24. SERVICE PROCEDURE 24.5.5 BELTS, GENERAL Replace badly worn, greasy or severely cracked belts immediately. These conditions prevent proper belt function. Prior to installing new belts, make sure all pulley grooves are clean and not worn. If a pulley is damaged or if the grooves are worn, it should be replaced. All pulley support bearings, shafts and brackets must be in working order. When replacing belts and pulleys, pulley alignment must be checked with belts tensioned and brackets securely clamped. A misalignment that can be detected by the naked eye is detrimental to belt performance.
During belt installation, do not force the belts into the pulley grooves by prying with a screwdriver op pry bar. This will damage the belt side cords which will cause the belts to turn and result in complete destruction of the belts in operation. Belts on new machines and replacement belts lose their tension as they seat into the pulley grooves. Check the tension of new belts at 20 hour intervals until tension is stabilized and thereafter, every 250 hours. If the tension falls below the required minimum, the belt slips, and damages the belts and pulley grooves. REMARK: When operating in abrasive conditions, check tension every 100 hours. Visualy inspect the belts for intersecting cracks.
Transverse (across the belt width) cracks are acceptable. Longitudinal (direction of belt length) cracks that intersect with transverse cracks are not acceptable. Replace the belt if it is frayed or has pieces of material missing. 24.5.6 CHECK FAN BELT TENSION-ADJUST TENSION To check belt tension a Gates type gauge must be used because of the wide drive belt. Loosen the idler pulley shaft locknut. Turn the adjusting screw clockwise to adjust the belt tension. Belt Tension N lbf 1330 New 300 530 to 1070 Used 120 to 240 Tighten the idler pulley shaft locknut. Torque Value: 190 N•m [140 ft.-lb] If a Gates type gauge is not available, tension may be checked by belt deflection.
Press the belt with your finger at the longest span and measure the deflection. Maximum deflection 9.5 to 12.7 mm (0.37 to 0.50 in). PC450-ENG 3-58 WARNING Before working on the engine or electrical system, disonnect the negative (ground) battery cable. Tag the cable and controls too warn against starting. WARNING