Document ZKyDX4zmZqY2kDMNrdBoJ0dJ

PLAINTIFF'S KXIIlim Finn nn ANTI-SKID BRAKING DEVICES . Presentation to 3 AAMVA COMMITTEE ON ENGINEERING AND VEHICLE INSPECTION June 4, 1963 K. A. Stonex Generol Motors Corporotion --1 i It is misleoding to confuse the application of onti-skid devices on oircrcrft or roilrood locomotives or roilrood cors with the opplicotion on outomobiles. The principol objective originally in the development of onti-skid devices in both aircraft ond roil applications i wos to ovoid weoring flat spots or destroying tires, becouse these require expensive ond premature replacement. Moreover, in the use of these brakes under landing conditions J where aileron ond rudder control ore also required os part of the steering of the oircroft, considerable investment in hordwore to eliminate or reduce these repoirs ond complicated control problems is justified. There hove been o number of onti-skid devices proposed for automotive use, and one dis cussed by the British Rood Reseorch Laboratory is claimed to reduce the stopping distance i somewhat from thof of uncontrolled slide under some conditioris ond still preserve the I copobility of Steering. This device operates on the four wheels of the vehicle ond pro vides independent front ond rear braking, ond it requires four separate and complete .--1 sensing and actuating units. Other devices recently proposed in Englond for automotive opplicotion ore simplified somewhat in on attempt to reduce the cost, and a still simpler device has been publi cized recently in the United States. Unquestionably, sofety would be enhanced if o reliable device could be developed which would preserve steering control during o panic broke stop and maintain or reduce the stopping distance. In our continuing observation of devices of this type, o series of tests was recently con ducted ot the General Motors Proving Ground to evoluate one of these devices. The re sults ore shown on the following chorts. Figure 1 is o tabulation of the stopping c/istonces required for severol speeds on a car in standard condition ond with this onti-skid device operating on snow-covered, wet, ond dry roods. --1i i -J &005 0214 PRODUCED BY FORD Anti-Skid Braking Devices 2. I On the upper port of the chart, covering the condition of snow-covered roods, it will be noted that the stopping distonce with the anti-skid device operative ranged from 16 to 22 feet greater than on the ponic stop on the standard car. At 40 mph, the stopping distonce with the anti-skid device being used was from 27 to 47 feet greater than that of the standard car. These increases in stopping distances range from 12 to 21 percent. In the central part of the chart, doto from tests from 30 to 50 mph on wet roods are re ported. At 30 mph the car required 7 and 12 feet farther to stop when the anti-skid de vice was operating than the standard car did, and at 50 mph the increase was 5 and 9 feet. These increases in stopping distance required when the anti-skid device was in use ranged from 4 to 27 percent. In the lower part of the chart, stopping distance tests at 30 and 50 mph on a dry road are shown. At 30 mph the car required approximately 9 feet more to stop when the anti-skid device was operating than when it was not, and at 50 mph the car required from 11 to 30 feet more to stop. These increases in stopping distance when the anti-skid device was operating ranged from 12 to 26 percent. Figure 2 is o comparison of the minimum stopping distances obtoined when steering con trol was maintained, in one case by careful braking control by the driver, and in the other by steering control preserved by the operation of the anti-skid device. At 30 mph the stopping distonce when the anti-skid control device was operating ranged from 7 to 12 feet less fhon the distonce required under driver control. At 50 mph the stopping dis tance required when the anti-skid device was operating ranged from 14 to 32 feet less thon that required under driver control. The reduction in stopping distonce when the onti-skid control was used ranged from 9 to 18 percent. Figure 3 shows the comparison of the stopping distances under panic ond driver-controlled conditions on a dry rood surface at 30 and 50 mph. At 30 mph the full panic stop is from 16 to 21 feet less thon the controlled stop, and at 50 mph the panic stop is from 25 to 54 feet shorter thon the controlled stop. At these speeds, the ponic stopping distonce is from 20 to 48 percent less than that of the controlled stop. Data ore summarized in bar chart form in Figure 4. On the snow-covered roods, stopping distances were approxi mately twice those on wet ond dry pavement; there is very little difference between the stopping distances on wet and dry pavements. In each case, the ponic stopping distonce Is significantly less than the stopping distance obtoined when th* anti-skid control device is used. On dry pavement, at both speeds, the stopping distonce required when the onti- skid device is used is intermediately between the panic stopping distance and the con trolled stopping distance. It is clear that on this group of tests the minimum stopping distance is obtoined on snowcovered, wet, ond dry roads during a full four-wheel slide and that the onti-skid device 8003 0215 PRODUCED BY FORD Z} Z1 _j I] I] n Anti-Skid Broking Device* 3, produces shorter stopping distonces thon the driver can while regulating broke application to the point that steering control is maintained. It is our opinion thot it would be unjustifiable to offer a device which provides anything more thon the minimum stopping distance, and that the advantages of steering control during emergency stop are less than the disadvantages of a significant increase in stopping distance. i J I <--J r" 8003 0216 4 PRODUCED BY FORD n 3 3 3 3 3 3 3 3 3 3 3 "1 -3 3 3 3 *PtCT Of AM ANJVSKO OtVKS PANIC MAO nOfftNO MSIANCB fut> tus mIM umi Figure 1 UIt I1t4 COWAWON Of PANIC AND Dtvw-comtouiD norr*x> dotangb Ui IiInI Figure 3 cmvaikon of nomo mranck wnx STtvuNO comic* MAMTAMD ioamwt --III ---M1C - f .11 -*i -It --* -Itt Figure 2 COMIAIHON Of AVBAOt tTOffMO MSTAMOB WITH AND WTTHOin AM ANTFWff) 6tVlCI Figure 4 8003 0217 PRODUCED BY FORD