Further to John's thread about his masochistic tendencies. I'm struggling to understand the basic principle of TBW. For eg, my car (I'm already calling it a tug in conversation lol) has a TBW of 350 stamped on the ball and on the plate. My 'van has a TBW of 200 (this is just an example). Does this mean that the car can now carry an extra 150kg of weight (as long as it's within it's gvm) or does the 150 differential mean that the 'van can carry an extra 150 or have I completely and utterly ballsed this up?
I hope someone understands what I'm trying to ask.
Cheers C.
-- Edited by tipsypixie on Monday 21st of May 2018 07:33:29 PM
-- Edited by tipsypixie on Monday 21st of May 2018 07:35:02 PM
The weights stamped on the ball and the towbar are simply the maximum the manufacturer of the tow ball and towbar said they can safely and legally carry.
These weights have no relevance to what your vehicle can safely or legally tow or the maximum payload for your vehicle.
To put it in another scenario; if I give you a piece of rope that can safely hold the weight of a 350kg item before it breaks, does this have any relevance to how strong you are or how much weight you can lift?
The only relevance is if you are able to lift up something heavier than the rope can withstand. ie, if you could lift up a 400kg item then that 350kg rope would not be suitable for that 400kg item, but, if you only used it to lift a 300kg item it would be safe.
So if your vehicle manufacturer (not the tow ball or towbar manufacturer) says the maximum tow ball weight of your 'tug' is 300kg, then your 350kg tow ball and towbar can handle it. This is NOT saying your 'tug' can handle it because now you have to also comply with the maximum payload for your vehicle (GVM) and the weight on the tow ball is part of that along with any passengers and other things you carry in the 'tug', and, you also have to comply with the maximum towing mass, and, you also have to comply with the maximum combined mass (GCM).
Often the maximum combine mass can only be allowed IF you have NOT maxed out the payload. ie, If you max out the payload you may NOT max out the tow mass.
An example might be that your tug handbook says your tug can carry 600kg. That same handbook says your tug can tow 3500kg. That same handbook says the GCM must not exceed 6000kg. Now if your tug alone weighed 2200kg and you hook up your van of 3400kg you have reached 5600kg and this means you can only carry an extra 400kg payload before you max out at 6000kg. Unfortunately, both you, the wife, the bull bar and towbar you had fitted, the 12v fridge in the back, and everything else in and on the tug, AND the tow ball weight is included in the payload, so a 3500kg van that probably has a 350kg tow ball weight and 100kg you has already made your combination 'illegal' to take on a public road.
Tipsypixie Please excuse me if I am completely wrong here but are you sure your tow-ball is marked 350 kg and not 3500 kg reason I ask is many tow balls are marked 3500 which I believe is the maximum load they can pull.
Landy
__________________
In life it is important to know when to stop arguing with people
and simply let them be wrong.
While I appreciate your position PeterD - it really was a hypothetical to help me try and verbalise something that I already knew but had difficulty explaining and was getting hung up on. In this instance I see no need to reveal the details and leave myself open to possible derision as to my choice of vehicle and caravan. My opening post had nothing to do with what I drive or tow and (although poorly worded) should be applicable to any towing combination.
While I appreciate your position PeterD - it really was a hypothetical to help me try and verbalise something that I already knew but had difficulty explaining and was getting hung up on. In this instance I see no need to reveal the details and leave myself open to possible derision as to my choice of vehicle and caravan. My opening post had nothing to do with what I drive or tow and (although poorly worded) should be applicable to any towing combination.
With respect C.
If youre towbar is rated to carry 350kg of downward force (weight imposed by towed trailer when hitched) and the weight of the (unloaded) caravans drawbar is 200kg, you have 150kg of spare capacity remaining on the car, but you havent loaded the van yet!
May I suggest you purchase a drawbar weigh scale, they can be had new from roughly $50, then monitor youre drawbar weight as you load the van while its not hitched. You will then get a pretty good idea how youre van can impact on youre car as you load youre stuff into the van.
Most importantly for me was knowing what filling the liquid tanks in different combinations did to the drawbar weight, ie, front tank empty and rear tank full and vice versa.
