Рус Укр Eng

Dissertation summary

Lifting machines are used in industrial and metallurgical workshops, covered and not covered warehouses, ports and other. They are used for moving of various hard and friable loads, coal , ore and other minerals; assembling and repair works and so on. In lifting machines, during lifting or lowering, load and gripper are not hold from transversal moving, because directing conductors are not present.(are absent).

The arbitrary moving of the loads in transversal direction is not useful because it is make an additional exploitation troubles in part of safety providing.

Today the correct work of transport and lifting equipment is deeply influence on enterprises economic indexes, so, researching of lifting proceses is an actual task for today and for the nearest future.

Fig. 1. Schemas of tower and bridge cranes

We will consider the simplest variant of load lifting, when carriage makes one-dimensional moving. This process is shown on fig.2        

Fig.2. The process of load lifting

Current position of load will be such

,

where is primary coordinate of carriage, is primary length of lift wire,  is curent length of lift wire,  is angle, between lift wire and pintle. Then

.                  

Square of load velocity is

,

Kinetic energy of the system is

,             

Potential energy of the system is

.

Lagrangian function is

After simplification

,

The equations of dynamic conditions of the system, after computing and simplification of partial derivatives from the Lagrangian function on generalized coordinates

The solution of that set of equations allows to find peak values of transversal moving of load and dynamic forces of lift wire at different character of torque change  and other.