Force of a 3-6 Ton Trailer on a hook to a bus? 1

[pedrorb]

Hello everyone

I am working out the apropiate size of the end transverse beam in a coach/bus which has a 3 to6 Ton trail tied to a hook in that beam. Does anybody know the appropiate horizontal/vertical force magnitude that I should take into account for my calculations? I consider braking (1 g) as the maximum effort. Is that right or do I miss some other extreme situation?

Thank you everybody

PedroRB

 

[GregLocock]

In the absence of any better info chassis parts are often designed to 3g vertical inputs, 2g longitudinal, and 1 g lateral, to the wheels. Determining how these loads relate to the tow ball is a task for the designer!

Cheers

Greg Locock

 

[hauptmann]

Hi,
The following equations are from SAE standard J684, regarding testing of the receiver tube, which ties into your beam.

1. V = .47R + 480
L = .47R + 480
2. L = -(.23R + 1530)
V = .15R
3. L = .23R + 1530
V = .15R
4. T = .20R + 500

Where V is the vertical force, positive in the downward direction; L is the horizontal force, positive in the forward direction towards the cab; T is the transverse force; R is the hitch rating, in your case 12,000#.
Remember, these are the loads at the the ball. You will get a moment from the vertical force multiplied by the distance from the ball to the beam.
Good luck,
hauptmann

 

[pedrorb]

Thank you all.

Just a pair of questions, Hauptmann, about the equations: are the forces expressed in Pounds or Newtons? What´s the hitch ratio? Is the SAE Standard J684 available in internet for free?

PedroRB

 

[hauptmann]

PedroRB,
All the forces are in pounds. The hitch will be rated at a weight representing the maximum allowable towable weight, 12,000 lb for your case. I do not know of any site with this standard available. We have the three volume set of SAE standards which covers just about everything you might have questions about. You can buy it online at sae.org for about $50.