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 utilized as a jacking member. The ordinary screw jack supports the excess weight by the thread self-locking function, and the structure is simple, however the transmission effectiveness is certainly low and the come back stroke is gradual. The thread of the self-propelled screw jack has no self-locking action and is equipped with a brake. When the brake is normally released, the weight can be quickly lowered alone and the return period can be shortened, but the framework of the jack is normally complicated. The screw jack can support heavy objects for a long time, and the utmost lifting capacity has reached 
100 tons, which is widely used. Following the horizontal screw is mounted on the lower part, the weight could 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 usage of the rocking of the rocker to rotate the pinion. It 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 whether the jack is normal, whether the elements are flexible, add lubricating oil, and properly estimate the fat of the heavy object. Make use of a jack of appropriate tonnage and prevent 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 into the rocker hole, move the deal with along, and the fat will rise. When the crimson warning line appears on the lifting sleeve, the handle should be Rotary Piston Vacuum Pump stopped instantly. If you want to lower the teeth in the contrary direction, the pounds will begin to fall.
Precautions:
1. Generally keep the top of machine clean, verify the internal structure regularly, make the pinion in the rocker versatile and reliable, and lift the lifting sleeve freely.
2. The friction surface between your lifting sleeve and the casing must be oiled at any time. Other essential oil filling holes ought to be lubricated regularly.
3. In order to consider the safety used, avoid overloading, work with illness, it isn’t appropriate to make use of multiple units to avoid danger.