Usage:
3512 (65Z)
Introduction
The 7C1649 Engine Mounting Group is used to adapt the existing engine mounting rails when installing a Caterpillar 3508 or 3512 Engine. A 7C1925 Flywheel Group and a 7C1927 Flywheel Adapter Group must also be used.
Necessary Parts
Assembly Procedure
Front Engine Mounting Point
1. With the engine removed and the generator still in place, measure the thickness of the 5L5702 Pad, located on inside of rail at front engine mounting point, as shown above. Remove the 5L5702 Pad and grind the inside of the rail smooth.
7C1929 Plate Mounting
2. Grind a new 7C1929 Plate to the same thickness as measured in step 1.
3. Weld the 7C1929 Plate to the existing rail. Be sure that the top edge of the 7C1929 Plate is flush with the top surface of the 5L5693 Pad.
Rear Engine Mounting
4. Measure and record thickness of the existing 5L5703 Pad at the rear engine mounting point. Use the same method of measurement as used in step 1. Remove the existing 5L5703 Pad and grind the inside of the rail smooth.
5. Grind a new 7C1929 Plate to the same thickness as measured in step 4.
6. Weld the 7C1929 Plate to the inside of the existing rail. Be sure that the top edge of the 7C1929 Plate is flush with the top surface of the 5L5694 Pad.
NOTE: Be sure to maintain tolerance "A" when welding the 7C1929 Plates.
The top of the 7C1929 Plate may be dressed slightly with a file, if necessary.
7. Existing holes in side rails which are covered by the two new 7C1929 Plates may be filled in with weld.
8. Using existing holes in the 7C1929 Plates as a guide, drill six- 20.5mm (.80 in.) diameter holes in front of rail and drill the front three holes in the rear of rail.
9. Use steps 1 thru 8 above to modify the other mounting rail.
Flywheel Housing Mount
10. Fasten two new 7C1930 Plates to new flywheel housing (part of 3508 or 3512 engine), using six 2H3743 Bolts and six 8G2077 Spacers.
12. Mount the new engine to rails using six new 0L1178 Bolts and six new 5P8248 Washers at front of engine on each side. Use three of the same bolts and washers at the rear of engine on each side.
13. Weld four new 7C1928 Gussets in place as shown above.
14. Connect the engine flywheel to the 7C1926 Adapter Group using 12 new 313185 Bolts. The bolts must be inserted through the front of the flywheel housing, through the 44mm (1.74 in.) diameter hole (at approximately eight o'clock as viewed from the rear of engine). The bolts go through the flywheel and into 7C1926 Adapter. The flywheel must be manually rotated to install each succeeding bolt.
15. Shimming and final generator alignment instructions are given in the following topic.
Engine Generator Alignment
NOTE: GT-601 generator is used with the Caterpillar 3508 and 3512 diesel engines.
Checking Generator Alignment
Typical Engine -Generator Arrangement
Generator alignment may be checked by measuring the web deflection of the crankshaft throw at the rear of the engine. The engine and its base must be at the same relative temperature when the following checks and adjustments are made.
1. Remove the rear crankcase inspection cover from each side of the engine block.
2. Turn the crankshaft in the direction of normal rotation until the center of the counterweights go just beyond the connecting rod.
Measuring Web Deflection of the Crankshaft (Typical)
3. Install a Starrett Crankshaft Distortion Dial Gauge No. 696 with Starrett No. 696B Balancer Attachment between the counterweights as shown. Place the indicator pivot pins (1) approximately 40 mm (1.57 in.) from the outside edge of the counterweight (2). Turn the dial of the indicator to get alignment of the zero and the pointer. Turn the indicator on its end points until the pointer of the indicator will not move from zero. The indicator should be preloaded to assure that the reading will be accurate and that the instrument will not drop out of its position.
4. Observe and record the indicator readings with the rear crankshaft throw in the following positions.
*Approximately 1/2" from rod. Do not allow the indicator to touch the connecting rod. Set the indicator to read "0" at this point. See below, View "A".
*Approximately 90 degrees before top vertical center, crank pin horizontal on right side of engine. See below, View "B".
*At top vertical center. Indicator must read +0,076 mm to +0,127 mm (+0.003" to +0.005 "). See above, View "C".
*Approximately 90 degrees after top vertical center, crank pin horizontal on left side of engine. See above, View "D".
*Approximately 1/2" from rod. Do not allow the indicator to touch the connecting rod. See above, View "E". The indicator reading at "E" must not differ more than ±0,0125 mm (±o.0005") from the reading at "A". Recheck the indicator reading at "A".
NOTE: Indicator readings at positions "B" and "D" must not differ more than 0,025 mm (0.001").
If measurements taken are not within the limits specified, the generator must be realigned as described in the following paragraphs.
GT-601 Generator longitudinal section, showing axial position of armature
Generator Mounting and Alignment
If the generator is to be realigned or a new generator is to be installed, proceed as follows:
Surface Preparation
1. Remove paint, chips, burrs, rust and dirt from the face and rabbet fit of the engine flywheel, the face and bore of the generator spider, the bottom of the generator feet, and the top of the engine bed extension.
2. Place shims on engine bed extension where generator will be placed. Align holes in shims with those in base. Use one each of the following shims on each side initially, placing the thickest shims on the bottom. 2,25 mm; 0,80 mm; 0,25 mm (0.090"; 0.032" 0.010")
Positioning and Aligning the Generator
1. Remove the rear crankcase inspection cover from each side of the engine.
2. Insert two guide pins diametrically opposite each other in the face of the generator coupling. Remove all blocking from the generator armature and fan. Coat all contact surfaces with a film of heavy oil or grease.
NOTE: Before proceeding, see steps 5 and 6.
3. With the shim stacks in place, lower the generator into position on the extension bed. At the same time, rotate the engine crankshaft to align the flywheel bolt holes with guide pins. Then align the generator forward to engage the coupling pilot. Support the rear of the generator during positioning to prevent it from tipping.
4. Remove the guide pins and install the flange bolts through the flywheel. Tighten the bolts to between 210 - 230 N·m (155 - 170 lb ft) torque. Tighten evenly and in a diametrically opposite sequence.
5. Position the armature axially with respect to the magnet frame by the 74.6 ± 0.5 mm (2.937 ± 0.019") dimension as shown above. Since this dimension cannot be measured directly when the armature is bolted to the engine, the flange thickness of the Caterpillar Inc. adapter should be measured prior to assembly, or held to a decimal dimension and this dimension added to the 74.6 mm (2.937") dimension.
6. An alternate method which may be used to axially locate the generator magnet frame with respect to the armature is to position the magnet frame to obtain a 68.3 mm (2.687") dimension between the end of the commutator segments and the inside face of the end frame. See above.
7. Insert mounting bolts at the four corners through holes in the generator feet, shims and engine bed extension and draw up tight. Do not attempt to check alignment without tightening mounting bolts, since tightening will compress shims and change alignment.
To add or remove shims, screw in four jacking bolts as shown above (Engine-Generator Arrangement). Be sure jacking bolts are backed off sufficiently before mounting bolts are tightened.
Measure the generator air gap by inserting a feeler gage between the armature fan and the generator frame. Make four measurements 90 degrees apart, checking the gap at the top and bottom and at each side.
Adjust the air gap by moving the generator frame vertically or laterally so that gap is equal to within 0.125 mm (0.005") at all four points.
8. After the air gap has been set, and with the generator mounting bolts tight, check the generator alignment. Measure crankshaft web deflection as described under Checking Generator Alignment.
9. If the indicator deflections are not within limits specified for step 8, make adjustments as follows:
* Loosen mounting bolts.
* Install four jacking bolts and raise generator frame just high enough to free shims.
* Add or remove shims to correct alignment. Back-off jack screws and retighten mounting bolts. Repeat steps 8 and 9 until alignment and air gap is correct.
NOTE: Before final check is made, install all generator frame mounting bolts and tighten to 270 N·m (200 lb ft) torque.
10. Drill and ream dowel pin holes in engine bed extension.
11. Apply white lead to dowel pin holes and dowel pins. Install dowel pins and jam nuts. Be sure dowel pins extend through full thickness of supporting flanges beneath generator feet, are accurately fitted, and do not bind in shims. The dowel pins should have an interference fit of 0.025 mm (0.0010").