Hiza-guruma (knee wheel) can be the stumbling block of many Judoka. This, caught right, on the move is a relatively simple technique. However, many struggle with this technique, due to an expectation that the leg will some how miraculously throw the uke.
Whilst Hiza-guruma is an ashi-waza, it relies on a great deal of work with your hands. Your hands need to work in a circular movement, in a clockwise direction if throwing to the left, or anti-clockwise to the right. In this sense this technique can be quite flexible as can be controlled by either your tsurite or hikite. Either way, one hand needs to be pulling towards the floor, whilst the other directing your uke out and over.
The leg simply blocks the uke, so where the would be able to regain balance by stepping forward, instead they flip over at the mercy of the pull of the hands.
I believe that this throw is classified as ashi-waza more to the ‘walking / to step’ translation of the word ‘ashi’.
This throw can be done in a few ways, as ever a huge debate can ensue as to which is correct!
1. As above. Tori steps backwards/to the side and uses this momentum to continue the throw with their hands.
2. Tori steps forward so that the technique uses a horizontal circle as well as the vertical one created in the above technique by tori’s hands.
3. Tori steps forward, uke retreats by stepping backwards. This balance is the exploited by tori who lifts their foot to the receding leg and executes the throw as usual.
[From akitasjudo.com. Original page is here]