Iso Tr 14179-2 Pdf

ISO/TR 14179-2:2001 provides standardized, alternative methods for calculating and measuring the thermal load-carrying capacity of gear units, focusing on power loss and heat dissipation. The technical report assists engineers in preventing lubricant failure and sizing cooling systems by analyzing heat transfer through housing, foundation, and shafts. The document is available for review and purchase through the ISO Standard Store ISO - International Organization for Standardization ISO/TR 14179-2:2001 - Thermal load-carrying capacity

ISO/TR 14179-2:2001 (Gears — Thermal capacity — Part 2: Thermal load-carrying capacity) provides a standardized framework for calculating the thermal behavior and cooling requirements of gear units.

While Part 1 focuses on rating gear drives at a fixed equilibrium temperature (95 °C), Part 2 offers a more flexible method to determine the actual power loss and heat dissipation under practical operating conditions. Key Objectives

The document helps engineers estimate the quasi-stationary temperature in the oil sump of a gearbox. It is used to:

Determine if a gearbox requires auxiliary cooling (like fans or heat exchangers). iso tr 14179-2 pdf

Predict power losses within the system to improve energy efficiency.

Prevent material failures caused by excessive thermal stress. Core Calculation Areas

The technical report breaks down the thermal load-carrying capacity into several major components:

ISO/TR 14179-2:2001(en), Gears — Thermal capacity — Part 2 Relationship to Other Standards | Standard | Role

Relationship to Other Standards

| Standard | Role | |----------|------| | ISO/TR 14179-1 | Calculation procedure for thermal capacity | | ISO/TR 14179-2 | Explanations, examples, and practical use | | ISO 6336 (parts 1–6) | Load capacity (tooth bending/pitting) – not thermal | | AGMA 925-A03 | Similar guidance (US standard) |

Note: ISO/TR 14179-2 is informative, not normative. It does not replace ISO 14179-1 but helps you apply it correctly.

How to obtain the document (legal note)

ISO/TR 14179-2 is a standards publication; obtain the official PDF via authorized distributors (ISO or national standards bodies) or your organization's standards subscription. I cannot provide or link to pirated copies.

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Key Objectives of the Standard:

To provide a method for calculating the thermal rating of a gearbox (the maximum power that can be transmitted without exceeding permissible oil or bearing temperatures).
To account for heat generation (power losses) versus heat dissipation (cooling via housing, shaft, and external fans).
To guide engineers on adjusting gearbox design for high-temperature environments.

3. The Unusual Story: Why It’s a "TR" Not a Full "ISO"

Here’s the interesting twist: ISO TR 14179-2 is a Technical Report, not a full International Standard. Why?

Because the standard’s authors admitted: "Heat dissipation is too dependent on real-world conditions to make a rigid standard."
A TR allows for case studies and empirical back-calculations rather than prescriptive rules. In practical terms, this means the PDF includes:

Annexes with real test rig data from gearboxes ranging from 1 kW to 1 MW.
Permissible oil sump temperatures for mineral, PAO, and PAG lubricants.
A worked example stepping through a 50 kW industrial gear unit – showing how ignoring Part 2 leads to a 25°C underestimation of operating temperature.

Step 2 – Determine dissipation capacity

From Table 3 in ISO TR 14179-2 (heat dissipation for a cast iron housing of 0.8 m² surface area): Note: ISO/TR 14179-2 is informative, not normative

Natural convection coefficient = 15 W/(m²·K)
Dissipated power = 0.8 × 15 × (max allowed oil temp 90°C – ambient 40°C) = 0.8 × 15 × 50 = 600 W = 0.6 kW

Key topics covered (typical contents)

Risk assessment linkage: How to translate risk assessment results into control system safety functions and performance levels.
Safety function specification: Guidance on specifying safety functions, safety requirements, and acceptance criteria.
Architectures & redundancy: Recommended control system architectures (e.g., single-channel, redundant, monitored redundancy) and selection criteria based on required performance levels.
Diagnostics & fault handling: Techniques for diagnostics, detection of faults, fail-safe behavior, and diagnostic coverage considerations.
Validation & verification: Methods for verifying and validating safety-related functions, including test strategies and evidence generation.
Software considerations: Guidance for software design, development lifecycle activities, and measures to reduce systematic faults.
Hardware reliability: Considerations for component selection, mean time to dangerous failure (MTTFd), and common cause failure reduction.
Integration & interfaces: Guidance on integrating safety functions across subsystems and safe human–machine interfaces.
Documentation & management: Recommended documentation practices, traceability, and maintenance of safety integrity over the machine lifecycle.

Q1: Is ISO TR 14179-2 mandatory for CE marking?

A: No. It is informative. However, EN standards often reference it for declaring thermal ratings.

Practical implications for engineers

Use the report as a companion to normative standards (e.g., ISO 13849, IEC 62061) when designing safety control systems.
Map risk assessment outputs to required performance levels and then choose architectures and diagnostics to meet them.
Implement systematic design controls (software lifecycle practices, configuration management) to reduce design errors.
Provide clear test plans and traceability from requirements through verification evidence to satisfy assessors and inspectors.
Consider maintainability and in-field diagnostic capability to preserve safety performance during the lifecycle.