Gearboxes (also known as speed reducers or reduction gears) are intermediate devices between an electric motor and the driven machinery. They utilize gear sets or worm shafts to reduce rotational speed and increase torque, allowing for precise speed adjustment in the system.
Construction and Operating Principle
Construction of Gearboxes
A gearbox is a mechanical transmission device composed of various components working together to reduce speed while simultaneously increasing torque.
Internal construction of NMRV gear motor
General construction of Gearboxes
Housing: The gearbox housing is usually made from cast iron or aluminum alloy. Its primary function is to protect internal mechanical components such as gears, shafts, and bearings from external factors like dust and moisture. Additionally, the housing serves as a reservoir for lubrication oil for the entire system of Speed Reducers.
Gearing System: This is the most critical part of the construction. The system includes various types of gears such as spur gears, helical gears, bevel gears, and worm and worm wheels.
Shafts and Bearings: The shafts in an electric motor gearbox are responsible for transmitting motion and torque between gears. Bearings (rolling elements) support the rotating shafts, reduce friction, and ensure that the shafts operate in the correct position.
Main components in Gearboxes and their functions
Anchor Bolts: Mechanical parts used to secure the gearbox to the machine base or frame.
Inspection Port: An important component integrated into the mechanical housing, allowing operators to easily check the internal condition without disassembling the entire device.
Housing Cover and Bearing Caps: The upper part of the gearbox housing, which can be removed for assembly, inspection, or maintenance of internal parts such as gears, shafts, and bearings.
Drain Plug and Vent Plug: Positioned at the lowest point of the housing to drain old oil during replacement. The vent plug (breather) helps balance internal pressure.
Dipstick: An essential tool used to check the level of lubrication oil inside Speed Reducers.
Operating Principle
Most electric motors have very high rotational speeds (commonly 1450 rpm or 2900 rpm). However, actual machinery often requires slower speeds and stronger pulling force. This is where Gearboxes play their role:
Reducing Rotational Speed: Constraining the angular velocity of the motor to the required level (e.g., from 1450 down to 50 rpm).
Increasing Torque: According to physical principles, as the speed decreases by a certain factor, the pulling force increases by the same factor. This is why heavy-duty series like ZQ Gearboxes can easily pull dozens of tons of goods.
Classification of Gearboxes at Thanh Thai Motor
To choose the right equipment, customers need to understand the characteristics of each type. Thanh Thai Motor classifies its inventory based on construction and practical applications:
Heavy Duty Group
This is the heavy-duty reduction group, specialized for harsh environments.
ZQ Gearbox (ZQ, JZQ): Utilizes helical gears and extra-thick cast iron housing. Specialized for cranes, steel rolling mills, and stone crushers.
ZQ Gearbox size 1000
R, K, F, S Heavy Duty Series: European technology series.
R-Series Inline Helical Gearbox: Installed for agitators and conveyors.
R-Series Inline Helical Gearbox
K-Series Helical Bevel Gearbox: High efficiency, energy-saving, with a right-angle output shaft.
Worm Gearbox (WPA, WPS, WPO, WPX): Better load capacity than aluminum housing, used for hoists and milling machines.
NMRV gear motor and WPA, WPS, WPO, WPX
High Transmission Ratio Group
When you need extremely slow output speeds (below 20 rpm), standard 1-Stage types cannot meet the requirement.
Mechanical Speed Variator: Has the function of varying the output shaft speed, allowing users to easily select the appropriate speed.
Mechanical Speed Variator with variable output speed function
Screw Jack Gearbox: Offers extremely high precision with static and dynamic load capacities up to dozens of tons.
Lifting screw jack with extremely high precision
2-Stage Gearbox: Combines two gear transmission sets in series. This provides deep speed reduction without overloading the motor.
2-Stage Gearbox consisting of a Mechanical Speed Variator attached to an R-Series shaft
3-Stage Gearbox: Combines three gear transmission sets in series. Achieves ultra-high transmission ratios, suitable for requirements of extremely slow output speeds and maximum torque.
3-Stage Gearbox assembled from 2 UDLs and 1 R-Series inline shaft
Cycloidal Gearbox: Uses pins and discs, excellent for shock load resistance, with ratios reaching up to 1/87 in just a 1-Stage configuration.
Cycloidal Gearbox
Latest Price List for Gearboxes at Thanh Thai Motor
Various types of Gearboxes available at Thanh Thai Motor warehouse at good prices
The price of Gearboxes (Speed Reducers) depends on the size, transmission ratio, and housing material (cast iron or aluminum). Below is a reference price list for common series at Thanh Thai Motor:
NMRV gear motor Price Quote
This aluminum housing series is classified primarily by size from 30 to 150. Costs may vary depending on whether you choose the standard hollow shaft configuration or add single/double shafts or connection flanges.
The price for worm gear Speed Reducers is determined based on the cast iron body style (WPA, WPS, WPO, WPX) and shaft size. Product lines using high-quality alloy bronze worm wheels will have different prices compared to standard lines.
The quote for this series depends on the lifting load (measured in tons) and the travel length of the screw. Costs will also fluctuate based on the choice of shaft end type (flat, threaded, or ball end) per technical requirements.
This is a heavy-duty helical Gearbox series. The unit price is calculated based on the center distance and transmission ratio. You can refer to different prices for specific codes from ZQ250 to ZQ1000 in the table below.
Prices for this series are clearly separated between foot-mounted and flange-mounted types. The investment cost will depend on the gearbox code corresponding to the accompanying motor power, ensuring optimal load capacity and transmission efficiency.
The quote for stepless speed variators is built based on the power range and speed variation capability. Costs will change when you combine this variator with gear heads or NMRV gearboxes.
HB-Series Helical Gearbox and T-Series Right-Angle Bevel Gearbox Price Quote
These are specialized gearboxes with quotes based on ultra-high torque or 90-degree redirection features. The unit price reflects the quality of the gear steel and the precision in mechanical machining.
Pricing for the F-series is optimized for space-saving installation designs. Specific costs will be based on the gearbox size and output shaft diameter (hollow or solid) depending on actual needs.
The K-series quote focuses on the advantages of spiral bevel gears, providing high load capacity and quiet operation. Prices will fluctuate depending on accessory modules such as torque arms or output flanges.
The S-series helical-worm reduction series offers a very economical price for applications requiring a right-angle shaft with moderate loads. Detailed quotes are classified by each product code.
This is the most popular reduction series in the heavy-duty segment with highly diverse pricing. Costs are calculated based on the radial load capacity and your desired output speed.
Pricing for 1-Stage Gearboxes (low transmission ratio) is usually quite favorable due to the simple construction. Prices focus on the durability of the primary gear set and the housing.
The 2-Stage series quote reflects the capability for deeper speed reduction with stable transmission efficiency. The cost will be higher than the 1-Stage series due to the increased number of gears and bearings inside.
This series features very large transmission ratios for applications needing ultra-slow speeds and extremely strong pulling force. The quote is built based on the complexity of the multi-stage gear system inside the gearbox.
Note: The above prices do not include VAT and shipping fees. For bulk purchases, please call the Hotline for the best trade discount.
Gearbox price quotation video 10/2026 - Thanh Thai Motor
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4 “Golden” Criteria When Buying Gearboxes
The technical team at Thanh Thai Motor advises customers to clearly define these 4 parameters to avoid buying the wrong unit, which could cause gearbox failure:
Motor Power: The gearbox must be compatible with the motor power. Note: Installing a small size gearbox on a high-power motor will cause the gears to break immediately.
Mounting Type: Foot-mounted (B3) or Flange-mounted (B5)? Solid shaft (protruding) or Hollow shaft (bore)?
Service Factor: If the machine runs 24/7 or under shock loads, a safety factor > 1.5 must be selected.
Installation and Maintenance Guide
For Gearboxes to last 5-10 years, the installation process is very important. You can refer to technical summary videos at Thanh Thai Motor or watch actual gearbox series videos to understand the most accurate operation and maintenance procedures.
Base: Must be secured on a flat, solid surface without vibration.
Alignment: The motor shaft and gearbox shaft must be perfectly aligned (if connected via a coupling). Misalignment will destroy bearings very quickly.
Lubrication:
First time: Change the oil after the first 100-200 hours of run-in.
Periodically: Change every 2500 hours of operation.
Oil type: Use gear oil 90 or 140 (such as Castrol, Shell Omala).
Installation and maintenance process for Gearboxes
Frequently Asked Questions (FAQ)
How to check and fix abnormal overheating in Gearboxes?
Standard operating temperatures for Speed Reducers usually range from 60°C to 80°C. If it exceeds this level, you need to check immediately:
Lubrication Oil: Too little oil causes dry friction, while too much oil hinders movement and generates heat.
Overload: Check the motor current; if it exceeds the rated amperage, the gearbox is handling a load larger than its design.
Installation: Misalignment between the motor and gearbox shafts causes residual stress and heat at the bearings.
To handle this, ensure ventilation for the cooling fan and check the concentricity of the coupling.
Why do Gearboxes experience shaft play or heavy vibration during operation?
Vibration usually stems from worn bearings or chipped gears after long-term use.
Axial Play: Due to worn bearings or loose retaining rings, causing the shaft to move in and out.
Vibration: Often caused by an uneven installation foundation or loose anchor bolts. If not fixed promptly, this play will damage the oil seals and destroy the internal gear set.
What is the difference in self-locking capability among various Speed Reducers?
Self-locking capability is a very important technical characteristic in lifting systems or inclined conveyors.
Worm Gear Series (such as NMRV, WP): Have high self-locking capability due to the large lead angle of the worm thread, helping to hold loads safely.
Heavy Duty Gear Series (such as R, K, F, S): Transmission efficiency is very high (>95%), so self-locking capability is very poor. They must usually be combined with a Brake Motor (electromagnetic brake) to stop the machine instantaneously.
