Why a Gearhead

Portescap manufactures high performance miniature gearheads that are subjected to rigorous quality tests during manufacturing. With a range of planetary and spur gearheads from 8 mm to 40 mm in diameter, Portescap can offer an entire drive train based on its motor gearbox solutions. Resident experts in gear technology can select metal or plastic gears based on your application need. Both technologies feature sleeve or ball bearing options. Also, customizations can be offered such as special grease, special shaft, mounting, etc., to provide you with the exact solution you require.

Every application has power requirements and specific values of speed and torque. With a load demanding high torque at low speed, use of a large motor capable of developing the torque would not be economical, and system efficiency would be low. In such cases, a better solution is to introduce some gearing between the motor and the load. Gearing adapts the motor to the load, be it for speed, torque or inertia. The motor/gearbox assembly will provide greater efficiency and will be an economical solution.

Reduction Gearboxes Using Spur Gears
This gear technology offers advantages in current-limited applications where the lowest input friction and high efficiency are essential. The broad range of Portescap spur gearboxes is well adapted to our motor lines, spanning the range of motor diameters.

Planetary Gearboxes
The main advantages of Portescap planetary reducer gearboxes are their high rated torque and high reduction ratio per gear train, utilizing high-quality composite materials. The all-metal planetary reducer gearboxes have a very compact design with excellent performance and lifetime.

High Speed Planetary Gearboxes
This high-performance product line was designed for use on brushless DC motors with iron core windings. The gearboxes tolerate input speeds in the range of 10,000 to 70,000 rpm and output speeds of several 1,000 rpm. This facilitates a motor-gearbox unit of very small dimensions that can provide extremely high values of speed and torque.


Principle of the Spur Gearhead:
The pinion of radius r1 and number of teeth z1 drives the input wheel of radius r2 and number of teeth z2.
The reduction ratio per train “i” is z2:z1 which is equal to r2:r1.

Principle of the Planetary Gearhead:
The pinion S (sun pinion) having “s” teeth is driving the planets P (3 or 4 per train) which have “p“ teeth and are fixed to the planet carrier.
A = stationary annulus with “a “ teeth.
The reduction ratio per train is i = (a:s) +1.

Gearhead details

Spur gear concept: Only one transmission point per trainLow friction per train
Arrangement of several trains as intended by the designer
Input and output shaft not necessarily in line
Dual output shafts possible
Direction of rotation of the gearhead output is different from the motor's, when odd number of reduction stages
Good efficiency, about 0.9 per train
Long gearbox of smaller diameter or short gearbox of large diameter
Free choice for placing the motor relative to the output shaft
Mounting of a sensor, potentiometer, etc.
Planetary concept: 3 or 4 transmission points per trainReduction ratio per train is higher but so is friction
Can transmit higher torques
Input and output of a train have the same direction of rotation. Less backlash
Less trains for a given reduction ratio efficiency; about 0.85 per train. Very compact gearbox for its performance
For any number of trains, the load always rotates in the same direction as the motor.
Smaller shock in case of a rapid reversal of motor rotation

Planetary technology

Spur technology