IMHO....
All WD bars/trunnions are tensioned by the chains mounted on the trailer tongue. Think of standing on the trailer tongue and lifting up on a 5'-6' bar shoved into the TV reciever pin box. This will lift the TV's rear end and WD some of that weight to the TV's front axle...remove some of that weight from the TV's rear axle and since standing on the trailer tongue...come weight is transferred back onto the trailer tongue
Hitch Head tilt is to move the bars (round or trunnion) to point down more. That means the chains or whatever is used to tension them...more distance to bend them. Therefore more bar tension. Otherwise, the chains would NOT be able to pull them higher for more tension. Washers (regular round with a hole, serrated, etc) on some. Blue Ox is fixed via the casting
Trunnion bars slide on the saddle that is mounted on the trailer tongue. Some metal on metal, another has friction material at the mating (touching) area. This is the 'noise' that some complain about and some then advise to grease it to reduce/eliminate that noise...but that is how this setup works...friction to hold back the trunnion from sliding on that saddle to provide a push/pull against the trailer trying to move side to side (sway)
Cams will have both a saddle area on the bar end (a bend to form a 'V' saddle area that the cam nestles in). The cam is held in place by extensions that are mounted on the trailer tongue. This also makes noise as the cam is forced out of that saddle when the trailer sways side to side. One side will have the distance between the saddle and pivot of the bar reduce and other side lengthen. This is the push/pull against the trailer trying to move side to side (sway). The noise is the metal to metal between the saddle and cam. Some advise to grease this area, but that then makes it easier for the cam to come out of that saddle...reducing the amount of anti-sway
Blue Ox does this differently. Their bars are tapered from the hitch head (round) via a flattened and tapered to the end. It is bent way more than the others above. This will have one side straightened out when the trailer sways in one direction and the other side will have the bar bent even more. This provides a push/pull against the trailer trying to move side to side (sway)
Since no metal on metal sliding/rubbing/etc there is no noise generated. Just bending a spring bar more on one side and straightening the other side to then pull. This setup has very short chains, so the amount of travel is very small and the chain mechanism captures the chain to NOT allow the chain to move side to side
The Andersen works completely different
It's chains pull the trailer towards the TV's ball. The ball then hits the trailer coupler latch pawl and pulls the ball out of the coupler capture dome. The tapered friction material in the hitch 'head' has the special ball/shank (tapered shank) ride on that friction material. Any side to side movement has to overcome that friction material to ball/shank (that tapered shank is held in that tapered area via both the nut at the bottom and the weight of the tongue itself.
Since the Andersen chains pull the tongue into the TV ball...there is a compliant series of plastic bushings on the end of the chain. When the trailer sways side to side...one side compresses the stack of bushings and the other side releases the compression force...but IMHO, that stack is not long enough and the system bottoms out. Report of bushings breaking up have been reported...and/or the bracket on the tongue has also been reported to be pulled towards the TV when the side to side is high enough off center
HA/etc has spring bars too and works just like above...but no push/pull to control sway. There is a complicated mechanism that projects the sway pivot center forwards towards the TV to reduce sway. I've not looked at this setup in detail and might if ever consider getting one
My choice is Blue Ox, but have not purchased one. As no longer have a trailer of mine. Just borrow others and at 70 this year...not towing as much anymore.
