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.

Model Range:Frame 14 / 17 / 20
Structure: Ultra-short hat (simple + keyway)
Reduction Ratio: 50 : 1 – 160 : 1 (custom)
Keyway: With keyway

3 model codes · frame 14 / 17 / 20 · See the model matrix ↓

Get a Quote Products

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
Keyway	With keyway

Model Matrix

WHS-HSD Model Matrix

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

Frame	U-I · Keyed bore
14	WHS-HSD-14-XX-U-I
17	WHS-HSD-17-XX-U-I
20	WHS-HSD-20-XX-U-I

Frame size = outside diameter of the circular spline (mm). "—" marks a combination that is not offered. Ultra-short hat with keyway, built in frames 14 / 17 / 20 only.

All five series · 53 codes → Request a Quote

Technical Detail

Structure & Working Principle

The HSD series is the ultra-short version of the hat-type design. It keeps the hollow flanged flexspline and center through-bore but reduces overall height, giving a low-profile hollow reducer for space-constrained joints. The compact body still supports center cable routing.

Key Features

Ultra-short, low-profile hat structure
Hollow center bore retained for cable routing
Reduced height for compact, low-profile joints
High rigidity with wide mounting flange
Smooth, precise strain-wave transmission

Selection Guide

Choose HSD when you need hollow-bore cable routing in the lowest possible profile — compact robot joints, delta/SCARA wrists and embedded rotary stages. Confirm that the reduced height still provides the torque and bore size your design requires.

Products

Related Products

Cup-Type

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.

Learn more →

Integrated

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.

Learn more →

Cup-Type

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.

Learn more →

Hat-Type

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.

Learn more →

Need a Quote?

Get a Quote