Actually the rotor heads on '46s and '47s are somewhat different.
Hookdriver is correct concerning the blade fold on '47s but on CH-46s the blade dampers have a slightly different set up. The rotor heads on CH-46s are equipped with blade fold motors and "gearing abosorbers" mounted inside the vertical hinge pin.
Blade folding on CH-46s is accomplished by activating a switch in the cockpit that results in the blade folding sequence that takes a little more than a minute (actually there is more to it than that, such as the rotor positioning motor located on the aft vert shaft and a series of micro switches in the flight control closet and segment lighting in the cockpit)...Unless of course there is problem with the wiring harness on the rotor head, or problems with the gearing absorber or balde fold motor. For that reason, I used to use the feature as much as possible to make sure that it worked. It seemed that if it was not used for long periods of time, it wouldn't work when it was needed.