Just a little information from Nolting longarm site.
What we know as hand-guided quilting machines have been around a long time. As far back as the 1960s and 1970s there were a few individuals and small companies offering what we now call short-arm quilting machines on frames. The basic short-arm is usually a commercial sewing machine taken out of a tabletop and set into a carriage system. The carriage system had two sets of wheels on a long frame. This system made it so you could move the machine over the stationary fabric. This was the first major step away from the more traditional machine sewing where you moved the fabric under a stationary machine.
These were great and slowly began to gain some popularity with decorator workrooms making bedspreads and comforters. Working with these item’s thicker batting and larger sizes begged for a larger machine. A few people began to stretch the commercial sewing machines used to make short-arm systems. The stretching process involved sawing the commercial sewing machine in half, adding a spacer in the middle and lengthening the shafts to the needle and bobbin area. These stretched machines allowed the quilter to quilt larger designs. But the thick batting and long bedspreads rolled up larger than the 5 of the inside height of a typical commercial sewing machine.
Lengthening the shafts that drive the needle and the rotary hook can be a challenge. Increasing the inside height of the sewing machine was another matter altogether. There are more complicated mechanisms involved in doing this. Innovation stalled here.