Created on:2021-10-22 10:31

Railway engineering equipment_ Failure of slewing brake of hydraulic rescue crane

Railway engineering equipment_ Failure of slewing brake of hydraulic rescue crane

(1) Overview

During an accident rescue of NS1601 160t telescopic boom hydraulic rescue crane in a locomotive depot, it was found for the first time that the slewing brake of the crane failed or the brake was slow. When the slewing operation was stopped, it could not be braked immediately and continued to slide for a certain distance. Only reverse slewing was used for emergency response. In another accident rescue, there was a dangerous accident due to the failure of slewing brake during lifting operation. Due to the existence of this problem, the operators have lingering fear during operation, and there are serious potential safety hazards in the use of the equipment, which has a direct impact on the locomotive rescue work.

The problem was reported to the manufacturer. After several inspections and handling, including the on-site guidance of the manufacturer's technicians and the help of brother units for inspection and analysis, the slewing control circuit of the crane was repeatedly inspected for many times, and the cause was not found out.

After in-depth analysis of the design structure and dynamic process of the hydraulic system, a possibility of this phenomenon is put forward. It is verified that it is in line with the actual situation, the fault cause is found, the normal braking is restored after improvement, and the potential safety hazards in use are eliminated.

(2) Working principle of swing control

The hydraulic system is shown in Figure I. Gear pumps 10 and 5-1 provide low-pressure control oil source and main oil circuit drive oil source for the hydraulic system respectively. The hydraulic motor brake 16-3 presses the friction plate by the spring to brake. When the pressure oil enters, the spring is compressed to release the brake. The combined shuttle valve 17-3 controls the brake release oil pressure.

Operate the rotary handlebar 14-2 to make the low-pressure oil supplied by pump 10 enter the multi-way reversing valve through A5 or B5 to control the reversing of the motor, and supply oil to the combined shuttle valve to make the two position three-way valve act and open the brake of the rotary motor. The high-pressure oil supplied by the multi-way valve to the rear pump 5-1 enters the swing motor to drive the swing mechanism for forward or reverse rotation.

When the swing operation stops, A5 or B5 pressure is relieved, the two position three-way valve returns, and the brake is released for braking. At the same time, the multi-channel directional valve returns to the position, stops supplying oil to the motor, and the rotary movement stops.

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