The screw jack, also known as the mechanical jack, is driven by a manpower through a screw pair, and a screw or nut sleeve is used as a jacking member. The ordinary screw jack supports the weight by the thread self-locking function, and the framework is simple, but the transmission efficiency is low and the return stroke is slow. The thread of the self-propelled screw jack has no self-locking action and is equipped with a brake. When the brake can be released, the weight can be quickly lowered by itself and the return period can be shortened, however the structure of the jack can be complicated. The screw jack can support heavy items for a long time, and the utmost lifting capacity has reached 100 tons, which is trusted. Following the horizontal screw is definitely mounted on the lower part, the weight can be traversed at a small distance.
Principle of use:
The mechanical jack is one of the types of manual lifting tools. Its compact framework makes reasonable use of the rocking of the rocker to rotate the pinion. It really is operated by a set of conical gears to operate a vehicle the screw to rotate and force the lifting sleeve to ensure that the excess weight rises or decline.
Instructions:
1. Before use, it’s important to check if the jack is regular, whether the components are flexible, increase lubricating oil, and properly estimate the fat of the heavy object. Make use of a jack of suitable tonnage and steer clear of overloading.
2. Adjust the technique of supporting the teeth on the rocker. Firstly, turn the rocker directly in the clockwise direction by hand to help make the lifting sleeve quickly ascend the top weight.
3. Insert the handle into the rocker hole, move the handle along, and the weight will rise. When the red warning line appears on the lifting sleeve, the handle should be stopped immediately. If you need to lower one’s teeth in the opposite direction, the fat will begin to fall.
Precautions: 
1. Usually keep the surface of the machine clean, verify the internal structure regularly, make the pinion in the rocker Water Ring Vacuum Pumps flexible and dependable, and lift the lifting sleeve openly.
2. The friction surface between the lifting sleeve and the casing must be oiled at any time. Other essential oil filling holes ought to be lubricated regularly.
3. To be able to consider the basic safety in use, avoid overloading, work with illness, it is not appropriate to use multiple units to avoid danger.