Symptom

Possible Causes

Corrective Action

Unit Fails to Operate

No power

Consult local power company.

Blown fuse or open circuit breaker

• Replace fuse or reset circuit breaker.

• Check for grounded motor winding.

Voltage too low at motor terminals due to line drop

• Consult local power company.

• Check for poor connections Increase wire size.

Improper line connections

Check connections against diagram supplied with unit.

Defective motor

Repair or replace.

Defective control switch or starter

Repair or replace.

Overload, motor starter tripped

• Check and reset overload relay in starter.

• Check heater rating against gear motor nameplate current rating.

Gear motor may be overloaded

• Reduce load or increase gear motor size.

• Check load and alignment of coupling.

Unit Stalls During Operation

Overload

Determine cause of overload and either reduce load or increase gear motor size.

Low voltage

Verify that nameplate voltage is maintained

Unit Operational, No Output

Defective gear(s)

Check and replace if necessary.

Gear loose on shaft

Check and replace if necessary.

Loose coupling, sheave or sprocket

Check and tighten if necessary.

Sheared key on output shaft

Replace key and inspect keyway for damage.

Intermittent Rotation of Output Shaft

Damaged intermediate gear caused by shock load

Replace and if possible, avoid shock load.

Excessive Noise

Bearing worn or damaged

Replace.

Belt or chain too tight

Adjust tension.

Overhung-load exceeds rating and causes bearing wear

Correct load and/or replace bearing.

Defective gear(s)

Replace.

Output shaft misaligned

Realign.

Loose sheave or sprocket or misaligned coupling

Tighten set screw(s) and realign coupling.

Defective motor winding

Repair or replace.

High or unbalanced voltage

Check wiring connections and consult local power company.

Three-phase motor running single-phase

Check for open circuit, blown fuse or unbalanced voltage.

Unit Overheats While Running Under Load

Overloaded, belts or chain too tight

Reduce load, increase gear motor size.

High or low voltage

Check voltage at motor connections, should not be more than 10% above or below.

Faulty connection

Check and tighten if necessary.

Dirt blocking ventilation openings

Clean motor.

If three-phase, one phase may be open

• Check lines for open phase.

• Check voltage with gear motor disconnected.

• One fuse may be blown.

If three-phase, unbalanced supply voltage

• Check for faulty connections.

• Voltage on all three lines should be balanced within 1%.

Defective motor

Repair or replace.

Unit Does Not Come Up to Speed or Takes Too Long to Accelerate

Voltage too low at motor terminals

• Check for poor connections.

• Increase wire size.

• If three-phase, check for voltage unbalance.

Starting load too high

• Unit may be under size to start load.

• Increase unit size.

Load contains a bound condition

Clear condition.

Excessive loading, tight belts or chain

• Reduce load and increase unit size.

• Adjust belt or chain tension.

Defective gearmotor

Repair or replace.

Inadequate starting torque

High inertia load

Replace with larger unit.