Connecting Rod Drive Mechanism: Converts Vertical Motion into Rotational Motion
1.1 Overall Transmission Chain
Lift hook/down movement → Spring and connecting rod drive rope → Guide block slides along the triangular plate → Triangular plate rotates around the axis → Drive connecting rod rotates → Swing arm swings → Turn-lock mechanism connecting rod → Turn handle rotates → Turn lock rotates ±90°
1.2 Core Components: Triangular Drive Plate and Sliding Guide Block
The triangular drive plate (usually in a right-triangle shape) is fixedly installed in the connecting rod mechanism, with a sliding groove machined on its hypotenuse.
The guide block is slidingly connected to the groove and is also connected to the drive rope.
Working Principle: When the lift hook pulls the drive rope upward, the guide block slides up along the triangular plate's inclined groove. Due to the groove's guidance, the guide block applies a tangential force to the triangular plate, forcing the triangular plate to rotate around its fixed axis. Conversely, when the hook descends, the guide block slides downward, and the triangular plate rotates in the opposite direction.
This design essentially functions as an inclined-plane–crank conversion, turning linear displacement into angular displacement. Theoretical calculations show that if the incline of the groove relative to the horizontal is α, the relationship between the guide block displacement S and the triangular plate rotation angle θ approximately satisfies:
tan θ ≈ (groove offset × movement distance) / crank radius
By optimizing the shape of the triangular plate and the curve of the groove, accurate ±90° rotation can be ensured throughout the lifting stroke.
1.3 Fine Angle Adjustment: Stop Block and Adjustment, Shim
To ensure that the rotary lock can accurately rotate to the fully unlocked or locked position each time, the end position of the triangular plate rotation needs to be precisely located. The specification requires adjusting the height of the stop block through the adjustment shim at the bottom of the stop block.
Stop Block: A rigid limit component that restricts the maximum rotation angle of the triangular plate.
Adjustment Shim: Multiple thin metal sheets that can be added or removed layer by layer to change the limit position.
Operation: During on-site installation or maintenance, use a feeler gauge to measure the actual deviation of the rotation angle, then add or remove shims so that the block height changes in 0.1 mm increments, corresponding to a fine rotation adjustment of about 0.5°~1°.
This purely mechanical fine-tuning method is more reliable than hydraulic or electric limit switches and is not affected by electromagnetic interference, making it suitable for ports with high dust and vibration environments.
1.4 Adaptive Tensioning of Spring and Drive Rope
Spring: Installed between the drive rope and the hook, it absorbs impact loads during lifting while ensuring that the guide block always fits closely to the slide groove, preventing empty travel.
Drive Rope: Made of steel core wire rope, wear-resistant with minimal elongation. Its length needs to be precisely set to ensure that the guide block is in the middle of the slide groove when the lifting device is unloaded, allowing symmetrical up and down travel.
