Electro-Hydraulic Control System 6

Original spare parts

Reset all shields with which the conveyor is raised. Recheck the setting pressure. Never disengage the canopy bar from the roof. It must always be in contact over the entire length. If you raise the conveyor with several shields, make sure that these are not in direct proximity to one another. For raising the conveyor, employ only: J undamaged, high-strength round link chains, J the fastening points provided for the purpose (Check the fastening points for cracks at the welds and damage to the load-supporting rings.), J hoisting gear with sufficient permissible load-bearing capacity.

Maintenance

Be sure to observe the indicated intervals for maintenance and inspections. Examine the shield at least once per shift for externally visible damage. Inform the supervisory personnel and coal face crew about maintenance and repair work. Provide them with information on the intended work and the probable duration. Secure your working area over a wide range, in order to avoid endangering other persons. Replace damaged components immediately. Immediately shut down the shield concerned, if immediate repair is not possible. Secure this area and notify the entire coal face crew and the responsible foremen without delay. Use only spare parts which conform with the specified technical requirements. This is ensured only by the use of original spare parts from DBT. The catalogue numbers are indicated in the spare parts lists. Do not perform any conversions or modifications which impair the safety of the shield. All conversions and modifications require approval by DBT. During work on the walking travel gear, isolate the working area for the winning machine. Working in the winning track is permissible only if J the roof has been secured against rock fall, J the coal face has been secured against running out, and J the winning machine and conveyor have been shut down and secured against restarting. Before disconnecting the shield from the conveyor, you must: J stop production, and J relieve the load on the components which are under hydraulic pressure or mechanical stress. Immediately discontinue work on the shield, if production and crushing operations are in progress in your working area.

Handling of hydraulic fluids

Maintenance, repair

Permissible tubing

Secure the shield before all work: J mechanically against inadvertent yield, for instance with the use of: – wooden wedges between the lemniscatic links, – and safety chains between the gob shield and roof. In coal faces with inclined stratification, secure the components to be replaced with the use of chains or hoisting gear, for instance. Immediately after completion of the work, reinstall protective devices which have been removed, and check them for correct functioning.

Hydraulics

Avoid direct contact between the skin and hydraulic fluids. Hydraulic fluid can penetrate the skin and cause serious infections. Never use hydraulic fluids for rinsing or cleaning. Hydraulic fluids represent a very serious danger to health. Only persons who have and can demonstrate a special knowledge of hydraulics may be allowed to work on the hydraulic system. Carry out a visual inspection of all the hydraulic components at regular intervals. In particular, pay attention that: J The hoses are not pinched or trapped. J The hoses have no bubbles or blisters. J The hoses or the outer sheathes of the hoses are not abnormally rigid or hard. J The outer sheath of the hoses is not damaged. J The connectors are securely inserted into the sockets. J The connections are leak-tight. Ensure that no dirt enters the hydraulic system during repair work. Dirt in the hydraulic system can cause serious damage in the whole system! Flush out the hydraulic lines thoroughly before connecting. If hydraulic hose couplers are difficult to disconnect or cannot be disconnected, the hydraulic line may still be pressurized. Be sure to depressurized the line before disconnecting couplers. Secure the connectors of the hydraulic elements only with the proper coupling clamps. Always fasten the clamps completely and with both sides. Never use nails, wire or similar materials for securing. After finishing repair work, check all connectors and connections for leaks before pressuring the system again. Use only hydraulic hoses approved for the prevailing pressures. Do not use any hydraulic hoses with damaged connectors or worn O-rings. Replace hydraulic hoses only with hoses of the same or a higher quality. Observe the date of manufacture stamped on the hydraulic hoses. Never use hydraulic hoses which are more than 2 years old, even if they have no visible signs of damage. Never try to hold a jumping hydraulic hose. Depressurized the line in question immediately.