Why Can't a Trailer with Friction Sway Control be Backed Up

Question:

I have read the question by James K and the expert reply by Michael H who writes:- inch But with these systems you have to disengage and/or remove them when backing up. This is because when backing up you are putting a different direct of force on the unit that it is not designed to handle I find that your explanation for not allowing a backing up movement with the unit engaged is so vague that it does not make any sense at all. May I suggest to you that the anti sway device does not know whether the vehicle / trailer rig is moving forward or backwards. All it senses is that distance between the two ball joints is changing, therefore the alignment of the two parts of the rig is also changing. As I understand it, these devices work by strongly resisting any change in the distance between the two ball joints. This is independent of the rigs direction of movement I accept that trailers with surge brake system cannot use this type of sway control. Is there something else that I have not allowed for? Thank you.

asked by: Trevor L

Expert Reply:

If you are backing up in a straight line or with only slight turns then you can back up when using friction sway control such as # 17200. But on unlevel terrain or if you have to make tighter turns while backing up (which at some point you will) then you have disengage the system or it can damage it.

It also makes backing up easier since the vehicle doesn't have to fight the friction sway system (backing up is sort of a simulated low speed sway event only with more torque on the system than a swaying trailer traveling forward could produce).

The direct of travel is actually important. When you are backing up you are pushing back against the friction system like you would on a surge coupler. That friction plate doesn't want to move and by going backwards and turning puts a lot of pressure on it, more than moving forward and turning.

expert reply by: Michael H