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 utilized as a jacking member. The ordinary screw jack supports the weight by the thread self-locking function, and the structure is simple, however the transmission performance can be 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 is definitely released, the weight could be quickly lowered alone and the return time can be shortened, however the framework of the jack is normally complicated. The screw jack can support heavy objects for a long time, and the maximum lifting capacity has reached 100 tons, which is trusted. Following the horizontal screw is certainly mounted on the low part, the weight can be traversed at a small distance.
Principle useful:
The mechanical jack is one of the types of manual lifting tools. Its compact structure makes reasonable utilization of the rocking of the rocker to rotate the pinion. It is operated by a pair of conical gears to drive 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 normal, whether the elements are flexible, add lubricating oil, and Helical Reducers properly estimate the weight of the large object. Use a jack of appropriate tonnage and avoid overloading.
2. Adjust the technique of supporting the teeth on the rocker. First of all, turn the rocker directly in the clockwise path by hand to help make the lifting sleeve quickly ascend the very best weight.
3. Insert the handle in to the rocker hole, move the handle up and down, and the pounds will rise. When the reddish colored warning line shows up on the lifting sleeve, the handle should be stopped immediately. If you want to lower one’s teeth in the opposite direction, the pounds will begin to fall.
Precautions:
1. Always keep the top of machine clean, examine the internal structure regularly, make the pinion in the rocker flexible and reliable, and lift the lifting sleeve freely.
2. The friction surface between the lifting sleeve and the housing must be oiled at any time. Other essential oil filling holes should be lubricated regularly.
3. In order to consider the protection in use, avoid overloading, work with illness, it is not appropriate to make use of multiple units to avoid danger.