Telescopic control system and engineering machine

Abstract

The invention discloses a telescopic control system and an engineering machine. The telescopic control system comprises a telescopic operation valve (1), a two-way hydraulic motor (3), a brake (4), a travel switch valve (5), a second braking and reversing valve (6) and a first braking and reversing valve (7), wherein the telescopic operation valve (1) and the two-way hydraulic motor (3) are arranged in a master control loop, and the brake (4), the travel switch valve (5), the second braking and reversing valve (6) and the first braking and reversing valve (7) are arranged in a brake control loop. A hydraulic locking method is adopted, when a telescopic mechanism extends out to the pole location, decompression and oil returning of a brake oil cavity of the brake are realized by operating the travel switch valve, the two-way hydraulic motor is locked by the brake and fails to operate, and therefore the locking reliability is improved fundamentally. The second braking and reversing valve is additionally arranged, when a ladder assembly needs change direction and draw back, the second braking and reversing valve can still realize breakover of the brake control loop and guide pressure oil into the brake oil cavity even if the brake is locked through oil returning by operating the travel switch valve at the pole location where the telescopic mechanism extends out, as a result, locking is relieved, and the automatic hydraulic unlocking function is achieved.

Description

technical field [0001] The invention belongs to the field of construction machinery, and in particular relates to a telescopic control system of a telescopic mechanism and construction machinery with the telescopic mechanism and system. Background technique [0002] In the aerial ladder fire truck, there are two common ways for the expansion and contraction of the ladder frame. One is to use the hydraulic cylinder to drive the wire rope pulley block to realize the expansion and contraction of the ladder frame for the aerial ladder fire truck with a relatively small telescopic length; stretching of the frame. [0003] When the hoisting mechanism is used to drive the ladder frame to expand and contract, safety protection measures must be taken when the ladder frame extends to the extreme position to prevent the ladder frame from extending too much or even slipping out. There are two common methods of prevention: one method is to send an electrical signal through the electric...

AI Technical Summary

Problems solved by technology

However, when the ladder frame and the wire rope are adjusted or manually operated, an excessive engagement force may be generated between the second stopper 15 and the first stopper 14, thereby causing deformation of the ladder frame structure.

[0004] It can be seen that there are certain shortcomings in locking the ladder frame mechanically or electrically.

When using electrical control, the induction of the proximity switch may fail due to various reasons, and the accuracy and reliability of the ladder frame locking cannot be guaranteed; when the ladder frame and wire rope are adjusted, the ladder frame locking protection of the electrical control is generally canceled ; When the hydraulic system is manually emergency or manually forced to operate, the electrical control of the ladder frame lock is already invalid; when the fire truck is debugging the hydraulic system, the electrical system is usually not used, and the electrical control of the ladder frame lock is also invalid

When mechanical locking is adopted, the locking structure has to bear a large force, which will cause certain damage to the locking structure in the long run, resulting in poor locking reliability.

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