How to Size a Welding Manipulator


Lift & Reach

The lift and reach requirement is determined by the most extreme vertical and horizontal arc location.  This is based on the work envelope size.  Lift and reach dimensions are measured from the centerline of the mast/upright and boom/ram.  There is a minimum and maximum dimension; the lift and reach size represents the total range provided.  A typical welding set-up is shown in the sketch below. The distance to the top of the vessel above the floor can be determined by first finding "side b" of the triangle a-b-c, with known values for "a" and "c" using the formula b = √a² - c². Add the value of "b" to the Axle Height above floor, plus the "R" Radius of the vessel. Next, add the distance from the arc to the centerline of the boom.  This will give you the maximum required for the lift range. Follow the same procedure to find arc height needed for the smallest vessels.

Load Capacity

Koike Aronson/Ransome manipulators have a rated load capacity that must be considered.  This load is expressed as a value at either or both ends of the boom/ram, and is rated directly at the end. No over-hung capacity is stated.  All additional weights, including operator, catwalks, operator chairs, cross slides, and welding equipment, must be considered when calculating the weight capacity required.  All load ratings vary depending on lift and reach specified. Please refer to the manipulator load capacity table on page 5.


Standard Manipulators only include lift and reach capability.  Travel cars, travel rail, operator seats, catwalks, cross slides, welding equipment, mast rotation, and seam trackers are all examples of options that must be specified when ordering a manipulator.


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