« Back to Dictionary Index

Tooth Heel

The tooth heel refers to the wider outside end of a gear tooth, specifically in the context of a differential ring gear in an automobile. Here’s a detailed explanation of its features and functionality:


  • Location: The tooth heel is found on the differential ring gear, which is a crucial component of the vehicle’s differential system.
  • Shape: It is the broader, outermost part of the gear tooth, as opposed to the narrower inner part, which is called the toe.
  • Design: The ring gear teeth are typically helical or spiral, allowing for smooth engagement with the pinion gear.


  • Power Transmission: The ring gear, along with its teeth, transmits power from the drive shaft to the differential, which then distributes torque to the drive wheels.
  • Load Distribution: The heel of the tooth engages later during the rotation, contributing to the gradual and smooth transfer of load between the gears.


  • Differential Gears: The tooth heel is an integral part of the differential ring gear, which is essential for the operation of the vehicle’s differential system.
  • Torque Distribution: Helps in the distribution of torque to the wheels, allowing for smooth and efficient vehicle operation, especially during turns.

Operation in Differential System:

  1. Engagement: As the pinion gear rotates, its teeth engage with the teeth of the ring gear, starting from the toe and moving towards the heel.
  2. Torque Transfer: The gradual engagement from toe to heel ensures a smooth transfer of torque, reducing stress and wear on the gear teeth.
  3. Differential Action: This process allows the differential to adjust the speed of each wheel independently, essential for smooth turning and handling.


  • Smooth Operation: The helical design and gradual engagement from toe to heel ensure smooth and quiet operation of the differential.
  • Durability: Proper load distribution across the tooth profile reduces wear and extends the lifespan of the gear.
  • Efficiency: Enhances the efficiency of power transfer in the differential system, improving overall vehicle performance.


  • Complex Manufacturing: The precise design and manufacturing of the ring gear teeth, including the heel, can be complex and costly.
  • Maintenance: Requires regular inspection and maintenance to ensure optimal performance and prevent wear-related issues.

The tooth heel is a critical component in the differential ring gear, playing a vital role in the efficient and smooth transfer of power within the differential system of a vehicle. Its design and function are essential for the proper operation and longevity of the differential gears.

« Back to Dictionary Index