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In truck and trailer door locking systems, the cam and keeper are key components used in pairs to achieve mechanical closing and locking of the door. They are the core locking mechanism of the entire door locking gear.
What is a Cam?
A cam is a metal component mounted at the bottom (or top) of the truck door handle or locking rod. When the operator rotates the handle, the cam turns as well.
Due to its eccentric shape, it:
- Pushes the end of the locking rod inward;
- Engages tightly with the Keeper on the door frame;
- Thus ensures the door is firmly closed and locked.
Common Shapes
- Round Cam.
- Flat Cam.
- Eccentric Cam.
What is a Keeper?
A keeper is a fixed metal seat mounted on the door frame. When the door closes, the Cam rotates and fits into the Keeper to achieve secure locking.
Main Functions:
- Receives and holds the cam in place;
- Bears the locking pressure from the door;
- Ensures sealing and stability between the door and frame.
Common Types
- Flat Keeper
- U-Type Keeper
- Heavy-Duty Keeper
How It Works
Rotate the lock handle → turns the vertical rods.
Rods move the cams at top and bottom.
Each cam rotates into the keeper mounted on the door frame.
The eccentric cam shape pulls the door tightly against the seal, ensuring a weatherproof closure.
