will the trailer tip over?
will the trailer tip over?
(OP)
Hi,
Quite a simple problem but it has been a while since I have done these sorts of problems.
Need to design a trailer and make sure it will not tip over when turning corners.
-The trailer has uniform geometry and load so the center of mass will be in the middle.
-Trailer is towed by a vehicle at point A. see attached file.
-I need to find out if the trailer will tip over at the trailer's worst situation. Is it at the max speed? or max acceleration? or max turning circle? or a combination of these things?
-How do I find out if it will tip over? Is it simply summing the moments about some point, perhaps point B. So there will be 4 reaction points, the force from the vehicle and the trailers mass.
Help would be very much appreciated.
Note that the trailer in the picture is simplified. The geometry of the actual trailer is more complicated but it is uniform and isnt required to be shown here, I think!
Quite a simple problem but it has been a while since I have done these sorts of problems.
Need to design a trailer and make sure it will not tip over when turning corners.
-The trailer has uniform geometry and load so the center of mass will be in the middle.
-Trailer is towed by a vehicle at point A. see attached file.
-I need to find out if the trailer will tip over at the trailer's worst situation. Is it at the max speed? or max acceleration? or max turning circle? or a combination of these things?
-How do I find out if it will tip over? Is it simply summing the moments about some point, perhaps point B. So there will be 4 reaction points, the force from the vehicle and the trailers mass.
Help would be very much appreciated.
Note that the trailer in the picture is simplified. The geometry of the actual trailer is more complicated but it is uniform and isnt required to be shown here, I think!





RE: will the trailer tip over?
It is a capital mistake to theorise before one has data. Insensibly one begins to twist facts to suit theories, instead of theories to suit facts. (Sherlock Holmes - A Scandal in Bohemia.)
RE: will the trailer tip over?
You need to maintain a low centre of gravity. The lower, the better. Research "tipping moment" or something equivalent on the net.
Good luck with it.
Kenneth J Hueston, PEng
Principal
Sturni-Hueston Engineering Inc
Edmonton, Alberta Canada
RE: will the trailer tip over?
There is also over turning when cornering to consider at speed, go to this link and scroll down to page 10 it should give you all you need.
desertfox
http://www.freestudy.co.uk/c103/t10.pdf
RE: will the trailer tip over?
The 4x "wheels" cannot be "5" feet in diameter - if this is a road-worthy trailer, or even one going to be pulled by a road-rated track/tractor/fork lift (?) or whatever. The load will "tip" based on its height above ground, the actual max slope (worst case slope) of the roadbed or gravel lot you are pulling it over
The tipping is going to be VERY strongly influenced by the wheel and axle and suspension "details" = their attachment points (which are NOT the overall length of the trailer!) under the trailer and by the suspension "springiness" and sway resistance, and by the distance to the fwd pulling point from the hitch point. The wheel base width resisting tipping will be based on the center-center distance between the tires, NOT the trailer width.
The sideways pulling force of the hitch will be at some height -> probably this will be at the axle height, if the hitch is going to be near-horizontal when the trailer is being pulled. The axle height will not be half the "5" (feet ?) of the sketch: you need to account for the suspension margin.
Recommend you go to a track stop parking lot and look at a few double-long trailers for nominal dimensions and "best practices" before re-inventing the wheel. And axle. And trailer. 8<)
RE: will the trailer tip over?
If the cornering sideways G-force (lateral acceleration) is more than half the track width (distance side to side between the centers of the tire contact patches with the ground) divided by the center of gravity height, the trailer is gonna flip. Suspension that doesn't have enough roll stiffness or roll damping can lead to it flipping sooner than this. Improper loading conditions that lead to a condition of instability (trailer sway) can lead to it flipping sooner than this. Braking problems, either caused by the driver or by improper brake balance that lead to wheels locking up (and therefore losing directional stability) prematurely and thus leading to the trailer going sideways down the road, can flip it sooner than this. Aerodynamic forces caused by extreme cross-winds can flip it sooner than this (I've seen the results of tractor-trailers blown over by severe cross-winds). Trailers loaded partially full with liquids can tip very easily due to sideways sloshing of the liquid. And you can tip over ANY vehicle by driving it off a sufficiently steep-shouldered embankment.
RE: will the trailer tip over?
The point of no return is when the CG crosses over the tires, but you don't want to design, or specify, to that limit. So, if you assume your CG is at the top of the trailer, then roughly 1/2g of lateral force will put your trailer at the tipping point.
But, that shouldn't be the starting point of the design space.
TTFN
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RE: will the trailer tip over?
In practice you can roll a trailer at lower lateral accelerations than are given by the schoolboy equation.
Cheers
Greg Locock
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RE: will the trailer tip over?
Mike McCann
MMC Engineering
RE: will the trailer tip over?
RE: will the trailer tip over?
I should have been more clearer and have perhaps lead some people in the wrong direction.
The "trailer" is more similar to a trolley actually. It has caster wheels and is intended to be used in a warehouse. Max speed wouldn't be more than 30 km/h.
Dimensions in my file are in cm.
Thanks again
RE: will the trailer tip over?
RE: will the trailer tip over?
RE: will the trailer tip over?