I have watched RU all my life and I understand most of the rules but over the years I have seen a trick that the AllBlacks use very effectively and I am not sure if it is legal or not... When the A.B are defending in a corner and the opposition are going to feed a scrum,the A>Bs always wheel the scrum round so that when the opposition get the ball they can only go on the blind side nearest to the touchline....is this legal or not??.
Yes, its legal, provided that the wheel is accomplished by pushing the opposing scrum around, and not by pulling them around (this latter method is called "whip-wheel;" and is illegal)
A few important things to consider.
1. The engagement is offset to the left....
so the centreline of the scrum passes through the right shoulders of the two hookers...
The result of this is that the majority of the pushing force is on the left side of the centreline, so when the pressure comes on the scrum will naturally tend to wheel to the right (clockwise when viewed from above)
2. A legally wheeled scrum is usually achieved by having your Tight Head Prop (no. 3, the Prop on the right of your scrum) anchor himself, and have the rest of your scrum players try to accentuate the natural tendency of the scrum to wheel clockwise. Your THP has to be bloody strong and have good technique to achieve this.
3. It is very rare to see a scrum wheel to the left (although I have seen it happen) and it is for this reason that you only usually see the ABs try this tactic when they are defending in their right corner (the opponent is feeding on the blind side). Wheeling to the left (counter-clockwise) is very difficult to do as it not only requires the Loose Head Prop to anchor while the scrum pivots around him, its also going against the scrum's natural tendency to wheel.
ETA:
The counter to this tactic is for the hooker to strike down channel 2 (right towards the gap between the No. 8 and the openside flanker) instead of the usual channel 1 (left between the No 8 and the blindside flanker). The No 8 then picks up the ball and passes to his right, or if he has managed to draw the opposing flanker to follow him, he can make an inside pass to the scrum half who has followed him around and run the inside channel between him and the scrum.
This presupposes that the Hooker actually knows how to strike... many don't these days, more's the pity.