What is a coaxial gearbox (gear reducer)?

　　 What is a coaxial gearbox (gear reducer)?

　　 Coaxial gearbox (gear reducer)

　　A coaxial gearbox (gear reducer), also known as an in-line gearbox (reducer), has its drive shaft and output shaft aligned on the same rotational axis. Coaxial gearboxes typically employ spur gears, which are available in various configurations.

　　In a single-stage gear drive, the axes of the spur gears are parallel and fixed. The direction of rotation of the input and output shafts is determined by the number of gear pairs and may be either in the same direction or in opposite directions.

　　Even though a single straight‑tooth gear is not, in principle, a coaxial gearbox, two pairs of gears—four gears in total—can still be used to achieve concentricity. In this arrangement, the two pairs of gears are mounted in parallel on a single shaft.

　　A special type of coaxial gearbox is the planetary gearbox. Unlike a single spur gear, in a planetary gear set not all shafts are fixed. Spur gears can also have internal teeth. In a planetary gear reducer, multiple spur gears mesh between an internal‑toothed ring gear and an external‑toothed sun gear, all mounted on concentric axes. This is how the system derives its name. The specific design of these coaxial gearboxes ensures that the input and output shafts are arranged coaxially.

　　Another distinctive feature of planetary gearboxes is that not all spur gears need to rotate about their own axes to transmit torque. Spur gears with internal teeth are typically fixed, causing the input and output shafts to rotate in the same direction.

　　Compared with a single-stage spur gear, a planetary gear reducer offers exceptionally high power density. This is because the torque is distributed across the planet gears, enabling multiple teeth to be in mesh simultaneously. As a result, extremely compact designs and very high efficiency can be achieved. Multi‑stage gear ratios can also be obtained by arranging single‑stage internal gears in series within the same housing. The overall gear ratio is the product of the individual ratios of each planetary stage.

　　The method of converting speed and torque is the same as for a single spur gear. For example, with a gear ratio of 10:1, torque increases by a factor of 10, while speed decreases by a factor of 10 (ignoring transmission losses).

　　This series of helical‑gear coaxial gear motors/gear‑brake motors comprises seven sizes, with output rotational speeds ranging from 9 to 400 min⁻¹ and torques from 44 to 5,700 Nm.

　　We are a well‑known organization specializing in high‑quality, foot‑mounted helical gear reducers. Our comprehensive product range is widely used across various industries and sectors, systematically addressing their diverse needs. Moreover, thanks to their compact size and low maintenance costs, these products are highly favored by our esteemed customers.

　　 Feature

　　• Easy installation

　　• Outstanding performance

　　• Industry-proven design

　　 RM Series Helical Gear Motor/Reducer, Foot-Mounted

　　• Cast iron body

　　• The motor is directly connected to the gearbox and mounted parallel to the output shaft.

　　• Compact structure

　　• Can be mounted on the foot or connected using several types of flanges.

　　• Models with bearings specifically designed for agitators

　　 Example application:

　　• Conveyor

　　• Drive units for waste treatment plants

　　• Food industry

　　• Paper industry

　　• Cement plant equipment

　 　Parameters:

　　• Installation locations: B3, B5, B6, B7, B8, V1, V3, V5, V6

　　• Sizes: 7, 15, 30, 60, 120, 240, 450

　　• Levels: 2, 3

　　• Assembly versions: RM, RMFA, RMFB, RMFD

　　• Ratio: 3.55 - 80 • Torque: 44 - 5680 Nm

　　• Power: 0.3 - 29.5 kW

　　Advantages of a coaxial gearbox:

　　- The input shaft and output shaft are arranged coaxially.

　　- Extremely high efficiency

　　- Extremely high power density

　　- Compact design

　　- Suitable for a wide range of applications

　　- Easy to implement multi‑stage gearboxes, resulting in a high transmission ratio.