Frequently Asked Questions (FAQ)

DC Geared Motors Manufacturers - Hennkwell Ind. Co., Ltd.


Hennkwell Introduction

Hennkwell Ind. Co., Ltd. is Taiwan supplier and manufacturer in Mechanical Components Industry. Hennkwell has been offering our customers high quality Gear Motor, Geared Motor, 12V DC Gear Motor, Dc Gear Motor, 24V DC Gear Motor, DC Geared Motor, 12V DC Motor with Gear Reduction, Dc Motor with Gearbox 24V, Gear Box DC Motor, Planetary Gearbox since 1995. With both advanced technology and 20 years experience, Hennkwell always make sure to meet each customer's demand.



Hennkwell integrate in-house production of own motors and gearbox over three decades of industry experience, we also offer customization to meet with client design.
DC gear motors are applied to plenty of devices not just home appliance but alsocommercial use. With various operating conditions, we could adjust our gearmotor parameters to reach the Max. efficiency.

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Before using a gear motor, make sure you follow the instructions and precautions as followed.

Inappropriate installation or usage will cause the gearbox/motor to break down.


1)Please do not strike a gear or sprocket into the output shaft by hand or hammer or something similar. It can cause the shaft to be bent or damaged and shorten the bearing's life.

2)Please do not modify the shaft, please inform Hennkwell to perform this procedure.

Motor Connecting and Operation to your Application

1)If the machine where the motor is connected to, generates strong vibration or shock's. It can damaged the motor, in this case, a cushion will be required to solve this issue.

2)When using a chain or a belt, and if a stopper is installed at the area where the product stops by being against the stopper during the transmission.

Please pay extra attention to the proper adjustment of the correct degree of the shaft.It is crucial to the length of the motor's life.

3)Please make sure there is no over-loading on the shaft when using the motor, the permissible load will be advised on our dynamic test report as a guideline. It is available upon request. When mounting the shaft, when mounting your machine to the motor's shaft,please mount as close to the root of the shaft as possible.

4)Be careful so there is no excessive tightness on the chain and belt. Both too loose or too tight can cause vibration or excessive pressure that could damage the motor.

5)During installing gear motors, do not use wrenches or the other tools to adjust the designed angle or fixture of output shaft While POWER-OFF. The proper way to adjust the angles is under condition of "POWER-ON". To avoid the damage of gearbox, please ensure the motor is electrified once you intend to adjust the angles of output shaft.

6)When soldering to connect the power lead on the (+)&(-) terminals,the soldering time should be completed within 3 seconds for the purpose to avoid too much soldering leftover sticking on the metallic bottom of the motor.

(Tips: the temperature of solder head had better control between 340゚C ~ 400゚C)

7)Do not operate the motor at an higher voltage than on the label.

Gearbox Maintenance

1)Make sure there is no dust, fluid that penetrate inside the gearbox. If the motor is going to be condition,working under humid condition please kindly equip the motor with a plastic tube or cover to protect the motors.

2)Please do not overload on the gearbox, for acceptable range of loading,please refer to our dynamic test report, which is available upon request.

3)To avoid the damage of gearbox or break the driving shaft, please do not perform any machining such drilling,cutting and broaching on the shaft or any other parts without consulting Hennkwell.

Motor Usage and Maintenance

1)Do not decompose the motor parts, the characteristics will change.

2)When the brush of the motor has been worn out, the insulation resistance will be reduced.Therefore please measure it regularly.

3)Please make sure the screws or bolt being used to mount the motor has enough depth,otherwise the vibration will damage the motor.

4)Please do not attempt to change the running direction (polarity) while the motor is rotating, please turn-off the power, make sure the motor stopped completely at least 5 seconds, and then change the running direction.(CW/CCW)

5)If working under a application with unstable current supply and high temperature, please add an over-heat protector or a over-current protector to protect the motor.

6)When the motor is working under a supply current or supply voltage that is under therecommended value,it will decrease the torque and speed. In another words, if the motor works at the current or voltage above the recommended value, it might damage the motor. Please operate the motor at its recommended supply current and voltage.

Other cautions

Please ensure that to further improve our products, specifications, the method of use of our products and so on described in this catalogue may be change without any notice.

Unit Conversions

1 = 13.8874 = 0.867962 = 9.8 mNm = 0.07233 lb.ft = 1000 = 9.8 Ncm
1 = 0.0720 = 0.0625 = 7.06155 mNm
1 = 1.15212 = 16 = 112.985 mNm
1 mNm = 0.010197 = 0.1416 = 0.8851

1 inch = 2.54 cm = 25.4 mm = 0.00833 ft
1 mm = 0.0394 inch = 0.0033 ft = 1000 μ
1 ft = 12 inches = 304.8 mm = 30.48 cm

1 kg = 1000 g = 2.205 lb = 35.28 oz
1 oz = 0.0283 kg = 0.0625 lb = 28.35 g
1 lb = 0.4536 kg = 16 oz = 453.6 g

T(℃) Celsius = 5/9 T (℉)-32
T(℉) Fahrenheit = 9/5 T (℃)+32

Terminology for the Gear Motor
  1. Rated Voltage: The specific voltage required by the gear motor under normal working conditions for which its optimal performance is displayed. Typically, the power supply voltage should not vary by more than 10% of the motor's rated voltage so as not to negatively affect the speed, current, torque, and temperature. An operation requiring over-voltage will result in a higher current running through but the gear motor may experience a shortened life span. An under-voltage operation will not be running at peak levels resulting in experiences of lower current, efficiency, and torque. Therefore, maintenance of the proper voltage is an important factor in obtaining good performance.
  2. No-Load Speed: The revolutions per minute with no load applied to the drive shaft. This is linearly proportional to the applied voltage.
  3. Rated Speed: The most favorable speed (rpm) of the gear motor shall be a rated voltage and rated output torque.
  4. No-Load Current: Current drawn at rated voltage under no-load conditions. The current is caused by internal mechanical friction losses occurring between the brush and commutator segments as well as the bush/bearing and shaft friction.
  5. Rated Torque: The rated torque is a loaded turning force under rated voltage. The applied gear motor may be operated only at the allowable level. Operation at a load higher than rated torque for the gear motor is never recommended.
  6. Starting Torque: The torque delivered by a motor at the instant and maximum current. Starting torque is much higher than rated running or full load torque.
  7. Duty Cycle: The relationship between the operating and rest time, or repeatable operation at different load. Duty cycle in percentage values is equal to the ON-time divided by the sum of the On-time plus the Off-time x 100%. The DC brush gear motor can operate under intermittent or continuous duty within the temperature limits. But, most micro DC brush gear motors are often used within a short time of intermittent duty.
  8. Duty Cycle
  9. Duty Cycle(%)= On-time ÷ (On-time + off-time) × 100%
    Maximum Allowable Torque
    : The running torque can be increased in accordance with the bigger gearbox reduction ratio. However, the practical limitation of loading torque shall be affected by the gear material, rising temperature, and some other conditions. Please refer to the gearbox specifications on page.
  10. Gear Train Transmission Efficiency: Expressed in percentage values, the transmission efficiency determines the friction between the bush and gears as well as the resistance of lubricant, etc. The efficiency is about 81% when the gear ratio is in the first gear section and 73% in the second section; that is, as the gear (reduction) ratio becomes greater, the section number increases and the transmission efficiency decreases by 66%, 59%, 53%, and 48%.
  11. Radial Load: A force pushing or pulling the side of side of the output shaft. If the force exceeds the allowable radial load for the motor or gear motor, it will cause the output shaft to break and cause premature wear of the output shaft bearing/bush as well as the gears.
  12. Axial Load: A force on the output shaft into or out of the motor or gear motor. If the force exceeds the allowable axial load for the motor or gear motor, it will cause premature wear of the output shaft bearing and gearing.

The relationship between torque (T), speed (N), current (I), efficiency (E), and output power (P), as below figures shown, represents the characteristics of a Hennkwell micro DC gear motor. Figure-1 shows how the loaded torque on the gear motor is in proportion and is directly related to the output speed and current. Figure-2 shows how the no-load speed and starting torque also change proportionally to a different supply voltage. The output speed at a given voltage is parallel to those at other voltage.

As the load on the gear motor increases, speed will decrease accordingly. Additionally, the current (I) is an inverse relationship to torque. The peak of output power (P) and efficiency (E) exist at different torque points, as indicated in figure-1. Output power presents a curve by torque while efficiency (E) decreases straight down beyond the peak normally. Maximum output (Pmax) is at half the starting torque (Ts) point and maximum efficiency exists at a much lower point of torque. A gear motor's basic rating point is lower than its maximum efficiency point. Load torque can be determined by measuring the current drawn when the gear motor is installed in a machine where actual load value is known.

Moreover, the actual operating load torque must be selected lower by a few times than the stall torque. The purpose is to prolong the motor’s life and to bring out the most optimal performance. Besides the full load torque has to operate within the maximum allowable torque limit, although the gear motor could produce an over torque.

The maximum efficiency is generally much lower than the maximum stalled torque, because although the motor can operate at a higher torque than the maximum efficiency torque, it can also shorten the motor’s life due to high current generated. Thus, selecting a motor with a torque that is several times higher than the actual operating torque is strongly recommended.

Gear Motor Characteristics
Gear Motor Characteristics
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