Presets
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Engine, belts and cloth
The engine torque droops with shaft speed. A belt clutch can pass at most 4 + 0.62 x tension N m; above that it slips, heats and the loom slows.
Looms
Model checks
The science
What is modelled
An engine of drooping torque drives a line shaft of fixed inertia. Each loom hangs on a belt clutch whose torque follows the speed difference but is capped by the belt tension, so a slack belt or a heavy weave slows the loom and warms the belt.
Equations
- Engine torque
116 x throttle x (1 - w/31); shaft drag3.2 + 0.042 w2. - Clutch torque
clamp(21 (w_shaft - w_loom), +/- (4 + 0.62 T)). - Shaft
27 dw/dt = T_engine - T_drag - sum(T_clutch); each loom has inertia 5.4 kg m2. - One pick per loom revolution; cloth length
picks / (100 x density).
Checks run in the page
- Unloaded steady state against a bisection root.
- Energy balance of input work.
- Clutch torque never above its capacity, with slip flagged.
- Cloth length from the crank angle.
Honest simplifications
An idealised teaching model: no belt creep or elasticity, no real steam-engine governor, illustrative heating, and constants not calibrated to a historical mill.
What to try
- Press Slack belts and watch the slip warning and the belt temperature.
- Press Dense cloth to raise the load on both looms.
- Open one clutch and see the shaft speed rise.