What type of jacks are typically considered least stable under load?

Ratchet jacks are often cited as the least stable under load due to their design and mechanism. Ratchet jacks utilize a ratcheting mechanism combined with a straight arm for lifting. This design can make them less stable compared to other types of jacks, especially as weight and load conditions change. The reliance on a mechanical locking system can be vulnerable under dynamic conditions or if the load shifts, which may compromise stability.

In contrast, hydraulic jacks utilize fluid pressure for lifting and can handle heavier loads more smoothly, providing a more stable lifting experience. Scissor jacks, while not as strong as hydraulic jacks, have a wide base and a crisscross mechanism that provides stability while lifting. Bottle jacks, which are also hydraulic, have a smaller footprint but offer substantial lifting capability and stability due to their design and the hydraulic mechanism. Each of these options typically features characteristics that enhance their overall stability under load compared to ratchet jacks.