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ASME B29.3M-1994 scan — Steel Bushed Rollerless Chains, Attachments, and Sprockets (Metric)
🛤️ ASME B29.3M-1994 is the metric (SI) edition of the American National Standard for steel bushed rollerless chains, their attachments, and sprockets; together with the inch edition B29.3-1994 it forms a two-unit system for the same standard. The “M” suffix indicates that all dimensions are stated in SI units such as millimetres. This PDF is a scanned copy without a text layer, so this article is written from the domain knowledge of the standard’s subject area. A rollerless chain is the simplest family in the chain-drive world: it is made of alternately assembled bushing links and pin links, with pins articulating inside bushings, and the sprocket teeth engage directly on the bushing outside diameter — no rollers are fitted. Compared with roller chain it omits the roller components: construction is simpler, chain weight lower, and cost less, but speed and life are lower, so it is widely used for low-speed heavy-duty conveying and elevating equipment such as grain elevators, drag conveyors, bucket elevators, and agricultural machinery.
💡 The value of the metric edition is international compatibility: with SI units the tables can be used directly on metric-market drawings and manufacturing, avoiding inch-to-metric conversion errors. The same chain number keeps the same pitch and bushing diameter in both editions — only the unit expression differs.
1. Metric Structure and Scope 📌
This edition continues the technical framework of the B29.3 family (ASA B29.3-1952, ANSI B29.3-1977, etc.) and applies to steel bushed rollerless chains, attachments, and mating sprockets. Its content includes:
- Link construction: inside link (bushing link: two plates plus two bushings) and outside link (pin link: two plates plus two pins) assembled alternately.
- Rollerless engagement: sprocket teeth contact the bushing outside diameter directly in sliding friction.
- Attachments: K-type, A/D-type, and extended-pin forms.
- Sprockets: tooth count, pitch diameter, tooth form, and face-width matching.
⚠️ A scanned PDF cannot supply copyable precise values; for design or acceptance, always use the official ASME B29.3M-1994 text. This article’s figures are indicative only.
2. Metric Parameters and Acceptance Items 📏
The metric edition states the following core parameters in mm:
| Parameter (SI) | Description | Engineering Function |
|---|---|---|
| Pitch P (mm) | Center distance between adjacent joints | Basis for chain and sprocket sizing |
| Bushing OD/width (mm) | Engagement contact dimensions | Sets sprocket face width and capacity |
| Pin diameter (mm) | Joint strength and wear | Checked with M.U.T.S. |
| Measuring load (N/kN) | Tension for length measurement | Standardized length acceptance |
| Ultimate tensile strength (kN) | Static breaking limit | Strength selection criterion |
💡 A metric purchasing note: keep drawings, orders, and acceptance records consistently in mm/kN. Even if you consult the inch edition for conversion, label the values as “converted” and confirm metric nominal dimensions with the manufacturer to avoid mixed-unit errors.
3. Attachments and Sprocket Matching ⚙️
Attachments (K-type scraper plates, A/D straight plates, extended pins) also include mounting hole positions and dimensions in the metric edition, and sprocket tooth forms and face widths match the bushing outside width. Engineering points:
- Tooth-form fit: tooth thickness and tooth space must avoid interference and allow smooth entry and exit of engagement.
- Face-width match: sprocket face width slightly exceeds chain outside width to prevent edge crushing.
- Lubrication: grease or drip oil at low speed, covering both the bushing/pin and bushing/tooth pairs.
🚨 Rollerless sliding engagement is extremely lubrication-sensitive: without oil, bushing OD and tooth face wear accelerates sharply, pitch elongates rapidly, and tooth skipping and derailing follow. Establish a periodic lubrication routine for low-speed heavy-duty service and monitor pitch elongation.
4. Engineering Practice Essentials 🛠️
- Selection: compute tension from conveying rate/lift height including impact factor, then choose the chain number by ultimate tensile strength with a safety factor; confirm linear speed is within the rollerless-chain range.
- Length acceptance: pre-stretch and measure under the measuring load; install twin parallel strands at equal length.
- Alignment and tension: align sprocket faces and control shaft parallelism; maintain moderate slack-side sag.
- Maintenance: inspect bushing wear, plate cracking, pin bending, and attachment tightness.
5. Frequently Asked Questions ❓
❓ Q: How do B29.3M and B29.3 relate?
A: They are the metric (M, SI units) and inch editions of the same steel bushed rollerless chain standard; the technical content is identical and only the unit system differs.
A: They are the metric (M, SI units) and inch editions of the same steel bushed rollerless chain standard; the technical content is identical and only the unit system differs.
❓ Q: Why is the speed of rollerless chain limited?
A: The sprocket tooth and bushing are in sliding contact; as linear speed rises, wear and temperature climb steeply, so it suits only low-speed heavy-duty duty — use roller chain at higher speed.
A: The sprocket tooth and bushing are in sliding contact; as linear speed rises, wear and temperature climb steeply, so it suits only low-speed heavy-duty duty — use roller chain at higher speed.
❓ Q: What should be watched when purchasing to the metric edition?
A: Draw and order consistently in mm/kN, cite standard edition B29.3M-1994, and avoid mixing converted values with metric nominal values.
A: Draw and order consistently in mm/kN, cite standard edition B29.3M-1994, and avoid mixing converted values with metric nominal values.
❓ Q: Does the scanned PDF limit use?
A: A scanned copy has no text layer and cannot be copied or searched; for engineering design use the official text, and treat this scan as reference material.
A: A scanned copy has no text layer and cannot be copied or searched; for engineering design use the official text, and treat this scan as reference material.
