curve is used.

Formula Variables, Conditions, Functions, etc.
Example Formula Derived using Excel Trendline


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