驱动桥5000字外文翻译文献

As the bearing cage rotates, read the value

7. indicated on the scale.

Preload normally is specified as torque re-8. quired to rotate the pinion bearing cage, so take a reading only when the cage is rotating. Starting torque will give a false reading.

To calculate the preload torque, measure the 9. diameter of the bearing cage where the cord was wound. Divide this dimension in half to get the radius.

10. U se the following procedure to calculate the

bearing preload torque:Standard.

Pull (lb) 3 radius (inches) 5 preload (lb-in.)or

Preload (lb-in.) 3 0.113 (a conversion constant) 5 preload (N .m)

Install the yoke, flat washer, and nut. Tighten 6. the nut snugly. Tap the end of the input shaft lightly to seat the bearings.

Measure the input shaft endplay again with 7. the dial indicator. If endplay is still incorrect, repeat steps 3 through 7.

With the endplay correct, seal the shim pack 8. to prevent lube leakage. Then torque the i nput shaft nut and cover capscrews to the correct value.

24.5 A XLE ADJUSTMENTS

AND CHECKS

This section introduces the differential carrier adjust-ments, checks, and tests that the truck technician must be capable of performing; some have been

r eferred to previously in the text. For the most part, the procedures described here are general in nature. The truck technician should refer to OEM service

l iterature for specific procedures.PINION BEARING PRELOAD

Most differential carriers are provided with a press-fit outer bearing on the drive pinion gear. Some older rear drive axles use an outer bearing, which slips over the drive pinion. The procedures for adjusting both types follow.

Press-Fit Method Adjustment

To adjust the pinion bearing preload using the press-fit method, use the following procedure:

Assemble the pinion bearing cage, bearings, 1. spacer, and spacer washer (without drive pin-ion or oil seal). Center the bearing spacer and spacer washer between the two bearing cones (Figure 24–49).

When a new gear set or pinion bearings are 2. used, select a nominal size spacer based on OEM specifications. If original parts are used, use a spacer removed during disassembly of the drive.

Place the drive pinion and cage assembly in a 3. press, with the gear teeth toward the bottom.Apply and hold the press load to the pinion 4. bearing. As pressure is applied, rotate the bearing cage several times so that the bear-ings make normal contact.

While pressure is held against the assembly, wind 5. a cord around the bearing cage several times.Attach a spring scale to the end of the cord 6. (Figure 24–50). Pull the cord with the scale on

a horizontal line.

FIGURE 24–49 Assembly of the pinion bearing cage.

(Courtesy of Dana Corporation)

FIGURE 24–50 Cage in press to check bearing

p reload.

Sleeve must apply

must be against the outer bearing. If the fit between the yoke or flange splines and drive pinion splines is tight, use a press to install the yoke or flange (Figure 24–51).

Temporarily install the drive pinion and cage 4. assembly in the carrier (Figure 24–52). Do not install shims under the bearing cage.

Install the bearing cage to the carrier cap-5. screws. Washers are not required at this time. Hand-tighten the capscrews.

Fasten a yoke or flange bar to the yoke or 6. flange (Figure 24–53). The bar will hold the drive pinion in position when the nut is

t ightened.Metric.

Pull (kg) 3 radius (cm) 5 preload (kg-cm) or

Preload (kg-cm) 3 0.098 (a conversion constant) 5 preload (N .m)

Examples. We can convert the foregoing equa-tions into examples by applying some data to them:

Standard

7.5 lb 3 3.31 in. 5 24.8 lb-in. (preload) or

24.8 lb-in. 3 0.113 5 2.8 N .m (preload)

Metric

3.4 kg 3 8.4 cm 5 28.6 kg-cm (preload) or

28.6 kg-cm 3 0.098 5 2.8 N .m (preload)

11. I f necessary, adjust the pinion bearing preload

by changing the pinion bearing spacer. A thicker spacer will decrease preload, whereas a thinner spacer will increase the preload.

12. O nce the correct bearing preload has been

established, note the spacer size used. Select a spacer 0.001 inch (0.025 mm) larger for use in the final pinion bearing cage assembly pro-cedures. The larger spacer compensates for slight expansion of the bearing, which occurs when pressed on the pinion shank. The trial spacer pack should result in correct pinion bearing preload in three times out of four cases.

Y oke Method of Adjustment

To adjust the pinion bearing preload using the yoke or flange method, proceed as follows:

Assemble the complete pinion bearing cage 1. as recommended in the press-fit method.A forward axle pinion is equipped with a heli-2. cal gear. For easier disassembly during bear-ing adjustment procedures, use a dummy yoke (if available) in place of the helical gear.Install the input yoke or flange, nut, and 3.

washer on the drive pinion. The yoke or flange

FIGURE 24–51 Using a press to install the yoke or

flange to the drive pinion. (Courtesy of Arvin Meritor)

FIGURE 24–52 Install the pinion and cage assembly in the carrier housing. (Courtesy of Arvin Meritor)

i

ndicated on the torque wrench (see Figure 24–55). Typical value is 50 lb-ft. (68 N .m)

m aximum applied to one side gear.If the torque value exceeds the specification, 5. disassemble the differential gears from the case halves.

Check the case halves, spider, gears, and 6. thrust washers for the problem that caused the torque value to exceed specifications. Re-pair or replace defective parts as required. Remove any foreign debris.

Check/Adjust Pinion Cage Shim Pack

This procedure is used to check and adjust the thick-ness of the shim pack used in the pinion bearing cage. Use this procedure if a new drive pinion and crown

Tighten the nut on the drive pinion to specifi-7. cation, typically 400 to 700 lb-ft. (542 to 950 N .m).

Remove the yoke or flange bar.

8. Attach a torque wrench to the drive pinion 9. nut. Rotate the drive pinion and read the value indicated on the torque wrench. Preload is correct when the torque required to rotate the pinion bearing cage is from 15 to 35 lb-in. (1.7 to 4.0 N .m).

To adjust the pinion bearing preload, disas-10. semble the pinion bearing cage and change the pinion bearing spacer size. A thicker spacer will decrease preload, whereas a thin-ner spacer will increase preload.

Differential Rolling Resistance

A check to measure and establish differential rolling resistance follows. To perform this check, a special tool must be made. You can easily make this tool from an old axle shaft that matches the spline size of the differential side gear. Figure 24–54 illustrates the fab-rication specifications for this special tool.

To check differential resistance to rotation, use the following procedure:

Install soft metal covers over the vise jaws to 1. protect the ring gear (Figure 24–55).

Place the differential and crown gear assem-2. bly in the vise.

Install the special tool into the differential until 3. the splines of the tool and one side gear are engaged.

Attach a torque wrench to the nut of the spe-4. cial tool and rotate the differential gears. As the differential gears rotate, read the value

FIGURE 24–55 Reading the torque value to check the rolling resistance. (Courtesy of Arvin Meritor)

FIGURE 24–53 Using a flange bar to hold the drive

pinion in position. (Courtesy of Arvin Meritor)

FIGURE 24–54 Fabrication details for a tool to check

the rolling resistance. (Courtesy of Arvin Meritor)

If the new pinion cone number is a minus (–), sub-8. tract the number from the standard shim pack

thickness that was calculated in step 3 or 4.

The value calculated in step 7 or 8 is the 9.

t hickness of the new shim pack that will be

i nstalled. Figure 24–59 illustrates several e xamples of determining shim pack t hickness.Install the drive pinion, bearing cage, and new

10. shim pack into the differential carrier.

gear set is to be installed, or if the depth of the drive pinion has to be adjusted. You are checking the rolling resistance using a torque wrench.

To check/adjust the shim pack thickness (Figure 24–56), do the following:

With a micrometer, measure the thickness of 1. the old shim pack removed from under the pinion cage (Figure 24–57). Record the mea-surement for later use.

Look at the pinion cone (PC) variation number 2. on the drive pinion being replaced (Figure 24–58). Record this number for later use also.If the old pinion cone number is a plus (+), 3. subtract the number from the old shim pack thickness that was recorded in step 1.

If the old pinion cone number is a minus (–), 4. add the number to the old shim thickness that was measured in step 1.

The value calculated in step 3 or 4 is the 5.

t hickness of the standard shim pack without variation.

Look at the PC variation number on the new 6. drive pinion that will be installed. Record the number for later use.

If the new pinion cone number is a plus (+), 7. add the number to the standard shim pack

thickness that was calculated in step 3 or 4.

FIGURE 24–56 Drive pinion depth controlled by shim

pack thickness. (Courtesy of Arvin Meritor)

FIGURE 24–57 Measuring the thickness of the old shim pack. Mike each shim individually then add to

calculate total thickness. (Courtesy of Arvin Meritor)

FIGURE 24–58 Location of the pinion cone (PC)

v ariation number. (Courtesy of Arvin Meritor)

Adjust Differential Bearing Preload

One of two methods can be used to check and adjust the preload of the differential bearings.

Method One.

Attach a dial indicator onto the mounting 1. flange of the carrier and adjust the indicator so that the plunger rides on the back surface of the crown ring gear (Figure 24–60).

Loosen the bearing adjusting ring that is op-2. posite the ring gear so that a small amount of endplay is indicated on the dial indicator. To turn the adjusting rings, use a T-bar wrench that engages two or more opposite notches in the ring (Figure 24–61).

Move the differential and crown gear to the 3. left and right using prybars as you read the dial indicator. Use two prybars that fit be-tween the bearing adjusting rings and the ends of the differential case (Figure 24–62). You also can use two prybars between the differential case or crown gear and the carrier at locations other than those just described. In either case, the prybars must not touch the differential bearings.

EXAMPLES:

Inches

mm 1.

Old Shim Pack Thickness Old PC Number, PC +2

Standard Shim Pack Thickness New PC Number, PC +5New Shim Pack Thickness .030.76–.002–.05.028.71+.005+.13.033.842.

Old Shim Pack Thickness Old PC Number, PC –2

Standard Shim Pack Thickness New PC Number, PC +5New Shim Pack Thickness .030.76+.002+.05.032.81+.005+.13.037.943.

Old Shim Pack Thickness Old PC Number, PC +2

Standard Shim Pack Thickness New PC Number, PC –5New Shim Pack Thickness .030.76–.002–.05.028.71–.005–.13.023.584.

Old Shim Pack Thickness Old PC Number, PC –2

Standard Shim Pack Thickness New PC Number, PC –5New Shim Pack Thickness

.030.76+.002+.05.032.81–.005–.13.027

.68

FIGURE 24–59 Determining shim pack thickness.

(Courtesy of ArvinMeritor Inc.)

FIGURE 24–60 Dial indicator attached to carrier-

mounted flange. (Courtesy of Arvin Meritor)

FIGURE 24–61 Turning the adjusting ring using a

T-bar wrench. (Courtesy of Arvin Meritor)

FIGURE 24–62 Using pry bars to adjust play in the crown gear. (Courtesy of Arvin Meritor)

Tighten the same bearing adjusting ring

4.

so that no endplay shows on the dial

i ndicator.

Move the differential and crown gear to the

5.

left and right as needed. Repeat step 3 until

zero endplay is achieved.

Tighten each bearing adjusting ring one

6.

notch from the zero endplay measured in

step 4.

Method Two.A second method of checking pre-load is to measure the expansion between the bearing caps after you tighten the adjusting rings. Use the following procedure:

Turn both adjusting rings hand tight against

1.

the differential bearings.

Measure the distance X or Y between oppo-

2.

site surfaces of the bearing caps (Figure

24–63A) using a large micrometer of the

c orrect size (Figure 24–63B). Make a note of

the m easurement.

Tighten each bearing adjusting ring one

3.

notch.

Measure the distance X or Y again. Compare

4.

the dimension with the distance X or Y mea-

sured in step 2. The difference between the

two dimensions is the amount that the bear-

ing caps have expanded.

Example: Measurements of a carrier.

Distance X or Y before tightening adjusting rings

5 15.315 inches (389.00 mm)

Distance X or Y after tightening adjusting rings

5 15.324 inches (389.23 mm)

15.324 inches minus 15.315 inches

5 0.009 inch (0.23 mm) difference

If the dimension is less than specification, repeat steps 3 and 4 as needed.

Crown Gear Runout Check

To check the runout of the crown/ring gear, do the f ollowing:

Attach a dial indicator on the mounting flange

1.

of the differential carrier (Figure 24–64).

Adjust the dial indicator so that the plunger or

2.

pointer is against the back surface of the

crown gear.FIGURE 24–63 (A) Location of distances measured to check expansion between bearing caps after

t ightening adjusting rings; (B) measuring this distance.

(Courtesy of Arvin Meritor)

FIGURE 24–64 Checking crown gear runout. (Courtesy of Arvin Meritor)

Pinion and Crown Tooth Contact

A djustment Correct tooth contact between the pinion and crown gear cannot be overemphasized, because improper tooth contact results in noisy operation and prema-ture failure. The tooth contact pattern consists of the lengthwise bearing (along the tooth of the ring gear) and the profile bearing (up and down the tooth). F igure 24–68 shows crown gear tooth

n omenclature.Adjust the dial of the indicator to zero.

3. Rotate the differential and crown gear when

4. reading the dial indicator. The runout of the crown gear must not exceed 0.008 inch (2 mm) (a typical value; refer to the applicable OEM service literature for the specific

v alues).If runout of the crown gear exceeds the speci-5. fication, remove the differential and crown gear assembly from the carrier. Check the dif-ferential components, including the carrier, for the problem causing the runout of the gear to exceed specification. Repair or replace defec-tive components.

After the components are repaired or re-6. placed, install the differential and crown gear into the carrier.

Repeat the preload adjustment of the 7. differential bearings. Then repeat this runout procedure.

Check/Adjust Crown Gear Backlash

If the used crown and pinion gear set is installed, ad-just the backlash to the setting that was measured before the carrier was disassembled. If a new gear set is to be installed, adjust backlash to the correct speci-fication for the new gear set.

To check and adjust ring gear backlash, do the

f ollowing: Attach a dial indicator onto the mounting

1. flange of the carrier (see Figure 24–64).

Adjust the dial indicator so that the plunger is 2. against the tooth surface at a right angle.

Adjust the dial of the indicator to zero, making 3. sure that the plunger is loaded through at least one revolution.

Hold the drive pinion in position.

4. When reading the dial indicator, rotate the

5. crown gear a small amount in both directions against the teeth of the drive pinion (Figure 24–65). If the backlash reading is not within specification (typically ranging from 0.010 to 0.020 inch or 254 to 508 mm), adjust backlash as outlined in steps 6 and 7.

Loosen one bearing adjusting ring one notch 6. and then tighten the opposite ring the same amount. Backlash is increased by moving the crown gear away from the drive pinion (Figure 24–66). Backlash is decreased by moving the crown gear toward the drive pin-ion (Figure 24–67).

Repeat steps 2 through 5 until the backlash is 7.

within specifications.

FIGURE 24–65 Check crown gear backlash. ( C

ourtesy of Arvin Meritor)

FIGURE 24–66 Adjustments to increase backlash. (Courtesy of Arvin Meritor)

the pattern in an unloaded condition (such as when you are performing this test) will be approximately one-half to two-thirds of the crown gear tooth in most models and ratios.

Checking Tooth Contact Pattern on a Used Gear Set. Used gearing will not usually display the square, even contact pattern found in new gear sets. The gear will normally have a pocket at the toe-end of the gear tooth (Figure 24–71) that tails into a contact line along the root of the tooth. The more use a gear has had, the more the line becomes the dominant characteristic of the pattern.

Adjusting Tooth Contact Pattern. When dis-assembling, make a drawing of the gear tooth con-tact pattern so that when reassembling it is possible to replicate approximately the same pattern. A cor-rect pattern should be clear of the toe and centers evenly along the face width between the top land and the root. Otherwise, the length and shape of the pattern can be highly variable and are usually con-sidered acceptable—providing the pattern does not run off the tooth at any time. If necessary, adjust the contact pattern by moving the crown gear and drive pinion.

Checking Tooth Contact Pattern on a New Gear Set. Paint 12 crown gear teeth with a marking compound (Figure 24–69) and roll the gear to obtain a tooth contact pattern. A correct pattern should be well centered on the crown gear teeth with lengthwise contact clear of the toe (Figure 24–70

). The length of

FIGURE 24–67 Adjustments to decrease backlash.

(Courtesy of Arvin Meritor)

FIGURE 24–68 Crown gear tooth nomenclature.

(Courtesy of Dana Corporation)

FIGURE 24–69 Application of a marking compound

to check tooth contact. (Courtesy of Dana Corporation)FIGURE 24–70 Correct tooth contact pattern

for new gearing. (Courtesy of Dana Corporation)

FIGURE 24–71 Correct tooth contact pattern for used gearing. (Courtesy of Dana Corporation)

making adjustments, first adjust the pinion and then the backlash. Continue this sequence until the pattern is satisfactory.

Thrust Screw Adjustment

For those differential carriers equipped with a thrust screw, perform the following procedure. (If the carrier assembly does not have a thrust block, proceed to step 4 of this procedure.)

Rotate the carrier in the repair stand until the 1. back surface of the crown gear is toward the top.

Put the thrust block on the back surface of 2. the ring gear. The thrust block must be in the center between the outer diameter of the gear and the differential case.

Rotate the crown gear until the thrust block 3. and hole for the thrust screw, in the carrier, are aligned.

Install the jam nut on the thrust screw, one-4. half the distance between both ends (Figure 24–74).

Install the thrust screw into the carrier until the 5. screw stops against the crown gear or thrust block.

Loosen the thrust screw one-half turn, or 180 6. degrees.

Tighten the jam nut to the correct torque value 7. against the carrier (typical values range from 150 to 295 lb-ft. or 200 to 400 N .m) (Figure 24–75).

Axle Tracking

Axle tracking can be measured using the older tram bar method or electronic alignment equipment. The procedures for setting axle alignment and tracking are

explained in Chapter 25.

FIGURE 24–72 Two incorrect patterns when adjusting pinion position. (Courtesy of Dana Corporation)

Crown gear position controls the backlash setting. This adjustment also moves the contact pattern along the face width of the gear tooth (Figure 24–72). Pinion position is determined by the size of the pinion bear-ing cage shim pack. It controls contact on the tooth depth of the gear tooth (Figure 24–73).

These adjustments are interrelated. As a result, they must be considered together even though the

pattern is altered by two distinct operations. When

FIGURE 24–73 Two incorrect patterns when adjusting backlash. (Courtesy of Dana Corporation)

? Most differential carriers are replaced as rebuilt/exchange units, so the role of the technician is, more often than not, to diagnose the problem and then, if necessary, to replace the defective assembly as a unit.

? The technician who has disassembled and reas-sembled differential carriers should find trouble-shooting procedures easier to follow.

? Follow the OEM procedure when disassem-bling differential carriers. Taking a few mo-ments to measure shim packs and gear tooth contact patterns on disassembly can save considerable time when reassembling the

c arrier.? A crown an

d pinion gear set often can be

r eused when rebuilding a differential carrier. Make sure that you inspect it properly on

d isassembly.? Crown and pinion gear sets ar

e always replaced as a matched pair during a rebuild.

? When setting crown and pinion backlash, it is increased by moving the crown gear away from the drive pinion and decreased by moving the crown gear toward the drive pinion.

? Adhering to OEM-recommended lubrication schedules is the key to ensuring the longest service life from both drive and dead axles.

? Knowing the correct procedure to check lubricant level is essential. The level is correct when lubri-cant is exactly level with the bottom of the fill hole.? Because most OEMs approve of the use of syn-thetic lubricants in final drive carriers, lubrication drain schedules have been greatly increased in recent years. Drain schedules are determined by the actual lubricant used and the type of appli-cation to which the vehicle is subjected.

? Servicing of axles on heavy-duty trucks consists of routine inspection, lubrication, cleaning, and, when required, troubleshooting and component overhaul.

? Failure analysis is required to prevent recurrent failures.

? Drive axle carrier components usually fail for one of the following reasons: Shock load Fatigue Spinout Lubrication problems

Normal wear

FIGURE 24–74 Installing the jam nut on the thrust screw. (Courtesy of Arvin Meritor)

FIGURE 24–75 Tighten the jam nut to the correct torque value. (Courtesy of Arvin Meritor)

SUMMARY