ENGINE AR-PRIM 7E7923 - Caterpillar

Getting Started
Install the brake drum in a horizontal or vertical lathe. Use a dial indicator to check the amount of runout on the outer circumference of the brake drum flange and the flange face to make sure that the brake drum is perpendicular (at a 90° angle) and concentric (having a common center) to the boring tool. Do not apply too much force to the chuck as it will distort the brake drum.Tools Needed
An American standard carbide tool, grade C2 with an aluminum oxide coating and a 1.57 mm (0.062 inch) nose radius or,
An American standard carbide tool, grade 570 with an aluminum oxide coating and a 1.57 mm (0.062 inch) nose radius or,
An American standard ceramic tool, grade HC2 with a 3.17 mm (0.125 inch) nose radius.Refer to Table 3 for the feeds and speeds.
Table 3
Tool Feed per Revolution Surface Speed
C2 Carbide 0.20 mm (0.008 inch) 107 m/minute
(350 ft/minute)
570 Carbide 0.23 mm (0.009 inch) 213 m/minute
(700 ft/minute)
HC2 Ceramic 0.36 mm (0.014 inch) 274 m/minute
(900 ft/minute)
Remove only enough material from the brake drum bore so at least 80% of the bore is a new machined surface. If there are fine cracks in the brake drum bore, the drum must be machined to remove them.
Use the 6V-0114 Gauge Assembly to measure the brake drum diameter. If the mark on the gauge rod can be seen in the opening of the gauge tube, the brake drum can be used again.
If the mark on the gauge rod is between the lines on the tube in the space marked “STD” use the standard brake linings.
If the mark on the gauge rod is between the lines on the tube in the space that had the mark “.12 O.S.,” use 3.18 mm (0.125 inch) oversize brake linings.
If the mark on the gauge rod is between the line and the edge of the opening in the space that has the mark “.25 O.S.,” use 6.35 mm (0.250 inch) oversize brake linings.
Illustration 11 g02175038
Brake drum with grooved wear. Measure the brake surface diameter.
If the 6V-0114 Gauge Assembly is not available, measure the diameter of the drum. If the diameter of the drum is more than the “Use Again Diameter” shown in Table 2, the drum cannot be used again. Of the diameter is less than the “Use Again Maximum Diameter,” use standard or oversize linings as shown in Table 3.
Illustration 12 g02175124
Measure to see if the new surface is concentric to the outer circumference of the flange.
Put a small chamfer on both ends of the bore. Check the new surface to see if it is concentric to the outer circumference of the flange. Use a micrometer to measure the distance from the outer circumference of the flange to the brake surface.