dana spicer drive axle failure analysis service manual
Contents
1. Two Speed Planetary Pitting and Spalling Failures 42 Wearand COMING uay estas i sects unu ua 43 Drive Axle Housing Spindle Damage and Fatigue Cracks 44 Loose or Over torqued Hardware 45 Steer Axle Bushing Damage Installation 46 Bushing and Kingpin Wear Contamination 47 Bushing and Kingpin Wear Normal 48 Introduction Overview This document is a general reference guide to mechanical failures of heavy truck axles We approach the subject of axle failure from several perspectives ranging from basic principles of drive train operation to the evidence available from examining failed parts In preparing this guide our objective was to help the skilled technician identify all the contributing causes of drive axle failures With improved understanding of how and why an axle failed the technician will not only be able to repair the carrier successfully but also pinpoint any conditions that may need to be changed to prevent a repeat failure Here is an overview of the different sections of this guide e Failure Prevention Explains how to prevent axle failures through proper procurement operation and maintenance e Glossary and Nomenclature Covers the terminology of axle components including function fatigue and failure This2. CD 9 o 9 lt e CD o seals and Yokes General Description Seal Inspection A seal has two critical functions to retain lube and to exclude dust and dirt For proper function the seal must be correctly installed clean and free of defects Careful inspection of seal condition plays an important role in both routine maintenance and failure analysis Below are some conditions to look for Check carefully as the smallest defect on the seal lip could cause a leak In general any of these observed defects calls for a replacement seal e Check ofr damaged seal lip bent outer shell cups and nicks or scoring e Examine seal edge new seal lip has a sharp edge If sharp edge is flattened greatly replace the seal e Check for hardness or a brittle or cracked lip This condition is usually caused by excessive temper atures If the seal lip area is not flexible replace it e Check seal lip contact area If the contact area is over 1 32 the seal may be excessively worn or the material may have lost its consistency e Look for bonding separation of seal to outer shell This could change the flexibility of the seal lip and cause a leak e Check seal spring for fit of the seal on the yoke or low tension The seal lip may have lost its tension or consistency Replace it e Check inside under the seal lip and the casing for dirt between seal and bearing cage or an accumu lation of sludge and other contamination T
3. e Continuous overloading e Contaminated lube e Incorrect lube e Low lube levels Shock e Rough trailer hook up e Misuse of the lockouts e Trying to free up frozen brakes e Spinning wheels grabbing on firm road surface Usual Causes Failure Prevention e Vehicle Operation and Drive Practices see Failure Prevention Section 42 Two Speed Planetary Wear and Scoring Clutch Plate Improper Shift Sliding Clutch Improper Shift Crack b um Bronze Idler Pins Normal Excessive Wear Bronze Idler Pin Scoring Normal Excessive Eccentric wear wear wear u i Fo e j ios a 01 General Description Usual Causes Failure Prevention 43 Clutch plate and gear wear Improper shifting and excessive periodic shock loads result in wear on the teeth of the sliding clutch gear and mating plate Scoring Incorrect lubrication or contaminated lube can cause etching scoring or pitting to the contact surface of bearings gears bushings and thrust washers Foreign materials in the lube act as an abra sive weakening the protective film and resulting in seizure of mating parts Clutch Plate and gear wear e Improper shifting e Excessive shock loads Scoring e Incorrect lubrication e Contaminated lube e Maintenance Rebuilding and Adjustment see Failure Prevention Section Drive Axle Housing spindle Water Contamination Fatigue Cracks J Housing Arm Fati
4. 20 Ring Gear and Pinion Fatigue Failure Ring Gear Catastrophic Fatigue Failure Ring Gear Start of a Fatigue Failure Fatigue crack a Drive Pinion Torsional Fatigue Failure Star or spiral fracture General Description Progressive destruction of a shaft or gear teeth Extremely high rotating and bending forces produce the initial crack The crack progresses to the center of the core resulting in complete failure Usual Causes Overloading the vehicle beyond rated capacity e Abusive operation over rough terrain Failure Prevention e Correct Specifications see Failure Prevention Section e Torque is Important see Failure Prevention Section e Vehicle Load Ratings see Failure Prevention Section Drive Practices and Vehicle Operation see Failure Prevention Section 21 Ring Gear and Pinion Pitting and Spalling Failures Ring Gear Pitting Drive Pinion Pitting Drive Pinion Case Crush Drive Pinion Spalling e ep D D 9 Advanced spalling General Description Progressive destruction of gear teeth An overload puts pressure between the meshed surfaces Re peated overloads result in teeth failure Usual Causes e Continuous overloading e Contaminated lube e Incorrect lube Failure Prevention e Correct Specifications see Failure Prevention Section e Torque is Important see Failure Prevention Section e Vehicle Load Ratings see Failure
5. 9 Cow 9 o cD O o paa uen e Inputtorque SA In high range the pu drive is through the Inter axle differential pinion and ring gear not operating E 7 only both axles Drive is from Mg output shaft side gear to rear axle gearing Torque is transmitted to both axles without inter axle differential action Lockout Engaged Gearing and Torque Distribution Spin out Combinations opin out is a term used to describe excessive differential action Wheel differential spinout occurs when one wheel remains sta tionary while the other spins Inter axle spinout occurs when either one wheel or one axle spins while the opposing wheel remains stationary These figures illustrate some of the spin out combinations that can cause spinout failure Wheel differential spinout Inter axle differential spinout Inter axle differential spinout Wheel differential spinout Inter axle Wheel differential differential spinout spinout Wheel differential spinout Inter axle differential spinout Failure Analysis How to Diagnose a Failure Failure analysis is the process of determining the original cause of a component failure in order to keep it from happening again Too often when a failed component is replaced without determining its cause there w
6. Usual Causes Overloading the vehicle beyond rated capacity e Abusive operation over rough terrain Failure Prevention e Correct Specifications see Failure Prevention Section e Torque is Important see Failure Prevention Section e Vehicle Load Ratings see Failure Prevention Section Drive Practices and Vehicle Operation see Failure Prevention Section 28 Power Divider Pitting and Spalling Failures Helical Side Gear Pitting Side Gear Pitting Pitting Side Pinion Pitting Pitting General Description Progressive destruction of gear teeth An overload puts pressure between the meshed surfaces Re peated overloads result in teeth failure Usual Causes e Continuous overloading e Contaminated lube e Incorrect lube Low lube levels Failure Prevention e Correct Specifications see Failure Prevention Section e Torque is Important see Failure Prevention Section e Vehicle Load Ratings see Failure Prevention Section e Maintenance Rebuilding and Adjustment see Failure Prevention Section 29 Power Divider Spinout Failures IAD Spider Arm Galling E 0 e CD CD Li An 30 Power Divider Helical Side Gear Bearing Damage Output Side Gear Stub End Bore Galling General Description Usual Causes Failure Prevention 31 Spinout is excessive wheel spinning that produces damaging heat High heat breaks down lube film allowing
7. Cap Flange half Ring Side pinion Side bearing cup gear Side gear thrust washer pinion Flange half Flange V Z Flange half Wheel diff bearing Half diff case spider adjuster Bearing Side Gear Cone 18 f OO 99 04 Sh _ ZN mm e mua carrier ca cap bolt amp d P ep e o o D 9 lt e CD ps cD Plain half Plain half gear diff case bearing cup side Gear Plain half Plain half thrust washer bearing cone bearing adjuster Pinion Inner pinion Inner pinion Pinion Outer pinion Helical Pinion pilot bearing bearing cone bearing cup cage bearing cup gear roll pin Pinion Pinion Pinion Outer pinion Pinion bearing spacer cage shim bearing cone nut Glossary and Nomenclature Output Shaft Output bearing Outer Inner yoke snap ring bearing cone bearing cup Output Output Outer Inner Output shaft nut seal bearing cup bearing cone shaft Output su Inter axle Helical side gear gear differential side gear Helical bearing cup put Input shaft Helical pushings Side gear de gear ring side gear thrust cone washer 06 Do a 6 0 Lockout Input Input shaft Power divider sliding clutch shaft oil retainer COVer Input shaft px 5 6 Shift fork CU spring NS am NG Shift fork Input Input Input Input cage shim cage seal nut Input shaft Input cage In
8. Prevention Section e Maintenance Rebuilding and Adjustment see Failure Prevention Section 22 Ring Gear and Pinion Lubrication Failures Ring Gear Incorrect Lube Drive Pinion Incorrect Lube Teeth at top land Teeth at top lands worn to a point worn round Drive Pinion Low Lube Scoring Crows foot 97 ER P ET Ver Te JA Fe Ray gt Ne x LAN ANA NASAN KAMA Pear 1 i NG N r NG NG b Ip A General Description Incorrect lube wrong viscosity or wrong lube type Will reduce the life of bearings gears bushings and Usual Causes and thrust washers Containment Lube Water foreign material and normal wear or break in material can cause etching scoring or pitting to the contact surfaces Foreign material in the lube is abrasive Low or no lube Will create friction which causes overheating break down of the protective film and finally parts seizure of the surfaces of mating parts Failure Prevention Maintenance Rebuilding and Adjustment see Failure Prevention Section 23 Wheel Differential Shock Impact Failure Wheel Differential Catastrophic Failure Wheel Diff Spider Shock Load Side Gear Catastrophic Shock Side Pinion Shock Loaded O Granular fracture surface General Description Shock damage occurs from overstressing the
9. areas of bushing material bunched up or missing or gouges in bushing material Usual Gauses e Improper kingpin installation e Improper tools used to size bushings if using reamable bushings e Use recommended reaming tools See Spicer Service Manual AXSM 0038 if using reamable bushings Failure Prevention e Follow assembly procedures found in the Spicer Service Manual AXSM 0038 46 Steer Axle Bushing and Kingpin Wear Contamination Bushing Clogged with Contamination Kingpin Grooving from Contamination oo Grooving Bushing Lack of Grease Kingpin Lack of Grease Rust No Grease Lec Scoring Rust General Description Rust grooving and scoring to the bushing area of the kingpin bushings excessively worn and contamination built up in bushing Usual Causes e Lack of grease greasing intervals too infrequent e Contamination damage greasing not long enough to flush contaminants from kingpin joint e Excessive knuckle vertical play e Wrong grease type Failure Prevention e Grease intervals must be adjusted to match the environment of the vehicle The more contamination the more you need to grease e Greasing should continue until clean grease is seen coming from between the joints e Knuckle vertical play should not exceed 040 e Use 2 lithium grease only 47 Steer Axle Bushing Worn in One Area Only No Wear on Kingpin No Grooves Tie Rod End Water C
10. cross section area in a fatigue failure Flaking See Surface Fatigue Progression Fretting An action that results in surface damage especially in a corrosive environment where there is a relative motion be tween solid surfaces in contact under pressure Frosting See Surface Fatigue Progression Galling The transfer of material between two moving compo nents at extremely high temperatures Grooving Chips of metal particle contaminates become wedged in the softer cage material and cut grooves in the roll ers resulting in the grooving of the cup and cone races Head Assembly The entire drive unit consisting of the D Head and the R Head The axle housing and wheel equipment are not included in the head assembly I A D Inter axle differential Lubrication Break Down When a lubricant is thermally stressed the viscosity is lowered and the lube can no longer maintain a barrier between metal parts Oil Contamination Pollution of lubricating oil by a foreign substance Overloading A load or torque that is greater than the design load or torque specification of a particular component a Shock Load Instantaneous overload A very rapidly applied force that causes immediate component damage b Sustained Overload consistent application of force that is greater than the part can withstand Pitting See Surface Fatigue Progression Plastic Deformation Plastic Flow Deformation that re mains per
11. plug would be an obvious cause for concern e for cracks in the carrier housing harder to see but sometimes visible e Does the general mechanical condition of the vehicle indicate proper maintenance or are there signs of neglect e Are the tires in good condition and do the sizes match e f equipped with a torque limiting device is it working properly During the preliminary investigation write down anything out of the ordinary for later reference Items that appear insignificant now may take on more importance when the subassemblies are torn down Prepare the Parts for Inspection After the preliminary investigation locate the failure and prepare the part for examination In carrier failure analysis it may be nec essary to disassemble the unit e When disassembling subassemblies and parts do not clean the parts immediately since cleaning may destroy some of the evidence e When tearing down the rear axle do it in the recommended manner Minimize any further damage to the unit e Ask more questions when examining the interior of the carrier Does the lubricant meet the manufacturer specifications regarding quality quantity and viscosity As soon as you have located the failed part take time to analyze the data Find the Cause of the Failure Here begins the real challenge to determine the exact cause of the failure Keep in mind that there is no benefit to replacing a failed part without determining the cause of the f
12. the failure s X DI Correct the cause of the problem Document the Problem Here are some guidelines for starting to learn about a failure including questions to ask e Talk to the operator of the truck e Look at the service records e Find out when the truck was last serviced e In what type of service is the truck being used e Ask Has this particular failure occurred before e How was the truck working prior to the failure You need to be a good listener Sometimes insignificant or unrelated symptoms can point to the cause of the failure e Ask Was the vehicle operating at normal temperatures e Ask Were the gauges showing normal ranges of operation e Ask Was there any unusual noise or vibration After listening review the previous repair and maintenance records If there is more than one driver talkto all of them and compare their observations for consistency with the service and maintenance records Verify the chassis Vehicle Identification Number VIN number from the vehicle identification plate as well as the mileage and hours on the vehicle Failure Analysis Make a Preliminary Investigation These steps consist of external inspections and observations that will be valuable when combined with the results of the parts examination e for leaks cracks or other damage that can point to the cause of the failure e note of obvious leaks around plugs and seals A missing fill or drain
13. For technical reference this section describes and illustrates the way power flows through an axle under different gearing and differential configurations Single Speed Power Flow and Torque Distribution Inter axle Differential is Operating Torque power flow from the vehicle driveline is transmitted to the input shaft and the inter axle differential spider At this point the differential distributes torque equally to both axles For the forward axle torque is transmitted from the helical side gear to the pinion helical gear drive pinion ring gear wheel dif ferential and axle shafts For the rear axle torque is transmitted from the output shaft side gear through the output shaft to the inter axle driveline to the drive pinion ring gear wheel differential and axle shafts Torque Distribution Lockout Disengaged Drive is from differential through helical gears to Inputtorque forward axle gearing 3 In high range the Inter axle es drive is through the differential pinion and ring gear only both axles Drive is from differential through output shaft to rear axle gearing Torque is transmitted to both axles through inter axle differential action Lockout Disengaged Torque Distribution Lockout Engaged Drive is from input shaft through helical gears to forward axle gearing ep CD
14. High Mileage Contamination Scratching Contamination Bruising Denting UJ cD D lt General Description Uneven wear pattern low mileage Uneven wear pattern typical of low mileage and light to moder ate loads It is caused by the bearing preload during assembly and will gradually become more even as mileage increases If not otherwise damaged parts showing this wear pattern may be reused Even wear pattern high mileage Even wear pattern with light pitting typical of advanced mileage with normal loads Pitting is caused by contaminates in the lube eContamination wear Scratching and bruising occur when hard metal particles pass through the lube system This damage is an early sign of bearing failure Possible causes include poor lube maintenance and or overloading the axles Failure Prevention e Maintenance Rebuilding and Adjustment see Failure Prevention Section 34 Bearings Pitting and Spalling Damage Bearing Cup Pitting Initial pitting Bearing Cup Spalling Bearing Cup Water Contamination 35 g Water Contamination ias sddil General Description Usual Causes Failure Prevention Bearings This failure may start as bruising or denting then progress to frosting pitting and finally spalling As the failure progresses the material flakes away e Hard metal particles in the lubricant Consistent overloading in the lubricant e Correc
15. ailure For example after examining a failed part and finding that the failure is caused by a lack of lubrication you must determine if there was an external leak Obviously if there is an external leak just replacing the failed gear is not going to correct the situation Another important consideration is to determine the specific type of failure which can be a valuable indicator for the cause of fail ure The following pages show different types of failures and possible causes Use this as a guide in determining types of failures and in correcting problems Correct the Cause of the Problem Once the cause of the problem has been determined refer to the appropriate Service Manual to perform the repairs Ring Gear and Pinion Shock Impact Failure Ring Gear Catastrophic Failure Ring Gear Coast Side Shock Failure Granular fracture surface Drive Pinion Torsional Shock Failure uoiuid pue 1299 General Description Shockdamage occurs from overstressing the gear teeth or shaft beyond the strength of the material The failure could be immediate from a sudden shock or progressive cracking of the teeth or shaft surface following the initial shock Usual Causes e Rough trailer hook up e Spinning wheels grabbing on firm road surface Misuse of the inter axle differential lockouts e Trying to free up frozen brakes Failure Prevention Vehicle Operation and Drive practices see Failure Prevention Section
16. cially effective in minimizing the possibility of spinout 2 Speed Dual Range Gearing See Spicer Driver Instruction AXDR 0134 opicer drive axles are equipped with 2 speed gearing to provide maximum operating efficiencies in two extreme situations e Off highway fully loaded e On highway fully loaded The low range provides deep reduction and maximum torque when off highway or on steep grades The high range provides a faster ratio for cruising and fuel economy Premature failures of shifting parts drive axles and other drive train components can be prevented by proper driving per manual instructions and training There are two important rules to follow e not abuse axle shifting parts Follow the instructions for shifting the axle e Do not abuse the drive train components Use low range when torque requirements are high such as on rough roads on steep grades and under other adverse conditions Drive Axle Wheel Differential Lock See Spicer Drive Instruction AXDR 0130 The drive axle wheel differential lock is an air actuated clutch which positively locks the differential gearing in the rear axle When this clutch is engaged power flows to the tires without any differential action giving each wheel all the torque the road conditions will permit cab mounted valve moves the wheel differential lock in or out of engagement This motion also trips an electrical switch that activates a light in the cab or sounds an audible dev
17. ck Failure Teeth failed 90 ue from each other dem Le D AY jim z N MATANG TE VN v 1 T ng x J a j a 7 EJ Teeth faile at root gt E gt Input Shaft Torsional Shock Failure Output Shaft Torsional Shock Failure General Description Shock damage occurs from overstressing the gear teeth or shaft beyond the strength of the material The failure can be immediate as from a sudden shock or progressive as cracking of the teeth or shaft surface following the initial shock Usual Causes e Rough trailer hook up e Rough trailer hook up e Spinning wheels grabbing on firm road surface Misuse of the inter axle differential lockouts e Side stepping the clutch Failure Prevention e Vehicle Operation and Drive Practices see Failure Prevention Section 27 Power Divider Fatigue Failures Input Shaft Torsional Fatigue Failure at Splines Input Shaft Fatigue Failure Ade otar shaped wv s pattern Output Shaft Torsional Fatigue Failure at Splines IAD Spider Fatigue Failure o 4 4 0 e CD CD Te oun Ng Aro X LT T Star shaped pattern General Description Progressive destruction of a shaft or gear teeth high load causes the initial crack The crack progresses to the center of the core Repeated overloads finally cause the shaft to fail
18. damaging metal to metal contact Long term spinout could produce complete axle break down e Single rear axle Main differential spinout occurs when one wheel remains stationary while the other wheel is spinning e Tandem axles Spinout occurs in the inter axle differential when either one wheel or one axle spins while its mate remains stationary Drive Practices and Vehicle Operation see Failure Prevention Section Power Divider Output Side Gear Bearing Low Lube Input Shaft Bearing Low Lube Helical Side Gear Bushing Lubricant Contamination Helical Si n CD O ET CD 32 Power Divider Input Shaft Stub End Water Contamination Output Side Gear Water Contamination Usual Gauses Incorrect lube wrong viscosity or wrong lube type Will reduce the life of bearings gears bush ings and thrust washers e Containment Lube Water foreign matierla and normal wear or break in material can cause etching scoring or pitting to the contact surfaces Foreign material in the lube is abrasive Low or no lube Will create friction which causes overheating break down of the protective film and finally parts seizure of the surfaces of mating parts Failure Prevention e Maintenance Rebuilding and Adjustment see Failure Prevention section 33 Bearings Normal and Contamination Wear Normal Uneven Wear Pattern Low Mileage Normal Even Wear Pattern
19. ed or defective parts is extremely important in achieving good life from an axle overhaul Cleaning and close inspection of parts is vital To achieve maximum value from a rebuild replace lower cost items such as thrust washers seals and bushings as well as worn and damaged major parts Follow instructions for correctly adjusting bearing preloads shaft endplay and gear and pinion tooth contact patterns All these procedures will help extend the life of your rebuilt axle Refer to Spicer Axle Service and Maintenance Literature for detailed information Glossary and Nomenclature Glossary Abrasion The process of rubbing grinding or wearing away of material from a surface by friction Backface Runout The total amount of movement in the back face surface of the ring gear during one revolution Backlash The total amount of movement between two mating gears Beach Marks Contour lines on a somewhat smooth failed surface that indicate fatigue Beach marks occur as a part suc cessfully resists for a time the advance of a fatigue crack Bending Fatigue Characterized by beach marks on the frac tured area The phenomenon leading to fracture under repeat ed or fluctuating stresses having a maximum value less than the tensile strength of the material Fatigue fractures are pro gressive beginning as minute cracks that grow under the ac tion of the fluctuating stress Fatigue results from load and time Brinelling Fa
20. ession There are four stages of fatigue for the surface of a metal part under operating stress e Frosting Superficial material displacement on gear teeth that present a non destructive burnished ap pearance Pitting This surface fatigue condition occurs when the endurance limits of the material are exceeded e initial This is the mildest stage of pitting It consists of definite pits from a pin hole size to 030 in diame ter Initial pitting continues until the tooth is able to carry the load without further distress e Moderate In this stage the pits are approximately double in size of the initial pitting The gear teeth have not been weakened and there is no danger of break age e Destructive At this stage the pits are considerably larger and deeper than those with moderate pitting Gears found in this stage should be replaced e Flaking An advanced type of pitting resulting from contact fatigue Material falls away from the surface in the form of shallow flakes or scale like particles e Spalling Deterioration of a highly stressed surface by surface fatigue producing irregularly shaped sharp edged deep cavities Spalling is a severe form of flaking Torsion A twisting action resulting in shear stresses and strains o D o o lt co lt o o Glossary and Nomenclature Stress Overview Most failures involve some form of mechanical s
21. gear teeth or spider beyond the strength of the material The failure can be immediate as from a sudden shock or progressive as cracking of the teeth or shaft surface following the initial shock Usual Causes e Rough trailer hook up e Spinning wheels grabbing on firm road surface e Misuse of the inter axle differential lockouts Failure Prevention e Vehicle Operation and Drive Practices see Failure Prevention Section 24 Wheel Differential Spinout Over Heat Failures Side Pinion Thrust Washers Scoring Side Pinion Galling Cracks Grooving General Description Spinout is excessive wheel spinning that produces damaging heat High heat breaks down lube film allowing damaging metal to metal contact Long term spinout could produce complete axle break down Usual Causes Main differential spinout occurs when one wheel remains stationary while the other wheel is spinning Failure Prevention e Drive Practices see Failure Prevention Section 25 Power Divider Shock Impact Failure IAD Spider Shock Failure Spider Smooth Even Surface Shock Failure Granular fracture Side Pinion Gear Shock Failure O e cD cD Granular fracture Surface S v Da pr me E 3 w n k i Mig v y A e x ie ME S 9 Eu nd Output Side Gear Shock 26 Power Divider Helical Side Gear Shock Failure Output Side Gear Sho
22. gue Hulsnoy General Description Spindle Damage Worn and scored bearing mounting surfaces seized bearings or loose adjust ments result from a lube deficiency e Fatigue Crack Cracking starts at the bracket weld and extends along the lines The failure is generally caused by induced repetitive loads at the bracket mounting surface during operation The basic cause of these cracks could be misapplication material or weld problems Another indicator of a cracked condition could be a wet spot caused by lube leakage When this condition does exist replace the hous ing Usual Causes e Contamination e Lack of Lube e Load misapplication e Weld Problems Failure Prevention e Maintenance Rebuilding and Adjustment see Failure Prevention Section 44 Drive Axle Housing Loose or Over Torqued Hardware Loose Clamping Hardware Over torqued Clamping Hardware General Description Sufficient clamp load at the spring pad area is important to keep the joint tight Loose clamping or over torqued clamping hardware resulting in cracks in the drive axle housing Usual Causes e Non OEM specified clamping hardware e Failure to follow OEM torque specifications Failure Prevention Maintenance Rebuilding and Adjustment see Failure Prevention Section 45 Steer Axle Bushing Damage Installation Improper Kingpin Installation Improper Reaming 2 CD I 1 General Description Damaged bushing material
23. he power in the form of torque The transmission multiplies this torque and delivers it to the drive axle which multiplies torque a second time The drive axle gearing and its related components must be designed to transmit this torque to the driving wheels so they will move the combined weight of the vehicle and load over expected road conditions Torque requirements vary with different grades and road conditions Off highway vehicles such as construction trucks must op erate on rough or soft surface roads and steep grades This requires greater torque for efficient operation Vehicles with equivalent load ratings and operating at constant speeds on highways require less torque Vehicle Load Ratings There are two different vehicle load ratings e Trucks are rated by Gross Vehicle Weight GVW which is the truck weight plus the weight of its load e Tractor trailer rigs are rated by Gross Combination Weight GCW which is the weight of the tractor trailer and payload These ratings as they relate to engine power and the torque required to move the weight determine the required axle gearing strength Vehicle Operation A vehicle is designed to do a certain job under certain conditions More severe use of the vehicle such as overloading or operating under adverse road conditions not considered when spec ing the axle is termed misuse or incorrect operation Under severe mis use the axle could fail immediately With lesser misuse the axle pa
24. he seal must be as clean as possible and void of foreign contaminants Note Reference Seal Maintenance Guide TCSM 0912 39 Axle Shafts Axle Shaft Twisted Splines Torsional Shock Torsional Shock Failure Close up Rough surface failed at a 45 angle 23 2 3227 ES Spline Wear 40 Axle Shafts General Description Usual Causes Failure Prevention 41 Shock damage occurs from overstressing the shaft beyond the strength of the material The failure can be immediate as from a sudden shock or progressive as cracking of the shaft surface following the initial shock e Rough trailer hook up e Spinning wheels grabbing on firm road surface Misuse of the inter axle differential lockouts e Vehicle Operation see Failure Prevention Section Two Speed Planetary Pitting and Spalling Failures Sliding Clutch Pitting Planetary Gear Spalling Pitting Granular fracture surface e CD O CD pasara e lt Pitting and spalling Progressive destruction of gear teeth An overload puts pressure between the meshed surfaces Repeated overloads result in teeth failure General Description Shock Damage from overstressing the gear teeth or shaft beyond the strength of the material The fail ure can be immediate as from a sudden shock or progressive as cracking of the teeth or shaft surface following the initial shock Pitting and Spalling
25. ice to indicate that the wheel differential lock is engaged When the clutch is disengaged the differential operates normally dividing torque equally between the tires and compensating nor mally for cornering or tire size variations Failure Prevention Maintenance Rebuilding and Adjustment Proper maintenance is essential to achieve the maximum life designed and built into a drive axle Perhaps the most important element of maintenance is proper lubrication Incorrect or lack of lubrication is extremely detrimental to the life of drive axle parts Lubricant is the life blood of the axle gears and bushings It prevents metal to metal contact and keeps the parts clean and running cool To get all the benefits of lubrication you must e Use the proper lube e Maintain the proper lube level e Change lube at specified intervals e Periodically clean magnetic plugs e Clean the magnetic drain plug to remove metallic dust or fine particles e Keep filters and strainers clean and filled after an initial break in of 5 000 miles When filled with a Spicer approved synthetic lubricant at the factory the 5 000 mile drain is not required To assure correct lubrication and long life for your Spicer drive axle follow instructions in the Spicer Service Manuals For additional lubrication information see TCMT 0021 mu zo CD D CD CD Rebuilding and Adjusting Proper reassembles and replacement of all damag
26. ill be a recurring failure If a carrier housing is opened revealing a ring gear with a broken tooth it is not enough to settle on the broken tooth as the cause of the carrier failure Other parts of the carrier must be examined For a thorough understanding of the failure and possible insight into related problems the technician needs to observe the overall condition of the vehicle No one benefits when a failed component goes on the junk pile with the cause unknown Nothing is more disturbing to a customer than a repeat failure Systematically analyzing a failure to prevent a repeat occurrence assures quality service by avoiding unnec essary downtime and further expense to the customer The true cause of a failure can be better determined by knowing what to look for determining how a piece of the equipment was running and learning about previous problems In some cases the part itself is at fault In the case of a rebuilt rear axle mis matched gears may have been installed The more successful shops prevent repeat equipment failures by developing good failure analysis practices Knowing how to di agnose the cause of a premature failure is one of the prerequisites of a good heavy equipment technician The following five steps are an effective approach to good failure diagnostics RL o 2I o o 1 Document the problem Make a preliminary investigation Prepare the parts for inspection Find the cause of
27. lse Depressions produced when bearings are subjected to vibration or low radial angle oscillation or to both while not rotating The bearing surfaces are either pol ished or show a characteristic red brown stain Brinelling True Indentation produced by plastic flow when rolling elements are forced against the bearing raceway surfac es by stationary overload or especially by impact during mounting Original surface features such as machine marks are usually visible at the bottom of the indentations Burnishing In sliding contacts the oxidation of a surface due to local heating in an oxidizing atmosphere Bruising A type of damage caused by foreign material or hard particles passing though the rollers and the races Damage ap pears as small indication and or denting Burning Permanent damage to metal or alloy by overheating Carrier The primary casting that supports and houses the rest of the components of the head assembly Coking A lubricant that has been overheated for an extended length of time may cause the carbon in the lube to separate and collect on internal components The build up will have the ap pearance of black paint Fatigue Strength The maximum stress that can be sustained for a specified number of cycles without failure Final Fast Fracture Zone The part of a breakthrough cross section that has a rough crystalline appearance It could be the entire area in a shock failure or a small part of a
28. manent after removal of the load which caused it An example of plastic deformation is metal flow on the surface ex tending over the tips of gear teeth This condition can quickly become destructive pitting Glossary and Nomenclature Radial Runout Refers to the total amount of movement of the outside diameter of the ring gear during one revolution Rear Axle The drive axle located in front of the rear rear drive axle This axle will have a power divider unit and is described as D Head in Spicer Literature Rear Rear Axle The drive axle located the furthest to the rear of a tandem set of axles This axle is described as the R Head in Spicer Literature Scoring Damage caused by embedded particles of metal ocoring may show up as either deep wide grooving or narrow shallow grooves Scuffing Adhesive wear from progressive removal of material from a rubbing surface caused by a localized welding and tear ing Shock Load A rapidly applied load or force that is severe enough to exceed the strength of the component and cause it to crack or fail instantly Sustained Overload A consistent application of force that is greater than the part can withstand Spalling See Surface Fatigue Progression Stress Force per unit of area often defined as force acting through an area within a plane Stress Risers Changes in contour or discontinuities in struc ture that cause local increases in stress Surface Fatigue Progr
29. ontamination Thread Loose Clamp Assembly _ FALL HE h uw KING DEN l 1 tee 047 Ud d en ate CRT NE L m ngaa tan TOUS PET o4 pM rio 25 Pagi ir Ir ar 3 ve He i General Description Normal wear to a bushing will show an even wear pattern at one location only It will be on the outboard side of the top bushing on the inboard side of the bottom bushing This wear is indicated by an endplay reading of more than 015 Usual Causes e High mileage e Small amounts of contamination e High loads over long periods of time 48 CD CD gt AN CD For spec ing or service assistance call 1 877 777 5360 or visit our website at www dana com Dana Commercial Vehicle Products Group 3939 Technology Dri Hn DANA SP CER x Drivetrain Products www dana com All applications must be approved by the Application Engineering Department Specifications and or design are subject to change without notice or obligation Printed in USA AXSM 0020 06 09
30. opicer Drive Axles Sana SPICER Drivetrain Products Service Manual Failure Analysis AXSM0020 June 2009 Table of Contents Introduction Failure Prevention Correct Specificato NS re e tees Glossary and Nomenclature IOS SAI Stress Overview a Gearing and Torque Distribution Power F OW ies cate orbe oe dU EDU PEE EN Failure Analysis How to Diagnose a Ring Gear and Pinion ohock Impact Fatigue Pitting and Spalling Failures Lubrication Failures a Wheel Differential Shock Impact Failures Spinout Over Heat Failures Power Divider Shock Impact FAUNE uu u ner AN Fatigue Failures AA Pitting and Spalling Failures Spinout Failures e teen EUDTICATIONEANURES ny u eee faa te Bearings Normal and Contamination Wear Pitting and Spalling Damage Seals and Yokes Yoke Wear and Seal Lip Wear Installation Problems Axle Shaft Shock and Fatigue Failure_
31. put bearing v ring yoke Glossary and Nomenclature Rear Drive Axle Nomenclature Flange half carrier cap Flange half bearing cup 3 a half bearing AC adjuster f di Carrier cap bolt Flange half bearing p cone N Side pinion gt Plain half 057 carrier Side gear Side thrust washer gear N N NO Wheel diff Spider Side gear Side pinion Flange half diff case _ Plain half inner cup Plain half bearing adjuster N thrust thrust washer Washer Plain half Plain half diff case inner cone Thrust bolt jam nut Thrust Pinion Binion hi N im cage Outer T Outer pinion bearing cone A bearing cup o 2 Pinion seal yoke Pinion Oer 2 nut ous AS R head carrier nu 1 Or rear carrier 7 3 Pinion Inner pinion bearing cone Pinion bearing Inner pinion Spacer bearing ep e o o D lt 9 lt e CD ps CD Glossary and Nomenclature Parts Identification CUST PART NO OEM Part Number SERIAL NO Assembly Number RATIO Axle Ratio SPEC Dana s Build Sheet Bill of Material MODEL Axle Model Part NO Carrier Assembly Part Number Tag Locations CUST PART NO SPICER SPEC SERIAL NO 214936 658231907 MODEL PART NO RATIO DS404 00390 MADE IN Gearing and Torque Distribution Power Flow
32. rength to work under the planned vehicle operational environment as well as the vehicle load rating Operating a vehicle outside of the specification i e overloading and or operating under more demanding conditions may in crease torque requirements and could cause premature damage or failure of axle components The drive axle must be designed with strength capable of withstanding the punishment of a loaded truck in operation All compo nents gears shafts bearings and housing must meet three essential requirements e To carry the load In most instances the drive axle supports the major portion of the truck and its payload e To withstand the stress of torque developed by the engine and multiplied by the drive train e withstand the stress of impact and shock forces created by road conditions and vehicle operation The capability of a drive axle to carry its share of the vehicle load is expressed as axle rated capacity Gross Axle Weight Rating GAWK To prevent axle overloading the axle rating must be compatible with the weight specification of the vehicle load and expected operating conditions Overloading will cause damage to the axle assembly parts See Spicer Drive Axle Application Guidelines AXAG 0200 Torque is Important The primary function of a drive axle is to provide gear reduction which multiplies torque and transmits it to the driving wheels In a truck power train the engine develops horsepower and delivers t
33. ring in the drive axle A well informed driver with proper training will eliminate many drive axle failures Failure Preventing Equipment opicer tandem axles incorporate design features that can help prevent axle failures Four important equipment features are e nter axle Differential Lockout e Controlled Traction Differential e 2 Speed Dual Range Gearing e Drive Axle Wheel Differential Lock The driver must know the purpose as well as the proper use of these important design features Inter axle Differential Lockout See Spicer Driver Instruction AXDR 0126 The inter axle differential lockout increases traction effort under adverse road conditions When engaged the lockout provides positive drive to both axles When the drive wheels of one axle are subjected to a condition of wheel spinning the drive will continue to the other axle to the wheels with traction and move the truck Proper use of this lockout feature is important not engage lockout while wheels are spinning e not engage lockout when driving conditions are good Improper use of the lockout could result in unnecessary axle parts failure Failure Prevention Controlled Traction Differential controlled traction differential is a biasing unit designed into the axle wheel differential It provides the truck with effective trac tion control under adverse driving conditions especially off the highway A controlled traction differential is espe
34. rts could progressively fail over a period of time When unusual operating conditions are anticipated get professional help in spec ing a drive axle Failure Prevention Driving Practices Driving practices have a large influence on the service life of a truck axle Good driving practices can eliminate shock and prevent undue strain not just on the axle but on the entire truck There are two driver practices that are detrimental to axle parts life e Subjecting the vehicle to undue rough handling e Driving under road conditions not specified Either of these practices could cause premature axle failure Even conscientious drivers may encounter an unusual adverse situation of an exceptionally rough road The driver should be trained to regulate speed and brake application according to road conditions Training is Essential Driving a truck is an important job that can be performed more effectively with thorough training The driver needs to know all the specifics about the hauling job such as payload characteristics anticipated road conditions and roads to be avoided The driver must also be well informed about the equipment For example the driver should know answers to such questions as e What was the truck designed for TI 9 CD D CD CD e e Why does the truck have a differential lockout e What is the function of a controlled traction differential e What are the benefits of 2 speed gea
35. section illustrates the primary forms of mechanical stress and also provides gearing and gear tooth nomenclature e Gearing and Torque Distribution Reviews the principles of power flow through drive axles in various gear ranges and equipment configurations This section also illustrates different forms of spin out a major operating cause of axle failure e Failure Analysis Explains how to diagnose the cause of a component failure The main feature of this section is a pho tographic review of actual failed parts matched with a description of the failure the probable cause and methods of pre vention At Dana we are interested in knowing your reaction to this guide and we welcome comments and contributions to future reference materials Contact your Dana representative or contact us directly at www dana com rmja o o 5 Failure Prevention Correct Specifications This section considers three general areas of truck procurement operation and maintenance that will help prevent axle failure e Correct Specifications matching the axle to the load and expected road conditions e Drive Practices training combined with proper use of installed equipment e Maintenance Rebuilding and Adjustment with special emphasis on lubrication Correctly spec ing a drive axle for the vehicle and for the job to be done is an essential factor in preventing axle failures It is ex tremely important to spec an axle of sufficient st
36. t Specifications see Failure Prevention Section e Vehicle Load Ratings see Failure Prevention Section e Maintenance Rebuilding and Adjustment see Failure Prevention Section 36 o e CD CD seals and Yokes Yoke Wear and Seal Lip Wear Yoke to Seal Interface Normal Wear Yoke to Seal Interface Extreme Wear Seal Lip Normal Wear Narrow wear band width Wide wear band width General Description e Normal Wear Flattened Edge Notice the flattened edge of the seal lip indicating incorrect positioning and Unusual Causes Failure Prevention 3 of seal lip against the yoke Incorrect placement of seal lip will result in lube leakage from the seal or as shown above permit dust or dirt to contaminate the lube itself In order to retain lube and exclude dust and dirt from the system the seal must be clean void of defects and properly installed e Extreme Wear Gap on Seal Lip Contact area on seal lip is too wide over 1 32 This indicates ex cessive wear or loss of material consistency The seal must be replaced e Scoring If the yoke displays a rough or scored condition replace the seal and or yoke e Maintenance Rebuilding and Adjustment see Failure Prevention Section seals and Yokes Installation Problems Bent Outer Shell Do Not Reuse Dirt Between Seal and Bearing Cage Bent shell Damaged Seal Lip Contamination Contamination 38 c
37. tress Even when the initial or basic cause of the failure results from a problem such as excessive heat or improper lubrication the part becomes weakened and more subject to stress failure This page illustrates four basic forms of mechanical stress torsion tensile shear and compression In the Failure Analysis sec tion parts photographs show the resulting failures and the patterns characteristic of the different stresses Torsion Stress Tensile Stress Shear Stress Compression Stress Glossary and Nomenclature Gear Tooth Nomenclature Tooth Identification Drive side of Pinion Top land ep e e D lt co 2 lt CD e o m m Root E nr Heel Coast side flank Drive side of ring gear Heel Top land Glossary and Nomenclature Primary Gearing Nomenclature Ring and Pinion Identification To aid in identifying gear sets both parts are stamped with information such as number of pinion and ring gear teeth individual part numbers and match set numbers Reminder The ring and pinion are a matched set and must be replaced together Match set Part number Manufacturing number numbers 1 29723 37 T PETS OI Number of pinion teeth Date code gear teeth G os Pa Manufacturing W4 numbers Part number 2 12 Match set number Date code Glossary and Nomenclature Front Drive Axle Nomenclature Flange half Carrier
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