Question

in the lifting device which type of gear pair is used​

Answer 1

A horizontal gear unit will use a helical gear set and a vertical gear unit will use a spur gear unit. Most modern manufacturers will use a helical gear set as the teeth are set at an angle to the gear axis. This means they can apply greater power than a spur gear unit due to the greater tooth strength and are smoother and quieter at high loads. In addition the shafts in a helical gear do not need to run parallel to each other unlike a spur gear. One downside of helical gears is that they produce 'axial thrust' which spurs do not. Spurs main advantage is that they are cheaper and easier to design and manufacture. They are often preferred in circumstances where owner repairs might be wanted.