DC motors are the driving force behind many battery-operated devices in dozens of industries throughout the world. Often these motors are paired with a gearbox, as without one the shaft speed of the DC motor can exceed application requirements. A DC motor’s shaft speed can be in the region of 1500-6000 RPM and the gearbox can control and reduce the shaft speed making the motor and the application more reliable, as well as increasing the torque output.

Implementing a gearbox into your application can be hugely beneficial and is in some cases essential, but it is important to identify whether a gearbox is a) needed and b) suitable for the application. For some applications adding a gearbox can actually be detrimental and can reduce rather than improve performance depending on the application. Take an electric fan for example, the faster it can spin the better it does its job, so the shaft speed doesn’t need to be reduced to be suitable.

Other applications, on the other hand, will require a gearbox. The motor on a sliding door for example, where the shaft speed needs to be controlled.

Benefits of using a gearbox

There are various benefits of reducing the shaft speed and increasing the torque which includes:

  • Cost-effectiveness – The most cost-effective means of reaching the required torque is a smaller motor combined with a gearbox, rather than a larger motor.
  • Compact design – Using the smaller motor alongside a gearbox can ensure a more compact design but with the required power for the application. The gearbox can add more torque in a small space which can be ideal for driving slow shaft speeds. Using a motor alone means the slower it needs to go, the larger and more cumbersome the motor needs to be.
  • Slow speed If your motor needs to run at a slow speed a gearbox is the best way in achieving this. 
  • Heavier loads – The higher the torque the heavier the loads a conveyer could transport for example. Therefore a motor alone may not have the torque output to move a load and will quickly fail.
  • Bespoke applications – Gearbox and DC motor combinations can be tailored to the precise torque and speed required for a specific application. A gearbox provides a wider range than would be available purely in a DC motor.

Naturally, a DC motor and associated gearbox isn’t suitable for all applications and choosing the most efficient equipment for the requirements is key. The most suitable applications include:

  • Low-speed but high torque requirements.
  • Peristaltic pumps or large rotating turntables.
  • Direct drive applications such as small robots.
  • Single assembly processes where multiple wheels could have independent drives.

As with anything, the solution has to be suitable for the problem, which means there are times when adding a gearbox to a DC motor may not be the most efficient solution. These could include:

  • Closed loop applications – these become more problematic with a gearbox, and although encoders or pots can be used, the accuracy is less than 100%.
  • Inefficiency – With many planetary gearboxes as much as 25% (and more depending on ratio) of rotary power is wasted in heat and noise, which for some applications means more input power is required which could be impractical. 
  • Maintenance – Adding a gearbox can mean there is another piece of hardware which can go wrong and therefore will need to be repaired. This can cost in both financial terms but also in time if the application is off-line.

It is essential when choosing a motor and gearbox that you choose the most effective one for the application required and assess whether speed or torque is more important for your application as well as looking at the space for installation. There are various types of gears which include a planetary, parallel shaft, right angle worm and right angle planetary (bevel) gears.

Worm Wheel Gearboxes

One of the most common types of gear used with both AC and DC motors is the worm wheel gear and it can be found in applications in multiple industries across the world. Some applications and industries are more suited to a worm wheel gear in an electric motor gearbox.

These gearboxes are used alongside electric motors to change the torque or output speed and use a traditional toothed wheel gear. The two sections of the gear are the wheel and the ‘worm’, or shaft with a spiral section that engages the wheel during use.

The electric motor applies rotational energy to the worm, which circulates against the wheel and is pushed via the teeth. This rotates the load. Gearboxes can come in a right angle or inline orientation and the type of gear used depends on application requirements.

One of the downsides of this type of gear is that the sliding motion of the worm wheel gears causes lubricant to be wiped away faster meaning it needs to be replaced more often. Some self-lubricating materials can be used to combat this. Worm wheel gearboxes are incredibly versatile and can be found in a number of applications including:  

There are two main benefits to a worm wheel gear which are; they are quiet so energy isn’t wasted on noise and they are compact meaning they work well in space-limited applications.

At Parvalux, we pride ourselves on our high-quality and reliable motors and gearboxes. Parvalux electric motor gearboxes can be built to any size and specification, to accommodate your industry needs. We also supply motor gearboxes in standard variations. Just give us a call to discuss the most appropriate gearbox options for your requirements or take a look at our range of gearboxes here!