Which component of an ascender or rope grab is designed to grip the rope when a load is applied?

The cam is the component of an ascender or rope grab specifically designed to grip the rope when a load is applied. This mechanism functions by creating friction against the rope, which allows the device to ascend easily when there is little to no load but locks onto the rope securely when a weight is applied. This dual functionality is crucial in rescue and climbing scenarios, as it ensures that the user can ascend and descend safely without the risk of accidental slippage.

The cam's design typically features a sloped surface that allows it to pinch the rope as it bears weight, effectively preventing downward movement while permitting upward movement. This capability is vital for the safety and reliability of any rescue operation or climbing activity where maintaining control over one's descent or ascent is critical.

Other components like hooks, sheaves, and brakes serve different roles in the mechanism; for example, hooks are used for attaching the device to a harness or anchor point, sheaves guide the rope through the device, and brakes help in controlling the descent but do not have the same gripping function as the cam. Thus, the cam is essential in ensuring the effective operation of ascenders or rope grabs under load.