Industrial Weaving
On heavy canvas most of the sley force never reaches the fell — it goes into accelerating the sley itself, and it scales with the square of loom speed.
— N/m
Sley inertia plus fabric resistance, per metre of reed
Simple harmonic motion is an idealisation of a real four-bar sley drive, which is asymmetric and peaks harder than this on the beat-up stroke — treat the inertial figure as a floor. Because it scales with the square of loom speed, dropping speed a little relieves the sley far more than it costs in production.
Heavy Canvas Beat-Up Force & Sley Capacity Calculator — free, with the formula and a worked example, at Textile School.