Overview
ISO 9131:1993 - Three-wheeled mopeds and motorcycles - Dimensions - Vocabulary defines the standardized terms used to describe the geometric dimensions and related angles of three‑wheeled mopeds and motorcycles (as referenced in ISO 3833). It covers vehicles with one front/two rear wheels, two front/one rear wheels, and two‑wheeled vehicles fitted with a side‑car. The standard provides a consistent vocabulary for vehicle length, width, height, wheelbase, track, overhangs, ground clearance and ramp angle.
Note: ISO 9131:1993 does not specify measurement methods, units, required accuracy or order of magnitude - it is strictly a vocabulary standard.
Key topics
- Scope and applicability: three‑wheeled configurations and two‑wheelers with side‑car; excludes pedestrian‑controlled vehicles, vehicles for exclusive use by handicapped persons, agricultural/forestry tractors and earth‑moving equipment.
- Base terms: axle, wheel plane, wheel centre, longitudinal (vehicle) median plane and related definitions used to reference dimensions.
- Dimensional terms: vehicle length, vehicle width, vehicle height, wheelbase, track, front and rear overhang, ground clearance.
- Angles and manoeuvre geometry: ramp angle (defines the maximum ramp the vehicle can negotiate), with a specific note that ramp angle does not apply to vehicles with a side‑car.
- General conditions: definitions assume vehicle on a horizontal supporting surface, stationary, tyres inflated to pressure corresponding to manufacturer’s maximum total mass (per ISO 9132), and mass distributed per manufacturer’s instructions.
Practical applications
- Producing unambiguous technical drawings, CAD models and component specifications for three‑wheeled mopeds and motorcycles.
- Preparing type‑approval, homologation and regulatory documentation where standardized dimensional terminology is required.
- Creating vehicle data sheets and marketing specifications that use consistent dimension terms (wheelbase, track, overhang, ground clearance).
- Supporting interoperability between suppliers, OEMs and testing laboratories by ensuring common vocabulary across design and compliance teams.
- Using as a reference glossary when developing measurement procedures (while measurement methods themselves are covered in other standards).
Who should use this standard
- Vehicle designers and engineers working on three‑wheeled mopeds and motorcycles
- OEMs and component suppliers
- Compliance, homologation and regulatory agencies
- Test laboratories, technical writers and standards engineers
- CAD modelers and documentation teams preparing specification sheets
Related standards
- ISO 3833: types and definitions for road vehicles (referenced)
- ISO 6725: dimensions of two‑wheeled mopeds and motorcycles - terms and definitions
- ISO 9132: three‑wheeled mopeds and motorcycles - masses - vocabulary
Keywords: ISO 9131:1993, three‑wheeled mopeds, motorcycle dimensions, vehicle vocabulary, wheelbase, track, ground clearance, ramp angle, ISO 3833.