When maintaining or upgrading a loader or excavator, one of the most important questions operators ask is: “How many teeth should my gear have?” Whether you’re replacing a sun gear, a planetary gear, or a transmission gear inside the final drive, selecting the correct tooth count is essential for smooth power transmission and long-term durability.
Although gear selection may look complicated, the logic behind tooth count is actually very clear once you understand what each number influences. So today, let’s break it down in a simple, beginner-friendly way.
The tooth count affects almost every aspect of how a gear performs:
Speed ratio: More teeth typically reduce speed but increase torque
Torque output: Fewer teeth can rotate faster but carry less load
Gear meshing compatibility: Wrong tooth count makes the gear unusable
Load distribution: The number of teeth determines how force is shared
Wear pattern and lifespan: Proper tooth count reduces stress concentration
In loaders and excavators, the gear system experiences high impact, continuous torque transfer, and sudden load changes. Tooth count determines how well the gear can survive these stresses.
Different brands and models have standardized tooth counts. Here are some common examples:
15 teeth
17 teeth
18 teeth
18-tooth series
20-tooth series
50-spline types
51-tooth gears
62-tooth gears for Liugong loaders
67:50 spline combinations used in SDLG models
These numbers are not random — they are designed by the manufacturer to match torque requirements and the structure of the planetary gearbox.
This is the fastest and most reliable method.
For example:
Liugong 50: commonly uses 62-tooth gears
SDLG 50: may use 51 teeth or 67:50 spline types
XCMG: often applies 51-tooth versions
Lonking: includes reinforced 50-spline or 51-tooth designs
If you know your model, you’re halfway done.
This is especially important when:
The machine has been repaired before
A previous owner changed parts
There are multiple gear versions for the same model
The gearbox is not original
Simply count carefully — one tooth at a time — to avoid mistakes.
Gear tooth count must match:
Internal ring gear
Sun gear
Planet gears
Splines
Shaft diameter
If one number changes, the entire gear ratio changes, which can cause abnormal noise, vibration, and accelerated failure.
Let’s look at the impact in simple terms:
Higher torque handling
Lower rotational speed
Better for heavy-duty working
Smoother operation under impact loads
Faster speed
Lower torque capacity
Works well for lighter applications
Good for machines prioritizing speed over load capacity
In loaders, higher tooth count gears are often preferred because lifting and digging require strong torque.
No matter how many teeth the gear has, its durability comes from the heat-treatment process.
A properly quenching-and-tempering (QT)-treated gear will have:
Hard surface
Tough core
Excellent fatigue resistance
Better wear performance
This is crucial because loaders and excavators work in harsh conditions, and tooth count alone cannot guarantee strength. Heat treatment gives the gear its long-term reliability.
Most operators should stick to the original tooth count, but there are special situations where adjusting tooth count can help:
Custom speed reduction
Torque upgrade for heavy loads
Modified planetary gear ratio
Non-standard gearbox configurations
However, these cases require professional guidance because even small changes can affect the entire drivetrain.
Tooth count is important, but quality is even more critical.
A gear should be:
CNC machined
Made from high-strength steel
Properly heat-treated
Accurately measured
Metallurgically tested
Many global buyers prefer sourcing gears from large China manufacturers and suppliers because they offer stable quality, consistent production, and full in-house forging, machining, and heat-treatment lines.
And honestly, when a gear works well, you can immediately feel how smooth the machine becomes — no weird noises, no sudden vibration, just clean power transfer. Pretty nice, right?
