Log
writing
doneI've built the V-belt drive. It measures 540 × 135 × 220 mm, has 61 parts and matches the size I expected. It also builds correctly at both ends of the input ranges.
**What's in the model**
- **Driving pulley:** 160 mm, steel blue, with a red painted mark.
- **Driven pulley:** 80 mm, copper, with a goldenrod mark.
- **Pulley detail:** each has a V-groove drawn as two cones sloped to the groove angle. The groove sits between two rims, with a hub and a silver shaft stub.
- **Belt:** 40 short black boxes laid on the effective diameter. They follow the upper straight span, the wrap on the driven pulley, the lower span and the wrap on the driving pulley.
- **Base:** a dark olive-green base plate with two grey bearing pedestals and brass bearing housings.
**Motion:** the state input `drive-angle-deg` (0–720°) turns the driving pulley by that angle and the driven pulley by twice as much. The belt boxes move along their path by the same distance the driving pulley's rim travels, so the belt keeps pace with both marks.
**Results at the default inputs** (each is a result in the model, with its unit in the description):
| Result | Value |
|---|---|
| Speed ratio (driven speed ÷ driving speed) | 2 |
| Driven speed | 4000 rpm |
| Belt length | 1022 mm |
| Wrap angles | 194.4° (driving) and 165.6° (driven) |
| Belt speed | 16.76 m/s |
| Effective pull | 298.4 N |
| Wedge friction coefficient μ′ = μ / sin(19°) | 0.921 |
| e^(μ′β) on the smaller wrap angle | 14.35 |
| Tight side / slack side | 320.8 N / 22.3 N |
| Centrifugal force | 28.1 N |
| Pretension per span | 199.6 N |
| Shaft load at rest | 396.1 N |
| Bending frequency | 32.8 1/s |
**Inputs you can change** (Inputs panel, all with sliders):
| Input | Range |
|---|---|
| Driving diameter | 60–250 mm |
| Driven diameter | 50–200 mm |
| Centre distance | 260–600 mm |
| Belt width | 8–25 mm |
| Groove angle | 32–40° |
| Friction coefficient | 0.1–0.6 |
| Belt mass | 0.02–0.5 kg/m |
| Power | 0.5–30 kW |
| Driving speed | 500–6000 rpm |
| `drive-angle-deg` | 0–720° |
| Number of belt segments | 20–60 |
The pedestal height and base plate grow to fit the pulleys.
**How some results are defined:**
- The tight-side and slack-side forces are the forces needed just to transmit the power, without centrifugal force.
- Pretension per span is the average of the two plus the centrifugal force.
- Shaft load is the value at rest: 2 × pretension × sin(half the smaller wrap angle).
- Bending frequency counts two pulleys.
**Limits:**
- The groove is drawn with cones, not cut into the pulley, because this version of Gendl can't subtract one shape from another.
- The belt is a chain of straight segments along the effective diameter, with no sag.
- The wireframe viewer draws the circles as polygons.
toolevaluate
textThe model builds and the numbers match my hand calculations. I'm checking that it still builds at the ends of the input ranges.
toolrender
toolevaluate
toolcheck_model
toolwrite_model
toolevaluate
tool-errorwrite_model: Error compiling or loading the model file: Class named PL-D84CF70F3F5E::V-PULLEY not found.
Warnings first:
- In an anonymous lambda form at position 3372: (from object specification for :BELT)
The following is not recognized as any category of defined input-slot for
the object type 'BOX'. This will be assumed to be a pseudo-input.
:PTS
You can suppress this warning by including this name in the :pseudo-inputs
special input keyword for the child object, i.e:
...
:pseudo-inputs (PTS)
...
toolwrite_model
tooldescribe_object
promptAn open V-belt drive between two pulleys, as drives an auxiliary unit such as an air-conditioning compressor or a coolant pump. Parts: a driving pulley and a driven pulley on parallel shafts, each a grooved disc with a hub, a painted mark and a shaft stub; the belt, drawn as a chain of short boxes running round both wrap arcs and along the two straight spans; and a base plate with two bearing pedestals. Inputs: driving pulley effective diameter 160 mm, driven pulley effective diameter 80 mm, centre distance 320 mm, belt width 13 mm, groove angle 38 degrees, friction coefficient 0.3, belt mass per metre 0.1 kg, power 5 kW, driving speed 2000 rpm, and the STATE input drive-angle-deg. The driving pulley turns by the state angle, the driven pulley by that angle times the ratio, and the belt segments advance along their path by the matching arc length, so the belt is seen to run. Compute: speed ratio, driven speed, belt length, both wrap angles, belt speed in m/s, effective pull in N, the wedge friction coefficient mu / sin(half groove angle), the Euler-Eytelwein force ratio e^(mu' beta) on the smaller pulley, the tight-side and slack-side forces just sufficient to avoid slip, centrifugal belt force, required static pretension per span, shaft load, and bending frequency in 1/s.
(This prompt was written by Claude, Anthropic's AI model, as one entry in a catalog of simulative models of automotive systems.) House brief: key dimensions and operating values are root inputs with input-controls (ranges the model holds at); STATE inputs must really move the parts; each result named above is a computed-slot of MODEL with a doc string giving its unit; simplified but recognisable geometry, about 15 to 80 leaves; colours only from Gendl's own table, hyphenated: :steel-blue, :slate-gray, :dim-gray, :silver, :brass, :copper, :bronze, :firebrick, :goldenrod, :orange, :red, :black, :dark-olive-green.
noteSession d84cf70f3f5e opened for an external agent.