A hand chain hoist, also known as a manual chain hoist or chain block, is a mechanical device used for lifting and lowering heavy loads. It operates based on simple mechanical principles and consists of a few essential components. Here is an overview of the working principle of a hand chain hoist:
The load chain is a series of interlocking metal links that form a durable and flexible chain. It is designed to bear the weight of the load being lifted.
The hand chain is a manual control mechanism used by the operator to lift or lower the load. It is typically a looped chain that runs through the hoist mechanism.
Inside the hoist housing, there is a lifting mechanism that includes gears and a set of pawls (ratcheting mechanisms).
The gears are connected to the load chain, and they rotate when the hand chain is pulled or released by the operator.
Pawls and Ratchet:
The pawls and ratchet mechanism is crucial for preventing the load from descending unintentionally. It ensures that the load remains in place when the operator stops pulling the hand chain.
The pawls engage with the ratchet wheel, allowing the load to be lifted incrementally and preventing it from slipping back down.
Hand chain hoists are equipped with a braking system to control the descent of the load and hold it in place when not actively being raised or lowered.
The brake engages when the hand chain is released, providing a secure hold on the load.
The load is attached to the hoist using load hooks. These hooks are designed to securely hold the load during lifting.
The operator pulls the hand chain, causing the gears to rotate and lift the load chain.
The pawls engage with the ratchet wheel, preventing the load from descending when the hand chain is released.
To lower the load, the operator releases the pawls by pulling a separate release chain or by using a specific mechanism on the hand chain.
The brake system controls the descent of the load, providing a controlled lowering.
Hand chain hoists are simple, robust, and widely used in various industries for lifting and positioning heavy loads. They are especially useful in situations where electricity is unavailable or impractical.0