A spinning frame is driven from one belt through a tin roller and tapes to every spindle, and the twist stays right only if slip at the tapes is allowed for: 2-5% slip turns a nominal 20 twists per inch into 19.6-19.0, so for a warp floor of 18 the nominal setting must be at least 19. The belt shifter stops the frame in a few seconds, but the line shaft behind it keeps its full power until the water gate is closed, so a sleeve caught in a running belt is pulled with the force of power divided by belt speed, about 153 N for 400 W at 2.62 m a second.
Part of Spinning Frame
How power reaches every spindle and roller of a frame, what slip does to the yarn, and where the stops are.
One Drive, Two Speeds That Must Stay In Ratio
The overview’s drive: a main shaft from the water wheel or motor; a belt to the front roller shaft; a gear train from the front rollers to the middle and back rollers, whose exact ratios set the draft; a tin roller or belt driving each spindle whorl from a common drum; and roughly 10-20 W per spindle. The article is derived from those figures and assumed dimensions; no sourced tolerance exists for slip.
Twist per inch is spindle rpm divided by delivery speed (Twisting). If a drop in power slows the whole drive evenly, spindles and rollers slow together and the twist is unchanged; only the output falls. If only the spindle drive slips, the twist falls. Which of the two is true depends on how the frame is built, so run the rollers and the spindles from the same shaft and let slip occur only where it cannot be avoided.
The Tape Drive In Numbers
Take an assumed whorl of 25 mm and a spindle speed of 2,000 rpm. The tape speed is π × 0.025 × 2,000 ÷ 60 = 2.62 m a second. A tin roller of 250 mm (assumed) must turn 2,000 × 25 ÷ 250 = 200 rpm to give it, at a surface speed that is the same 2.62 m a second.
Slip: the corpus gives 2-5% belt slip for a well-tensioned belt (Mill Power Transmission). Slip at the tapes lowers spindle speed by the same fraction, so twist falls too:
- 2% slip: 20 × 0.98 = 19.6 twists per inch
- 5% slip: 20 × 0.95 = 19.0 twists per inch
- to guarantee the overview’s warp floor of 18 at 5% slip: 18 ÷ 0.95 = 18.9, so set at least 19
Slip is not constant: it rises when a tape is oily or wet, when a spindle sticks, and when the frame is overloaded. Yarn from a slipping spindle is soft and breaks on the loom. Check twist on every spindle’s bobbin (Twist Testing).
Tape pull: at 10-20 W per spindle the net pull per tape is P ÷ v, 10 ÷ 2.62 = 3.8 N to 20 ÷ 2.62 = 7.6 N. A frame of 20 spindles at 400 W puts 400 ÷ 2.62 = 153 N on the tin roller surface.
The Stops And Who Can Reach Them
| Stop | Where | Who reaches it | Effect |
|---|---|---|---|
| Belt shifter | At the frame’s head end, moving the belt from the fast to the loose pulley (Power Transmission) | The operator at that end, a few steps from the far end of a 1.6 m frame | Disconnects this frame only |
| Main belt or clutch | Line shaft | Whoever is near the line shaft | Disconnects the plant’s machines it serves |
| Water gate | At the wheel, outside the building | A designated person stationed there | Cuts the source |
Coasting after the shifter: the stored energy is small. For an assumed tin roller of 30 kg and radius 0.125 m treated as a ring, I = m r² = 0.47 kg·m² and at 200 rpm (20.9 rad/s) E = ½ I ω² = 103 J. Twenty flyers of two 20 g arms at 50 mm have I = 1.0 × 10⁻⁴ kg·m² each and at 209 rad/s store 2.2 J each, 44 J in all. The total is about 150 J. If friction takes 50-100 W while coasting (an assumed quarter of running power), the frame stops in 150 ÷ 100 = 1.5 to 150 ÷ 50 = 3 seconds. Measure this on your own frame with a stopwatch; the figure depends on assumed masses and friction.
The danger is not the stored energy. It is the power behind the belt. A line shaft driven from a wheel supplies its full power for as long as the water runs: a hand or sleeve wound into a running belt or onto a shaft is pulled with force P ÷ v and does not stop when the operator lets go. Shifting that frame’s belt does nothing for a person caught in the line shaft or in a main belt; only the water gate stops those, and the gate is out of the operator’s reach.
What You Need
- A belt shifter within reach of the operator, and a rope trip along the front of the frame that throws it (a design suggestion, not a corpus figure).
- A named person at the gate whenever the frame runs with others in the shed.
- Guards over tapes, tin roller, gears and the belt.
Method: Setting Up Drive And Stops
Step 1: Compute spindle speed, whorl and tin roller as above, and check tape speed against the tape’s rating.
Step 2: Set the nominal twist with the slip margin and test it on bobbins.
Step 3: Build the stops: shifter, trip rope, and signal to the gate.
Step 4: Time the coast and post it on the frame.
Step 5: Rehearse the stop with the whole shed once a month.
Worked Example
A frame of 20 spindles at 20 W each is 400 W. With 2.62 m a second at the tin roller the net pull is 153 N. A shifter that stops the frame in about 3 s still leaves a person pulled by 153 N for that time; a trip rope that throws the belt in 1 s is better, which is why the rope and a person at the gate are in the method.
Common Mistakes
- Treating the belt shifter as the plant’s stop. It is the frame’s stop.
- Setting twist at the nominal figure and ignoring slip.
- A tape drive with different tension across the row, giving a different twist per spindle.
- Oil near the tapes.
Safety
You cannot stop a line-shaft frame from where you stand
The stop for one frame is the shifter at its head end, a few steps away; the stop for the plant is the water gate, outside. After the shifter is thrown, the frame coasts for about 1.5-3 s on the assumed figures above (time yours). Anything caught on the shaft, belts or pulleys keeps being pulled until the gate is shut. Tie hair back, button sleeves, no loose cords or aprons, and nobody enters a belt run. Children do not work at running machinery (Task Assignment by Age). If a hand is caught, shut the gate first, then see Bleeding Control.
What’s Next
- Learn next: Doffing — changing bobbins without reaching into a running frame
- Combine with: Power Drive System — the same questions for the loom