In determining the strength of rocks, a scale effect or scale factor-dependence of test results on the size of samples has been found. Experimental studies of the manifestation of this phenomenon lead to contradictory results, and some authors generally deny its existence.

Despite the fact that nowadays lifting vessels are equipped with parachutes with brake ropes, there are still many mine lifting vessels equipped with parachutes, which, when triggered, capture the conductor.

When studying the vibrations of rigid reinforcement of mine shafts, it is necessary to distinguish two types of forces of interaction between the parachute device and conductors - braking and coupling. Under the braking force we will understand the force of interaction between parachutes and conductors when the lifting vessel is moving along the conductors, and under the coupling force we will understand the force of interaction between parachutes and conductors when the lifting vessel is stationary in relation to the conductors or moving at a very small speed. In general case, the coupling force is not equal to the braking force. Thus, at action of friction parachutes the difference in the value of braking force and clutching force will be determined by the difference in the value of motion and rest friction coefficients. It should be borne in mind that the rest friction is 1.7-2.8 times greater than the motion friction and, consequently, the clutching force will be greater than the braking force.

In the practice of mine shaft reinforcement design up to the present time the calculation of reinforcement elements is made according to the norms based on the “Prussian rules for lifting and lowering people” from 6/IV 1925, Thus, in 1934 S. L. Lazovsky drew attention to the fact that due to the elasticity of conductors the load is distributed unevenly between the shoots and gave a solution to the problem of load distribution between the shoots taking into account the elasticity of conductors.