Overview
ISO/TR 14179-2:2001 - Gears: Thermal capacity - Part 2: Thermal load-carrying capacity provides methods to determine how much power a gear unit can transmit without overheating. The technical report combines practical measurement procedures on original gear units with calculation methods for the thermal balance between power loss and heat dissipation. It supports both experimental approaches (power-loss or heat-dissipation measurement and sump temperature observation for splash-lubricated units) and analytical calculation of individual loss/dissipation components.
Key topics
- Scope and purpose: assessment of thermal load-carrying capacity for gear units under practical operating conditions.
- Measurement methods: procedures for measuring power loss, heat dissipation and quasi‑stationary oil sump temperature (splash lubrication).
- Power-loss components:
- Gear losses (load-dependent and no-load losses)
- Bearing losses (catalogue-based and empirical methods)
- Shaft-seal and auxiliary losses
- Heat-dissipation paths:
- Through housing (convection, conduction, radiation)
- To foundation (thermal coupling)
- Via shafts and couplings
- External cooling (oil coolers / injection lubrication)
- Calculation and modeling: iterative thermal equilibrium between generated heat and heat removed; symbols, units and indices; sample calculations are provided.
- Supporting material: extensive tables of symbols, recommended coefficients and a sample calculation; the report references analytical models and experimental validation (e.g., work used in WTplus and prior AGMA and research publications).
Practical applications
- Thermal rating of industrial gearboxes to prevent oil overheating, scuffing or loss of lubricant film.
- Design validation for gear designers and drivetrain engineers assessing maximum transmittable power at specified oil sump temperatures.
- Performance testing and diagnostic labs measuring power loss and heat dissipation on prototype or in‑service gear units.
- Selection and sizing of auxiliary cooling (external oil coolers) for spray/injection‑lubricated systems.
- Maintenance and reliability engineering - establishing safe operating limits and root‑cause analysis of thermal failures.
Who should use this standard
- Gear designers and drivetrain engineers
- Gearbox manufacturers and test houses
- Tribologists and lubrication specialists
- Bearing suppliers and mechanical design engineers
- Maintenance, reliability and thermal-analysis teams
Related standards
- ISO/TR 14179-1 - Rating gear drives with thermal equilibrium at 95 °C sump temperature (related methodology)
- ISO/TR 13989 - Coefficient of friction / scuffing load considerations (referenced)
- AGMA technical papers (e.g., AGMA 96FTM9) - foundational analytical methods and experimental data referenced in the report
Keywords: ISO/TR 14179-2:2001, thermal load-carrying capacity, gears, power loss, heat dissipation, sump temperature, splash lubrication, gearbox thermal rating.