Runway Survey |
Demag survey service offers effective preventive measures
If a malfunction occurs in a materials handling installation which is integrated into important process and production sequences, the fault has to be rectified as quickly as possible. Serious financial losses would otherwise result in many parts of the manufacturing chain. However, the emergency measures taken often fail to eliminate the cause, but rather exacerbate the situation.
A problem in this context is that the cause of poor running characteristics of cranes or other materials handling equipment is often difficult to localise precisely and quickly. For example, broken travel wheels are replaced without first finding out what caused the damage. A further example is extreme wheel flange wear, for which a maintenance technician fits a flange lubricating system or additional guide rollers, which transfers the forces causing the damage to other parts of the structure. The crane runways are then exposed to such strong forces that travel rails wear out, weld seams tear and the condition of the installation becomes even more critical. The results in even greater loss of production, rising repair costs and unpredictable hazards for both man and machinery.
However, all of these defects can be eliminated by means of specific preventive measures at comparatively low cost long before they occur. Examples of this are regular inspections, surveys with subsequent fault analysis and checks of the installation as required by relevant accident prevention regulations.
A practical example will illustrate this more clearly. The travel characteristics of a maintenance platform, which is used for inspection and repair purposes on a water tower at a height of some 70 meters, have strongly deteriorated over a number of years. The platform can no longer be operated safely, as the drive control system has become unreliable as a result of skewing and blockages and has already broken down several times. Therefore, the relevant inspection authority restricted use of the platform.
As part of a joint project, Demag Cranes & Components and Thyssen Krupp Fördertechnik offered the owner of the installation a concept to completely refurbish the platform. The upper and lower runway sections, which measure 4.8 meters and 20.6 meters, respectively, were first subjected to a close inspection. This demanding precision measurement task was performed by the Demag Survey Team. In order to determine the exact position and height of both runways, the team attached 72 foil reflectors to the lower edges of the girder flanges along the length of the girder. The foil reflectors were positioned at a distance of 10 degrees from and between the suspensions.
The three measuring unit locations were then determined, from which all measuring points could be observed on both runways. To achieve the necessary accuracy, the angle of incidence of the target beam had to be less than 50 Gon. The team performed the measurements using a Leica TC2003 surveying instrument and saved the results online. The three-dimensional co-ordinates were used to determine the track gauge dimensions and height differences between the individual points along the runway and represent them in the form of graphics and tables. Two sets of measurements were conducted under different meteorological conditions; at approx. minus three degrees Celsius and zero percent cloud cover on the one hand, and at plus 15 degrees Celsius and 100 percent cloud cover on the other hand. The measurements revealed deviations from the specified track gauge at certain points, which exceed the design tolerances of the maintenance platform, and consequently have a negative impact on the travel characteristics. This information now enables Thyssen Krupp Fördertechnik to make specific design changes to the maintenance platform travel units and therefore eliminate the problem in the long term.
This practical example shows that a dedicated search for the causes, when carried out by an experienced company, can contribute towards optimum economic solutions in the maintenance sector.
