The position of the motor’s shaft in relation to the output shaft of the speed reducer is one of the factors that influence the performance and behaviour of gear motors.
In this regard, we can find two main variants: right angle gear motors a.k.a. worm gear motors and parallel shaft gear motors. If we take a look at their properties, efficiency, sound level or durability, we will notice significant differences that make them more or less suitable for each application. Want to know why? Keep reading.
Characteristics of right angle gear motors
Right angle gear motors are characterised by having a driveshaft (the motor’s shaft) and output shaft of the speed reducer that are 90 degrees from each other. Depending on the requirements for the transmission, shafts can cross on a single plane or on two parallel planes, which would result in an axial motion.
When referring to their design, we can achieve such a disposition using worm screws and worm wheels, being able to use gears of different types of tooth and even combine different types of gears. In the case of single stage speed reducers, bevel gears and worm drives see the most use. Regarding the latter, and since they work with short stages (with a high gear ratio), right angle speed reducers can offer self-locking features.
Most common examples:
Bevel geared right angle gear motors. Within these gear motors we can find those that use intersecting shafts that use straight, helical or spiral bevel gears.
Hypoid gearboxes with helical bevel gear trains in which shafts are set at a right angle with a displaced shaft. Here it is worth mentioning that bevel gearboxes offer higher gear ratios per stage than those of classic bevel gears.
Lastly, right angle speed reducers using bevel gears can be combined with other types of speed reducers, such as planetary speed reducers, allowing for a great versatility in applications due to the wide range of gear ratios.
Applications of right angle gear motors
This type of actuator is closely related to applications where there is a significant space limitation. Achieving the right figures for speed, torque and efficiency in small spaces is not that simple, and therefore, this gear motor may offer a performance that better fits our needs in this case. In addition to this concept, its compact design is a feature to keep well in mind.
We may also opt for this gear motor when our application requires an angular disposition between the actuator and the output.
Lastly, this model will be useful to us in cases in which the input shaft has to be hollow, or requires a set of attachments.
Some of its common applications may be as actuators in automatic sliding doors or window opening systems.
Disadvantages of right angle gear motors
Generally speaking, a right angle gear motor has a lower performance ratio than a parallel shaft variant. Here, bevel gear stages produce large thrust and radial forces. This results in an increase in loss of power for each stage of the actuator.
This type of gear motor tends to be noisier, especially in the case of hypoid gearboxes.
It has a complex design.
It has a low torque in single stage gear ratios.
Parallel shaft gear motors
In this case, the shaft of the motor and that of the speed reducer are in parallel planes, which allows us to work with very flat gearboxes.
The design of parallel shaft gear motors do not use bevel gears as right angle geared motors do. Instead, they use the following gear types:
Helical gears. They have teeth that are oblique in relation to the rotation axis. They can therefore transfer more power and speed. Additionally, they are the best type when looking for a silent, lasting actuator.
Spur gears. It is the most common model. The teeth in their toothed wheels are straight and parallel to the driveshaft of the speed reducer.
Double helical gears. These gears are used when there are significant thrust loads associated with the rotation required by the shaft itself.
Advantages of parallel shaft gear motors
High range of power and torque. Specifically, parallel shaft gear motors reach powers of up to 200 kW (268 hp[I]) and a rated torque of up to 20,000 Nm (14,750 lbsf.ft).
They offer better efficiency, since their performance is better with high torques and they bear high radial forces.
Low sound levels and vibrations.
As a disadvantage, they tend to have a greater size than other types of gear motors. This is due to the disposition of their components, which require more space.