The logic and rationale behind transverse frictions, or "deep frictions", as Cyriax calls them, is outlined in the "textbook of Orthopaedic Medicine" volume one by James Cyriax, in chapter 2: Trauma to Soft Tissue, and the technique is described in "Cyriax's Textbook of Orthopaedic Medicine", volume 2, chapter 3.
the short term explanation is that due to the inflammation occuring post trauma a network of fibrils forms, which then starts to create adhesions, which later create problems. Transverse frictions break these adhesions, and "each fiber is drawn away from its fellow", and "the surface of a tendon may be smoothed off". Other considerations are: the right spot must be found, the therapist's fingers and the patient's skin must move as one, sufficient sweep is required, the friction must reach deep enough,muscles must be kept relaxed while being frictioned, tendons with a sheath must be kept taut.
Volume 2 then also deels with "Indication for and against Deep Friction" as well as technique in general, and in part 2, "The Plates" shows a number of specific techniques. Even if you are not a Cyriax fan, this part is really very useful, have a look at it.
neving