Hi Guys
Can anyone help me? How do you calculate the weight being imposed on each axle of an articulated combination? I know how to do it for a rigid vehicle: Payload multiplied by the distance of the centre of the payload from the rear axle, divided by the wheelbase gives the weight on the front axle. I think there are two seperate calculations for artics but I can’t remember.
Thanks
There are many variables to take account of but I have to ask why you want this information? If you’re asking as a driver trying to distribute the load evenly it’s a complex way of doing things! Trailer manufacturers would configure a trailer so that with a load that has it’s weight evenly distributed throughout, there is little chance of overloading any axle.
There isn’t really a simple method of calculating this for an artic combination, as the numbers would depend upon the positioning of the king pin on the trailer, as well as the fifth-wheel on the unit.
you asked!
tri axle flat trailer 13.6m loaded with a 13.6m steel beam weighing 30t. 30t/13.6m = 2.21t per meter
you need to break the load into 3 sections, front of the beam - pin (2m), pin - middle axle (8.6m), middle axle - end of the beam (3m). all rough lengths to get the idea, change to suit.
section 1 = 2m x 2.21t = 4.42t but because its a overhang it needs to be balanced. so we take the balance from the centre of section 2 (so it doesn’t effect anything else). the centre of section 2 is 4.3m from the pin, the centre of the 4.42t is 1m from the pin, so divide 4.3 by 1 = 4.3. take the 4.42 and divide by the 4.3 we’ve just got = 1.03t + the 4.42t = 5.45t on the pin plus half of the unknown at the moment section 2
(think seesaw with 4.42t with a metre to the pivot and balanced on the other side 1.03t 4.3m from the pivot)
same for section 3 = 3m x 2.21 = 6.63, 4.3 divide by 1.5 = 2.63, 6.63 divide 2.63 = 2.52t + 6.63t = 9.15t on the middle axle plus half of section 2.
section 2 = 8.6m x 2.21 = 19t. but its had 1.05t and 2.52t of balance weight taken out = 3.57t. 19t - 3.57 =15.45t divide this by 2 = 7.73t add each half to the pin and middle axle
pin = 13.18t (plus weight of trailer)
middle axle = 16.88t divide by 3 axles = 5.63 per axle (plus weight of trailer)
add the weights together to check we still have 30t = 30.06t near enough! slightly out due to rounding decimal places.
on a 4x2 unit, 4m wheelbase, lets say the fifth wheel pivot is 3.5m from the front axle
so 13.18t divide 4 then times 3.5 = 11.53m on the drive. 13.18 - 11.53 = 1.65 on the front plus the weight of the truck
stevie