Problem 4: Sparks at the commutator and/or rapid brush wear. c. Brush movement causes arcing and brush wear: Check the brush springs for cracks, and overheat signs (blue). Compare spring force with a new brush spring. Check the brush holder for oversize (larger size than for brush). Replace the brush spring if necessary. d. Loose brush leads or motor bus bar connections. Loose cable connections at motor terminals. Results are: Probable Cause: 1. Worn brushes: Make a replacement of the brushes. See New Brush Installation And Brush Inspection in Testing And Adjusting. 2. Overheating (too much heat) of the traction motor: Check for an overload motor or a motor with defects.
See Armature Commutator Inspection in Testing And Adjusting. Decrease the current limit (C/L) adjustments if set too high. See the MicroController System Operation module. Test the plugging rate, if set too short it will cause arcing and wear at the brushes. The duty cycle is too heavy, change the duty cycle. (1) High resistance and heating. (2) Faster brush wear. Check brushes for tight-connections. Replace the brushes if leads are loose in brush material. Check all cable and wire connections for tightness. e. Wrong grade of brushes installed that are not adaptable to the motor: Make sure all the brushes are of DAEWOO standards. Do not use other brands of brushes. 3. Defective drive motor:
See Armature Commutator Inspection in Testing And Adjusting. f. Possibly heavy working condition that causes too much motor heat and rapid brush wear: Make a replacement of the brushes and make sure the brushes are seated. See New Brush Installation and Brush Inspection in Testing And Adjusting. Check the brush springs for the correct installation and for the correct spring usage. Too strong a spring rate will increase amperage draw and brush wear rate. Prevent operation in stall condition. Excessive (too much) duty cycle which increases motor temperatures and rapid brush wear. a. Commutator bars burnt in two or more positions at 180Ў apart because: (1) Armature bars open.
Make a replacement of the armature. (2) Motor was stalled against a heavy load while power discharged and caused the two bars, in contact with the brushes, to burn. NOTICE Too heavy a load can stall the motor, and result in a failure to the drive motor. 4. Overload of the drive motor such as: towing loads, constant ramp operation, chiseling (hydraulic actions that are not practical) loads and dragging (pull or push loads on the ground) loads: Operator training for better working practices. Add an auxiliary cooling to the drive motors. (3) Short circuit in the armature. See Armature Tests in Testing And Adjusting. 5.
Current limit (C/L) set too high that causes too much current consumption through motors in the transistor range: Decrease the current limit (C/L) adjustment to the correct setting, see the MicroController System Operation module. (4) Armature not in balance, out of round, off center or with high commutator bars. This causes the brushes to bounce (move up and down). Make sure the diameter is the same all the way around and is in center line with the shaft. See Specifications. 6. Drive motor, armature or field windings have a defect that results in high current draw at low torque output: See Armature Tests and Field Coil and Terminal Tests in Testing And Adjusting. b.
Dirty motor that has a metallic or carbon dust. this dust is a conductor which causes electrical shorts, increase amp draw and decrease drive motor output: Remove any dirt with air pressure. Power Train Testing And Adjusting 11