The structure of the jack is classified
Driven by the human body through the lever and gear to lift the rack lift weight. From the general weight of not more than 20 tons, long-term support heavy objects, Mainly used in the operating conditions inconvenient place or need to use the lower claws to lift heavy objects occasions, such as rails from the track operations.
By the human through the screw drive, screw or nut sleeve as the top pieces.
Ordinary screw jacks rely on thread self-locking to support heavy objects, simple structure, but the transmission efficiency is low, slow return.
Self-lowering screw jacks have no self-locking threads, but are equipped with brakes.
Relax the brakes, heavy objects can quickly decline, shorten the return time, but this jack structure is more complex.
Screw jack to long-term support heavy objects, the maximum weight has reached 100 tons, wider application.
The lower part of the horizontal screw, but also make heavy objects to do a small distance traverse.
Driven by human or electric hydraulic pump, through the hydraulic system drive, with the cylinder or piston as the top pieces. Hydraulic jacks can be divided into integral and separate. Integral pump and hydraulic cylinder into one; separate pump and hydraulic cylinder separation, the middle with high pressure hose associated. Hydraulic jack structure is compact, can be a smooth lifting of heavy objects, from the maximum weight of 1,000 tons, travel 1 meter, transmission efficiency is high, so the application is wider; but easy to leak, not long-term support heavy objects.
Such as long-term support need to use self-locking jack, screw jack and hydraulic jack to further reduce the height or increase the jacking distance, can be made multi-level telescopic. In addition to the above basic type of hydraulic jack, according to the same principle can be converted into a slide jack jack, hydraulic lift, Tensioning machine, etc., for a variety of special construction occasions.