Hollow shaft encoder

Products introduction

Lorentzzi® is a Chinese manufacturer and we are proud of our commitment to encoder innovation and continuous improvement. We invest in cutting-edge technology, research and development to push the boundaries of encoder technology. By choosing Lorentzzi® hollow shaft encoders from China, you gain access to the latest advancements, ensuring your application is at the forefront of industry trends.

Why Choose Lorentzzi to be your supplier?

china supplier

Lorentzzi factory is located in the low-voltage electrical appliances zone in China. Our products offer unique advantages, resulting in superior quality and competitive pricing.

Complete range of products

Lorentzzi can supply a full range of incremental hollow shaft encoders, there are nearly 100+ different products available for your different requirements.

Stock available

We spend a lot of money to build our warehouse to stock different encoders, just to make sure our customer can get the products at the shortest time.

The Complete Guide To Hollow Shaft Encoder

Hollow-shaft encoder is a thru-bore encoder specially designed for numerous kinds of shaft motors such as DC motors, AC motors, torque motors, servo motors and stepper motors, etc.. Lorentzzi, as a leading hollow shaft rotary encoder manufacturer in China, can manufacture hollow shaft encoders from inner diameter 38mm to 120mm. From the shape aspect, we have both micro encoders and large diameter encoders. In the below parts, we will introduce the hollow shaft encoder from 5 aspects. They are benefits, types, some popular branded hollow type encoders, and their accessories. This type of encoder is widely used in many applications, for instance, CNC machine, milling machine, robot, wind power generator and package machine.

Table of Contents

Benefits of Hollow-Shaft Encoders

As mentioned above, the hollow shaft encoder can be found in many applications. Why? Because it has the following 3 advantages:

  • Easy Encoder mounting: There is a hole in the middle of its housing, making its installation in a much easier way, we can directly mount it to a motor shaft after choosing a suitable shaft sized encoder, and fasten it to the motor with a clamp as following:
  • Eliminating the need for a mechanical coupling: Unlike the solid shaft encoder, if we want to use it with a motor, we need an extra accessory named mechanical coupling to fix. The following is the photo of encoder couplings:
  • Space saving: Because of coupling plus encoder solid shaft length reasons, the solid shaft encoder body will be much longer than the hollow one. While for the hollow one, we can directly insert the motor shaft into the bored encoder. To understand it clearly, we will take the external diameter 40mm encoder as an example, we can see that for a same size encoder, the hollow-shaft encoder housing length is only 49mm, while the solid shaft one is 49mm. Thus, hollow shaft encoder is space-saving.

Types of Hollow-Shaft Encoders

There are two types of hollow-shaft encoders in the market, one is incremental hollow-shaft encoder, the other is absolute hollow-shaft encoder. Both of two encoders have thru bores, easy installation, and saving space advantages. Furthermore, they can all be used with a PLC to calculate the displacement of a motor.
Their differences are:

  1. Incremental hollow shaft encoder uses high level and low level pulse to measure displacement, angular velocity and acceleration, while absolute one uses Gray code to mainly measure the object rotation angle.
  2. Absolute hollow-shaft encoder can be divided into single turn encoder and multi-turn encoder, but both of the two encoders have the limitation of displacement distance. While the incremental one doesn’t have this limitation, it can measure the displacement distance forever only if the power is not failure.
  3. Incremental encoders need to find zero once power is failed, while absolute one will not.

For more information about the two encoder differences, you can have a look at this article about Incremental Encoders Vs. Absolute Encoder.

Featured Hollow-Shaft Encoders

There are several popular hollow shaft encoders in the market, their models are HS35R, HS20, F10 and HS56. We will list out all their specifications for you to compare:

Model Description Type Mounting Special Features
HS35R Ruggedized version of the original vector-duty hollow-shaft encoder. Designed for heavy-duty environments. Incremental 5/8" Shaft 400g shock rating, IP67 sealing, -40ºC to 100ºC temperature range
HS20 Designed for heavy-duty applications with a size 20 housing. Features a thru-hub design and an unbreakable code disk. Incremental Up to 5/8" or 16mm Hollow Thru-hub design, Unbreakable code disk, Short circuit and ESD protected
F10 Compact hollow-shaft encoder with flex servo ring mounting. Designed to replace size 10 pancake resolvers. Can operate in temperatures up to 120ºC without limiting motor performance. Incremental 6mm Hollow Pancake Style Servo Mount, 0ºC to 120ºC Operating Temperature
HS56 (Dynapar) Designed especially for maintenance, motor repair, and field personnel. Offers a means of applying a leading-edge digital encoder to motors and other devices that require an innovative method of installation. Incremental Encoders Max Bore 1-1/8" Hollow Magnetic Encoder, Suitable for devices without c-face mounting provisions, Designed for tough environments

How to install a hollow shaft encoder

Install a hollow shaft encoder is not so complex, please have a look at the below video for some ideas:

Accessories for Hollow-Shaft Encoders

To let the hollow shaft encoder run smoothly without any problem, here are some accessories needed.

  1. Tethers and cover kit-tethers and cover kit are fixtures, which can protect the encoder from vibration, as we can see that once a high power motor runs, it will generate much noise and vibration. If we don’t use the tethers and cover kit to fix the encoder, the vibration will gradually lose the separation between the encoder and the motor. And then cause measuring errors. Another potential risk is that strong vibration will damage the encoder disc if it is made of glass.
  2. Encoder cable: For 3 phases hollow shaft encoder, it has 5 cables, they are red(power source), black(ground), green(phase A), white(phase B), yellow(phase Z) and shield cable. For 6-phase encoder, besides these 5 cables, it also has brown(A-), gray(B-), orange(Z-). When using the cables, please make each cable output clearly in case of output errors. Also, if you want to prolong, understanding each cable output is necessary.


Hollow shaft encoder is a thru bore encoder, there is a hole in the middle of its housing. Relying on this thru bore, we can easily use it together with a motor. The bore diameter is from 38mm to 120mm.

No matter whether the incremental rotary encoder is hollow shaft one or solid shaft one, they are mainly used to measure motor displacement, ration angle and motor acceleration.

We can mount a hollow shaft encoder by the mounting/adapters tether arm kit, this accessory helps us fix the encoder and motor tightly. 

Thru-bore encoder is not only including hollow shaft incremental encoder, but also contains absolute hollow shaft encoder, it is another name for hollow shaft encoder. If we say thru-bore encore, we are trying to say hollow shaft encoder.


In conclusion, the complete guide to hollow shaft encoders provides a comprehensive overview of these specialized encoders. Hollow shaft encoders are designed for various types of shaft motors and offer several benefits, including easy mounting, space-saving design, and eliminating the need for a mechanical coupling. There are two types of hollow shaft encoders: incremental and absolute, each with its own advantages and differences in measuring displacement and rotation angle. Popular models of hollow shaft encoders include HS35R, HS20, F10, and HS56. Accessories such as tethers and cover kits are necessary to protect the encoder from vibration, while encoder cables need to be properly connected and understood for accurate output. The guide also includes frequently asked questions to provide further clarity on the functionality and usage of hollow shaft encoders. Overall, this guide serves as a valuable resource for understanding and utilizing hollow shaft encoders in various applications.

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