飞机轮胎介绍.pptx

单击此处编辑母版标题样式,单击此处编辑母版文本样式,第二层,第三层,第四层,第五层,*,Aircraft System,Aircraft Tires,Guangzhou Civil Aivation College,Aircraft System,Classification of Tires,Type,Size,Ply rating(,层数）,Tube or tubeless,Guangzhou Civil Aivation College,Aircraft System,Classification of Tires,Type tire,Characteristic:,Low pressure,piston-power aircraft.,Construction character:,The section width is relatively wide in relation to the bead,diameter.,Designating Method:,Section width and rim diameter,9.50-16 tire:the section width is 9.5 inches,the rim diameter is 16 inches.,Guangzhou Civil Aivation College,Aircraft System,Guangzhou Civil Aivation College,Aircraft System,Guangzhou Civil Aivation College,Aircraft System,Classification of Tires,Type tire,Characteristic:,Extra-high pressure,jet aircraft.,Construction character:,Ply rating from 4 to 38.,Designating Method:,Outside diameter and section width,3813 tire:,The outside diameter is 38 inches,the section width is 13,inches.,Guangzhou Civil Aivation College,Aircraft System,Guangzhou Civil Aivation College,Aircraft System,Guangzhou Civil Aivation College,Aircraft System,Classification of Tires,Type tire,Characteristic:,Jet aircraft,，,high load-carrying ability,Ply rating:4 to 38,Construction character:,Low profile.,Designating Method:,Outside diameter,section width and rim diameter.,3011.50-14.5 tire:,The outside diameter is 30 inches,The section width is 11.50 inches,The rim diameter is 14.5 inches.,Guangzhou Civil Aivation College,Aircraft System,Classification of Tires,Designating Method:,A Type VIII or three-part nomenclature tire is identified by 3 parameters:overall diameter,section width,and rim diameter.,They are arranged in that order with the first two separated,by an“X”and the second two separated by a“.”,For example:,18 X 4.2510,designates a tire that is 18 inches in diameter with a 4.25-inch section width to be mounted on a 10-inch wheel rim.,Guangzhou Civil Aivation College,Aircraft System,Guangzhou Civil Aivation College,Aircraft System,Bias or Radial Tire,Another means of classifying an aircraft tire is by the,direction of the plies used in construction of the tire,either,bias or radial.,Traditional aircraft tires are bias ply tires.The plies are wrapped to form the tire and give it strength.The angle of the plies in relation to the direction of rotation of the tire varies between 30and 60.,Guangzhou Civil Aivation College,Aircraft System,Bias or Radial Tire,In this manner,the plies have the bias of the fabric from which they are constructed facing the direction of rotation and across the tire.,Hence,they are called bias tires.The result is flexibility as the sidewall can flex with the fabric plies laid on the bias.,Guangzhou Civil Aivation College,Aircraft System,Guangzhou Civil Aivation College,Aircraft System,Ply Rating,It is just a strength index but in the past.,Tires are given a ply rating,rather than specifying the actual number of layers of fabric material used in the carcass.,The ply rating of a tire relates to its maximum static load and its inflation pressure.,Guangzhou Civil Aivation College,Aircraft System,Tube or Tubeless Tires,Tubeless tires:,one-tenth of an inch thick inner liner,“TUBELESS”,on the sidewall,Tube tires:,no inner liner,smoother inside surface.,no“,identification,”on the sidewall,Guangzhou Civil Aivation College,Aircraft System,Construction of Tire,Automobile and truck tires,1.different specifications from those used for aircraft tires.,2.to operate for long periods of time.,3.a relatively large but steady load at reasonably high rotational speeds,4.a relatively small amount of deflection,（变形）,.,Car Tires:,a continual deflection of only about 12 to 14%.,Guangzhou Civil Aivation College,Aircraft System,Construction of Tire,Airplane tires,1.strong enough to absorb the tremendous loads exerted on them at touchdown.,2.they must operate at very high speeds.,3.the ground roll duration is limited.,4.a deflection of between 32 and 35%,more than twice that allowed for automobile tires,Guangzhou Civil Aivation College,Aircraft System,BEAD,（胎缘）,The beads are made of bundles of high-strength carbon-,steel wire,with one,two,or three of these bundles used,in each side of the tire.,The most important part of a tire.,To provides a firm mounting surface for the tire on the wheel.,All of the ground forces on the tire terminate in the bead.Figure 9-71,Guangzhou Civil Aivation College,Aircraft System,Rubber Apex Strips,(,橡胶填充层,),Definition:,To pack and streamline the round bead bundles,so the,fabric will fit smoothly around them with no voids.,Guangzhou Civil Aivation College,Aircraft System,Flippers,（隔离层）,Definition:,Layers of rubber and fabric enclose the bead bundles to,insulate the carcass plies from the bead wires.,Function:,Because the greatest amount of heat in the tire is,concentrated in the bead area,this insulation increases the,durability of the tire.,Guangzhou Civil Aivation College,Aircraft System,CARCASS and TURN-UPS,（胎体和重叠层）,layers or plies of rubber-coated nylon-cord fabric.,the cords of the fabric at an angle of approximately 45,0,to the length of the strip,the strips extend completely across the tire and lap back over the beads to form the ply turn-ups.,each successive ply of the fabric is placed in such a way that the cords cross each other at approximately 90,0,to balance the strength of the carcass.,Guangzhou Civil Aivation College,Aircraft System,CHAFERS,（胎缘包覆层）,Definition:,Layers of fabric and rubber wrap around the edges of the,carcass plies and enclose the entire bead area.,Function:,They provide chafe resistance between the bead and the,wheel.,Guangzhou Civil Aivation College,Aircraft System,UNDERTREAD,（底胎面）,Definition:,A plies of specially compounded rubber placed over the,carcass,.,Function:,To provide good adhesion between the tread and the,carcass.,Guangzhou Civil Aivation College,Aircraft System,TREAD REINFORCING LAYER,（胎面加强层）,Definition:,One or more plies of nylon fabric strengthens the tread.,Function:,1.to opposes the centrifugal forces that try to pull the tread from the carcass during high-speed operation.,Guangzhou Civil Aivation College,Aircraft System,TREAD REINFORCING LAYER,（胎面加强层）,2.It also stabilizes the tread on the cord body and prevents it from squirming,（蠕动,)or moving.,3.This reinforcement does not enter into the ply rating of the tire,but it is used as a guide for the retreader when buffing the tire to remove the tread.,Guangzhou Civil Aivation College,Aircraft System,TUBELESS TIRE LINER,（无内胎轮胎衬层）,Definition:,A special compound of rubber that is less permeable than,the rubber used in the rest of the tire.,a thin coating of rubber over the inner ply cords protects the liner from chafing.,Function:,The liner acts as a container for the air and minimizes the,amount of air that seeps out through the casing plies.,Guangzhou Civil Aivation College,Aircraft System,TREAD,（胎面）,Definition:,The wearing surface on the outer circumference of the tire.,Characteristic:,1.It is made of specially compounded rubber.,2.A pattern of grooves molded into its surface to give the tire the required traction(,附着力）,according to the type of runway surface the aircraft will encounter.,Guangzhou Civil Aivation College,Aircraft System,Guangzhou Civil Aivation College,Aircraft System,TREAD PATTERNS,Plain Tread,Plain,or smooth,tread is used on some helicopter and,on very light airplanes.,All weather tread,1.All-weather treads have a rib tread in the center and diamonds molded into the shoulders,2.The diamond-shaped tread pattern is effective for aircraft operating on grass or hard-packed dirt,and the rib tread in the center gives good traction on hard surfaced runways,【Figure 9-72,Guangzhou Civil Aivation College,Aircraft System,Rib Tread,The rib tread is the most popular tread pattern found on,modern aircraft today.,1.use on hard-surfaced runways.,2.long tread wear life,3.good traction,4.exceptionally good directional stability.,Figure 9-73,The width and depth of the grooves,their placement on,the tread are determined by operating conditions of,aircraft for which they are designed.,Guangzhou Civil Aivation College,Aircraft System,CHINE(,胎脊、偏转器）,Chines or deflectors molded into the upper sidewall of tire,on the nose wheel.,Tires for dual nose wheel installations have chines on one side only,Single nose wheel installations have dual chines(deflectors),，,one on either side of the tire,Figure 9-74,Function:,To prevent water or slush from being thrown up,by the nose wheel and entering the engines,，,Figure 9-74,Guangzhou Civil Aivation College,Aircraft System,SIDEWALL,Definition:,A rubber covering that extends from the tread down to,the bead heel,Function:,To protect the carcass from injuries such as cuts or bruises,and from exposure to moisture and ozone.,Guangzhou Civil Aivation College,Aircraft System,VENT HOLES,Definition:,Vent holes in the lower sidewall to allow the air seeping,into sidewall to escape.,These holes are marked with paint and must be kept open when the tire is retreaded.,Function:,When the tire was heated,to avoid ply separation and the tread to be thrown from the tire.,Guangzhou Civil Aivation College,Aircraft System,TIRE INSPECTION ON THE AIRCRAFT,Most inspection on the aircraft,Scheduled inspections of the tires,The technician should take a look at the tires any time work,is being done in the vicinity of the gear.,Guangzhou Civil Aivation College,Aircraft System,轮胎充气旳基本要求,1.,假如将轮胎一直维持在正确压力，轮胎寿命会更长。,2.,假如用干燥旳空气给轮胎充气，确保氧气含量不超出,5%,。,3.,假如轮胎压力比正确压力低,5%,或更低，则为轮胎充气。,4.,假如轮胎压力比正常压力低,5%,15%,，给轮胎充气并在,24,小,时后检验。,5.,假如轮胎压力比正常压力低,15,30%,，拆卸并更换机轮和轮胎组件。,6.,假如轮胎压力比正常压力低超出,30%,，拆卸并更换机轮和轮胎组件。假如轮胎在压力下降后机轮转动并承担飞机重量，更换安装在轮轴对侧旳机轮和轮胎组件。,Guangzhou Civil Aivation College,Aircraft System,Heat Damage,The greatest enemy of an aircraft tire is heat.,Heat resource:,1.The heat generated within the tire as it rolls over the ground,the sidewalls flex and cause internal heat,2.The heat from external sources such as the brakes or hot runway surfaces.,Guangzhou Civil Aivation College,Aircraft System,Inflation Pressure,1.The pressure should be checked,Daily inspection,Preflight inspection,2.Differences in air pressure between dual mounted tires should cause concern.,It defeats the purpose of dual mounted tires,3.Any pressure difference should be corrected and noted in the aircraft logbook.Consult the aircraft service manual to determine the exact tire pressure tolerances.,Guangzhou Civil Aivation College,Aircraft System,Inflation Pressure,Inflation pressure should always be measured when the tire is cold.Two to three hours should elapse after a flight or before the pressure is measured.,Tire pressure check is the most important parts of,routine preventive maintenance.,The pressure in the aircraft service manual,rather than that listed in the tire manufacturers product manuals.,Reason:,tire pressures vary from one aircraft design to another.,Guangzhou Civil Aivation College,Aircraft System,Inflation Pressure,The pressure specified in the airframe manufacturers manual is for a loaded tire,If serviced and inflated off the aircraft,the inflation pressure should be,four percent less than the pressure specified.,(180psi,187psi in the AMM),Pressure gauges should be periodically calibrated.,Inflation pressure of a tire varies with the ambient temperature by about,one percent for every five degrees Fahrenheit.,Guangzhou Civil Aivation College,Aircraft System,Inflation Pressure,1.If a tire is inflated and allowed to stabilize with a,pressure of 180 psi in a shop where the temperature,is 70F.,2.And the airplane is rolled outside where it remains overnight with a temperature of 0F,the pressure will drop by 14%to about 155 psi.,3.Obviously,tire would then be seriously under-inflated and should be reinflated to 180 psi.,Guangzhou Civil Aivation College,Aircraft System,Inflation Pressure,An airplane is to fly into an area where the temperature,is much lower than that of the departing point.Theoretically,the pressure should be adjusted before the airplane leaves.,1.The temperature at the departing airport is 100F.,2.The airplane is to land at the another airport where the temperature is 40F.,3.The pressure should be increased before takeoff.,Guangzhou Civil Aivation College,Aircraft System,Inflation Pressure,4.If the tire requires 187 psi,the 60F temperature drop will require the pressure to be 12,greater,or 210 psi.,The maximum allowable safe-inflation pressure in AMM could not been exceeded.,Nylon tire will stretch and increase their volume enough to cause pressure drop after they are first inflated.The pressures should be adjusted 12 to 24 hours after first installation.,Conclusion:,Every 5F temperature drop will require the,inflation pressure to be increased 5,.,Guangzhou Civil Aivation College,Aircraft System,Over-inflation,It causes more centerline wear on the tread than that on the shoulder.,When a tire is worn in this way,it has much less resistance to skidding than when its tread wears uniformly.,Guangzhou Civil Aivation College,Aircraft System,Over-inflation,Guangzhou Civil Aivation College,Aircraft System,Under-inflation,It causes over deflection,Excess heat within the tire.,(45%deflection,three times heat builds up in tire),Tread worn away on the shoulders more than in the center.,Tires showing this pattern of wear should be carefully examined for evidence of hidden damage.,Guangzhou Civil Aivation College,Aircraft System,Under-inflation,Guangzhou Civil Aivation College,Aircraft System,TREAD CONDITION,Basic strength of a tire is determined by its carcass,a tire loses nothing of its strength as long as the tread does not wear down to the body plies.,It should be removed for retreading while there is still at least 1/32-inch of tread left at its most shallow point.,Guangzhou Civil Aivation College,Aircraft System,Guangzhou Civil Aivation College,Aircraft System,Correct Inflation Pressure,Normal Wear,The correct inflation pressure will wear the tread uniformly.,Figure 9-76,Guangzhou Civil Aivation College,Aircraft System,Guangzhou Civil Aivation College,Aircraft System,Abnormal Wear of Tire Tread,1.Uneven tread wear,Cause:,the landing gear is out of alignment.,Measures,:,Wheel alignment should be checked so it conforms to the specifications of the aircraft service manual.,If the uneven wear is slight and the landing gear is not adjusted,the tires may be removed,carefully inspected,and reversed so the wear will even out.,Guangzhou Civil Aivation College,Aircraft System,Abnormal Wear of Tire Tread,2 Tread wear in spots,Cause:,malfunctioning brakes,improperly torqued bearings,worn strut parts,landing with brakes engaged.,Guangzhou Civil Aivation College,Aircraft System,Tread cut,A tire should be removed form service if the tread is cut,across more than one-half of a rib width,Cause:,glass,rock,or metal Figure 9-80,grooved runway Figure 9-82,Note:,remove glass,rock,or metal with a blunt awl or screwdriver.,Guangzhou Civil Aivation College,Aircraft System,Tread burn,A tire should be