Please compare your gearmotor’s symptoms to find possible causes to fix the issues.

Failure Possible causes Measures
The noise in reducer fasteners The loose of fasteners Tighten bolt/nut to specified torque, replace damaged bolt/nut
Reducer’s noise changes Gear tooth get damaged Contact customers service department to check all the gear, replace damaged bolt/nut
Bearing clearance large gap Contact customer service department, adjust bearing clearance
Broken bearing Contact customer service department, replace damaged bearing
Too high working temperature High oil level of the inside box body Check oil surface height, adjust if necessary
Long-used oil Contact customer service department, check the last time oil change, replace if necessary
Oil gets severely contaminated Contact customer service department, change oil
For reducer that equipped with lubricating oil cooling system, too low or too high coolant flow rate Comprehensively regulate import and export of pipeline valves, check the free flow of water-cooling device
Too high temperature for coolant Check temperature and adjust according to demand
Too low oil flow through water cooling device, reason: oil filter seriously blocked Oil filter cleaning
Oil pump mechanical failure Contact customer service department, check whether the function of oil pump is normal or not, carry out repair or change the oil pump if necessary
Reducer that is equipped with fan, fan cover’s air inlet and/or body get seriously polluted Fan cover and housing cleaning
Reducer equipped with cooling spiral pipe: cooling spiral tube fouling inside Contact customer service department, clean or replace spiral pipe
Too high temperature in bearing Too high or too low oil level in reducer box Check oil surface height at room temperature and refueling on-demand
Long-used oil Contact customer service department, check last time oil change
Oil pump’s mechanical failure Contact customer service department, check whether the pump work normally or not, repair or change a new oil pump
Broken bearing Contact customer service department, check the vibration measuring data, check and change the bearing according to the need
Bearing amplitude rise Broken bearings Contact customer service department, check the vibration measuring data, check and change the bearing according to the need
Damaged gear Contact customer service department, check and change gear according to need
Non-return device temperature is too high, check function failure Damaged device Contact customer service department, check and change non-return device according to need
Reducer leakage Enclosure cover or joint sealing adverse Check seal and connection, if necessary, change a new seal
Radial shaft seal failure Contact customer service department, change new radial sealing ring
Have water in oil Have sundry in oil Check if water does exist in oil, and laboratory analysis.
Lube oil cooler or the cooling spiral pipe failure Contact customer service department, find out leakage position, change water cooler.
Reducer machine ventilation when come up with cool air and condensation Use the appropriate heat preservation material to guard the speed reducer, close air export or change its direction on structure
Pressure alarm monitoring device, equipped with a pressure lubrication device, lubricating oil water cooling and air cooling is the reducer Oil pressure<0.5bars At room temperature check the oil level height, according to the need to go check the oil filter, according to the need to change, contact the customer service department, check the normal functioning of the oil pump, oil pump repair or replace
Double switching filter indicator emit alarm Double switching filter clogging According to the specification toggle switch filter will be blocked filter down and clean up
Oil supply system fault See operating instructions on oil supply system description
Motor does not start Power interrupt Check wiring, when need correct
Fuse fusing Replace the fuse
Motor protection device has action Check motor protective device Settings are correct, when need discharge failure
Motor contactor action, not in the control system failure Check motor contactor control, when need troubleshooting
Motor not starting or starting difficulty Motor should be delta connection method, but it is a star connection Correct wiring way
Voltage or frequency gravely deviates from the rating when starting at least Try to improve the power supply; Check the power cord section
Direction of rotation error Motor wiring error Swapping two phase line
Rumble and current consumption Damaged winding Motor must send professional repair shop repair
Rotor windings touch
Fuse fusing or motor protective device immediately action Conductor short-circuit Short-circuit eliminate
Motor short circuit Professional repair shop discharge failure
Connection wires error Correct connection mode
Electrical grounding short circuit Professional repair shop discharge failure

The starting of the speed reducer (gearmotor) should, if possible, operate for no more than a few hours under no-load conditions. If there is no abnormality, the load may gradually increase. The reducer must be monitored during operation. Oil temperature (Design temperature of reducer for continuous operation: Continuous operation for mineral oil use, use synthetic oil at 90 ℃, high temperature, maximum temperature can reach 100 ℃ during short time operation); Running noise change; The housing and shaft seal may leak. Accurate oil level height.

Measures Frequency
Oil temperature check Daily
Abnormal sound silencer check Monthly
Confirmation of reducer leakage Monthly
Check oil level height Before starting the gear reducer
Checking the water ratio of the oil 400 hours after start of operation
1st oil change 400 hours after startup, at least once a year
Followed oil change Every 18 months or 5000 hours
Oil filter cleaning Every 3 months
Screw ventilation valve cleaning Every 3 months
Clean fan and fan covers and decelerating boxes Depending on your requirements or cleaning with oil change at the same time
Check cooling coil scale About every 2 years or at the same time with oil change
Oil water cooler check At the same time with oil change
Bolt fastening degree check After the first oil change, once every two oil changes
Comprehensive reducer check About every 2 years or at the same time with oil change
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Pre-sale services 1. Select equipment model.
2. Design and manufacture products according to clients’ special requirement.
3.Train technical personal for clients
Services during selling 1. Pre-check and accept products ahead of delivery.
2. Help clients to draft solving plans.
After-sale services 1. Assist clients to prepare for the first construction scheme.
2. Train the first-line operators.
3. Take initiative to eliminate the trouble rapidly.
4. Provide technical exchanging.

After using the reducer for a long time, a comprehensive inspection should be carried out so that we can find some hidden dangers in time. In order to make the equipment run efficiently, we generally refuel in time. But we should also solve the oil spill in time.

1. Carry out the maintenance process carefully. When overhauling, you must carefully implement the process regulations. The oil seal must not be installed reversely, the outer edge must not be deformed, the spring must not fall off, the joint surface must be cleaned, the sealant must be evenly applied, and the amount of oil must not exceed the scale of the oil scale.

2. Improve the vent cap and inspection hole cover. The internal pressure of the reducer is greater than the outside atmospheric pressure is one of the main reasons for oil leakage. If the pressure inside and outside the machine is balanced, the oil leakage can be prevented. The inspection hole cover must be opened every time the oil is added. Once opened, the possibility of oil leakage will increase once, and leakage will occur in the original place. For this reason, an oil cup type vent cap was made, and the original thin inspection hole cover was changed to 6mm thick, and the oil cup type vent cap was welded to the cover. The diameter of the vent is 6mm, which is convenient for ventilation. The pressure is equalized, and the oil is added from the oil cup when refueling, without opening and checking the hole cover of the reducer, reducing the chance of oil leakage.

3. Wipe. The static sealing points can generally be leak-proof through treatment. However, due to the aging of the seals, poor quality, improper assembly, and high shaft surface roughness, the dynamic sealing points still have small leakages. The working environment is poor, and coal dust sticks to the shaft, making it appear oily. Therefore, it is necessary to wipe off the oil on the shaft after the equipment stops running.

4. Maintain a smooth flow. To prevent the excess lubricating oil thrown on the bearing by the reducer gear from accumulating at the shaft seal, the excess lubricating oil needs to flow back to the oil pool in a certain direction. An oil return groove inclined toward the inside of the machine is opened in the center of the lower shell of the bearing seat, and a gap is also opened at the straight opening of the end cover.

5. New sealing materials are used. For static sealing point leakage, a new type of polymer repair material can be used for sticky plugging, so as to achieve the purpose of eliminating oil leakage.

6. Improve the shaft seal structure.

The oil leakage of the reducer is mainly related to some accessories. Especially check the fuel tank at this time. Note that the oil does not need to be very full, otherwise the possibility of oil leakage may increase. The other is to check the tightness of the equipment.

Main Technical Parameters of S series / R series / F series / K series Gearmotor


Gear type

Gear stage

Ratio range

Power range



Weight range


S series

Helical + worm gear





(7 sizes)


R series

Coaxial helical gear





(14 sizes)




F series

Parallel shaft helical gear





(11 sizes)




K series

Helical gear + bevel gear + helical gear





(12 sizes)


RKFS helical geared motor SEW