A power loom needs 375-750 W from a shaft that holds its speed, and the loom also needs the yarn of about 79 spindles drawing 790-1,580 W and someone who can repair it, which is why these machines arrived with factories and not in workshops. A 785 W water wheel runs one to two looms at the overview’s loom power and none of their yarn, and a plant of 2-4 looms with its own spinning needs roughly 2.3-9.3 kW.
Part of Power Loom Construction
Connecting a water wheel, treadle or motor to the loom, and what the loom needs around the drive for it to run at all.
The Overview’s Gearing, Checked
The overview runs the loom at 60-120 picks a minute, so the crankshaft turns 60-120 rpm, from a water wheel at 5-10 rpm. The speed increase needed runs from 60 ÷ 10 = 6 to 120 ÷ 5 = 24. The overview gets there in two stages: a gear stage of 4:1 to 6:1 on the wheel shaft and a flat belt of 2:1 to 4:1 to the loom, a product of 8 to 24. The first stage is wooden gearing, whose tooth speed should stay under 1 m/s (Speed Ratios), and the belt must be loose-and-fast so the loom can be stopped alone (Power Transmission, Belt Drives, Mill Power Transmission for the wheel to line shaft).
The Power Budget Is Larger Than The Loom
| Item | Figure | Source |
|---|---|---|
| One 1 m loom at 100 picks a minute | 375-750 W | overview |
| Yarn for that loom: 79 spindles at 10-20 W | 790-1,580 W | Multi-Spindle Frame Assembly |
| Loom plus its yarn | 1,165-2,330 W | sum |
| 2 looms with yarn | 2.3-4.7 kW | 2 × the sum |
| 4 looms with yarn | 4.7-9.3 kW | 4 × the sum |
Carding and roving are extra and unquantified. For scale, Water Wheel Types gives 785 W for 20 litres a second over 5 m at 80% efficiency, and Water Power gives 1.2 kW for 10 litres a second over 20 m at 60%. The overview says a modest wheel handles 2-4 looms. At 375-750 W per loom that is 0.75-3 kW for the looms alone, more than the 785 W example gives, and with the yarn the total is 2.3-9.3 kW. A site at the 1.2 kW scale runs about one loom with its yarn at best. A stream of, say, 40 litres a second over 20 m at 60% would give 40 × 20 × 9.81 × 0.6 = 4.7 kW, enough for two looms with their yarn at the high figures, or four at the low ones. Dry-season flow can drop power sharply (the corpus example falls to 300 W), so the plant’s size is set by the driest month (Head Measurement).
Steady Is Not The Same As Fast
A wheel’s speed follows its load and flow. If everything slows together, the twist in the spinning frame is unchanged (spindles and rollers share a drive; Drive System) and the cloth density is unchanged, because take-up is per pick (Take-Up and Cloth Beam); only the output falls. A sudden change is what hurts: a jam, or a neighbouring mill taking the water, can stall a loom mid-pick or let it overspeed the shuttle. A flywheel smooths short pulses (Flywheel); it does not replace water.
Why These Machines Came With Factories
Put together, one loom is: a frame and slay (Loom Frame Design), two thousand heddles from a wire-drawing line (Heddle Construction), reeds, shuttles and pickers that wear out, yarn from about 79 spindles on a drive of its own, a winder, and a power source that is steady enough, plus a person who can fix all of it. The machine does not make that a workshop job. The step from a treadle loom, a person’s own tool (Pedal Power), to a power loom is the step that needed the plant.
What You Need
- A power source sized for the dry season, with its water gate.
- A drive chain of gear and belt stages, with a loose-and-fast pulley at each loom.
- A named person for the gate and a loom fixer.
- Spare parts: heddles, reeds, pickers, straps, shuttles, belts.
The Stop
| Stop | Where | Who reaches it | Effect |
|---|---|---|---|
| Belt shifter | At the loom | The weaver at the loom | Disconnects that loom |
| Line-shaft belt or clutch | At the shaft | Whoever is near | Disconnects a group |
| Water gate | At the wheel, outside | A person posted there | Cuts the source |
Coasting after the loom’s belt is shifted: assume a 30 kg flywheel of 0.25 m radius treated as a ring, I = 30 × 0.25² = 1.9 kg·m² (about 1.875); at 100 rpm, ω = 10.47 rad/s and E = ½ I ω² = 103 J, plus about 11 J in a slay of 20 kg at its peak speed of 1.05 m/s. At an assumed friction loss of a quarter to a half of the 375-750 W running power, 94-375 W, the loom stops in 114 ÷ 375 = 0.3 s to 114 ÷ 94 = 1.2 s. The loom itself stops almost at once. What does not stop is the belt: at the 2.13 m/s of the belt-drives example (419 ft/min) the pull behind a running belt is power ÷ speed, 375 ÷ 2.13 = 176 N to 750 ÷ 2.13 = 352 N, and it continues until the gate is shut. A sleeve in the belt or line shaft is not freed by shifting one loom’s belt.
Common Mistakes
- Counting looms by wheel power and ignoring the spinning room.
- Sizing for the wet season.
- No named person at the gate.
- No spares, so a worn picker stops the plant.
Safety
The loom stops in about a second; the belt behind it does not
The shifter at the loom stops the loom, not the line shaft or the wheel. A hand, sleeve or hair caught in a belt, pulley or line shaft is pulled with 176-352 N (on the figures above) until the water gate is closed outside the building. Tie back hair, no loose clothing, a named person at the gate, a rope trip within reach of every loom, and a rehearsed stop. Looms and spinning frames have historically been tended by children for the jobs that maim, such as clearing jams, piecing threads and crawling under machinery; the corpus rule is the opposite, keeping children away from running machinery (Task Assignment by Age, Child Development & Welfare After Collapse, Avoiding Exploitation). For a crushed or severed limb see Bleeding Control.
What’s Next
- Learn next: Pedal Power — the human-powered alternative
- Combine with: Drive System — the same questions for the spinning frame