<p dir="&quot;&quot;ltr&quot;&quot;"><span style="color:#000000;"><span style="font-size:14px;"><span style="font-family:tahoma,geneva,sans-serif;">Single crane girder installations are useful in applications where no transverse movement is needed. Also known as monorail cranes, these machines can travel the length of the girder and lift or lower loads only. This type of crane is useful in narrow spaces where load movement is restricted to the length of the space. These cranes generally run on the bottom of the girder which is typically supported at several points along its top cross member. One disadvantage is reduced hook height because the crab and hook is usually located under the crane girder.</span></span></span></p> <p dir="&quot;&quot;ltr&quot;&quot;"><span style="color:#000000;"><span style="font-size:14px;"><span style="font-family:tahoma,geneva,sans-serif;">Bridge and double girder cranes are far more flexible and allow 3-dimensional hook movement. In these installations, the crab can move across the crane girder to cover the breadth of the space. In addition, the crane girder assembly can move along the length of the space covering a far wider area than a monorail. This type of crane has the additional benefit of having the crab girder run on top of the side support beams or be raised to run between them. This allows for extended hook heights and improved flexibility.</span></span></span></p> <p dir="&quot;&quot;ltr&quot;&quot;"><span style="color:#000000;"><span style="font-size:14px;"><span style="font-family:tahoma,geneva,sans-serif;">Crane girders, particularly the crab girder, are constantly subjected to a number of stress loads during operation. These include vertical stress exerted by the load, lateral stress caused by acceleration and braking of the crab, and transverse stresses caused by swinging of the load. Crane girders are often reinforced with flat plates or channels along their mounting cross sections to resist these stresses. To ensure the safety of operating personal and the loads the crane transports, crane girders need to be correctly rated and regularly inspected for signs of damage.</span></span></span></p>