General Consensus on Loading a trailer (Weight Displacement)

[quickfarms]

So what is the answer in this case? I have a 4000lb tow rig and a 6000lb M720 with functioning brakes. As this is an abnormal towing method, I have found nothing on the pitfalls or cautions.

You are towing a heavier drawbar trailer with a lighter towing vehicle.

This is only done for heavy haul applications at low speed.

For normal operations you have a truck towing the pup trailer and the GVW of the combination is around 80k. In this situation the truck out weighs the trailer by about 15k. This also requires a special endorsement on your license for towing trouble trailers.

 

[zebedee]

You are towing a heavier drawbar trailer with a lighter towing vehicle..... This also requires a special endorsement on your license for towing trouble trailers.

I don't think that towing a full trailer (drawbar type - M720, HEMAT etc., ie., one that can stand by it's self where as a "semi" trailer needs something else under the front to make it work) behind a rigid truck is considered as a double so shouldn't need that endorcement. Certainly not needed in NY. A double (or triple) is a full trailer that tows another (be it 'bumper pull' or 'hay wagon' style). I have seen a few horse "Goose neck" trailers that have a receiver hitch on the back for towing a 'whatever' (flatbed with pony cart etc., - maybe) [SAME AS: 5th wheel RV's on duallies with 'toy' bumperpulls behind them] strictly they are also a double, but if under the weight then it's not commercial therefore a CDL endorcement is not relevant.

So long as the brakes work then the weight difference - even negatively, isn't an issue so long as the GVW rating of the 'prime mover' isn't exceeded.
Only pitfalls I see are backing up (need lots of car park practice) and traction on icy hills.
Are you doing this commercially? Do you have a CDL? Going long distance and exposure to DoT State Troopers.....

I think the further we get into your situation, the more questions will be generated!!! Be safe.

 

[jw4x4]

A ball mounted over the rear axle is called a Gooseneck. A fifth wheel has a king pin under the trailer which couples to the Fifth wheel plate mounted on the frame or in the bed.

 

[rothroq]

So long as the brakes work then the weight difference - even negatively, isn't an issue so long as the GVW rating of the 'prime mover' isn't exceeded.
Only pitfalls I see are backing up (need lots of car park practice) and traction on icy hills.
Are you doing this commercially? Do you have a CDL? Going long distance and exposure to DoT State Troopers.....

I think the further we get into your situation, the more questions will be generated!!! Be safe.

Non commercial for sure. I do not have a CDL but am considering one for other projects. I will not be going long distances either unless I have found a new fangled way to haul stuff home from govliquidation.

I'll be pulling the M720 loaded with a forklift, within 10 miles. My tow rating is around 7000 lbs. I may see an extreme load of 12,000 using a larger M832 dolly. I can pull it, but stopping it is the main concern obviously.

As soon as a find a mechanical air compressor for my SUV, I'll be able to utilize the air brakes on the trailer through a trolley valve. I have an electric compressor but it's output is borderline for an air brake system. From my reading it's suggested to not use the trolley valve on semis while driving due to trailer wheel lock up and possible skidding, however in my application I see no difference compared to using my electronic trailer brake controller.

I have not read the threads here on air brakes and license endorsements but from other sites, air brakes on recreational vehicles require no endorsement. I have not received a consistent answer from DOT folks here in my area for the few months I have researched it. Some say they "think" yes you need a CDL, some say no, not for recreational. I have not seen any mention of hydraulic actuated rig brakes in combination with air controlled hydraulic actuated trailer brakes. The weight rating of this trailer requires brakes,,, and it has them. They did not see me coming.

I have seen tow rigs/SUVs using the bumper hitch dolly converter to pull 5th wheel and/or goose neck trailers so I know it's not unheard of.

Not sure if there is a discernible handling difference between a dolly converter and a trailer with a steering axle like the M720/M832.

I have been close to a jack knife situation on sand covered concrete while pulling a car dolly so I am aware it does not take much to end up with trouble even when well within the ratings. However pulling a heavy load with a lighter rig from my experience is fine if the trailer brakes are operating properly.

I am definitely open to hear the glaringly wrong aspects of my idea.

 

[m16ty]

A semi is loaded by axle weight and not a straight 50%.

Most semi trucks are weighed to make sure the loading is correct.

True. You usually don't run into a hitch weight problem on a semi trailer because the axles are usually mounted near the rear of the trailer and usually has close to 50% of the load on the truck. Truckers place the load and move the axles to get max payload without going over max axle weights (34K on tandems and 20k on single axles in most states).

When loading a tag-a-long or gooseneck it's usually better to have a little too much tongue weight than not enough. Like others have stated, I just go by the squat of the truck suspension and a visual idea of the load center of gravity to get the load placement right. It's kind of something that comes with experience to visually know when the load is right. If you're a towing newbie it's probably not a bad Idea to go to the local truck stop and use their scales to play with proper load placement.