Investigation of freight railcar air brake performance in cold temperatures
Bibliographic record
Abstract
This paper presents results from controlled climatic testing of 29 service-worn and 26 new / refurbished freight railcar air brake systems at temperatures from +5°C to -40°C. These systems were subjected to both service and emergency brake applications, at nominal brake pipe pressures of 90 psi and 75 psi. Service-worn systems were also analysed to observe effects of system age and time since refurbishment on brake per-formance. Findings show that service-worn systems held less force at the end of pre-determined hold times than new / refurbished systems, and this loss of force increased with decreasing temperature. Brake performance was also shown to decline with system age, and this was exacerbated by cold temperatures. Several service-worn systems which pass the industry standard automated single car air brake test failed to operate at colder temperatures, with different failure modes observed. Results demonstrate the loss of brake force at low temperatures, which affects freight train stopping distances, and could have implications for rail operation safety as well as for positive train control (PTC) algorithms in low temperature locations.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one teacher head, not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".