What is the maximum torque capacity of this small gear set?

The torque capacity depends on the gear pair and operating conditions. For the 20T-40T pair with 45-50 HRC tooth hardness, the rated torque is 15 N·m per pair at 1,000 rpm, based on a safety factor of 1.5 against tooth bending fatigue. The 20T-30T pair is rated at 12 N·m. These values assume proper lubrication with ISO VG 68 gear oil and a duty cycle of 60% or less. For continuous operation at higher speeds, derate by 20% for every additional 1,000 rpm. Always verify against your application's shock loads and alignment tolerances.

How do I install these gears to minimize backlash and noise?

Mount the gears on shafts with a fit of H7/h6 and secure with a key and set screw. Set the center distance according to the sum of pitch radii: for the 20T and 40T pair, the ideal center distance is 45 mm (30/2 + 60/2). Use a feeler gauge to set backlash to 0.10-0.15 mm at the tightest point. Apply a thin film of molybdenum disulfide grease (e.g., Molykote) to the teeth. After assembly, rotate the gear train by hand to check for binding; if noise persists, check shaft parallelism within 0.02 mm and adjust shims. Proper alignment reduces noise by up to 5 dB(A).

Can these gears be used in high-temperature environments?

The 45# steel gears with induction hardening are suitable for operating temperatures up to 150°C, provided that a high-temperature lubricant (e.g., PTFE-based or synthetic hydrocarbon grease) is used. Above 150°C, the material's hardness may degrade, and thermal expansion can alter backlash. For continuous operation above 120°C, we recommend increasing backlash by 0.02 mm to compensate for expansion. Avoid rapid temperature cycling, which can cause lubricant breakdown. For applications exceeding 200°C, consider our stainless steel or case-hardened variants.

What is the expected service life of this gear set?

Under rated load (15 N·m for the 20T-40T pair) and proper lubrication, the expected L10 life (10% failure probability) is 10,000 hours at 1,000 rpm. This is based on ISO 6336 bending fatigue calculations for 45# steel at 45 HRC. Actual life depends on alignment, lubrication cleanliness, and shock loads. To maximize life, maintain oil cleanliness to ISO 4406 18/16/13 and inspect for wear every 2,000 hours. Replacing lubricant every 5,000 hours is recommended. For higher loads or speeds, consider our precision-ground series with Grade 5 accuracy.

Small Gear Set

Module 1.5 Small Gear Set for Compact Automation and Precision Instruments

This small gear set features a 1.5 module, 20° pressure angle, and a three-gear configuration (20T, 30T, 40T) made from 45# steel with induction hardening to 45-50 HRC. It is designed for space-constrained applications such as robotic joints, medical devices, and small packaging machinery. The set offers a 2:1 reduction ratio between the 20T and 40T gears, enabling compact torque multiplication.

Module

1.5

Number of Teeth

20 / 30 / 40

Pressure Angle

20°

Material

45# Steel (C45)

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How Does the Module 1.5 Small Gear Set Deliver Reliable Performance in Tight Spaces?

The small gear set is a precision-engineered assembly comprising three spur gears with a module of 1.5 and a 20° pressure angle. The gears have 20, 30, and 40 teeth, providing flexible ratio options for compact drive systems. Manufactured from 45# steel (equivalent to C45) and induction hardened to 45-50 HRC, the teeth resist wear under repeated load cycles. The bore diameters range from 6 mm to 10 mm, allowing direct mounting on standard shafts without adapters. Each gear is hobbed and ground to GB/T 10095 Grade 7 accuracy, ensuring smooth meshing and low vibration. The set is ideal for applications where space is limited but reliable torque transmission is required.

Typical applications include robotic arm joints, where the 20T and 40T combination provides a 2:1 reduction for increased torque in a small envelope. In medical equipment such as syringe pumps, the precise tooth profile minimizes backlash, ensuring accurate fluid delivery. Small packaging machines benefit from the 30T intermediate gear for speed matching between motor and conveyor. The set also suits laboratory instruments, optical mounts, and hobby-grade CNC machines. Unlike larger industrial gear sets, this small gear set addresses the pain points of limited installation space, weight sensitivity, and the need for quiet operation—all without compromising load capacity.

Compared to other small gear sets in the same series, this module 1.5 variant offers a balanced trade-off between torque capacity and compactness. The 20T gear has a pitch diameter of 30 mm, while the 40T gear measures 60 mm, making the set suitable for enclosures as small as 100 mm × 100 mm. The 45# steel construction provides higher strength than plastic gears, and the induction hardening extends service life to over 10,000 hours under rated load. For applications requiring higher precision, consider our ground version with Grade 5 accuracy; for lighter loads, plastic gears may suffice. This set is the go-to choice for engineers who need a robust, off-the-shelf solution for small-scale power transmission.

Induction-hardened 45# steel teeth (45-50 HRC) for wear resistance in continuous operation.
GB/T 10095 Grade 7 accuracy ensures low backlash and smooth torque transmission.
Three-gear configuration (20T/30T/40T) provides flexible ratios from 1.5:1 to 2:1.
Bore range 6-10 mm with keyway option for secure shaft mounting.

Core Technical Features and Quantified Advantages

STEP 1

Module 1.5 with 20° Pressure Angle

The 1.5 module and 20° pressure angle conform to ISO 53 and DIN 867 standards, ensuring compatibility with standard cutters and interchangeability. This configuration provides a contact ratio of approximately 1.5, resulting in smooth, quiet operation at speeds up to 3,000 rpm. The 20° pressure angle balances load capacity and bending strength, making it suitable for both driving and driven gears in compact trains.

STEP 2

45# Steel with Induction Hardening (45-50 HRC)

Gears are machined from 45# carbon steel (0.45% carbon) and induction hardened to 45-50 HRC on the tooth flanks, while the core remains tough at 20-25 HRC. This selective hardening resists surface wear and pitting under loads up to 15 N·m per pair, while maintaining impact resistance. The material is equivalent to AISI 1045 and offers good machinability before hardening.

STEP 3

GB/T 10095 Grade 7 Accuracy

Each gear is inspected to GB/T 10095 Grade 7, which corresponds to a total composite tolerance of 0.05 mm for the 40T gear. This accuracy level limits backlash to 0.10-0.15 mm and reduces transmission error, ensuring precise motion control in positioning applications. The gears are hobbed and ground after hardening to maintain tooth profile integrity.

STEP 4

Three-Gear Set with 20T/30T/40T

The set includes three gears with 20, 30, and 40 teeth, providing ratios of 1.5:1, 2:1, and 1.33:1 when paired. The 20T gear has a pitch diameter of 30 mm, the 30T 45 mm, and the 40T 60 mm. All gears share a 20° pressure angle and 1.5 module, allowing interchangeable meshing. This flexibility enables designers to optimize speed and torque without custom parts.