Standard No.:	QC/T 777-2025
English Name:	Electromagnetic clutch for automobile cooling system
Chinese Name:	汽车冷却系统电磁离合器
Professional Classification:	QC    Professional Standard - Automobile
Source Content Issued by:	MIIT
Issued on:	2025-12-17
Implemented on:	2026-7-1
Status:	to be valid
Superseding:	QC/T 777-2017 The technical conditions of electromagnetic fan clutch for automobile
Target Language:	English
File Format:	PDF
Word Count:	8500 words
Translation Price(USD):	255.0
Delivery:	via email in 1~3 business day

QC/T 777-2025 Electromagnetic clutch for automobile cooling system English, Anglais, Englisch, Inglés, えいご This is a draft translation for reference among interesting stakeholders. The finalized translation (passing through draft translation, self-check, revision and verification) will be delivered upon being ordered. ICS T Professional Standard of the People's Republic of China QC/T 777-2025 Replaces QC/T 777-2017 Electromagnetic clutch for automobile cooling system 汽车冷却系统电磁离合器 (English Translation) Issue date: 2025-12-17 Implementation date: 2026-07-01 Issued by the Ministry of Industry and Information Technology of the People's Republic of China Contents Foreword 1 Scope 2 Normative References 3 Terms and Definitions 4 Performance Requirements 4.1 Vacuum Tightness 4.2 Low-pressure Tightness 4.3 High-pressure Tightness 4.4 Bleeder Screw Tightness 4.5 Inlet Port Tightness 4.6 Required Fluid Amount 4.7 Drag Torque 4.8 Caliper Rigidity 4.9 Piston Retraction Amount 4.10 Piston Sliding Resistance 4.11 Piston Actuation Pressure 4.12 Caliper Sliding Resistance 4.13 Brake Pad Sliding Resistance 4.14 Strength 4.15 Durability 4.16 Water Resistance 4.17 Corrosion Resistance 5 Test-related Requirements 5.1 Test Equipment Requirements 5.2 Sample Requirements 6 Test Methods 6.1 Vacuum Tightness 6.2 Low-pressure Tightness 6.3 High-pressure Tightness 6.4 Bleeder Screw Tightness 6.5 Inlet Port Tightness 6.6 Required Fluid Amount 6.7 Drag Torque 6.8 Caliper Rigidity 6.9 Piston Retraction Amount 6.10 Piston Sliding Resistance 6.11 Piston Actuation Pressure 6.12 Caliper Sliding Resistance 6.13 Brake Pad Sliding Resistance 6.14 Strength 6.15 Durability 6.16 Water Resistance 6.17 Corrosion Resistance Automotive Cooling System Electromagnetic Clutch 1 Scope This document specifies the terms and definitions, technical requirements, test methods, inspection rules, marking, packaging, transportation, and storage of electromagnetic clutches used in water pumps and fans for automotive cooling systems. This document applies to electromagnetic clutches for automotive cooling systems (hereinafter referred to as electromagnetic clutches). Other types of electromagnetic clutches may refer to this document for implementation. 2 Normative References The contents of the following documents become essential provisions of this document through normative reference herein. For dated references, only the edition corresponding to that date applies. For undated references, the latest edition (including all amendments) applies. GB/T 191 Packaging—Pictorial Marking for Handling of Goods GB/T 4942 Degrees of Protection Provided by Enclosures for Rotating Electrical Machines (IP Code)—Classification GB/T 2423.38—2008 Environmental Testing for Electric and Electronic Products—Part 2: Test Methods—Test R: Water Test Methods and Guidance GB/T 2828.1—2012 Sampling Procedures for Inspection by Attributes—Part 1: Sampling Schemes Indexed by Acceptance Quality Limit (AQL) for Lot-by-Lot Inspection GB/T 13384 General Specifications for Packaging of Mechanical and Electrical Products GB/T 17619 Limits and Methods of Measurement of Immunity to Electromagnetic Radiation for Electrical/Electronic Components of Vehicles GB/T 18655 Vehicles, Boats, and Internal Combustion Engines—Radio Disturbance Characteristics—Limits and Methods of Measurement for the Protection of On-board Receivers QC/T 413—2002 Basic Technical Requirements for Automotive Electrical Equipment QC/T 625 Coatings, Plating, and Chemical Treatment Layers for Automotive Use JB/T 4159—2013 General Technical Requirements for Tropical Electrical Products 3 Terms and Definitions The following terms and definitions apply to this document. 3.1 Engaged State The state of the electromagnetic clutch after the driving plate and driven plate are coupled. 3.2 Disengaged State The state of the electromagnetic clutch after the driving plate and driven plate are separated. 3.3 Engaged Gap The distance between the driving plate and driven plate of the electromagnetic clutch in the disengaged state. 3.4 Single-stage Electromagnetic Clutch An electromagnetic clutch that achieves two output speeds through the on/off switching of a single winding circuit. 3.5 Multistage Electromagnetic Clutch An electromagnetic clutch that achieves multiple output speeds through the on/off switching of multiple winding circuits. 3.6 Power-off Separation Type Electromagnetic Clutch An electromagnetic clutch where the driven plate separates from the driving plate when the winding circuit is de-energized. 3.7 Power-off Engaging Type Electromagnetic Clutch An electromagnetic clutch where the driven plate engages with the driving plate when the winding circuit is de-energized. 3.8 Variable Speed Water Pump A water pump capable of adjusting the impeller speed through an electromagnetic clutch. 3.9 Following Speed The output speed of the electromagnetic clutch in the disengaged state. 3.10 Synchronized Speed The output speed when the driven plate of the electromagnetic clutch rotates synchronously with the driving plate in the engaged state. 3.11 Multistage Speed Output speeds of a multistage electromagnetic clutch other than the following speed and synchronized speed. 3.12 Static Friction Torque The maximum torque that the electromagnetic clutch can transmit under conditions of room temperature and static engagement. Note: Static friction torque includes static friction torque before break-in and static friction torque after break-in. 3.13 Engagement Voltage The voltage at which the driven plate and driving plate of the electromagnetic clutch engage when the circuit is energized. 3.14 Disengagement Voltage The voltage at which the driven plate and driving plate of the electromagnetic clutch disengage when the circuit is energized. 3.15 Input Speed The driving speed of the electromagnetic clutch under the condition of engine rated speed and the speed ratio specified in the technical documentation. 4 Technical Requirements 4.1 General Requirements Electromagnetic clutches shall be manufactured according to product drawings and technical documentation approved through specified procedures and shall meet the requirements of this document. 4.2 Dynamic Balance The dynamic unbalance of each rotating component within the electromagnetic clutch shall not exceed 0.1M (g·mm). Note: M is a dimensionless quantity, and its value is the mass number in grams of the rotating components of the electromagnetic clutch. 4.3 Static Friction Torque 4.3.1 The static friction torque value before break-in shall comply with the requirements specified in the product drawings and technical documentation. 4.3.2 The static friction torque value after break-in shall not be less than 1.5 times the torque value required for the rated driving power, or shall comply with the requirements specified in the product drawings and technical documentation. 4.4 Speed Characteristics The speed characteristics of the electromagnetic clutch shall comply with the requirements specified in the product drawings and technical documentation. 4.5 Operating Voltage The operating voltage for 12V electromagnetic clutches and 24V electromagnetic clutches shall meet the requirements specified in Table 1.