HST Standard Hat-Type Harmonic Reducer

The HST-I series flexspline is a hollow-flange standard cylindrical structure; the whole unit is compact, the input shaft mates directly with the wave generator bore and connects via a flat key. It can be configured either with the circular spline fixed and flexspline as output, or vice versa. The HST-I harmonic reducer offers high precision, high efficiency and high rigidity, with compact structure and light weight — well suited to space-constrained applications.

Model Range:Frame 14 / 17 / 20 / 25 / 32 / 40
Structure: Standard hat
Variants: U-I simple / U-III vacuum / U-IV solid shaft
Reduction Ratio: 50 : 1 – 160 : 1 (custom)

17 model codes · frame 14 / 17 / 20 / 25 / 32 / 40 · See the model matrix ↓

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Specifications

Typical reference parameters. Final specifications are subject to our technical confirmation.

Parameter	Value
Reduction Ratio	50 : 1 – 160 : 1 (custom)
Rated Torque @2000 rpm (N·m)	5.4 – 686
Peak Torque (N·m)	up to 1,180
Backlash	≤ 20 arc-sec (≤ 10 optional)
Rated Input Speed	2000 – 3000 rpm
Design Life	≥ 7,000 h
Operating Temp.	-10 °C ~ +50 °C
Variants	U-I / U-III (vacuum) / U-IV (solid shaft)

Model Matrix

WHS-HST Model Matrix

17 orderable codes across frame sizes 14 / 17 / 20 / 25 / 32 / 40 — pick the frame first, then the structure code.

Frame	U-I · Simple	U-III · Vacuum	U-IV · Solid shaft
14	WHS-HST-14-XX-U-I	WHS-HST-14-XX-U-III	WHS-HST-14-XX-U-IV
17	WHS-HST-17-XX-U-I	WHS-HST-17-XX-U-III	WHS-HST-17-XX-U-IV
20	WHS-HST-20-XX-U-I	WHS-HST-20-XX-U-III	WHS-HST-20-XX-U-IV
25	WHS-HST-25-XX-U-I	WHS-HST-25-XX-U-III	WHS-HST-25-XX-U-IV
32	WHS-HST-32-XX-U-I	WHS-HST-32-XX-U-III	WHS-HST-32-XX-U-IV
40	WHS-HST-40-XX-U-I	WHS-HST-40-XX-U-III	—

Frame size = outside diameter of the circular spline (mm). "—" marks a combination that is not offered. U-IV (solid output shaft) stops at frame 32; frame 40 is available in U-I and U-III.

All five series · 53 codes → Request a Quote

Technical Detail

Structure & Working Principle

The HST series uses a hollow, flanged "hat" flexspline. The input shaft mates with the wave-generator bore via a key, and the unit can be configured either with the circular spline fixed and flexspline output, or flexspline fixed and circular spline output. The large flange gives a generous mounting face and the hollow bore passes cables or a through-shaft through the center.

Key Features

Hollow flanged hat flexspline
Large center bore for cables or through-shaft
Flexible input/output configuration
High precision, high rigidity, high efficiency
Well suited to robot wrists and rotary joints

Selection Guide

Choose HST for robot wrists and rotary axes that need a large center through-bore for cable routing combined with a wide mounting flange. The broad ratio range covers most servo applications; verify bore diameter and flange interface for your cabling and frame.

Products

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HCS Standard Cup-Type Harmonic Reducer

The flexspline adopts a cup-type standard cylindrical structure with compact size; the input shaft mates directly with the wave generator bore and connects via a flat key, typically with the circular spline fixed and the flexspline as output. Highly meshed and lightweight. The HCS harmonic reducer features high transmission accuracy, low noise, fast response and excellent reliability. Because multiple teeth engage simultaneously at two symmetric 180° positions, pitch and cumulative pitch errors average out, yielding very high positional and rotational accuracy.

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HYT Integrated Harmonic Actuator

The HYT-I series is a miniaturized product developed to meet market needs. Its flexspline is a hollow-flange standard cylindrical structure; the whole unit is compact and integrates the bearing flange internally, allowing the motor to be mounted directly and used immediately. Compared with the HCS series of the same torque capacity, HYT is more compact with a thin-wall structure, pursuing smaller size without changing performance. The HYT-I harmonic reducer offers high precision, high efficiency and high rigidity, with compact structure and light weight — ideal for space-constrained applications.

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HCD Ultra-Short Cup Harmonic Reducer

The HCD series is a miniaturized product developed to meet market needs. Compared with the HCS series of the same torque capacity, HCD is more compact with a thin-wall structure, pursuing smaller size without changing performance and pushing "small but beautiful" to the limit. In this harmonic reducer, the wave generator (usually a cam combined with a flexible bearing) is inserted into the flexspline, forcing it into an elliptical elastic deformation. The long axis fully meshes with the circular spline tooth space while the short axis fully disengages. As the wave generator rotates continuously, the flexspline deforms repeatedly through engage/disengage cycles, transmitting motion and reducing speed.

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Hat-Type

HSD Ultra-Short Hat-Type Harmonic Reducer

The HSD series is an ultra-short hat-type product developed from the HST platform. Its flexspline uses a hollow-flange structure; the unit is shorter axially and more compact, with an internal support bearing and fully sealed construction for easy installation. The HSD harmonic reducer offers high precision, high rigidity and light weight — ideal for axial space-constrained, weight-sensitive applications.

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