Detail of JB/T 8925-2017

Introduction of JB/T 8925-2017

Rolling bearings - Automobile U-joint cross assembly - Specifications 1 Scope This standard specifies the terms, definitions and symbols, codes, technical requirements, test methods, inspection rules, and marking, rust prevention, packaging, transportation and storage of universal joint cross assemblies for automobile propeller shafts (hereinafter referred to as "assemblies"). This standard is applicable to the universal joint cross assemblies for propeller shafts of medium and light trucks, passenger vehicles and passenger cars. It may also be referred to by the universal joint cross assemblies on steering knuckles of heavy trucks, construction machinery and automobiles. 2 Normative references The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. GB/T 230.1-2009 Metallic materials - Rockwell hardness test - Part 1: Test method (scales A, B, C, D, E, F, G, H, K, N, T) GB/T 1958-2004 Geometrical product specifications (GPS) - Geometrical tolerance - Verification prescription GB/T 3077-2015 Alloy structure steels GB/T 4199-2003 Rolling bearings - Tolerances - Definitions GB/T 4340.1-2009 Metallic materials - Vickers hardness test - Part 1: Test method GB/T 5671-2014 General purpose lithium lubricating grease for automobile GB/T 6930-2002 Rolling bearings - Vocabulary GB/T 8597-2013 Rolling bearings - Rust proof packaging GB/T 9450-2005 Steels - Determination and verification of the depth of carburized and hardened cases GB/T 24608-2009 Inspection rules for rolling bearings and commercial parts GB/T 25744-2010 Metallographic examination for carburizing quenching and tempering of steel parts JB/T 1255-2014 Rolling bearings - Parts made from high-carbon chromium bearing steels - Specifications for heat treatment JB/T 3232-2017 Rolling bearings - Needle roller bearings for universal joints JB/T 6639-2015 Rolling bearings - Rubber seals reinforced with a sheet steel insert - Specifications JB/T 6641-2017 Rolling bearings - Residual magnetism and its assessment method JB/T 7051-2006 Rolling bearing parts - Methods for the measurement and assessment of surface roughness JB/T 7940.1-1995 Straight hydraulic grease nipples JB/T 7940.2-1995 Angle hydraulic grease nipples JB/T 7940.7-1995 Grease nipples and lubricating cups - Technical specification QC/T 523-1999 Bench test method for automobile propeller shaft assembly 3 Terms, definitions and symbols (see Figures 1 and 2) 3.1 Terms and definitions For the purposes of this document, the terms and definitions given in GB/T 6930-2002 and the following apply. 3.1.1 universal joint an articulated mechanical device capable of transmitting torque and rotational motion from one shaft to the other when the angle between the two shafts remains constant or changes 3.1.2 automobile universal joint cross assembly a component for automobile propeller shafts, consisting of a needle roller bearing and a cross 3.1.3 cross an intermediate transmission element with four radially uniformly distributed journals in the same plane 3.1.4 static safety coefficient for torsional strength ratio of the torque measured when the assembly reaches the yield point in the static torsional strength test to the rated torque 3.1.5 torsional fatigue life number of cycles of an assembly under the action of a specified alternate torque to the time when a certain assembly part is damaged 3.1.6 wear life time of continuous operation at room temperature with the rated torque applied to the assembly until the assembly temperature rises to 60℃±5℃ 3.1.7 rated torque torque that the product can withstand, which is calculated according to the dimensions of the parts within the assembly 3.2 Symbols For the purposes of this document, the symbols given in GB/T 4199-2003 and the following apply. A: distance between two pilot holes of the wing-shaped universal joint cross assembly. D, D1, D2: nominal outside diameter of the bearing; dc: nominal diameter of the cross journal. L, L1, L2: assembled length of the assembly (or assembled arc diameter of wing-shaped universal joint cross assembly). l: distance between two end faces of the cross. ns: static safety coefficient for torsional strength.

Contents of JB/T 8925-2017

Foreword II 1 Scope 2 Normative references 3 Terms, definitions and symbols (see Figures 1 and 2) 4 Assembly codes 5 Technical requirements 6 Test and inspection methods 7 Inspection rules 8 Marking, rust prevention, packaging, transportation and storage Annex A (Normative) Test method of position of cross journal Figure 1 Assembly diagram Figure 2 Geometric tolerance diagram for the cross Figure 3 Diagram for structural types of assemblies Figure A.1 Schematic diagram for test method of position of cross journal Table 1 Structural type codes Table 2 Rear codes Table 3 Tolerances for assembled length of assemblies Table 4 Radial clearance of needle roller bearing in assembly Table 5 Heat treatment requirements for cross journal Table 6 Tolerances for journal diameter Table 7 Tolerances for distance between two end faces of cross Table 8 Coaxiality tolerances of two opposite journals Table 9 Cylindricity tolerances of journals Table 10 Tolerances for Axial circular runout from the journal end face to the common axis of two journals Table 11 Surface roughness of each part of cross Table 12 Maximum residual magnetism value Table 13 Compaction force P Table 14 Inspection items