The terms you often meet when first encountering a cycloidal gearbox can be organized into reduction ratio, input and output shafts, eccentric motion, and the Pinless structure. This article explains, in a natural way, the core gearbox terminology that a beginner needs to understand the structure and operating principle of a cycloidal reducer.
Table of Contents
Reduction Ratio, Input Shaft, Output Shaft: Basic Gearbox Terminology
Key Summary The reduction ratio means the ratio between the number of input-shaft rotations and output-shaft rotations. The input shaft connects to the motor, and the output shaft connects to the robot joint or drive system.
The reduction ratio is one of the most basic terms for a reducer and, literally, means the ratio of reduction. If the structure is one in which the output shaft turns once while the input shaft turns many times, it is a reducer with a large reduction ratio. The larger the reduction ratio, the slower the output shaft’s rotation speed becomes, but the greater the torque.
The input shaft is the shaft connected to the motor that receives rotational motion, and the output shaft is the shaft that transmits the reduced rotational motion to an external robot joint or drive system.
Between these two shafts, an output mechanism such as the cycloidal disc works together to perform the task of converting rotation into torque.
Surface Contact and the Cycloidal Curve: Structural Terms
Key Summary Surface contact means a state in which multiple tooth profiles on the disc engage the case-side structure at the same time, while the cycloidal curve is the mathematical curve used to machine the outer profile of the disc.
Surface contact is one of the important structural characteristics of a cycloidal reducer. It refers to a state in which the multiple tooth profiles on the outer rim of the disc engage the structure inside the case (the traditional pins, or the Bonsystems Pinless structure) at the same time. Because multiple tooth profiles, rather than a single one, share the load simultaneously, a characteristic that is strong in handling external shock loads is created.
The cycloidal curve is a mathematical curve derived from the path traced by a point on a circle as the circle rolls along a straight line or another circle. The outer rim of a cycloidal reducer’s disc is machined as a variant of this curve.
Looking at these gearbox terminology helps one understand a cycloidal reducer not as a simple reduction device, but as a motion mechanism refined through mathematical principles for accurate operation.
Slim Package, Pinless Structure: Bonsystems-Related Gearbox Terminology
Key Summary A slim package means a reducer with a thin form, and the Pinless structure means a cycloidal structure that removes the pin parts inside the case.
A slim profile literally means a reducer with a thin, slim form. It has established itself as a core component category in humanoid and collaborative robot applications that must achieve accurate power transmission even in confined joint spaces.
The Pinless cycloidal structure means Bonsystems’ own cycloidal reduction structure that removes the many pin parts once arrayed inside the case. Composed only of external and internal gear teeth without pins, it reduces the part count and lowers the pin-level wear variables.
The Pinless structure is applied in the Bonsystems BCSA V4 series actuators and in the BSR reducer 070 and 080 series.
Wide Reduction Ratios in a Single-Stage Structure, Actuator: Application Terms
Key Summary A wide range of reduction ratios in a single-stage structure is a strength of the cycloidal approach, and an actuator is a component that integrates the motor and reducer elements into a single module.
The cycloidal approach can create a wide range of reduction ratios within a single-stage structure. Because there is little need to stack multiple stages for large reduction, it is easy to keep the package thin, and the part count itself is easy to simplify.
An actuator means a drive component that integrates the motor, reducer, and other elements into a single module. When an integrated component is introduced as a module at the system design stage, the variety of parts and the wiring and alignment work can be simplified, enabling part minimization at the system level.
When beginners organize these gearbox terminology, it helps them connect and understand cycloidal reducers and actuators at the level of system design.
FAQ
Q: Among gearbox terminology, what exactly is the reduction ratio?
A: The reduction ratio means the ratio between the number of input-shaft rotations and output-shaft rotations. In general, the larger the reduction ratio, the slower the speed but the greater the output torque.
Q: What does eccentricity mean in a cycloidal reducer?
A: Eccentricity means a state in which the center of rotation is slightly offset from the original axis. In a cycloidal reducer, an eccentric cam connected to the input shaft moves the disc from a slightly offset position to generate motion.
Q: What does surface contact mean?
A: Surface contact means a state in which the multiple tooth profiles of the cycloidal disc engage the structure inside the case through surface contact and share the load. It is one of the core characteristics of the cycloidal approach, which is strong in handling external shock loads.
Q: Are a slim package and a Pinless structure the same thing?
A: The two terms are different concepts. A slim package means a thin form, while the Pinless structure means a cycloidal reduction structure that removes the pin parts inside the case. Bonsystems combines and applies the two together.
Q: How is an actuator different from a reducer?
A: A reducer means a power-transmission component whose function is to convert the motor’s rotational force into torque, while an actuator means a component that integrates the motor, reducer, control elements, and sensors into a single module.
