Scissor jack

Do material handling designs promote the use of hoists, scissor jacks, or drum carts ... 

There are many kinds of jacks including hydraulic, mechanical, and pneumatic ones. There are bumper jacks for older cars, scissors jacks, jacks with ratchet mechanisms, and jack screws. Each jack has a maximum design load. Although jacks are very common, users should understand how to use them safely and what their load limits are before using them. 

A more effective amplifier called a scissor-jack (Figure Id) has demonstrated high magnifying effect (Constantinou, 2000). It was reported that using this configuration reduces the required... 

Figure 1. Dampers configurations (a) Chevron brace, (b) toggle brace, (c) lever arm, (d) scissor jack...

Sigaher, A. N., Constantinou, M. C. (2003). Scissor-jack-damper energy dissipation system. Earthquake Spectra, 79(1), 133-158. doi 10.1193/1.1540999... 

The jack should scissor together, pushing the head upward into the jack point. Even after the cars weight is supported by the jack, refrain from putting any part of yourself underneath the vehicle. Despite your best preparation, cars can and do roll off jacks, and you don t want any part of yourself underneath any part of your car. Keep raising the car until the wheel to be changed is completely off the ground. 

---