Hi guys.... Every now and then I see a picture or hear about a single axle dump with a lift axle. I'm curious though as to the advantage over a standard tandem axle truck. The only thing I can think of is the single might be a shorter wheelbase overall, therefore a tighter turning truck....I know the weight rules vary from place to place, but in general I can't see a single with lift being able to carry much different for weight than the tandem either.... BTW, I'd love to gather up a bunch of pics of these trucks here for us to enjoy.....wish I could remember where I last saw some of them!!! Mark
I only see them around here being used by the various paving companies. They make sense for this since loaded they are pushing the limits, but empty they can save a lot of wear on the tires by lifting one axle. Sorry no pictures.
If you already had an SA truck, to add a drop axle would be cheaper than purchasing a tandem. Also, if you're driving in slippery conditions having a drop axle that could be unloaded could help traction wise.
I know that with a single axle and a pusher you can haul a pretty good jag. I have heard them called "tag-tandems" There is a logger here that has 2 of them and I am not sure what they haul foot wise but its a lot. We had to work on a road for them and I asked one of the drivers what would happen if he pulled up to the scales, and he said he would be legal. Those guys felt that for what little extra you could haul on a tri-axle it wasnt worth the extra investment. We considered having one but thought that if we were working up in the mountains that the tag-axle might screw us because the pusher can take enough pressure off of the drive tires to make you lose traction. A 33k GVW single axle with a 20K lbs pusher = 53K GVW. Truck weighs 15klbs so a payload of 38k lbs. Figure for the bridge formula and all of that you might be able to haul 15 ton which is a lot. Definitly want a driver who knows how to drive, and pays attention. definitly want a JAKE. I would still consider one. I'll look around and tri to get some pics.
You can turn tighter with the axle up. Thats why around here you see alot of the trucking companies put a lift on their tandems because if it was a "real" tri-axle the turning radius would be horrible.
For what I do I'm currently using a one ton with dump...eventually though I do see the need for bigger. We have a few singles in teh area, most are delegated to dedicated float work for small dozers and similar setups. Still some tandems, more and more though are going to tri-axles (tandem + lift). It's ok for a lot of the construction hauling, but I want something to go with the mini/compact equipment that I have/run. I can see in time that there will become a demand for the smaller stuff again, because of the developments being so tightly spaced ....when work needs to be done later only the small stuff will be able to do it. I'm wondering about watching for a single axle...if I can find the right truck in time, then adding a lift to it. Fortunately we have a good box manufacturer here locally (at least three within two hours drive), so whether it starts as a dump or not doesn't matter to me....same with frame lengths etc. I think it would be easier to find a s/a with a longer frame and shorten, to get the right length to use a lift as well, than to buy an existing s/a dump and adding the lift. The box size wouldn't be big enough to take advantage of the extra weight capacity. I don't want to go to a tandem....many sites that I work in it would simply be too big. A single would handle all the float/trailer requirements I ever plan on needing, equipment wise I can see that about 8 tons would be maximum weight of machines and attachments....I'm thinking a 12 ton flat bed float would be no issue at all behind the single anyway. On the truck, having the lift axle, and maybe an extra 2-3' of box would be nice when hauling material.....would be able to price it similar to a tandem, but still the size/agility of a single. Mark
The big drawback of a single axle with a tag axle is once the tag axle takes part of the load and your climbing a slope the drive tires lift off the ground. If you lift the tag axle the single drive axle isn't going to survive. I would go with a full tandem back east you guys use such short trucks anyhow they will go anywhere you need to go. We don't have triaxle dump trucks we have tridrive dump trucks which are becoming more common. With 3 driving axles you can go anywhere and you have a close to a 80,000lb gvw. A single axle dump with a tag axle is a little too mickey mouse if you want a tandem go with a tandem.
Paving companies use them here too. Advantages are lower cost than twin screws, both in initial purchase and maintenance. In some conditions it can be an advantage to lift the axle to gain traction, but in soft conditions, the axle will float in the muck and reduce traction.
I could see where it wouldn't be good in the mud, but that shouldn't be a problem for pavers who come in to work when the site is usually in good condition.
The only way to make a single axle with a tag axle work is if the truck was on air ride or walking beam suspension like a tandem. The only difference is the rear axle doesn't drive. Most paving companies around here run the heaviest spec'ed tandem you can get as most trucks hauling asphalt are trucks and transfer trailers they gross 135,000lbs and carry 25-30 yards of asphalt. When your traveling 60 miles or more away from the paving plant you want to carry as much as you can.
I started pushing around the idea of adding a lift axle on my F-750 later on down the road. The only reason for doing this would be to make sure I stay under GVW if I decide to start using 17' long 30 yard containers down the road. With my truck now I would be able to carry 6 tons legally in a 30 yd can. But again with going across state scales to get to my landfill I want to be safe. By having a lift axle I get to keep it up in most cases and save my self from having 4 extra tires on the ground by not having a tandem. Also in VA any truck under 26k gvw you have to pay 3% sales tax. 33k gvw no sales tax and 33,001 and over 12% tax. How much would it be to put on a lift axle? And is it hard to get my GVW upped?
read this kinda long but covers the topic well
I once had a 1966 Ford 700 with what must have been the ultimate cheapskate tag axle arrangment. The tag bolted to the frame, and cantilevered off the rear of the back axle leaf springs. The "actuator" was a pair of ramps that you set behind the tag wheels, and then backed up until the tag wheels were lifted off the ground, then hooked a chain from axle to frame to hold the tag wheels off the ground. Setting them down was the reverse, backing onto the ramps until tension came off the chains, unshackling, and the driving forward. The tag didn't have brakes or drive. It's only use was to satisfy a rule of the Minnesota MNDOT. During the spring frost-out season the tag was lowered to ride along on the ground. The rest of the time it just hung back there, taking up useful tonnage capacity.