Hollow Shaft Vs. Solid Shaft Encoders: Choosing The Right Fit for Precision Motion

In precision motion control, rotary encoders are the eyes and ears of the system. Selecting the right encoder type—hollow shaft or solid shaft—can significantly impact machine performance, installation complexity, and long-term reliability. As a source factory with deep expertise since 2001, Shanghai Hengxiang Optical Electronics Co., Ltd. offers both variants to match diverse industrial and defense needs.

Solid Shaft Encoders: The Classic, Robust Workhorse

A solid shaft encoder features a protruding shaft that connects to the motor or drive shaft via a flexible coupling. This separated design isolates the encoder from motor shaft misalignment and vibration, protecting internal bearings and optical or magnetic discs. Solid shaft units are traditionally used in general automation, packaging machinery, CNC machine tools, and heavy equipment where shocks are frequent and space is not critically constrained. They allow easy mechanical configuration, with standard shaft diameters such as 6 mm, 8 mm, 10 mm and common flange mounts. Hengxiang’s solid shaft encoders provide incremental or absolute output, high resolution up to 17 bits, and durable construction rated to IP67.

Hollow Shaft Encoders: Space-Saving, Direct Integration

A hollow shaft encoder, often called a through‑bore or blind hollow shaft encoder, eliminates the coupling by mounting directly onto the motor shaft. The large center hole slides over the shaft and is secured with a clamping ring or set screws. This design dramatically reduces overall axial length, a critical advantage in tight spaces such as robotic joints, AGV wheel drives, elevator traction machines, and UAV servo actuators. Because there is no coupling, hollow shaft encoders minimize torsional wind‑up and improve dynamic response. They also cut installation time and parts count. Hengxiang supplies hollow shaft encoders with bore sizes from as small as 4 mm to over 50 mm, supporting incremental, absolute, and commutation signals, with wide‑temperature operation from -40°C to 105°C and strong resistance to electromagnetic interference.

How to Decide?

Choose a solid shaft encoder when you need mechanical isolation from harsh vibrations, easy field replacement, or a standard interface for legacy systems.

Choose a hollow shaft encoder when space is limited, you want the simplest possible mechanical assembly, or your application demands the highest possible dynamic accuracy by avoiding coupling backlash.

At Shanghai Hengxiang, we manufacture both types entirely in‑house. Whether you require a stock solid shaft encoder with a 58 mm body or a customized hollow shaft unit with a 30 mm through‑hole and absolute SSI output, our engineering team can deliver. Our magnetic sensing technology options provide ruggedness beyond optical encoders, while still delivering excellent resolution and speed.

We understand that every rotation matters. That is why we control every step from raw components to final testing, ensuring that our encoders meet the reliability standards demanded by factory automation, renewable energy, and defense systems.

Contact Shanghai Hengxiang today to discuss your encoder requirement. Let our 20+ years of manufacturing experience turn your motion challenge into a precise, reliable solution.

Shanghai Hengxiang Optical Electronics Co., Ltd. – Source factory for rotary encoders since 2001.