1-15-96 96-8100
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TABLE OF CONTENTS
HAAS AUTOMATION, INC.
TROUBLESHOOTING
SERVICE
MANUAL
VF-SERIES
5. GEARBOX AND SPINDLE MOTOR
The gearbox cannot be serviced in the field and must be replaced as a unit. NEVER remove a motor from a VF-Series mill
that has a gearbox as this will damage the gearbox and void the warranty.
5.1 NOISE
When investigating complaints of gearbox noise, also refer to "Spindle" troubleshooting section. Gearboxes can be dam-
aged by failed air solenoids, gearshift cylinders, or bearings, resulting in noisy operation. It is not likely that poor finish on
a workpiece can be attributed to a bad gearbox.
´ Excessive or unusual noise coming from the gearbox and/or spindle motor.
Operate the machine in both high and lowgears. Monitor the gearbox for noise in both gear positions and if the pitch of
the noise varies with the motor or the output shaft speed.
Ø If the noise only occurs in one gear throughout the entire RPM range of that gear position, the problem
lieswith the gearbox, and it must be replaced ("Spindle Motor & Transmission" section).
Ø If the noise occurs in both gear positions, disconnect the drive belt and repeat the previous step. If the
noise persists, the gearbox is damaged and must be replaced, ("Spindle Motor & Transmission" sec
tion).
Ø With the drive belt disconnected, run the machine at 1000 RPM in high gear. Command a change of
direction and listen for a banging noise in the gearbox as the machine slows to zero RPM and speeds
back up to 1000 RPM in reverse. If the noise occurs, the motor has failed and the gearbox must be
replaced.
5.2 GEARS WILL NOT CHANGE
´ Machine will not execute a gear change.
NOTE: Whenever a gear change problem occurs, an alarm will also occur. Refer ALARMS section to diagnose each
problem before working on the machine.
When a gear change is performed, the following sequence of events occurs:
1) If the spindle is turning, it is commanded to stop,
2) Pause until spindle is stopped,
3) Gear change spindle speed is commanded forward,
4) Pause until spindle is at speed,
5) Command high or low gear solenoid active,
6) Pause until in new gear or reversal time,
7) Alarm and stop if max gear change time elapsed,
8) If not in new gear, reverse spindle direction,
9) Turn off high and low gear solenoids.
l Check the air solenoid assembly on the solenoid bracket (rear of gearbox). If the solenoid operates properly and the
limit switches on the gearbox operate properly, the problem lies with the gear change piston.
Replace the gearbox ("Spindle Motor & Transmission" section).
l Check contactor CB4.
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