I'm not certain on how to interpret these specifications from the user manual:For air suspension, is this stating the top of the ball can be no more than 1.3 inches above the hitch receiver centerline or can be no more than 1.3 inches below the centerline? I'm thinking below, but I need a sanity check.

 

The vertical measurement is from the center of hole where the pin is located to the point on the ball where the circumference is the farthest aft. It is unfortunate the picture has the top of the ball corresponding to the centerline of the pin hole. That adds unnecessary confusion.

I read the requirement for the coil suspension is to have the measuring point on the ball (as described above) to be not more than 0.6 inches above the centerline of the pin hole (as described above). The hitch point and the trailer hitch will lower when under load.

I read the requirement for the air suspension is to have the measuring point on the ball (as described above) to be not lower than 1.3 inches below the centerline of the pin hole (as described above). The hitch point and the trailer hitch will rise when the load leveling occurs at both the front and rear axles.

I expect the reason for the differences is to place the trailer hitch at the same distance above the ground when in use.

Both distances are measured with no load on the ball.

Enjoy !

 

THIS is why I troll this forum: I learn something new all the time. Thanks, @TrioLRowner !

 

Isn't the height of the ball going to be dictated by the height of the trailer's coupler?

I have a variable hitch for this reason, as I just rent trailers and don't know what height each one will be at.




I guess in an ideal scenario you'd tailor your trailer design to fit into the tow vehicle's design constraints but this isn't possible most of the time.

Maybe I'm way off track here.

 

Gavin C:

Yes, we in North America view our hitching up and going differently than in the UK, I expect (maybe?).

I believe the JLR approach in creating this specification is to ensure the pulling force axially imparted by the trailer is not moved a far vertical distance from the pin (so to not overload the vehicle with a twisting moment at the back of the vehicle), while at the same time giving equivalent performance for the same trailer on the air suspension and coil spring versions of the Defender -- while of course the owner stays within the tongue weight limit.

The UK version of a trailer hitch is not adjustable, I suspect; so they think, I suppose, that what they specify is what is needed.

Unlike in North America., I would not be surprised if in the U.K. the trailer manufacturers all must mount their hitch at the same height? Just guessing.

Enjoy !!

 

Yeah. That's so of my thinking on the LR specs. The UK/EU have he deployable tow ball which I guess will be mirrored by the US owner manual's measurements.

Thanks for the info.