| Show AVOID SKIDDING BY TWO METHODS rough hough tread tires or chains will prevent trouble to considerable sid erable extent why an automobile skids Is of in terest to a motorist but what nhat to do to prevent skidding and what to do when the car Is skidding are equally lm topics the main cause of skidding of rear wheels beels i of motor cars Is due to the action of the brakes operating through the rear wheels skidding of course normally occurs only oaly when the roads are slippery an automobile wheel rotates and progresses over the highway in but one direction diree tion or plane this diorec hon tion for tl e rear wheels ts Is determined ay by the front wheels under control of the driver while the ther rear wheels grip the ground and rotate they control the direction of the car however as soon as the wheels are locked by the brakes hey begin to slide and as they slide sidewise practically as easily as forward they lose the power to direct the car little friction locks wheels it takes comparatively little brake friction to lock and slide rilde rear wheels on roads because there is little friction between the tire an and the road surface when once the dr driving vang wheels begin to slip the car is kept in motion by the force of inertia acting at the cars car s center of gravity or mass this forward motion la Is opposed by the resistance of all four wheels on the grousd a resistance that Is greater in the ra eting front wheels heels than in the sliding lear wheels unless the corn com bained ground resistance of all wheels S tend ng to stop the car acts on the same came point as the force of inertia tend ing to carry the car forward there re suits what nihat Is called force couple which causes the car to skid or spin around after the wheels once start tart to slip a very nery force couple will nill pro dice gk idding ind the skid distance Is 19 dependent upon the magnitude of the force couple which in turn depenis pen N on car spee I 1 and NN weight turn ing the front wheels in the direction of the rear wheel skid helps to reduce skidding because it reduces the magni tide t ide of the force couple also peri perl releasing and applying reapplying re the bral e so the reir v wl I 1 eels can get a grip offsets forward slip and consequent side skid ways to prevent sk dd ng two tio means are employed to prevent Bk sl tiding dIdIng in motor vehicles the use ef of nonskid or rough tread tires and ef of anti skid chains nonskid Ion skid tires are designed to give forward traction and to present side slip As long as there ts is traction the rear wheels will turn and as long as the rear wheels turn there will be no serious side slip un less the front wheels are blocked chains accomplish the same purpose as the nonskid tire tread that Is give additional traction and reduce side slip nonskid chains should sup clement nonskid tires only when road conditions absolutely require them |
