This standard specifies the test conditions and test methods for the mechanical steering system of wheeled tractors. This standard applies to the mechanical steering system of wheeled tractors with front wheel steering. JB/T 7279-1994 Test methods for mechanical steering systems of wheeled tractors JB/T7279-1994 Standard download decompression password: www.bzxz.net

Mechanical Industry Standard of the People's Republic of China
JB/T7279-94
Mechanical Steering System of Wheeled Tractor
Test Method
Published on 1994-07-18
Ministry of Machinery Industry of the People's Republic of China
Implementation on 1995-07-01
Mechanical Industry Standard of the People's Republic of China
Mechanical Steering System of Wheeled Tractor
Test Method
1 Subject Content and Scope of Application
This standard specifies the test conditions and test methods for the mechanical steering system of wheeled tractors. This standard applies to the steering system of wheeled tractors with front-wheel steering. 2 General
2.1 This standard includes the following test items:
Determination of front wheel alignment parameters and front wheel side slip rate; b.
Determination of steering system parameters and steering angle transmission ratio: c.
Determination of steering wheel free travel and steering system rigidity in straight-ahead position; Determination of transmission efficiency in straight-ahead position;
Durability test.
JB/T7279—94
2.2 The test sample is the entire mechanical steering system and is installed on the supporting host. Before the test, fill in the relevant technical parameters of the tested system and the supporting host according to Table A1 in Appendix A (reference). 3 Test conditions
3.1. Inflate the front tire to the pressure value specified in the instruction manual. If this pressure value is not given, inflate the guide wheel to 0.2MPa; inflate the four-wheel drive front wheel to 0.16MPa.
3.2 Adjust the front wheel spacing to the normal state.
3.3 The main engine is equipped with the maximum front counterweight, but the front wheel reaches the rated load capacity. 3.4 During the test, the sample shall be maintained and adjusted as required in the operating instructions, but replacement of parts is not allowed. 3.5 The test instrument shall meet the following requirements
《The static angle measurement error shall not be greater than ±15°: b.
The linear measuring disc error shall not be greater than ±1mm: The steering wheel angular displacement measurement accuracy is ±1%, and the front wheel deflection angular displacement measurement accuracy is ±30°; c.
The torque measurement accuracy is ±1.5%.
4 Test method
4.1 Determination of front wheel alignment parameters and front wheel side slip ratea. Adjust the front wheel toe to the specified value, make the front axle in the horizontal and side swing limit positions respectively, perform full steering operation several times, check whether the steering system and its movement with the main machine are involved, and check the limit of steering movement;b. Put the tested tractor in the lowest gear, drive straight and forward at low speed past the slip meter, and read the maximum side slip rate displayed by the slip meter when the front wheel passes. Repeat the measurement three times and take the minimum value:c. Support the tractor on the ground and adjust it to a horizontal state. Use the front wheel alignment instrument to measure the front wheel camber angle α, vertical shaft inclination angle β, vertical shaft rear angle Y and other values:
Approved by the Ministry of Machinery Industry on July 18, 1994
Implementation on July 1, 1995
JB/T 7279 94
d. Calculate the steering resistance arm. 。 This value is the horizontal distance from the intersection of the vertical axis extension line and the front wheel support plane to the tire ground contact center when the tractor is in the straight-ahead position on the horizontal track. Fill in the above measurement results according to Appendix A Table A2. 4.2 Determination of steering system parameters and steering angle transmission ratio Place the tractor front wheel on the turning angle measuring instrument. An angular displacement sensor is installed on the steering wheel. Start from the front wheel straight-ahead position. Slowly turn the steering wheel until the front wheel turns to the dead point, and measure the left and right front wheel deflection angles and the corresponding steering wheel turning angles when left and right respectively. At least one point is measured for every 5° deflection of the inner front wheel, and the following parameters are measured or calculated: a.
Total steering wheel steering angle.(\);
Steering wheel steering angle from the straight-ahead position to the left dead center.(\); Steering wheel steering angle from the straight-ahead position to the right dead center -(\): Left front wheel deflection angle from the straight-ahead position to the left dead center (\): Right front wheel deflection angle from the straight-ahead position to the right dead center, (\); Calculate the angular transmission ratio according to formula (1):
Where: △9---Increment of steering wheel angle, (°): 28---Corresponding increment of inner front wheel deflection angle.(\). Fill in the measurement and calculation results in Table A2 of Appendix A, and draw the angular transmission ratio characteristic curve according to Figure AI. 4.3 Measurement of free travel of steering wheel in straight-ahead position and rigidity of steering system After the front wheel is in the straight-ahead position, the front wheel is fixed (fixed on the edge of the wheel rim), and a positive and negative torque of 2 N·m is applied to the steering wheel to measure the swing angle of the steering wheel. This swing angle value is used as the free travel of the steering wheel in the straight-ahead position b. After the front wheel is in the straight-ahead position, the front wheel is fixed (fixed on the edge of the wheel rim), and the steering wheel is slowly turned. The torque is added to 50 N·m, and the steering wheel angle is measured: The steering system rigidity C is calculated using formula (2): C (Mw/9) X 57.3 (Nm/rad)
In the formula, M is the steering wheel torque. N·m;
6 is the steering wheel angle, (*).
Fill in the above measurement and calculation results in Table A2 of Appendix A, and draw the rigidity test curve according to Figure A2. 4.4 Determination of transmission efficiency in straight-ahead position
Get the position,
Put the front wheel on a set of pads (the upper one is a spherical surface, the lower one is a flat plate, and a little butter is applied in between), and fix the front wheel in a straight-ahead position (fixed around the rim), turn the steering wheel, and measure the steering wheel torque and the front wheel deflection torque. Www.bzxZ.net
Calculate the positive transmission efficiency in the straight-ahead position by formula (3):
2(M, +M,)/(Mw× i.) × 100%
Where: M, M,--left, right, left ... (3)
c. Keep the steering wheel stationary, apply the same deflection torque to the front wheels on both sides (the force acts on the edge of the wheel), measure the resistance torque of the steering wheel, and calculate the reverse transmission efficiency in the straight-ahead position by formula (4): n' (Mw Xi,): (M -- M) × ecn In the formula, M... the resistance short on the steering wheel. V·m; 2,... the angular transmission ratio of the steering system in the straight-ahead position, MM--- the response J range of the right front wheel. N·5
The total value of the investment or efficiency test line is used as the steering system: in the straight-ahead position, the positive and reverse transmission data will be filled in as A: 4.5 Durability test
4.5.1 Test equipment
JB/T 727994
, the steering system endurance test can be installed on the main engine or on a test bench simulating the installation of the main engine: b. The test equipment can apply the required deflection resistance torque to the front wheel in the left and right directions. The steering wheel is driven by power, and its speed and angle can be controlled sequentially.
4.5.2 Test load
Adjust the front axle load so that the vertical load of the left and right front wheels is consistent with the ground reaction force value on the left and right front wheels in Table A1 of Appendix A, and the error does not exceed 5%.
Apply the deflection resistance torque to the left and right front wheels on average. The sum of the deflection resistance torques of the left and right front wheels is M. Calculated by formula (5): M. = G × 0. 75.2/p × /6/8 +a Where, G—front axle load, N;
a Steering resistance arm, mm;
6--Nominal width of front wheel grease, mm
-Friction coefficient between ground and tire, take 0.7. The maximum error of resistance torque is not more than 5%, 4.5.3 Test method
Drive the steering shaft, the steering shaft speed is 60r/min; a.
b, after every 10 small cycles of the steering shaft (the steering shaft rotates 180 degrees to the left and right from the neutral position and then returns to the neutral position), the secondary large cycle is performed (the steering shaft rotates from the neutral position to the left dead point and then to the dead point, and then returns to the neutral position); c, the steering shaft rotates 300,000 times in total: d During the test, pay attention to whether there is leakage in the steering gear housing, check the technical conditions of the connection parts of the steering system components, and at the end of the test, disassemble the steering system, check the wear, deformation, cracks, etc. of the main parts, and take relevant photos. Fill in the relevant test records and test results in Appendix A Table A3, and attach relevant photos. Tractor model
Steering gear and steering trapezoidal type
Front wheel
Rear tire
Maximum use mass of the van tractor.
Reaction force of the ground on the left front wheel
Remarks:
Tractor model
Test date
Front wheel toe-in 4,
Total wheel toe-in angle.
Total steering wheel steering angle:
JB/T7279-94
Appendix A
Graphic format in the test report
Reference)
Fresh factory
Inflating force
Inflating pressure
Chassis number
Operator
Inclination angle of vertical axis:
Steering wheel steering angle/maximum deflection angle of inner front wheel (right turn) Steering wheel steering angle/maximum deflection angle of inner front wheel (left turn): Straight position steering wheel free travel:
Transmission efficiency:
Test date
Mass of front counterweight
Reaction force of ground on right front wheel:
Front wheel sideslip rate:
Rear waiting angle:
Static radius
Static radius
Environmental humidity
Straight positionSteering system transmission ratio,
Separation C
Left steering
Steering wheel turning angle (\)
Inner front wheel deflection angle (\)
Outer front wheel deflection angle (\)
Remarks:
N·m/rad
Steering resistance arm. ：
Right steering
JB/T7279-94
Front wheel deflection angle
Steering wheel angle
Figure A1 Steering system angular transmission ratio characteristic curve Turntable wheel rotation
：Steering wheel angle
Figure A2 Steering system rigidity curve
Inner test front steering
Outer false front wheel
Push-pull machine model
Test date
The sum of the deflection resistance moments of the left and right front wheels M.
Cumulative number of steering cycles:
Fault conditions during the test:
Disassembly and inspection results after the test:
Conclusion of the durability test face.
Appendix:
JB/T 7279-94
Input from steering wheel
Input from front wheel
Torque input from turntable
Turning force input from front wheel
Figure A3 Steering system transmission efficiency test curve Table A3
Environmental stress
Operator
Additional instructions:
JB/T727994
This standard was proposed by the National Technical Committee for Tractor Standardization. This standard is under the jurisdiction of Luoyang Tractor Research Institute. This standard was drafted by Luoyang Tractor Research Institute. The main drafter of this standard is Sun Yigang.
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