飞机轮胎介绍.ppt

AircraftSystemAircraftTires2021/3/29 星期一1Classification of TiresType Size Ply rating(层数）层数）Tube or tubeless2021/3/29 星期一2Classification of TiresType tireCharacteristic: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 diameter9.50-16 tire:the section width is 9.5 inches,the rim diameter is 16 inches.2021/3/29 星期一32021/3/29 星期一42021/3/29 星期一5Classification of TiresType tireCharacteristic: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.2021/3/29 星期一62021/3/29 星期一72021/3/29 星期一8Classification of TiresType tireCharacteristic:Jet aircraft，high load-carrying ability,Ply rating:4 to 38Construction 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.2021/3/29 星期一9Classification of TiresDesignating 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.2021/3/29 星期一102021/3/29 星期一11Bias or Radial TireAnother means of classifying an aircraft tire is by thedirection of the plies used in construction of the tire,eitherbias 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 60.2021/3/29 星期一12Bias or Radial TireIn 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.2021/3/29 星期一132021/3/29 星期一14Ply RatingIt 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.2021/3/29 星期一15Tube or Tubeless TiresTubeless tires:one-tenth of an inch thick inner liner“TUBELESS”on the sidewallTube tires:no inner liner,smoother inside surface.no“identification”on the sidewall2021/3/29 星期一16Construction of Tire Automobile and truck tires1.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 speeds4.a relatively small amount of deflection（变形）.Car Tires:a continual deflection of only about 12 to 14%.2021/3/29 星期一17Construction of Tire Airplane tires1.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 2021/3/29 星期一182021/3/29 星期一192021/3/29 星期一202021/3/29 星期一212021/3/29 星期一222021/3/29 星期一23BEAD（胎缘）（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 9-712021/3/29 星期一24Rubber Apex Strips(橡胶填充层橡胶填充层)Definition:To pack and streamline the round bead bundles,so the fabric will fit smoothly around them with no voids.2021/3/29 星期一25Flippers（隔离层）（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.2021/3/29 星期一26CARCASS and TURN-UPS（胎体和重叠层）（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 450 to the length of the stripthe 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 900 to balance the strength of the carcass.2021/3/29 星期一27CHAFERS（胎缘包覆层）（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.2021/3/29 星期一28UNDERTREAD（底胎面）（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.2021/3/29 星期一29TREAD REINFORCING LAYER（胎面加强层）（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.2021/3/29 星期一30TREAD REINFORCING LAYER（胎面加强层）（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.2021/3/29 星期一31TUBELESS TIRE LINER（无内胎轮胎衬层）（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.2021/3/29 星期一32TREAD（胎面）（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.2021/3/29 星期一332021/3/29 星期一34TREAD PATTERNSPlain TreadPlain,or smooth,tread is used on some helicopter and on very light airplanes.All weather tread1.All-weather treads have a rib tread in the center and diamonds molded into the shoulders2.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 9-722021/3/29 星期一352021/3/29 星期一36Rib TreadThe rib tread is the most popular tread pattern found on modern aircraft today.1.use on hard-surfaced runways.2.long tread wear life3.good traction4.exceptionally good directional stability.Figure 9-73The width and depth of the grooves,their placement on the tread are determined by operating conditions of aircraft for which they are designed.2021/3/29 星期一372021/3/29 星期一38CHINE(胎脊、偏转器）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 tireFigure 9-74 Function:To prevent water or slush from being thrown up by the nose wheel and entering the engines，Figure 9-742021/3/29 星期一392021/3/29 星期一40SIDEWALLDefinition: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.2021/3/29 星期一41VENT HOLESDefinition: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.2021/3/29 星期一42TIRE INSPECTION ON THE AIRCRAFTMost inspection on the aircraftScheduled inspections of the tiresThe technician should take a look at the tires any time work is being done in the vicinity of the gear.2021/3/29 星期一43轮胎充气的基本要求轮胎充气的基本要求1.如果将轮胎始终维持在正确压力，轮胎寿命会更长。2.如果用干燥的空气给轮胎充气，确保氧气含量不超过5%。3.如果轮胎压力比正确压力低5%或更低，则为轮胎充气。4.如果轮胎压力比正常压力低5%15%，给轮胎充气并在24 小 时后检查。5.如果轮胎压力比正常压力低1530%，拆卸并更换机轮和轮胎组件。6.如果轮胎压力比正常压力低超过30%，拆卸并更换机轮和轮胎组件。如果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的机轮和轮胎组件。2021/3/29 星期一44Heat DamageThe 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 heat2.The heat from external sources such as the brakes or hot runway surfaces.2021/3/29 星期一45Inflation Pressure1.The pressure should be checked Daily inspection Preflight inspection2.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.2021/3/29 星期一46Inflation PressureInflation 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.2021/3/29 星期一47Inflation PressureThe 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.2021/3/29 星期一48Inflation Pressure1.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.2021/3/29 星期一49Inflation PressureAn 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.2021/3/29 星期一50Inflation Pressure4.If the tire requires 187 psi,the 60F temperature drop will require the pressure to be 12greater,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 5.2021/3/29 星期一51Over-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.2021/3/29 星期一52Over-inflation2021/3/29 星期一53Under-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.2021/3/29 星期一54Under-inflation2021/3/29 星期一55TREAD 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.2021/3/29 星期一562021/3/29 星期一57 Correct Inflation PressureNormal WearThe correct inflation pressure will wear the tread uniformly.Figure 9-762021/3/29 星期一582021/3/29 星期一59Abnormal Wear of Tire Tread1.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.2021/3/29 星期一60Abnormal Wear of Tire Tread2 Tread wear in spotsCause:malfunctioning brakes improperly torqued bearings worn strut parts landing with brakes engaged.2021/3/29 星期一61Tread cutA tire should be removed form service if the tread is cut across more than one-half of a rib widthCause:glass,rock,or metal Figure 9-80 grooved runway Figure 9-82Note:remove glass,rock,or metal with a blunt awl or screwdriver.2021/3/29 星期一622021/3/29 星期一632021/3/29 星期一64Tread burnA tire should be removed form service if the tread shows the burning mark on the contact point with the runway or water on the runway.Figure 9-81Cause:hydroplaning(打滑）a locked brake2021/3/29 星期一652021/3/29 星期一66Inspection of Tread1.If the cord body plies are visible,the tire cannot be retrodden.Figure 9-792.If the tread reinforcement just is showing,the tires are possibly retrodden.3.Any time the tread is cut more than halfway across a rib，or any of the carcass plies are exposed，the tire should be removed from serviceFigure 9-802021/3/29 星期一672021/3/29 星期一68Inspection of Tread4.bits of glass,rock or metal embedded in the tread should be carefully removed with a blunt awl or a small screwdriver.5.Tires showing burn at the point of contact should be removed from service.6.Operating on grooved runways can cause chevron-shaped(V-shape)cuts across the ribs of a tire.If they extend across more than one-half of the rib,the tire should be removed from service.2021/3/29 星期一69Inspection of Tread7.Any damaged or suspect area of the tire should be marked with a light-colored marker before deflating the tire.8.Any tread damage should be carefully evaluated by a licensed retreading agency to determine whether or not the tire is repairable.2021/3/29 星期一70SidewallPurpose:It protects the carcass plies from damage,either from mechanical abrasion,from deterioration by chemicals，or by the sun.1.if small snags,cuts,weather cracks dont expose the cords,the tire should not be removed for maintenance.2.Check for open holes on the sidewall.The vent is used to relieve the air diffused into the body plies from the tire compartment in order to protect the plies from separation.2021/3/29 星期一71Procedure of Tire Removal 1.jack the aircraft up.2.when the weight is off,deflate the tire using a deflator cap.3.removed the cover of inflation valve.4.remove the wheel.5.clean,inspection and repack the bearings with proper grease,protect it from damage.2021/3/