( Reaffirmed 2002) F?=rrl xT<+mr: +PFekvT v&T Indian Standard AUTOMOTIVEVEHICLES-SELF-CENTERINGMETHODOFTEST UDC 629’113’012’56 I @I BIS 1992 BUREAU MANAK October 1992 OF BHAVAN, INDIAN STANDARDS ZAFAR MARG e Price Gropp t 9 BAHADUR SHAH NEW DELHI 110002 .Vehicles Testing and Performance Evaluation Sectional Committee. observed or calculated. systems etc. For the purpose of deciding whether a particular requirement of this standard is complied. rounded off in accordance The number of significant places retained in the rounded off value should be the same as that of the specified value in this standard. after the draft finalized by Automotive Vehicles Testing and Performance Evaluation Sectional Committee had been approved by the Transport Engineering Division Council.: ‘AiltGn@tiye . TED 8 FOREWORD _ the This Indian Standard was adopted by the Bureau of Jndian Standards. expressing the result of a test or analysis. The overall performance of an automotive vehicle is a functicn of the perfcrmarce of its various components. shall be with IS 2 : 1960 ‘Rules for rounding off numerical values ( revised)‘. The self-centering is an important parameter to assess the steerability of an automotive vehicle. with the final value. 3.3 All the ball joints of steering linkages and wheel joints shall be well lubricated as recommended by the manufacturer.IS 13507 : 1992 Indian Standard AUTOMOTIVE VEHICLES .1 Inner/Outer Wheel Lock Angle 4 TEST PROCEDURE 4. The test shall be conducted in both left and right turns. when steered for a right turn and right wheel when steered for a left turn. jeeps.2 Instrument to be Used a) Angle transducer with the least count of 1”.1 Vehicle shall be loaded to specified Vehicle Kerb Weight and load distribution between the axles shall be as per the manufacturer’s recommendation. 2 TERMINOLOGY 2. Type of the tyre shall be as per manufacturer’s recommendation.2 Wheel Lock Angle Wheel lock angle is the acute angle in the horizontal plane between two centre lines of steered wheel projected on to the horizontal plane when the wheel is in the straight ahead position and when the wheel is steered to its extreme position. The outer wheel lock angle shall mean wheel lock angle of left wheel. dry concrete ground. While doing the test the steering wheel angle has to be moved to equivalent value of 1” wheel angle.6 The brakes shall be so adjusted that wheels shall be free of any brake grab/hold.2 The recommended limits of self-centering for light and heavy commercial vehicles shall be as given below: Vehicle Self-Centering 3. 5 EVALUATION OF SELF-CENTERING by the The wheel lock angle for the left wheel. 6. after driver leaves the steering wheel shall be recorded against time. 2. trucks and buses. Care shall be taken to maintain the speed throughout the test. c) Recorder. 3.2 Vehicle shall be fitted with tyres which have not covered more than 10 percent of its expected life. to Self-cen. when steered for left turn and right wheel when steered for a right turn. The angle reached at the end of three seconds after driver leaves the wheel is recorded for calculating self-centeringefficiencyof the vehicle. 3. The tyre shall be inflated to a pressure recommended by the manufacturer. the Vehicles steering Vehicles steering with with manual power 75% 65% .SELF-CENTERING METHOD OF TEST 1 SCOPE This standard specifies the test procedure for measurement of self-centering of cars.2. The continuous change in the road wheel angle. 3 PREPARATION OF THE VEHICLE Self-centering is expressed in percentages equation given below: 3. b) Suitable single conditioning module for angle transducer. The driver shall leave the steering without giving jerk to the steering wheel.1 Vehicle shall be driven at a constant speed of 10 kmph and shall be steered to full lock angle. 4.1 Self-Centering Self-centering is defined as the ability of the steered wheels to return to straight course from the steered condition without any manual input. 2.5 Test shall be carried out on a road having plain.1 The limits for self-centering the manufacturer and the agreed between purchaser.4 Wheel lock angles shall be adjusted manufacturer’s recommendation. light commercial vehicles. The calibration of the steering wheel rotation wheel angles in both left hand and right hand direction and graph shall be drawn for the steering wheel angle in relaction to the wheel angle. 3.__ tering % 6 LIMITS I L r Angle at three Wheel lock _ seconds after driver had left anale steering the wheel Wheel lock angle 1 X 100 J FOR SELF-CENTERING shall be as 6. 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