Overview
ISO 5353:1995 specifies a uniform method and a dedicated device for determining the Seat Index Point (SIP) for seats used in earth-moving machinery, tractors, and agricultural and forestry machinery. The SIP is a defined point on the central vertical plane of the seat used as a reference for operator seating position and workplace design. This second edition replaces ISO 5353:1978 and is intended to provide consistent SIP determination for seat manufacturers, machine OEMs, test laboratories and ergonomics practitioners.
Key topics and technical requirements
- Definition of SIP and fixing point: SIP is the point on the central vertical plane of the seat determined by the specified device; the fixing point is the manufacturer-specified reference on the seat to which the SIP coordinates are referenced.
- Measurement device: The standard provides dimensions and materials for the SIP device (hardwood work surfaces sanded to 200 grit or equivalent) and specifies mass requirements:
- Unweighted device: 6 kg ± 1 kg
- Intermediate weighting: total 26 kg ± 1 kg (added masses’ vertical center 40 mm in front of SIP mark)
- Final weighting: total 65 kg ± 1 kg (additional masses also 40 mm in front of SIP mark)
- Seat preparation and environmental conditions: Seat and device should be at room temperature of 20 °C ± 2 °C. Cover the seat with a single layer of muslin to minimize friction. Seats should be flexed (by a 75 kg ± 10 kg person seated twice for 1 minute) to settle cushions before testing.
- Adjustment and suspension settings: Place all fore/aft, vertical and angular adjustments in their centre positions; if no centre exists, use the nearest. Block suspension according to manufacturer instructions or at mid-oscillation if unspecified.
- Placement and measurement procedure: Device must be laterally central and level against the back cushion; measurements are taken symmetrically on both sides of the central plane and averaged. Record SIP coordinates relative to the fixing point within ±1 mm.
- Reporting requirements: Test report shall reference ISO 5353, note any deviations, include coordinate dimensions, a drawing/sketch showing the SIP and fixing point, and describe adjustment ranges used.
Applications
- Establishing consistent reference points for operator workplace design, seat specification and integration into vehicle cabs
- Comparative testing of seats for ergonomics and safety evaluations
- Supporting seat certification, procurement, and quality control for construction, agricultural and forestry machinery
- Informing human-factors analyses where the SIP approximates the torso-thigh pivot for seating posture studies
Who should use this standard
- Seat manufacturers and designers
- OEMs of earth-moving, agricultural and forestry machinery
- Laboratory test engineers and certification bodies
- Ergonomists, human factors specialists and occupational safety professionals
Related standards
- ISO 6165:1987 - Earth-moving machinery - Basic types - Vocabulary
- ISO 3339-0:1986 - Tractors and machinery for agriculture and forestry - Classification and terminology (Part 0)
Keywords: ISO 5353:1995, seat index point, SIP, earth-moving machinery, agricultural tractors, forestry machinery, seat measurement, operator seating, ergonomics, seat testing.
Open preview (PDF)Earth-moving machinery, and tractors and machinery for agriculture and forestry — Seat index point
