自動上料機機架部件設計及性能試驗(論文+DWG圖紙),自動,上料機,機架,部件,設計,性能,機能,試驗,實驗,論文,dwg,圖紙 The open differential divides the rotational speed unequally.if one wheel begins to silp,more of the speed is transferred to the faster-movingwhel.the wheel with good traction will slow and may stop.this may prevent the vehicle from moving if one wheel is on a slick surface. Limited-silp differential A limited-slip differential provides the same function as an open differential.the ring gear,differential case,spider pinions,spiderpinion shaft,and differential side gears all perform the same functions.the limited-slip design limits the amount of drive applied to a slipping wheel. One desgin uses multiple disc clutches,or cones,and clutch mating surfaces to limit the amount of drive applied. Multiple-disc clutches contain a serise of alternating friction discs and steel plates. The friction discs are splined to the axle side gears and rotate with them. The steel plates have tangs around the outside that fit into the differenatial case and hold them in position. Shim and spacers provide the proper clearance between the steel plates and the friction discs.see fig.3-10 Most limited-slip differentials have preload springs between the side gears.with the clutches engaged,the spring forces the friction discs and steel plates together. Friction between the friction discs and the steel plates locks the differential case to the side gears. The spring force push outward on the side gears to help provide quicker locking action. When the vehicle enters a curve, the clutchessupplying drive to the inner drive wheel begin to slip. This allows some differential action to occur. See fig.3-11. if a drive wheel begins to lose traction, the differential case becomes locked to the axle side gears.this clutch action forces both wheel to turn at about the same speed. One wheel cannot turn freely,as in the open differential design. A limited-slip differential requires special lubricant. The wrong lubricant can cause the clutch surfaces to grab. This produces a chattering noise during turns. Limited-slip differentials may also require service information for recommendations concerning heavy-duty,off-road, or commercial-use maintenance specifications. Torque-sensing Toresn differentials use an internal gear train instead of clutch packs or cones. See fig.3-12. the axle or side gears are worm gears. Their teeh are cut in a apiral pattern. The worm wheels drive the side gears. They are in constant mesh with the side gears. The worm wheels are mounted on shafts that are attached to the differential case. When the vehicle is traveling straight, the differential case, worm wheels,and worm gears are locked as a unit. Both drive wheels rotate at the same speed. As the vehicle enters a turn, the inner drive wheel slows and creates resistance. The resistance is transferred form the worm gears to the worm wheels and spur gears to the differential case. The worm wheels attempt to drive the side gear for the outer wheel. Worm gears can drive others gears,but they cannot easily be driven. The resistance between the gears creates friction. The inner wheel slows down slightly,providing limited differential action. A locking or ratchet-type differential is another limited-liap design. The differential case is divided into two pieces. Each piece is locked to a commom driving member by teeth. Torque is trasmitted to both sides of the differential case. This system uses a series of cams that are controlled by relative wheel speed. This arrangement is called a dog clutch. When the vehicle is traveling straight, both sides of the differential case are locked to the drive member. When one of the wheels speeds up or slip, the cams detect the change in wheel speed. The side of the differential case driving that wheel desengages. All power is applied to the wheel with traction. As wheel speed equalizeds, the differential case engages. Prower is them applied equally to both wheels. The locking and unlocking action of the dog clutch does not occur smoothly. However,the advantage of having two axle,or drive shafts,securely locked together makes this design uesful in certain applications. Testing limited slip differentials the operation of some limited slip differentials can be externally tested by measuring the rotating torque of the differential clutch mechanism. To measure the rotating torque of an external clutch mechanism: 1. jack up one drive wheel 2. place the transmissin in NEUTRAL and release the parking brake 3. use an appropriate adapter to attach a flexbeam or dial indicator torque wrench to the lugstuds of the raised wheel 4. measure the torque required to turn the wheel and compare the reading to manufacture’s specifications. These specifications can range from 40-170 ft.lbs.depending on the manufacturer. Objectives: A2 identify and interpret drive train concern; determine necessary action E1-1 diagnose noise and vibration concerns; determine necessary action E1-2 diagnose fluid leakage concerns; determine necessary action E1-11 reassemble and reinstall differential case assembly;measure runout; determine necessary action E1-10 disassemble,inspect,measure,and adjust or replace differential pinion gears(spiders) shaft, sidegears,sidebearings,ttrust washers,and case. E2-2clean and inspct differential housing;refill with correct lubricant. E1-7measure and adjust drive pinion bearing preload E1-8measure and adjust side bearing preload and ring and pinion gear total backlash variation on a differential carrier assembly(threaded cup or shim types). E1-5remove ,inspect,and reinstall drive pinion and ring gear, spacers,sleeves,and bearings. E1-4inspect ring gear and measure runout; determine necessary action E1-9check ring and pinion tooth contact patterns; determine necessary action E1-6measure and adjust driver pinion depth E1-3inspect and replace companion flange and pinion seal;measure companion flange runout E3-1diagnose drive axle shates,bearings, and seals for noise, vibration, and fluid leakage concerns; determine necessary action E3-2inspect and replace drive axle shaft wheel studs E3-5measure drive axle flange runout and shaft endplay; determine necessary action E3-3remove and replace drive axle shafts E3-4inspect and replace drive axle shaft seals, bearings ,and retainers Niagnosing noise When drives axle fail, one of the frist symptoms is unusual or excessive noise. Accurate noise diagnosis is one of the sklls a technician develops. It is difficult to accurately diagnose drive axle noise. Certain operating conditions mey need to occur before noise is created. The kind of noise can help determine what is causing the trouble. Note whether the noise is produced when the vehicle is traveling straight ahead or only on turns. Determine whether the noise louder under proer or when the noise is coasting. Ring and drive pinion gear nosie usually changes under load. Drive pinion –bearing noise changes with vehicle direction . Eliminate the possibility that the noise may be from another source such as : a worm universal joint A broken rear shock absorber mount Loose wheel lug nuts Tire noise. Noise on accelaration Noise that occurs on acceleration is often related to gears. For proper diagnosis,it is important to understand gear sturcture and how gears work together. The following terms are used to descibe the meshing and structure of gear teeth. Clearance is the distance between the top fo the tooth of one gear and the valley between the adjacent teeth of the mating gear. Backlash is the distance between adjacent meshing teeth in the drive and driven gear. It is the distance one gear can rotate backward before it will cause the other gear to move. Heel is the large section of the gear tooth and is farthese form the center of the ring gear Toe Is the smaller, or inner end , of the gear tooth Face is the contact area of the gear tooth Flank is the noncontact area of the tooth Pinch line separates the flank from the face A gear tooth must fit properly in its mating gear;otherwise, excessive gear noise will result. Gera noise that is louder during vehicle acceleration mey be caused by heavy contact on the heels ,or outerends, of the ring-gear teeth. Gear noise that is louder when the vehicle is coasting may be caysed by heavy contact on the toe ,or inner end, of the gear teeth.A loud clunk duing acceleration or deceleration may be caused by too much clearance between the drive pinion gear and the ring gear. A loud clunk that occurs when engaging the clutch or accelerating in a forward gear may also be caused by: Excessive ring-gear backlash Excess clearence between the spider pinion gears and side gears in the differential. A badly worn universal joint A loose or broken motor or tansmission mount. Humming A humming noise may become a growling sound as wear progresses. A hunmming noise may bi caused by : Insuffcient lubrication Incorrectly adjusted ring and drive pinion Worn gears Insufficient lubrication causes the moving parts in the differential and axle to wear prematurely:the metal-on-metal wear noise. Incorrect ring and drive pinion gear adjustment creates gear tooth contract problems,it can cause rapid tooth wear and gear failure. Noise on curves If noise is heard only when the vehicle is going around a curve,the cause is either a bad axle bearing or a problem within the differential. A bad axle bearing usually makes the mostnoise when it is on the outside of a turn. The outer axle bearing is running faster and carrying a greater load than bearing on the inner axle. Making a turn in the opposite driection will usually reduce or eliminate the noise from a bad axle bearing. Differential noise on a turn can be caused by: Spider pinion gears tight on the pinion shaft Damaged spide pinion gears or thrust washers. Too much backlash between the drive pinion gear and the ring gear. Worn differential-case bearings Vibration when driving Low-speed vibrations in the 30-35 mph[48-56kph]range may be the result of drive shaft imbalance, a worn universal joint, or incorrect drive shaft joint indexing. Wibrations in the 50-60mph[80-96kph]range (with14”[35.5cm]diameter wheels) are associated with tire imbalance or ecessive tire yunout. Large –diameter wheels cause vibration at higher speeds. Smaller-diameter wheels cause vibration at lower speeds. Servicing a differential The most common differential service is lubrication. Checking dfferential lubricant is simial to checking the fluid in a manual transmission .remove the threaded piug on the side or back of the differential carrier. The fluid should be within 1/2”[13mm]of the bottom of the hole. If the lubricant level is high,it will result in axle and drive pinion gear seal leakage. A clogged differential vent tube will also force lubricant past the seals.as with any automotive service, always check the vehicle service information for lubricant specifications. Diagnosong leaks Always use the proper lubricant as specified by the manufacturer. If impropre lubricant has been added to some limited slip units,it will be necessary to change the fluid and add a special additive to eliminate noise. When servicing the differential, always inspect for fluid leaks,if the differential runs low on lubricant,serious damge will occur.in spect for leakage at the pinion seal.axle seals,and carrier or cover gasket.some differential housing have a central carrier housing with axle housing tubes pressed in place and welded. Leakage can sometimes occur around these welds. To repair these leaks,the entire differential housingmust be replaced or the leaking area must be cleaned and a special sealant applied. Differential carrier The differential carrier contains drive pinion gear; the ring gear;differential case;and the asociated bearings,seals,adjusters and retainers. These are two differential carrier designs: Removeable carrier Integral carrier The removable carrier is bolted to the front of the axle housing, the entire carrier, including the pinion gear and differential, must be removed from the axle housing for service. Refer to the vehicle service information for removal procedures and specifications. A general procedure for removing a removable carrier is to : 1.disconnect the drive shaft and support it securely. 2.drain the lubricant form the differential 3.remove the axle shafts 4.remove the bolts attaching the differential carrier to the axle housing. 5.carefully remove the differential carrier from the axle housing. The integral differential carrier is part of the axle housing. The differential and associated componetsare accessed by removing a stamped metal cover on the back of the axle housing, To remove the differential components from the inthgral carrier: 1.remove the bolt that holds the spider pinion shaft 2.withdraw the carrier pinion shaft. 3.remove the axle shafts The two spider pinion gears rotate around the inside of the differential carrier(held in place by the pinion shaft). They may be removed,one at a time ,through the opening in the case after the shaft is withdrawn. When the spider pinion gears have removed,the side gears should slide out. The spider pinions and side gears have thrust washers behing them. Check these washers for washers for damage or unusual wear.replace them as necessary. Constructin,operation,diagnosis,and serviceof the differentials are simiar.removable differentials are serviced in much the same way as integral differentials. All assembly and adjustments can be performed off the vehicle. Figure3-15shouws a completely disassembled rear axle that has an integral carrier and a standard ,or open ,differential.inspecting the differential components often provides information about what service needs to be performed.you may discover that the only service required involves adjustments. Before servicing or disassembling a differential, measure the drive pinion bearing preload and ring-gear backlash. Always refer to the vehicle service information for proper procedures and specifications. Drive pinion gear bearing preload Drive pinion gearing preload is measured by the torque required to turn the gear. Preload is the process of adjusting a bearing soit has a specific amount of pressure placed on it .preload is measured with a torque wrench. When checking the preload,allow for resistance from the drive pinion seal. The resistance will increase the torque required to turn the drive pinion gear. A typical procedure foe checking drive pinion gear bearing preload is to : 1.place a torque wrench on the drive pinion gear input shaft 2.rotate the gear with the wrench in the direction of drive pinion gear rotation . 3.record the amount of torque required to move the gear. Ring gear backlash Ring gear backlash is the amount of clearancebetween the ring gear teeth and drive pinion gear teeth refer to the vehicle service information for procedures and specifications. Backsash is measured with a dial indicator. Generally, to measure backlash: 1. mount a dial indicator to the differential housing. 2. place the stem of the dial indicator against one the ring gear teeth 3. hold the drive pinion gear stationary 4. rotate the ring gear back and forth 5. record the measurement caused by movement ring gear backlash can be obseved by checking the tooth cantact pattern of the ring gear and the drive pinion gear. To check the tooth contact pattern: 1. drain the lubricant from the differential 2. disconnect the drive shaft 3. move the carrier cover 4. wipe the lubricant from the carrier,and clean each tooth on the ring and drive pinion gears. 5. coat both sides of the ring gear teeth with Prussian blue or a simial making compound. 6. slightly load the ring and drive pinion gears 7. rotate the ring gear one complete revolution in each drection. This procedures leaves a distinct contact pattern on both sides of the ring gear teeth Contact pattern and gear backlash are affected by the relative positions of the drive pinion gear and the ring gear. A general procedure to adjust contact pattern and back lash is to : 1.adjust the left and ringht ring gear adjustment nut to change the position of the differential case. The ring gear is bolted to the case. Backlash adjustment is usually measured at the centerline of the ring gear. The adjustment nuts also affect the differential carrier bearing preload 2.add or remove shims from the drive pinion gear,locating shim packs to sdjust the position of the drive pinion gear. The drive pinion adjustment is usually measured relative to the axle centerline and the ring gear. If adjustment is required,refer to the vehicle service informantion for adjustment procedures and specifications. Drive pinion gear depth Measurement and setting of the drive pinion depth is critical to proper operation of the differential .the drive pinion gear depth adjustment sets the depth that the pinion gear extends into the differential carrier. This adjustment affects how the drive pinion gear and ring gear teeth mesh. An adjustment error can result in con sideable noise and gear wear problems. Drive pinion depth is adjusted with shims. The existing pinion locating shim pack is used as a baseline. The measurement is made relative to the axle centerline and the ring gear. Adding shims ,removing shims,or replacing shims with those of a different thickness sets the correct drive pinion depth. Adding shims moves the drive pinion closer to the axle centerline. A new ring and drive pinion gear set may have numbers etched on the pinion gear.the numbers are represented in one-thousanbdths of an inch or in millimeters. One of the number is preceded by a plus or minus. This number is needed for use with a pinion depth gauge to determine the pinion depth adjustment shim required. When rebuilding a differential, it is important to carefully wash out the differential housing, axle tubes, and all resued parts.small particles of worn parts left in the differential will rapidly damage or cause wear to the new parts. Replacing the drive pinion seal The drive pinion seal is located in front of the pinion bearing.when replacing the pinion sae, the pinion bearingpreload must not be changed. A typical procedure for replacing the drive pinion seal is to : 1. properly raise and support the vehicle. 2. locate or make index marks on the drive shaft and yoke or pinion flange. 3.disconnect the drive shaft from the pinion flange .do not pull the slip yoke off the transmission output shaft. 4.support the rear of the drive shaft. 5.mark the position of the pinion flange,pinion shafts,and pinion bearing preload adjustment nut. 6.remove the pinion preload adjustment nut,washer,pinion flange,and seal. 7.inspect the seal surfaceon the pinion flange. If the surface is grooved or damaged, install a new pinion flange 8.remove any burrs in the carrier bore. 9.lubricate the new seal and install it in the carrier bore. 10.align the marks on the pinion shaft and pinionflange, and install the pinion flange. 11.lubricate the washer side of the pinion adjustmengt nut, and tighten to the index marks. 12.rotate the drive pinion gear by hand to seat the bearing, 13.measure the pinion bearing preload with a torque wrench. 14.tighten the pinion bearing preload nut as required to obtain the correct preload setting. Refer to the vehicle service informantion for proper procedures and specifications. Servicing axle shafts The axle shafts transmit torque from yhe differential to the rear wheels. Conventional rear axle shafts are one-piece units.the inner end of the shafts are splined. The splines mesh with the internal splines of the differential side geaes.the outer end of the shaft is a machined surface. This surface either accepts a press-fit bearing assembly or serves as the inner bearing race for the outer rear axle bearing. A wheel-mounting flange is mounted on the outer end of the axle.