What kind of judo throw is momo-guruma? It doesn't appear to be recognised by the Kodokan by this name, how is it performed and/or classified?
Momo-guruma (股車 "thigh wheel") is a throw similar to sasae-tsuri-komi-ashi and hiza-guruma, where tori uses their foot as a fulcrum on uke's upper outer thigh to wheel them over. The Kodokan officially classifies it as a variant of hiza-guruma:
Hiza-guruma - with the sole of the right foot supporting uke's left upper thigh
Both sides grapple in right natural posture. Similar to Application 1 (sono ichi), at the moment uke moves his left foot, tori changes his right grip to the outside of uke’s left middle sleeve, advances his left foot in front of uke's right foot (along the central line), and supports uke's body with his right foot by curving the toes of his right foot and placing the big-toe side on the outside of uke's left upper thigh (so that it touches his buttock) (photo 30). Tori opens his body to the right and pulls uke round with both hands to throw him down (photo 31).
The particular feature of this technique is that tori places the sole of his right foot on the outside of uke's left upper thigh. The area that he supports is different from that in the normal hiza-guruma but the concept is the same.
Kiyoichi Takagi, 7th dan, (later 9th clan), an expert in this technique, restyled his own version as momo-guruma. He gives an explanation of its most important points in Judo (published by Kodokan, July 1940 issue, 'Tokui waza kokai—an explanation of momo-guruma').
Hiza-guruma is a technique for throwing shorter people. When I was learning we practiced the standard hiza-guruma in the approved manner, and although we tried to learn it, it would not work properly however much we tried. After a lot of research, we found that hiza-guruma is a technique best executed by a tall person on a shorter person.
I wanted to create a set form to throw a short person with hiza-guruma and I came up with momo-guruma (as described here), which is for me the most suitable hiza-guruma. Momo-guruma is pretty much self-explanatory, you execute the technique on the outside of the thigh. I, however, go further and execute the technique on the opponent's buttock.
- Kodokan Judo Throwing Techniques (p.123)
Note that though momo uses the same character as mata (股 cf. uchi-mata), the former pronunciation refers to the thigh generally and the latter the crotch.