Unless Pivot Thrust actually drives #4 Accumulator through ImpactI understand this as 'blasting the left arm' off the chest. The #4 Power Accumulator (there are 4 power accumulators) is the left arm and the shoulders. The left arm at address forms almost a 90* angle with a line from the right shoulder. At the top of the swing it reduces to about a 45* angle, and the turns back into 90* angle at impact.
Here's a diagram below:
'Blasting the left arm off the chest' is basically saying that at the top of the swing when the left arm is connected to the left side of the body, the pivot will throw the left arm right off the chest. It's almost like throwing a frisbee with the left arm.
If a golfer uses pivot thrust (usually a swinger) that forfeits right arm thrust (a hitter procedure).
A very important quote by Homer:
The Hands are strong, educated, adjustable Clamps attaching the Club to the Arms for control of the Clubface alignments.I think it's very important to understand the clamps part (that's why I bolded it) and the strong part. The old saying that came from Sam Snead is that you should grip the club like you're holding a bird, light enough so you won't crush it, but strong enough so you won't let it fly away.
The problem with that is most people don't realize how big and strong Snead's hands were. And when they try to follow Snead's advice, they wind up losing that strong clamp onto the club. Ben Doyle, GSED probably had more sound advice where the hands could strongly hold the club, but the wrists are loose. I believe golfers who loosen the clamp struggle to use the power points to their full effect.
Another great quote from Homer Kelley:
The greatest hazard this Component faces is the belief that 'Effort' is 'Power.' No amount of effort will produce more than a player's maximum turning speed. Regardless of effort, you simply cannot push anything faster than you can run.One of the big goals in developing a precise Golf Swing is to do it with effortless power, not powerful effort.
Homer then briefly gets into some kinesiology terms and what they effect in the swing, all of it is pretty self-explanatory.
2-M-4 (Body Power)
Gets into mostly 'blasting the left arm off the chst' and pivot thrust. Most of which I've already gone over.
The swinger can take from these as a way to use their pivot to contact the ball. 'Blasting the left arm off the chest' is very much like Jimmy Ballard's teachings of 'left side connection.' We've gone over some of the typical components of a swinger, so if you want to use left side connection, things like horizontal hinging should probably be one of the components of your swing.