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 normal screw jack supports the pounds by the thread self-locking function, and the framework is simple, however the transmission effectiveness is definitely 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 definitely released, the weight could be quickly lowered alone and the return period can be shortened, but the framework of the jack can be complicated. The screw jack can support heavy objects for a long time, and the utmost lifting capacity has reached 100 tons, which is trusted. Following the horizontal screw can be mounted on the low part, the weight could be traversed at a little distance.
Principle useful:
The mechanical jack is one of the types of manual lifting tools. Its compact structure makes reasonable usage of the rocking of the rocker to rotate the pinion. It is operated by a pair of conical gears to operate a vehicle the screw to rotate and drive the lifting sleeve to Rotary Vane Vacuum Pumps ensure that the excess weight rises or decline.
Instructions:
1. Before use, it’s important to check if the jack is regular, whether the parts are flexible, put lubricating oil, and properly estimate the fat of the heavy object. Make use of a jack of appropriate tonnage and avoid overloading.
2. Adjust the method 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 handle up and down, and the excess weight will rise. When the crimson warning line appears on the lifting sleeve, the handle should be stopped instantly. If you need to lower one’s teeth in the contrary direction, the fat will begin to fall.
Precautions:
1. Generally keep the top of machine clean, examine the internal structure frequently, make the pinion in the rocker flexible and dependable, and lift the lifting sleeve openly.
2. The friction surface between your lifting sleeve and the casing must be oiled anytime. Other essential oil filling holes should be lubricated regularly.
3. To be able to consider the security in use, avoid overloading, work with illness, it isn’t appropriate to use multiple units to avoid danger.