Boom Angle Indicators: Mechanical & Electronic
A manual type inclinometer usually has degree numbers from -20 to +90 degrees. The numbers should remain clean and visually readable at all time. The capacities that are listed on the crane load charts are also based on and vary with the boom angle of the crane.
For example: On hydraulic cranes, the boom angle is the angle between the bottom of the boom butt and the horizontal while the boom is under load (fig 1, view A). The boom angle on lattice boom cranes is the angle between center line of the boom (from the boom butt pins to the boom tip sheave) and the horizontal while the boom is under load (fig 1, view B) Figure 1
To check the accuracy of the boom angle indicator, place a 3-foot builders level on the center boom section and raise or lower the boom until the level indicates the boom is level. At this point the boom angle indicator should show the boom is at zero degrees or adjusted to read zero degrees.
Please note: The boom angle indicator is a quick reference for the operator to know what angle the boom is at. However, do NOT rely on the boom angle indicator for radius accuracy especially when the lift exceeds 75 percent of the rated capacity. Use the radius measurement to determine the capacity of the crane from the load charts and to avoid any possibility of error. |
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