[Code of Federal Regulations]

[Title 49, Volume 6]

[Revised as of October 1, 2005]

From the U.S. Government Printing Office via GPO Access

[CITE: 49CFR571.124]



[Page 468-469]

 

                        TITLE 49--TRANSPORTATION

 

                            OF TRANSPORTATION

 

PART 571_FEDERAL MOTOR VEHICLE SAFETY STANDARDS--Table of Contents

 

            Subpart B_Federal Motor Vehicle Safety Standards

 

Sec. 571.124  Standard No. 124; Accelerator control systems.



    S1. Scope. This standard establishes requirements for the return of 

a vehicle's throttle to the idle position when the driver removes the 

actuating force from the accelerator control, or in the



[[Page 469]]



event of a severance or disconnection in the accelerator control system.

    S2. Purpose. The purpose of this standard is to reduce deaths and 

injuries resulting from engine overspeed caused by malfunctions in the 

accelerator control system.

    S3. Application. This standard applies to passenger cars, multi-

purpose passenger vehicles, trucks, and buses.

    S4. Definitions.

    S4.1 Driver-operated accelerator control system means all vehicle 

components, except the fuel metering device, that regulate engine speed 

in direct response to movement of the driver-operated control and that 

return the throttle to the idle position upon release of the actuating 

force.

    Fuel metering device means the carburetor, or in the case of certain 

engines the fuel injector, fuel distributor or fuel injection pump.

    Throttle means the component of the fuel metering device that 

connects to the driver-operated accelerator control system and that by 

input from the driver-operated accelerator control system controls the 

engine speed.

    Idle position means the position of the throttle at which it first 

comes in contact with an engine idle speed control appropriate for 

existing conditions according to the manufacturers' recommendations. 

These conditions include, but are not limited to, engine speed 

adjustments for cold engine, air conditioning, and emission control, and 

the use of throttle setting devices.

    Ambient temperature means the surrounding air temperature, at a 

distance such that it is not significantly affected by heat from the 

vehicle under test.

    S4.2 In the case of vehicles powered by electric motors, the words 

throttle and idle refer to the motor speed controller and motor 

shutdown, respectively.

    S5. Requirements. The vehicle shall meet the following requirements 

when the engine is running under any load condition, and at any ambient 

temperature between -40 degrees Celsius and +52 degrees Celsius after 12 

hours of conditioning at any temperature within that range.

    S5.1 There shall be at least two sources of energy capable of 

returning the throttle to the idle position within the time limit 

specified by S5.3 from any accelerator position or speed whenever the 

driver removes the opposing actuating force. In the event of failure of 

one source of energy by a single severance or disconnection, the 

throttle shall return to the idle position within the time limits 

specified by S5.3, from any accelerator position or speed whenever the 

driver removes the opposing actuating force.

    S5.2 The throttle shall return to the idle position from any 

accelerator position or any speed of which the engine is capable 

whenever any one component of the accelerator control system is 

disconnected or severed at a single point. The return to idle shall 

occur within the time limit specified by S5.3, measured either from the 

time of severance or disconnection or from the first removal of the 

opposing actuating force by the driver.

    S5.3 Except as provided below, maximum time to return to idle 

position shall be 1 second for vehicles of 4536 kilograms or less GVWR, 

and 2 seconds for vehicles of more than 4536 kilograms GVWR. Maximum 

time to return to idle position shall be 3 seconds for any vehicle that 

is exposed to ambient air at -18 degrees Celsius to -40 degrees Celsius 

during the test or for any portion of the 12-hour conditioning period.



[38 FR 2980, Jan. 31, 1973; as amended at 60 FR 13645, Mar. 14, 1995]