MG-5061A MARINE TRANSMISSION Caterpillar

Assembly of Rear Housing Group.

1. If bearing inner races were removed for replacement, press the new races into their respective bores in the rear bearing.

2. Apply a film of sealant to the outer case of the output oil seal (figure 6-26, 10) and press it into its bore flush with the outer face of the housing.

3. Thoroughly degrease the tapered bore of the output gear (figure 6-26, 7) and its mating surface on the output shaft (figure 6-26, 11) with a suitable solvent. All traces of grease of oil must be removed from the tapered surfaces. Dry the parts with clean of paper towels.

4. Determine output gear advance on shaft as follows:

a. Measure and record the distance from the shoulder at the front of the shaft to the rear face of the snap ring groove (figure 9-1, dimension A).

b. Place the output gear on the shaft and seat it using 100 to 200 lbs force.

c. Measure and record the distance face of the gear (figure 9-1, dimension B).

Figure 9-1 : Determining output gear advance.

d. Substract distance B (step c) from distance A (step a). The result obtained is the advance of the gear. This must be from .096 to .128 inch.

e. Remove the gear from the shaft.

5. Place the output shaft on the bench seating on the output flange face. Install the rear housing over the output shaft, seating it on suitable wooden blocks so that the output oil seal is further to the rear of the shaft than its normal position (refer to figure 9-2). Take care not to damage the seal by running it onto the radius at the front of the output flange.

6. Install the rear bearing inner race onto the shaft and press it into position using special tool TD-300409 with items TD-300409/4 and 5 (see figure 9-2).

Figure 9-2 : Rear bearing inner race installation.

7. Ensure that there are no traces of oil or grease on the output shaft taper or on the mating surface of the output gear. If necessary degrease the parts again as in paragraph 3. Install the gear onto the shaft and seat it firmly on the taper. Press the output gear into position using special tool TD-300409 and item TD-300409/4 (see figure 9-3).

Figure 9-3 : Installation of output gear.

The gear should be positioned on the shaft so that the front face of the gear is flush with the rear face of the snap ring groove in the output shaft to within .002 inch. A force of 35 to 50 tons will be necessary to acheive this (see chart in section 12 of this manual).

Remove the special tooling and install retaining snap ring (figure 6-26, 6).

8. Press the front bearing inner race onto the end of the output shaft using special tools TD-300419 and 300420 (see figure 9-4).

Use at least 6 tons force to ensure that the bearing is seating correctly.

9. Install the oil dam (figure 6-25, 52) and secure it with the two screws and washers. Torque the screws 21 lbs. ft.

Figure 9-4 : Installation of front output bearing inner race.

10. Install the forward and reverse clutch assemblies into the rear housing (see figure 6-19).

Tapered Roller Bearing Adjustment.

11. Install the clutch and output shaft front bearing outer races, with their spacers, into the front housing (see figure 9-5).

Figure 9-5 : Bearing spacer installation

Do not install shim packs at this stage.

NOTE: To prevent the bearing outer races from falling out of their bores when installing the front housing, they should be held in place with a thin bead of paper glue (see figure 9-6).

12. Install the front housing on to the rear housing taking care to align the two dowel pins with their respective holes.

DO NOT APPLY SEALANT BETWEEN THE FRONT AND REAR HOUSINGS AT THIS STAGE.

Figure 9-6 : Location of bearing outer races with paper glue.

13. Install the screws that secure the front and rear housings (figure 6-24, 17) and torque them to 28 lbs. ft.

14. Install the SAE adaptor (figure 6-24, 13) and secure it with the screws and washers (figure 6-24, 8, 9 and 12). Torque the screws to 38 lbs. ft. (see figure 9-7).

NOTE: Screws indicated by arrows must be sealed with Loctite 572.

Figure 9-7 : SAE adaptor installation.

15. Turn the unit over, front side down, on to suitable wooden blocks, so that the rear face of the unit is horizontal.

16. Check the end play on the clutch groups as follows:

a) Attach a dial indicator on to the rear housing so that the indicator finger rests on the end of the clutch shaft (see figure 9-8).

Figure 9-8 : Checking clutch group end play.

b) Apply a downward load to the end of the shaft and rotate the shaft several times. Set the indicator to zero.

c) Install special tool TD-300408 onto the end of the clutch shaft. Check that the indicator does not move from the zero position when the tool is installed.

d) Using a pain of pinch bars, apply an upward load to the clutch shaft and lift it as it will go (see figure 9-8). Note the indicator reading. Repeat the operation several times, turning the clutch shaft one and a quarter turns each time. Indicator readings obtained should be the same each time. The readings obtained are the effective end play of the clutch group.

17. Repeat operations 6. a) to 6. d) for the second clutch group and note the end play obtained.

18. Check the end play on the output shaft as follows:

a) Attach a dial indicator to the rear housing, with the indicator finger resting on the end of the output shaft (see figure 9-9).

Figure 9-9 : Checking output shaft endplay.

b) Apply a downward load to the shaft and rotate the shaft several times. Set the indicator to zero.

c) Using a pair of pinch bars apply an upward load to the shaft and lift it as far as it will go (see figure 9-9). Note the indicator reading. Repeat the operation several times, turning the shaft one and a quarter turns each time. Indicator readings obtained should be the same each time. The readings obtained are the effective end play of the output shaft.

19. Remove the front housing. Remove the front bearing outer races and the spacers and install under the spacers shim packs of the appropriate dimensions to reduce the effective end play of the shafts to .001 to .005 inches (see figures 6-26, 1 and 8-17, 8-18, 1). Replace bearing outer races and spacers in their respective bores.

20. Clean the mating surfaces of the front and rear housings with a suitable solvent to remove oil and grease residue.

Test for clean surfaces by applying a few drops of cool water to the surfaces. Parts are sufficiently clean if water covers the surface of the parts in a film. If the water puddles or forms beads use fresh solvent and reclean.

21. Use Twin Disc primer MA-579 on both mating surfaces. Allow primer to dry. This usually takes three to four minutes. Keep surfaces clean and free from oil or grease from this point on.

22. Apply a continuous bead of Twin Disc M-2828-A anaerobic plastic sealant to the mating surface of the rear housing (see figure 9-10).

Make sure that narrow overlap areas are covered. It is optional to spread sealant into a thin film just before mating surfaces are assembled.

Figure 9-10 : Sealant application.

23. Install the front housing, with bearing outer races, spacers and shims, on to the rear housing and secure with the screws. Torque the screws to 28 lbs. ft.

24. Repeat the clutch and output shaft end play checks to ensure that final endplay is correct (.001 to .005 inch). Should the end play not be correct, the entire adjustment procedure should be repeated. Mating faces of front and rear housings should be recleaned to remove all traces of old sealant.

Assembly of External Parts.

25. Place a thin film of sealant around the outer diameter of the input oil seal (figure 6-24, 11). Press the seal into its bore flush with the outer face of the rear housing.

26. Heat the drive spider to 100° C. and install it on to the splines of the input (forward clutch) shaft. (See figure 9-11).

Figure 9-11 : Drive spider installation.

27. Ensure that the drive spider is in its correct position against the forward clutch shaft front bearing. Measure the distance drom the drive spider hub face to the end of the input shaft. Install a shim pack (figure 6-24, 3) .001 to .004 inch less than the distance measured. Fit the rubber seal ring, retainer washer and capscrew (figures 6-24, 4, 2 and 1). Torque the capscrew to 45 lbs. ft.

28. Install a new manifold gasket (figure 6-25, 50) and place the manifold in position over the ends of the clutch shafts taking care not to damage the piston rings (see figure 9-12).

29. Install the filter screen into the manifold and secure it with the O ring plug cover (figure 6-25, 36 and 37). Secure the O ring plug cover with one 1/2-13 UNC × 2.25 screw and washer. Tighten the screw finger tight at this stage.

30. Clean the mating surfaces of the PTO replacement cover (figure 6-25, 27) and the manifold as described in paragraph 20. Apply a continuous bead of Twin Disc M 2828 or M 2828-A sealant to the manifold mating surfaces (see figure 9-13).

Figure 9-12 : Installing manifold.

Figure 9-13 : Sealant application for PTO replacement cover.

31. Install the PTO replacement cover and secure it with the four screws tightened finger tight.

32. Install the remaining manifold retaining screws and tighten all screws evenly to 65 lbs. ft. torque (see figure 9-14).

Figure 9-14 : Final torque on manifold screws.

33. Install the pump gasket and hydraulic pump assembly (figure 6-25, 33 and 39). Ensure that the driving tang on the pump shaft is properly aligned with the slot in the reverse clutch shaft (see figure 9-15).

Figure 9-15 : Oil pump installation.

Secure the pump with the four capscrews (figure 6-25, 32). Torque the screws 15 lbs. ft.

34. Install the oil level gauge tube and oil gauge (figure 6-25, 9 and 8).

NOTE: Allow two hours curing time (at room temperature) for the sealant before filling with oil. If the Twin Disc MA 579 primer was not used (see step 21) then allow 24 hours curing time.

Prior to Installation.

General.

The transmission front housing flange and pilot, and the engine flywheel and flywheel housing must be checked for trueness. Make certain the engine flywheel and the flywheel housing are clean prior to making the tests.

Alignment (Also reference SAE J-1033).

1. Bolt a thousandths increment dial indicator or gauge to the engine flywheel so that the indicator is perpendicular to the face of the engine flywheel housing, and the indicator stem is riding on the face of the flange. See figure 9-16.

Figure 9-16 : Checking the face of engine flywheel housing.

2. Rotate the engine flywheel, always keeping a thrust in the same direction, and note the face deviation of the engine flywheel housing flange. The face deviation must not exceed the figures given in Table 9-1.

3. With the indicator mounted as in the above paragraph, adjust the indicator stem so that it will ride on the bore of the engine flywheel housing. See figure 9-17.

4. Rotate the engine flywhell and note the bore eccentricity of the engine flywheel housing bore. See Table 9-1.

Figure 9-17 : Checking the bore of engine flywheel housing.

5. Bolt a thousandths dial indicator or gauge to the engine flywheel housing so that the indicator is perpendicular to the engine flywheel, and the indicator stem is riding on the face of the flywheel. See figure 9-18.

Rotate the flywheel. The variation of the face runout of the surface to which the driving is bolted should not exceed 0.0005 per inch of diameter.

6. With the indicator mounted as in the paragraph above, adjust the indicator stem so that it will ride on the driving ring pilot bore of the engine flywheel. See figure 9-19. Rotate the flywheel. The driving ring pilot bore eccentricity of the engine flywheel should not exceed 0.005 inch maximum total indicator reading. Thrust on the flywheel should be in one direction at all times to obtain a correct reading.

Figure 9-18 : Checking the driving ring surface of engine flywheel.

Figure 9-19 : Checking the driving ring pilot bore of engine flywheel.

7. Readjust the indicator so that the stem will ride on the pilot bearing bore of the flywheel. See figure 9-20. Rotate the flywheel. The eccentricity of the pilot bearing bore should not exceed 0.005 maximum total indicator reading. Eccentricity between the driving ring pilot bore (figure 9-19) and pilot bearing bore (figure 9-20) should not exceed 0.008 inch total indicator reading.

8. With the indicator stem on the inside diameter of the driving ring pilot (figure 9-19), apply pressure with a prybar between the flywheel and flywheel housing on the opposite side from the indicator. The indicator will measure vertical movement of engine flywheel. Maximum allowable movement is 0.005.

Figure 9-20 : Checking pilot bearing bore of engine flywheel.

Installation.

Alignment.

Proper alignment of an engine and marine unit is critical... both during the initial installation and at frequent intervals during the life of the boat. It is rather common for a boat to change its form with various loads and with age. A bend is actually formed in the keel which changes the original engine and shaft alignment. The following steps may be taken to secure proper marine transmission alignment.

Propeller shaft installation.

1. A wire is run through the shaft log and secured to a brace near the engine bed, giving the wire a position equivalent to the shaft centerline.

2. The stern bearing and stuffing box are installed and bolted into position with the wire passing through each in the exact center of the bore. With the bearing and stuffing box in place, the wire is then removed.

3. The propeller shaft is then installed in its proper position.

4. If an intermediate shaft is used, it is blocked into position and its coupling is aligned with the propeller shaft coupling (see the following section - "Engine and Marine Transmission Alignment"). If there is an intermediate bearing in the line, this is installed and positioned with shims during the alignment process.

5. If a light shaft is used without an intermediate bearing, the shaft must be centered and supported to take out the droop while alignment of the flange couplings is being made.

Engine and Marine Transmission Alignment to propeller shaft. See figure 9-21.

1. It is important to align the engine and transmission, only when the boat is afloat, and NOT in drydock. During this alignment period, it is also advisable to fill the fuel tanks and add any other ballast that will be used when the boat is in service. With the engine and transmission in position on the engine bed, arrangements must be made to have a controlled lifting or lowering of each of the four corners of the engine. If threaded holes are provided in each of the engine mounts, jacking screws can be used in them. The engine can be raised by screwing down, or lowered by backing off the desired amount. Steel plates must be inserted under the jacking screws so that the bolts will not damage the engine bed. Lifting can also be accomplished by the used of chain hoists or properly placed jacks. Adjustable shims also are available and can simplify the whole problem, particularly for future realignment.

2. It will also be necessary to move the engine and transmission from one side or the other on the bed to obtain horizontal alignment. This can be done with a jack placed horizontally between the engine and the foundation. At the same time, a straight edge is laid across the edges of the flanges at the top and side to check the parallel alignment of the coupling edges. See figure 9-22.

3. As the engine and marine transmission comes into their aligned position, it will be possible to match the output flange and propeller the coupling, and prepare for bolting together. Care should be taken not to burr or mark this connection because the fit is very critical. Place a 0.002-inch feeler gauge between the flanges of the coupling. The feeler gauge is moved (slid) completely around the coupling.

4. Then the marine transmission flange coupling is rotated 90, 180 and 270 degrees with the feeler blade being moved around the flange again in each successive position. If the alignment is correct, the feeler gauge will fit snugly, with the same tension, all around the flange coupling.

5. If the alignment varies during rotation, then further alignment is necessary, or the marine transmission and shaft couplings should be checked for improper face runout. Face runout on the marine transmission output flange can usually be corrected by repositioning the coupling on its spline. Shaft coupling runout is usually due to inaccuracy of taper fit or key interference.

Figure 9-21: Alignment of engine and Marine Transmission - Schematic view.

Figure 9-22: Checking alignment (parallelism) of coupling and propeller flanges.

6. Some boats are not structurally rigid and some carry their load in such a way that they will 'hog' or go out of normal shape with every loading and unloading. Where this condition exists, it may be necessary to make a compromise between the top and bottom coupling clearance by leaving a greater clearance at the bottom of the marine transmission output flange and propeller coupling. This clearance might be 0.005 to 0.007-inch while the top would maintain the standard 0.002-inch.

7. During the process of securing final alignment, it may be necessary to shift the engine many times. When it becomes apparent that the alignment is reasonably close, the holes for the lag studs are marked and drilled. Then with final alignment secured, the necessary steel or hardwood shims are made up and the engine and transmission is fastened in place. The alignment is then rechecked and if satisfactory, the coupling is bolted together.

In the case of a unit being returned after repair or maintenance, line up the match marks on the output flange and companion flange before bolting together.

8. Although it is not necessary to align a flexible coupling as accurately as a solid coupling, the closer it is the initial alignment, the more vibration-free if will be. The most accurate method of alignment is to align the shaft onto the marine transmission with flexible coupling out of the system. This can be done with a spacer the same size as the coupling but not flexible in nature. Flexible couplings are used only for noise and vibration dampening... and not to correct inadequate alignment.

9. Replace any wiring or any other items that were removed prior to removal and connect the plumbing to and from the heat exchanger. Connect the selector valve control linkage.

IMPORTANT NOTE

Make sure that the linkage is correctly adjusted and that the selector valve control lever comes perfectly into the detented position in all three operating modes (Forward, Neutral and Reverse). Failure to do this may result in faulty positioning of the selector valve lever which could lead to excessively low clutch pressures causing severe damage to the transmission. Control linkage should be checked regularly as it can easily come out of adjustment due to cable stretch, wear in moving parts, etc. Twin Disc will not be responsible for damage caused by faulty control linkage or bad linkage adjustment.

10. When a heavy boat is dry-docked, it naturally undergoes some bending. Therefore, it is always good practice to unbolt the marine transmission coupling and prevent bending of the shaft.