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 the rail and the ﬂange height of the left wheel before it started to slide was 1-1/16 inches above the tread.

At Edgewood, several marks made by the wheel flange were found on the heel blocks of switches and several marks made by the false flange were found on the frogs of turnouts

Numerous other marks were found on the track between Edgewood and the point of the accident.

3. Later Examination of Unit 4031

In preparation for moving unit 4031 to the ICRR shops at Paducah, Kentucky, where the cause of the locked wheels and the failure .of the Wheel-slip device would be determined, the rear truck was replaced with another truck and the unit moved to Centralia, Illinois. While the unit was at Centralia, a review of the locomotive inspection reports by an official of the carrier disclosed that there was no notation on the reports that the blocked reverser had been corrected. The official examined unit 4031 in Centralia and found that the ⅜-inch pin was still in place in the power reverser of the No. 2 motor circuit, blocking the reverser in neutral position. With the reverser so blocked, power could not be supplied to the traction motors and the function of the wheel-slip device was nullified.

4. Examination of Unit 4031 at ICRR Shops in Paducah, Kentucky

The leading pair of wheels and the traction motor were removed from the rear truck. The journal roller bearing boxes were removed and the bearings were found to be free of defects. The flat spots on the wheels were measured and the wheels examined. The results are shown in Figure 8. The traction motor was removed from the axle and the suspension hearings were found to be in good condition with sufficient oil. An attempt then was made to rotate the traction motor, but it was locked and would not move.

Indications of excessive heating were observed on the armature hearing caps.

The armature was removed from the motor and disassembled. The commutator end roller bearing was damaged by heat and the grease was charred. (See Figure 9.) The pinion end roller bearing was damaged by heat. The steel rollers were flattened, grooved, and discolored. The inner and outer races were damaged. (See Figure 10.)

5. Examination of the Armature Bearings

The bearings, manufactured by SKF Industries, Inc. (SKF), were examined by a consultant from Purdue University and by representatives of SKF as part of the Safety Board's investigation. The inner rings of the bearings had attained a temperature of from 1,750°F. to 1,850°F. The rollers in the pinion end had reached a temperature of about 1,400°F, while the rollers in the commutator end reached a temperature of from 1,200°F. to 1,3000F. The H-ring showed no evidence of plastic flow in the areas where the flange contacted the rollers. It appeared that for a short period of time before seizing, the rollers had not turned although the inner race had rotated on the shaft.

Chemical and metallurgical examinations of the hearing by both the consultant and SKF representatives disclosed that the steel complied with the SKF specifications for bearings of this design.

Other parts of the bearing assembly such as the H-ring, the locking plate, and the oil seals and throwers on both bearings showed excessive wear on the parts which would have been affected by excessive lateral movement of the armature toward the pinion end. The H—ring on the commutator end hearing displayed no excessive wear. The end plate which bore against the H-ring indicated evidence of excessive wear where it contacted the end cover only. The end 16