The American machines were very large at first and while they had drums that, in some cases, were 24 inches in diameter, they were compromised compared to the size of most dryer drums. They washed better than tumbler washers because the drum was bigger, but the drums were not as large as most dryers of the time. I have seen good tumbling during drying in most of the vintage combos I have used. I satisfactorily washed and dried a full set of king size bedding in both my 52 Duomatic and my 29" Lady Kenmore combo. The king size bedding washes and dries fine in a GE combo and in the big 33" WP combo and the similar Kenmore combo from the late 50s. When I had my 27" wide Philco Duomatic, I dried the bottom fitted sheet and the pillow cases in one load and the top sheet by itself, but all were washed together. When the combos were invented, the average washer load size was between 5 and 10 pounds. Even the Halo of Heat dryers were designed for the smaller tub Maytag washers. The capacity of the big combos was greater than the small machines from overseas marketed today and many easily handled 8 pound loads from start to finish. In spite of the poor water extraction in all but the Bendix machines, the fact that the vintage combos used 230 volt heating elements or gas for heat during the drying part of the operation, meant they were still faster than today's 115 volt combos with better water extraction.