Position of pintle.

Are you saying that the manufacturer has set different capacities based on the position of the pintle?

Printed on my tow hitch which is a toyota OEM part there is a diagram showing the pintle being position down or up and the 300kg point load is written as the same in either position.

David

racinrob
Have you got a pintle hitch on your vehicle or are you asking about another kind of tow hitch ?
A pintle hitch takes a round ring trailer coupling , iby its design it would only pull in one position - in the centre at the back.

Cheers, brownie

To clarify my original post, I have a genuine Toyota towbar which is also called a hitch receiver into which goes what I call the pintle. On my pintle is a small plate which shows the two positions, in the down position it says "Towing capacity 2270kgs" and in the up position the towing capacity drops to 1600kgs.
I can't see why it differs as the direction of pull is basically the same. I also have a Hayman Reese pintle which has no plate so I presume it doesn't matter which position it is in ?

Confused Rob.

Makes a bit of sense (I suppose).

Look at the vectors of force in the different positions (its been over 30 years since I’ve studied any physics so forgive me any errors)

If the pintle is attached directly to the receiver in a straight line the towing force will be directly along that line of the receiver and the only other forces would be downwards ‘ball weight’. The connections to the chassis only have to cope with the linear towing force and the downwards ‘ball weight’.

Think as it a right angle triangle. If the pintle is level the towing force is a straight line plus downward weight. When you raise or lower the pintle the forces will go along the hypotenuse of the resultant triangle and the downward ball weight will include either a positive or negative element of the towing force.

This will change the effective ‘ball weight’ and depending on the design of the towbar may move the centre of force of the tow bar away from the designed strong points of the connection to the chassis.

Far too complex calculations for my aging memory and brain to prove

Rob,

The towing capacity is determined by assessment of the total forces and strengths of the towbar and its attachments.

The position of the coupling point (ball) determines the rotational force on the assembly due to towing thrust thus it is likely to be different between the upward or downward positions. This force will then influence the towing rating.