How to Choose a Gearmotor
When tasked with choosing a new gearmotor, spending time researching and planning on the front end can lead to a big payoff in terms of overall efficiency and cost savings throughout the lifetime of the motor. Choosing a proper gearmotor will allow the application to operate at its optimal capacity and will ensure the motor lasts for many years.
Gearmotors, which are sometimes referred to as geared motors, are gearing and motor packages. These two-in-one combinations are designed to work together and are engineered for durability and reliability. Gearmotors are preferred in high-torque, low-speed applications since the motor is paired with a gear reducer.
Gearmotors are available in right angle and parallel shaft designs in both Alternating Current (AC) and Direct Current (DC) models. AC gearmotors are commonly used in conveyors, packaging machines, mixers, farm equipment, cranes and hoists. DC gearmotors are often found in conveyors, packaging machines, spreaders and low voltage or battery-operated equipment.
When selecting a gearmotor, the manufacturer has already considered all performance calculations and conducted extensive testing on the motor and gearing combination. While this makes the task much easier, below are four steps to follow to ensure you choose the right gearmotor for your application.
Choose a Gearmotor in Four Steps
Step 1: Review all application requirements
The first step is to be sure you know all your application requirements. Requirements to consider include:
- Application environment- temperature requirements, any IP ratings necessary, and any other application specific requirements
- General requirements- mounting type, size, orientation, envelope size, lubrication type
- Input power source- voltage, frequency, maximum current, control type
- Gearmotor specifications- weight, size, noise level requirements, maintenance requirements
- Performance needs- torque, speed, horsepower, starting/running torque
- Overhung load- the force exerted at right angles to a shaft beyond the outermost bearing. When that force exceeds the maximum rated capacity for the equipment, shafts and bearings become overloaded and wear out at a higher-than-normal rate. The problem with such a load is that it causes a bending force in the gearbox output shaft, which must be resisted by the reducer shaft as well as the bearings. Since an excessive overhung load can impact the gearmotor life, consideration on the mounting of the drive component close to the reducer will minimize the force as well as the negative effects on the bearings and shaft.
Step 2: Choose the proper gearmotor
Now that you have gathered and reviewed requirements for your specific application, it’s time to look at gearmotor specifications for the gearmotors you are interested in. By comparing these specifications with your requirements, you can find the best gearmotor for your needs.
Step 3: Know speed and torque requirements
You will want to match output speed and torque to the needs of your application. Once you have calculated these speeds, you can use the manufacturer’s performance curve to find a motor that suits your needs. Again, the benefit of choosing a gearmotor is that both the motor and gearing has already been designed and tested for compatibility and optimal performance.
Step 4: Testing
The manufacturer’s specifications and ratings are based on testing of the gearmotor rating. Since there are many variables in applications which may vary, it is important to test under the actual operating conditions to be sure the gearmotor operates properly. Be on the lookout for any high temperatures, loud noises, or signs of stress. If you find any issues with the gearmotor at this point, you will want to contact the manufacturer and discuss with an applications engineer.
When selecting/sizing a gearmotor, it is vital to take the time and put in the effort to properly select a gearmotor. If not done so, an impulsive decision and lack of testing can cause a host of problems with the gearmotor and could possibly damage the application. Although the gearmotor selection process can be difficult, a properly selected gearmotor will optimize an application to its peak potential and efficiency. Conducting the proper research when you have the opportunity to replace gearmotors can create efficiency and cost savings for your company over the lifetime of the gearmotor.