my understanding was the change in rpm is what walked the gear off. by change in rpm I'm talking about goin from max rpm to idel or idel to max rpm quickly. the gear is cut so it always is trying to walk itself off and when you add the extra force of turning the ppump fast to slow it could walk off.

 

Not so much, The problem was high RPM , lots of vibration, and a built pump and or aftermarket springs. I've heard lots of opinion but failures are almost non existant on factory trucks. I've seen very few low HP trucks loose a cam gear!