Machinery Dynamics
Inertia goes as the square of loom speed. From 400 to 600 picks a minute is not half again more force — it is more than double.
— kN
At front dead centre, where beat-up occurs
Only the first two harmonics of slider-crank motion are included, which is standard practice and adequate for the peaks, but a real cam-driven sley follows whatever profile the cam designer chose and can differ substantially — particularly in jerk, which the harmonic approximation understates and which is what actually cracks brackets. The reciprocating mass must be the effective mass referred to the sley, including the appropriate share of the swords and rod, not just the reed and race. Inertial force is also only one of the loads on the frame: beat-up resistance from the fabric and shedding forces arrive at the same time and are calculated separately.
Loom Sley Acceleration Profile & Frame Loading — free, with the formula and a worked example, at Textile School.