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Bench test method for automobile drive axle
This standard is applicable to the drive axles of trucks with cargo capacity less than 8t (excluding 8t) and the corresponding off-road vehicles and buses, excluding the bench test method for axle shaft.
1 Symbols used in this standard, and requirements for test load
1.1 See Table 1 for uniform requirements for symbols used in this standard.
Table 1
S.N. Symbol Name of symbol Unit
1 Mo Test calculated torque N·m
2 Me max Maximum torque of engine N·m
3 ik1 First gear ratio of transmission
4 iD1 Low gear ratio of transfer case
5 iD2 High gear ratio of transfer case
6 i0 Gear ratio of drive axle
7 p Full axle load N
8 rk Rolling radius of tyre
9 φ Adhesion coefficient
10 Kk Static torsional strength safety factor
11 Mk Static torsional breaking torque N·m
12 Kn Vertical bending failure safety factor
13 Pn Vertical bending failure load N
14 M Output torque of torque tester N·m
15 θ Rotation angle of output end of torque tester (°)
1.2 Requirements for test load
1.2.1 Test calculated torque for static torsion of drive axle assembly
1.2.1.1 It is calculated using Equation (1) if calculated according to the maximum torque of engine:
(1)
Where,
Mpe——the test calculated torque according to the maximum torque of engine;
n1——the number of drive axles where transfer case is in low gear.
1.2.1.2 It is calculated using Equation (2) if calculated according to the maximum adhesion:
M_Pφ=P∙φ∙r_k 1/i_0 (2)
Where,
Mpφ——the test calculated torque for the drive gear of reduction gear according to the maximum adhesion;
φ——0.8.
1.2.1.3 Selection of test calculated torque Mp for static torsion of drive axle assembly:
Mpe or Mpφ, whichever is smaller.
1.2.2 Test calculated torque for fatigue test of drive axle assembly gear and support rigidity test of bevel gear
1.2.2.1 It is calculated using Equation (3) if calculated according to the maximum torque of engine:
M_Pe=M_(e max ) i_kl∙i_p2∙1/n_2 (3)
Where,
Mpe——the torque calculated according to the maximum torque of engine;
n2——the equivalent number of drive axles in case of using high gear of transfer case, n2=2 for 6×6 and 6×4 vehicles and n2=1 for 4×4 vehicles, which is specified in this standard temporarily .
1.2.2.2 If calculated according to the maximum adhesion:
The calculation equation is the same as that in 1.2.1.2.
1.2.2.3 Selection of test calculated torque for fatigue test of drive axle assembly gear and support rigidity test of bevel gear:
Mpe or Mpφ, whichever is smaller.
1.2.3 Selection of load for vertical bending fatigue test of drive axle housing
1.2.3.1 Selection of the maximum load:
The tested vehicle, if used as a truck, shall be calculated by 2.5 times the full axle load of the truck drive axle, while 3 times the full axle load of the off-road vehicle drive axle if used as an off-road vehicle. During the test, the measured static stress under the above two kinds of loads is taken as the standard of maximum static and dynamic loads.
1.2.3.2 Selection of the minimum load:
The load with stress equal to zero.
2 Static torsion test of drive axle assembly
2.1 Test objective
To inspect the weakest anti-torsion part in the drive axle assembly and calculate the static torsional strength safety factor of the assembly.
2.2 Test samples
The entrusting party shall provide three samples meeting the requirements of design drawings and attached with necessary design and process information.
2.3 Test methods
2.3.1 Test device
Torsion tester, XY recorder, sensor, etc.
2.3.2 Test procedures
2.3.2.1 Fix the axle housing of the assembled drive axle assembly on the bracket firmly. Connect the input end of the drive axle assembly (i.e. the end of the drive gear of reduction drive) with the output end of the torque tester. Fix the output end of drive axle (i.e. the output end of axle shaft or hub) on the bracket.
2.3.2.2 Adjust the force arm of the torsion tester to make it swing up and down in the horizontal direction during the test, and calibrate the instrument.
2.3.2.3 Start the torque tester to load slowly (the rotational speed of the output end of torque tester is n≯0.25rpm), and record M-θ curve with XY recorder until any part is twisted off. Record the torque and twist angle in case of twisting.
2.3.3 Data processing
2.3.3.1 Calculation of static torsional strength:
Take the arithmetic average of the torques of the three samples.
2.3.3.2 The static torsional strength safety factor is calculated using Equation (4):
(4)
2.4 Result processing
Analyze the fracture surface, metallography and data of damaged parts after test, and write the test report or test result notice.
3 Test on vertical bending rigidity and vertical bending static strength of drive axle housing
This test is only applicable to rigid drive axle housing and drive axle housing with full-floating axle shaft structure.
3.1 Test objective
To inspect the vertical bending rigidity and vertical bending strength of the drive axle housing and calculate its anti-bending safety factor.
3.2 Test samples
The entrusting party shall provide three samples meeting the requirements of design drawings and attached with design and process information.
3.3 Test methods
3.3.1 Test device
Hydraulic fatigue tester and (or material tester), hydraulic jack, dial indicator (or displacement sensor), strain gauge, strain foil, etc.
3.3.2 Test procedures
3.3.2.1 The axle housing with reduction drive housing and rear cover is installed on the bracket, wherein, the axle housing must be leveled. If the force point is located at the center of the two-leaf springs, the pivot point is the corresponding point of the wheel track of the axle; or the positions of the force point and the pivot point are exchanged.
3.3.2.2 During installation, the force application direction shall be perpendicular to the axle tube centerline of the axle housing, and the pivot point shall be able to roll so as to adapt to deformation under loading without movement interference.
3.3.2.3 After installation, load to full axle load for 2~3 times; after unloading, formal measurement is carried out.
3.3.2.4 When unloading is carried out to zero, adjust the dial indicator (or displacement sensor) to zero; at least seven points shall be measured, as shown in Figure 1.
3.3.2.5 Load slowly, record the dial indicator (or displacement sensor) from zero and monitor the load with a strain gauge. Make the vertical bending rigidity test load of axle housing reach the value specified in 1.2.3.1. The records shall not be less than 8 times from zero to the maximum load value in 1.2.3.1, and the displacement amount of each measuring point must be recorded under the full axle load and the maximum load value in 1.2.3.1. Each axle housing shall be tested for at least three times. At the beginning of each test, the dial indicator (or displacement sensor) shall be set to zero.
1 Symbols used in this standard, and requirements for test load
2 Static torsion test of drive axle assembly
3 Test on vertical bending rigidity and vertical bending static strength of drive axle housing
4 Vertical bending fatigue test of drive axle housing
5 Support rigidity test of drive axle assembly bevel gear
6 Fatigue test of drive axle assembly gear
7 Noise test of drive axle assembly
Additional explanation
