The screw jack, also called 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 fat by the thread self-locking function, and the framework is simple, however the transmission performance is normally low and the come back stroke is sluggish. The thread of the self-propelled screw jack does not have any self-locking action and is equipped with a brake. When the brake is certainly released, the weight can be quickly lowered alone and the return period can be shortened, however the framework of the jack is usually complicated. The screw jack can support heavy items for a long time, and the maximum PTO Drive Shaft lifting capacity has reached 100 tons, which is trusted. After the horizontal screw is normally mounted on the low part, the weight can be traversed at a small distance.
Principle useful:
The mechanical jack is among the types of manual lifting tools. Its compact framework makes reasonable utilization of the rocking of the rocker to rotate the pinion. It really is operated by a pair of conical gears to operate a vehicle the screw to rotate and force the lifting sleeve to ensure that 
the fat rises or decline.
Instructions:
1. Before use, it's important to check if the jack is normal, whether the elements are flexible, increase lubricating oil, and properly estimate the weight of the heavy object. Make use of a jack of suitable tonnage and prevent overloading.
2. Adjust the technique of supporting the teeth on the rocker. First of all, 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 along, and the excess weight will rise. When the reddish colored warning line shows up on the lifting sleeve, the handle should be stopped instantly. If you want to lower the teeth in the opposite direction, the weight will start to fall.
Precautions:
1. Always keep the surface of the machine clean, verify the internal structure frequently, make the pinion in the rocker versatile and dependable, and lift the lifting sleeve openly.
2. The friction surface between your lifting sleeve and the housing must be oiled at any time. Other oil filling holes should be lubricated regularly.
3. To be able to consider the basic safety used, avoid overloading, work with illness, it is not appropriate to use multiple units to avoid danger.