The screw jack, also referred to 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 pounds by the thread self-locking function, and the framework is simple, however the transmission efficiency is normally low and the return stroke is gradual. The thread of the self-propelled screw jack has no self-locking action and has a brake. When the brake is normally released, the weight can be quickly lowered alone and the return time can be shortened, but the structure of the jack is definitely complicated. The screw jack can support heavy objects for a long time, and the maximum lifting capacity has reached 100 tons, which is trusted. After the horizontal screw is normally mounted on the lower part, the weight can be traversed at a small distance.
Principle of use:
The mechanical jack is among the types of manual lifting tools. Its compact structure makes reasonable usage of the rocking of the rocker to rotate the pinion. It really is operated by a set of conical gears to drive the screw to rotate and press the lifting sleeve 
so that the excess weight rises or decline.
Instructions:
1. Before use, it's important to check if the jack is normal, whether the parts are flexible, add lubricating oil, and properly estimate the excess weight of the large object. Use a jack of appropriate tonnage and avoid overloading.
2. Adjust the method of supporting the teeth on the rocker. Firstly, turn the rocker straight in the clockwise direction by hand to make the lifting sleeve quickly ascend the top weight.
3. Insert the handle in to the rocker hole, move the deal with up and down, and the excess weight will rise. When the crimson warning line appears on the lifting sleeve, the handle ought to be stopped immediately. If you need to lower one's teeth in the contrary direction, the fat will start to fall.
Precautions:
1. Usually keep the surface of the machine clean, verify the internal structure regularly, make the Conveyor Chains pinion in the rocker flexible and dependable, and lift the lifting sleeve freely.
2. The friction surface between the lifting sleeve and the casing must be oiled anytime. 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.
