ZQ Series Gear Speed Reducer Simple Structure Cylindrical Gear Reducer ZQ-750 ZQ-850 ZQ-1000

ZQ Series and Its Variants simple structure, easy manufacturing, low cost, and convenient maintenance

1. Introduction

The ZQ series (and its predecessor JZQ, variants ZQH, ZQSH) is the most famous and widely used series of soft-gear cylindrical gear reducers in Chinese history. Originating from the Soviet Ч-type reducer, it was an icon of its industrial era. Its characteristics are simple structure, easy manufacturing, low cost, and convenient maintenance. However, with technological progress, its drawbacks of soft gears, low load capacity, and large size have led to its gradual replacement by hardened gear reducers (e.g., ZLY, ZSY) in new projects. Nonetheless, it remains in use and requires maintenance on a vast number of old equipment.

• ZQ / JZQ: Basic model. JZQ is the old code, essentially the same series as ZQ. Horizontal mounting, double stage.

• ZQH: A horizontal mounting variant of ZQ, usually referring to a different assembly form, but with the same basic structure as ZQ.

• ZQSH: A triple-stage variant of ZQ (“S” stands for “San” meaning “Three”), used to achieve larger reduction ratios.

2. Key Parameters

• Models: Denoted by center distance, e.g., ZQ-350, ZQ-400, ZQ-500, ZQ-650, ZQ-750, ZQ-850, ZQ-1000 (number represents center distance in mm).

• Transmission Stages: ZQ/ZQH: Double stage; ZQSH: Triple stage.

• Ratio Range (i):

  • Double-stage (ZQ): 8.23, 10.35, 12.64, 15.75, 20.49, 23.34, 31.5, 40.17, 48.57

  • Triple-stage (ZQSH): Larger ratios, e.g., 65.62, 84.39, 105.94, 137.56, 172.36, 211.5

• Center Distance (a): From 250mm to 1000mm.

• Gear Design:

  • Tooth Profile: Involute cylindrical gears.

  • Surface Hardness: Soft-gear. Gear material is generally 45# steel or 40Cr, with tooth surface hardness typically ≤ HB350 after quenching and tempering.

• Mounting Position: Horizontal mounting.

• Lubrication: Splash lubrication.

3. Product Advantages (Advantages in Historical Context)

• Simple Structure, Mature Process: Low barriers to design and manufacturing; once produced by almost all machinery factories, resulting in an extremely extensive supply chain.

• Low Cost: Low requirements for materials and heat treatment, making manufacturing costs much lower than hardened gear reducers.

• Easy Maintenance: Simple structure allows for easy on-site repair or replacement after damage, requiring less technical skill from maintenance personnel.

• Good Interchangeability: As a long-standing national standard, products from different manufacturers have excellent dimensional interchangeability.

4. Typical Applications (Mainly found on old equipment)

These series were once widely used in various industries. Now they are primarily used as spare parts for maintenance and retrofits.

• Lifting Equipment: Travel and hoist mechanisms of overhead cranes, gantry cranes (now largely replaced by hardened gear products like ZQA).

• Conveying Equipment: Belt conveyors, apron conveyors.

• Metallurgy & Mining: Auxiliary steel rolling equipment, mine hoists, feeders.

• General Machinery: Various low-speed, heavy-duty applications like mixers, winches.