Backing event means an amount of time which starts when the vehicle's direction selector is placed in reverse, and ends at the manufacturer's choosing, when the vehicle forward motion reaches:
Convex mirror means a mirror having a curved reflective surface whose shape is the same as that of the exterior surface of a section of a sphere.
Effective mirror surface means the portions of a mirror that reflect images, excluding the mirror rim or mounting brackets.
Environmental test fixture means a device designed to support the external components of the rear visibility system for testing purposes, using any factory seal which would be used during normal vehicle operation, in a manner that simulates the on-vehicle component orientation during normal vehicle operation, and prevents the exposure of any test conditions to portions of the external component which are not exposed to the outside of the motor vehicle.
External component means any part of the rear visibility system which is exposed to the outside of the motor vehicle.
Key means a physical device or an electronic code which, when inserted into the starting system (by physical or electronic means), enables the vehicle operator to activate the engine or motor.
Limited line manufacturer means a manufacturer that sells three or fewer carlines, as that term is defined in 49 CFR 583.4 , in the United States during a production year, as that term is defined in S15.
Rearview image means a visual image, detected by means of a single source, of the area directly behind a vehicle that is provided in a single location to the vehicle operator and by means of indirect vision.
Rear visibility system means the set of devices or components which together perform the function of producing the rearview image as required under this standard.
Small manufacturer means an original vehicle manufacturer that produces or assembles fewer than 5,000 vehicles annually for sale in the United States.
Starting system means the vehicle system used in conjunction with the key to activate the engine or motor.
Unit magnification mirror means a plane or flat mirror with a reflective surface through which the angular height and width of the image of an object is equal to the angular height and width of the object when viewed directly at the same distance except for flaws that do not exceed normal manufacturing tolerances. For the purposes of this regulation a prismatic day-night adjustment rearview mirror one of whose positions provides unit magnification is considered a unit magnification mirror.
"USE CROSS VIEW MIRRORS TO VIEW PEDESTRIANS WHILE BUS IS STOPPED. DO NOT USE THESE MIRRORS TO VIEW TRAFFIC WHILE BUS IS MOVING. IMAGES IN SUCH MIRRORS DO NOT ACCURATELY SHOW ANOTHER VEHICLE'S LOCATION."
Table I-Conversion Table From Spherometer Dial Reading to Radius of Curvature
Dial reading | Radius of curvature (Inches) | Radius of curvature (mm) |
.00330 | 85.2 | 2164.1 |
.00350 | 80.4 | 2042.92 |
.00374 | 75.2 | 1910.1 |
.00402 | 70.0 | 1778.0 |
.00416 | 67.6 | 1717.0 |
.00432 | 65.1 | 1653.5 |
.00450 | 62.5 | 1587.5 |
.00468 | 60.1 | 1526.5 |
.00476 | 59.1 | 1501.1 |
.00484 | 58.1 | 1475.7 |
.00492 | 57.2 | 1452.9 |
.00502 | 56.0 | 1422.4 |
.00512 | 54.9 | 1394.5 |
.00522 | 53.9 | 1369.1 |
.00536 | 52.5 | 1333.5 |
.00544 | 51.7 | 1313.2 |
.00554 | 50.8 | 1290.3 |
.00566 | 49.7 | 1262.4 |
.00580 | 48.5 | 1231.9 |
.00592 | 47.5 | 1206.5 |
.00606 | 46.4 | 1178.6 |
.00622 | 45.2 | 1148.1 |
.00636 | 44.2 | 1122.7 |
.00654 | 43.0 | 1092.2 |
.00668 | 42.1 | 1069.3 |
.00686 | 41.0 | 1041.4 |
.00694 | 40.5 | 1028.7 |
.00720 | 39.1 | 993.1 |
.00740 | 38.0 | 965.2 |
.00760 | 37.0 | 939.8 |
.00780 | 36.1 | 916.9 |
.00802 | 35.1 | 891.5 |
.00822 | 34.2 | 868.7 |
.00850 | 33.1 | 840.7 |
.00878 | 32.0 | 812.8 |
.00906 | 31.0 | 787.4 |
.00922 | 30.5 | 774.7 |
.00938 | 30.0 | 762.0 |
.00960 | 29.3 | 744.2 |
.00980 | 28.7 | 729.0 |
.01004 | 28.0 | 711.2 |
.01022 | 27.5 | 698.5 |
.01042 | 27.0 | 685.8 |
.01060 | 26.5 | 673.1 |
.01080 | 26.0 | 660.4 |
.01110 | 25.3 | 642.6 |
.01130 | 24.9 | 632.5 |
.01170 | 24.0 | 609.6 |
.01200 | 23.4 | 594.4 |
.01240 | 22.7 | 576.6 |
.01280 | 22.0 | 558.8 |
.01310 | 21.5 | 546.1 |
.01360 | 20.7 | 525.8 |
.01400 | 20.1 | 510.5 |
.01430 | 19.7 | 500.4 |
.01480 | 19.0 | 482.6 |
.01540 | 18.3 | 464.8 |
.01570 | 17.9 | 454.7 |
.01610 | 17.5 | 444.5 |
.01650 | 17.1 | 434.3 |
.01700 | 16.6 | 421.6 |
.01750 | 16.1 | 408.9 |
.01800 | 15.6 | 396.2 |
.01860 | 15.1 | 383.5 |
.01910 | 14.7 | 373.4 |
.01980 | 14.2 | 360.7 |
.02040 | 13.8 | 350.5 |
.02100 | 13.4 | 340.4 |
.02160 | 13.0 | 330.2 |
.02250 | 12.5 | 317.5 |
.02340 | 12.0 | 304.8 |
.02450 | 11.5 | 292.1 |
.02560 | 11.0 | 279.4 |
.02680 | 10.5 | 266.7 |
.02810 | 10.0 | 254.0 |
.02960 | 9.5 | 241.3 |
.03130 | 9.0 | 228.6 |
.03310 | 8.5 | 215.9 |
The width of the bars in Figure 4 indicating three minutes of arc and nine minutes of arc are derived from the following formula:
For 3 minutes of arc:
X = D * 0.000873,
Where:
X = the width of a line, in the unit of measurement D, representing 3 minutes of arc;
D = distance from center point of driver's eye location to the center of the mirror's surface; and
0.000873 = tangent of 3 minutes of arc.
For 9 minutes of arc:
X = D * 0.002618,
Where:
X = the width of a line, in the unit of measurement D, representing 9 minutes of arc;
D = distance from center point of driver's eye location to the center of the mirror's surface; and
0.002618 = tangent of 9 minutes of arc.
where i can take on the value of either test object A, B, or C, and arcsine is calculated in units of degrees.
49 C.F.R. §571.111