pulley
Enable an AI agent to recognise a pulley, assess its compatibility and condition, and determine which routing, rotation, adjustment or service actions are supported by available evidence.
Research draft, second pass
A second pass drafted this model: the structure a model of this thing needs, and what is known about it in the world. The line under this one says how the second half was obtained - researched against sources, or recalled without web access, in which case nothing here was read anywhere and every claim is a lead to verify. Unreviewed either way.
Researched by: Codex + Grok
Purpose and description
Enable an AI agent to recognise a pulley, assess its compatibility and condition, and determine which routing, rotation, adjustment or service actions are supported by available evidence.
A pulley is a rotating machine element whose rim, groove, or toothed profile carries a flexible tensile member (rope, cable, belt, or chain), thereby changing the direction of tension and, in multiple-wheel arrangements, producing a mechanical advantage.
It can be Identify the pulley and distinguish it from its enclosing block or machine assembly.; Check a proposed rope, cable or belt against documented engagement requirements.; Assess the installed routing, alignment and retention of the flexible member.; Inspect accessible working surfaces and evaluate rotation under an authorised inspection procedure.; Determine whether adjustment, lubrication, replacement or removal from service is supported by condition evidence and applicable instructions..
Distinguishing features
Check whether a flexible member is intended to engage the circumference of a wheel that rotates about an axis; distinguish this from a stationary eye or fairlead.
Check the intended mating member: engagement with a rope, cable or belt supports pulley identification, while intended engagement with another gear or a chain requires a neighbouring classification.
Check whether the working circumference routes or drives a passing flexible member rather than primarily accumulating successive wraps for storage, as a drum or reel would.
Check whether the wheel directly engages the flexible member rather than directly supporting the transported object, as a conveyor roller may.
Check whether the identified item is one pulley or a larger block or tackle containing pulleys, attachment hardware and other components.
Scope
+ Recognition of the pulley and identification of its working surfaces
+ Wheel, groove or tooth geometry and compatibility with the intended flexible member
+ Hub, bearing or bushing arrangements and attachment interfaces
+ Installed alignment, engagement and rotational behaviour
+ Observed damage, wear, maintenance needs and evidence supporting permitted use
- The construction, condition and service history of the rope, cable or belt
- The complete hoist, tackle, conveyor or belt-drive system
- The structural adequacy of supporting beams, anchors and machine frames
- The load being lifted or the machines supplying and receiving power
- System-wide guarding, control logic and operating procedures
Characteristics
- Functional role
- redirecting, supporting, tensioning, driving, driven, multiple roles, unresolved The intended role determines which engagement, mounting and operating evidence the agent needs.
- Flexible-member compatibility
- Identified rope, cable or belt specification, with compatibility evidence Appearance alone does not establish that a flexible member will fit or operate acceptably.
- Working circumference form
- Smooth, crowned, grooved, multiple-grooved, toothed, other, unresolved The contact form helps distinguish how the pulley guides or transmits force to its mating member.
- Wheel diameters
- mm; distinguish outside, groove-root and specified working or pitch diameter Diameter measurements support identification and compatibility checks only when their reference surfaces are explicit.
- Engagement profile
- Groove count, width and depth in mm, profile angles in degrees, or tooth pitch in mm as applicable Profile dimensions help assess seating and distinguish similar-looking pulley variants.
- Rotational support and mounting
- Bearing or bushing arrangement, bore and hub form, shaft coupling and retention method These features determine how the wheel rotates, transfers torque and remains attached.
- Installed engagement geometry
- Wrap and entry/exit angles in degrees; alignment offsets in mm, with reference frame Installed geometry provides evidence for investigating tracking, rubbing and member escape.
- Mechanical condition
- Observed cracks, deformation, wear, corrosion, looseness, rough rotation or unassessed areas Condition observations support service decisions without treating an uninspected feature as sound.
- Documented operating envelope
- Applicable manufacturer or engineering evidence for load, torque, speed and environmental limits Permitted use depends on limits applicable to the specific pulley and installation.
Also called
Where this came from
wikidata · CC0 1.0
Drafted structure
Bundle to layer to finding to question, as the second pass will find it: 6 bundles · 11 layers · 18 findings · 28 questions.
Pulley identity Establish what item is being modelled and how its circumference interacts with a flexible member.
An agent must distinguish an individual pulley from similar wheels and from assemblies containing several pulleys.
Recognition and boundary
Identify the rotating working wheel and establish the extent of this instance.
Working wheel boundary
Record the evidence identifying the pulley and separating it from adjacent components.
- Which circumferential surface engages a rope, cable or belt, and about which axis does it rotate? definition
- Does this instance denote the wheel alone, a pulley with integral support, or an assembly that needs a separate model? boundary
Role and identification
Connect physical identity with intended use and traceable product evidence.
Identified pulley role
Record the intended role without inferring a rating from its appearance.
- Is this pulley intended to redirect, support, tension or drive its flexible member, and what establishes that role? definition
- Which markings, drawings or product records identify this exact pulley variant? provenance
Flexible-member engagement Describe the contact geometry and evidence needed to match the pulley to a rope, cable or belt.
A pulley cannot be judged suitable independently of the member engaging its working circumference.
Contact profile
Capture the dimensions and form that govern seating and engagement.
Rim, groove or tooth geometry
Record applicable geometry with explicit measurement references.
- Is the working surface smooth, crowned, grooved or toothed, and which dimensions identify its profile? measurement
- Which measured diameter is outside, groove-root or working diameter, and how was each established? measurement
Compatible member
Establish which member specifications the contact geometry is intended to accept.
Member fit evidence
Separate documented compatibility from an observed ability to place a member on the wheel.
- Which rope, cable or belt sizes and profiles are explicitly supported by the pulley documentation? provenance
- What checks are required before fitting a proposed replacement member to this pulley? action
Rotation and attachment Describe how the wheel rotates, is retained and connects mechanically to its surroundings.
A pulley may rotate freely on an axle or transmit torque through a shaft connection, requiring different checks.
Rotational support
Identify the moving interfaces and their service requirements.
Hub and bearing arrangement
Record where relative rotation occurs and which components provide support.
- Does the wheel rotate relative to a stationary axle, or does it rotate with a shaft? definition
- Which bearings, bushings or contact surfaces support that rotation, and what instructions apply to their servicing? provenance
Retention and coupling
Capture attachment features that keep the wheel located and, where applicable, transmit torque.
Attachment integrity
Record the pulley-side interfaces and evidence that their assembly is correct.
- Which shoulders, retainers, fasteners, keys or clamping features locate this pulley and couple it to its support? definition
- What inspection or assembly evidence is needed before accepting its axial retention and torque connection? action
Installed routing Relate the pulley to the actual path and engagement of its flexible member.
Correct component selection alone does not establish acceptable installed alignment or member containment.
Path and alignment
Record the member's approach, departure and contact around the wheel.
Installed contact path
Capture routing geometry relative to the pulley axis and working profile.
- What are the member's entry direction, exit direction and wrap angle relative to the pulley axis? measurement
- Which installation specification defines acceptable alignment for this pulley and member combination? provenance
Tracking and containment
Assess seating and the features intended to keep the member on its path.
Member tracking evidence
Record observed contact and containment without assuming that flanges or keepers eliminate escape.
- What evidence shows the member remains seated, or instead rubs, climbs, slips or leaves its intended track? measurement
- Which flanges or keepers belong to this pulley instance, and which containment components belong to its surrounding assembly? boundary
Condition and permitted use Connect pulley-specific inspection evidence and applicable limits to decisions about continued use or service.
The agent needs a defensible basis for action when wear, uncertain ratings or abnormal rotation are present.
Wear and rotation
Assess working-surface damage and the behaviour of the supported wheel.
Pulley condition evidence
Record inspected areas, observed defects and relevant acceptance criteria.
- What groove, tooth, rim or hub wear, cracking or deformation is visible, and which areas remain uninspected? measurement
- What play, runout, binding or roughness is observed during an authorised rotation check, and how does it compare with applicable criteria? measurement
Limits and disposition
Determine which operating and maintenance actions the available evidence supports.
Supported use decision
Associate operating limits and condition findings with an explicit action or unresolved decision.
- Which load, torque, speed and environmental limits apply to this exact pulley, and under what installation assumptions? provenance
- Do the documented limits and observed condition support continued use, adjustment, servicing or replacement, and what missing evidence prevents a decision? action
Evidence and external alignment What the world already says about this thing, gathered so the model can be checked against it.
A model that cannot be lined up against existing standards, identifiers and practice cannot be adopted by anyone who already uses them.
Reported evidence
Findings from the breadth pass, kept separate from the structural claims.
Kinds and varieties
Reported by the breadth pass; each item needs checking against its source before it becomes normative.
- Fixed pulley (direction change only; ideal mechanical advantage of 1)
- Movable pulley (load attached to the moving wheel; ideal mechanical advantage of 2)
- Compound pulley / block and tackle (two or more sheaves in frames, used to multiply force)
- V-belt and V-ribbed pulley (friction power transmission)
- Synchronous / timing-belt pulley (toothed, positive drive)
- Wire-rope sheave (crane, hoist, elevator, and mine-hoist wheels sized to the rope)
- Snatch block (side-opening rigging block for mid-line attachment)
- Idler or tensioner pulley (guides or tensions a belt without delivering shaft power)
- Which of these kinds and varieties hold for the sense of pulley this model covers, and on what evidence? provenance
Identifiers and schemes
Reported by the breadth pass; each item needs checking against its source before it becomes normative.
- Wikidata - Q188507 - Item labelled pulley; sheave and block are neighbouring items, not this one.
- Harmonized System (HS / HS6) - 8483.50 - Flywheels and pulleys, including pulley blocks; national tariff splits vary below six digits.
- ISO V-belt pulley designation - {SPZ|SPA|SPB|SPC} + datum diameter (mm) - Narrow V-belt pulleys under the ISO datum-width system; classical sections use A/B/C/D/E in much North American stock.
- Synchronous belt pulley designation - tooth profile (e.g. MXL, XL, L, H, HTD 3M/5M/8M/14M, GT) + tooth count + belt width - Pitch is set by profile and tooth count, not by outside diameter alone.
- Which of these identifiers and schemes hold for the sense of pulley this model covers, and on what evidence? provenance
Standards and regulation
Reported by the breadth pass; each item needs checking against its source before it becomes normative.
- ISO 4183 - grooved pulleys for classical and narrow V-belts (International Organization for Standardization)
- ISO 5294 - synchronous belt drive pulleys (International Organization for Standardization)
- ISO 16625 - selection of wire ropes, drums and sheaves for cranes and hoists (International Organization for Standardization)
- 29 CFR 1910.219 - mechanical power-transmission apparatus, including pulleys and belts (US Occupational Safety and Health Administration)
- 29 CFR 1926.251 - construction rigging equipment, including sheave practice with slings and hoist lines (US Occupational Safety and Health Administration)
- Directive 2006/42/EC - machinery incorporating belt drives or lifting blocks placed on the EU market (European Union)
- EN 13157 - safety of hand-powered lifting equipment, including pulley blocks (CEN)
- Which of these standards and regulation hold for the sense of pulley this model covers, and on what evidence? provenance
Real-world use
Reported by the breadth pass; each item needs checking against its source before it becomes normative.
- Redirecting and multiplying force in construction cranes, chain hoists, and rope-access or rescue mechanical-advantage systems
- Driving accessories from an engine or motor with V-belts or synchronous belts (alternators, fans, pumps, compressors, CNC axes)
- Sailing and theatrical fly systems, where framed blocks reeve running rigging
- Elevator, mine-hoist, and conveyor head/tail/take-up sheaves carrying wire rope or belts
- Cable-exercise machines, window sash weights (historic), well buckets, and flag halyards
- Which of these real-world use hold for the sense of pulley this model covers, and on what evidence? provenance
Typical measurements
Reported by the breadth pass; each item needs checking against its source before it becomes normative.
- Pitch, datum, or pitch-circle diameter - about 15 mm (small timing pulleys) to more than 2000 mm (hoist and conveyor sheaves) - mm
- Sheave-to-rope diameter ratio (D/d) - about 16:1 to 40:1, set by rope construction and duty class - dimensionless ratio
- Working load limit of a commercial block - about 0.25 to 100 (larger crane sheaves exceed this) - t
- V-belt groove angle - about 34 to 40 - degree
- Belt or rim speed in power-transmission service - typically kept at or below about 30 to 40 - m/s
- Ideal mechanical advantage of a tackle - 1 (single fixed) to about 4-8 in common reeving; higher in specialised multi-sheave gear - dimensionless ratio
- Which of these typical measurements hold for the sense of pulley this model covers, and on what evidence? provenance
Failure modes and hazards
Reported by the breadth pass; each item needs checking against its source before it becomes normative.
- Seized sheave or failed bearing, so the rope or belt slides in a stationary groove and is cut or glazed
- Groove wear or too-small D/d, causing wire-rope fatigue, birdcaging, or premature belt failure
- Thrown or derailed belt; jumped rope from an under-flanged or misaligned sheave
- Overload or side-load of a snatch block, failing the axle, cheek plates, or attachment point
- Unguarded in-running nip between belt and pulley, drawing in clothing, hair, or limbs
- Corrosion and UV or salt degradation of marine and outdoor blocks, reducing load rating without obvious warning
- Which of these failure modes and hazards hold for the sense of pulley this model covers, and on what evidence? provenance
Regional variation
Reported by the breadth pass; each item needs checking against its source before it becomes normative.
- In nautical and theatrical English the framed assembly is a block and the wheel is a sheave; 'pulley' is the usual word in physics teaching and belt-drive catalogues
- North American belt stock still uses classical A-E sections and QD/taper-lock bushings; much of Europe specifies ISO SPZ/SPA/SPB/SPC datum-width pulleys
- German practice splits the concept as Riemenscheibe (belt pulley) versus Seilrolle (rope sheave); French uses poulie for both
- Rigging hardware ratings and inspection regimes differ between OSHA/ASME practice in the United States and the Machinery Directive plus EN lifting standards in Europe
- Which of these regional variation hold for the sense of pulley this model covers, and on what evidence? provenance
Neighbouring kinds and how to tell them apart
Reported by the breadth pass; each item needs checking against its source before it becomes normative.
- Sprocket - A sprocket has teeth that engage a chain's rollers or links; a pulley presents a groove, crown, or belt-tooth profile to a belt, rope, or cable.
- Capstan or winch drum - A drum stores and hauls line by accumulating wraps on a powered barrel; a pulley redirects a member that continues past the wheel rather than being stored on it.
- Gear - Gears mesh tooth-to-tooth with another rigid wheel; a pulley works through a flexible tensile member.
- Fairlead or chock - A fairlead guides a line, often with a low-friction surface or small rollers, but is not sized or grooved as a load-bearing rotating sheave.
- Block (rigging) - A block is the framed assembly that contains one or more sheaves, a becket, and an attachment; 'pulley' may mean that assembly or only the wheel, depending on trade.
- Plain roller or idler roller - A roller is typically a cylinder supporting a belt or web across its width; a pulley is profiled for a discrete tensile member and usually has flanges or a groove.
- Which of these neighbouring kinds and how to tell them apart hold for the sense of pulley this model covers, and on what evidence? provenance
Sources
- Pulley - Simple-machine classification (fixed, movable, compound), block-and-tackle practice, and the everyday distinction between the wheel and the framed block.
- ISO 4183, Belt drives - Classical and narrow V-belts - Grooved pulleys (system based on datum width) - The industrial identity of grooved V-belt pulleys, including datum-width groove geometry and profile families used in power transmission.
- ISO 5294, Synchronous belt drives - Pulleys - Toothed timing-belt pulleys as a distinct product class from friction V-belt pulleys.
- ISO 16625, Cranes and hoists - Selection of wire ropes, drums and sheaves - Wire-rope sheaves as a lifting-gear element whose diameter is chosen relative to rope construction and duty.
- 29 CFR 1910.219, Mechanical power-transmission apparatus - Workplace guarding, location, and running practice for power-transmission pulleys and belts in US industry.
- Harmonized System heading 8483.50, Flywheels and pulleys, including pulley blocks - Customs identity of pulleys and pulley blocks as a named class of goods.
What the second pass must settle
- Does registry usage include toothed belt pulleys and smooth idlers within this entry, and where does it place the boundary with sprockets and rollers?
- Should integral bearing carriers and rope-retaining side plates belong to a pulley instance or to a separately registered block assembly?
- Which authoritative sources establish profile compatibility and diameter requirements for the pulley families covered by this entry?
- Which inspection and rejection criteria apply to each pulley material, construction and intended service?
- How should documented component ratings be related to installed-use decisions when the surrounding system's loads or configuration remain unresolved?