Converted Dump Truck Questions

[drillstix]

Hi, I'm new on here but I have some questions about a truck that we are converting to a dump truck. We have a 1994 Fld 112 with a 50 series Detroit that we used to use for a water truck. We removed the tank and now have just the cab and chassis and have purchased a 13' dump bed to put on it. The cylinder that is with the bed is a 6 inch, 3 stage cylinder with only one hydraulic hose connection. We have not purchased a valve yet and don't really know what would be the best choice. Any advice on that would be great, or maybe some pictures of how most people set up their controls. If I'm not mistaken we will need controls for pto, dump, tailgate, shaker, and tarp. Also, with the way that our axles are and the length of the bed, our hinges will end up a little further past the rear axle than most of the dump trucks I have seen around town. How far back is acceptable for a 13' box?

 

[Shimmy1]

Hinges first. I recommend the hinges be no further than a foot from the end of the dump box. Hopefully you have enough truck frame to accomplish this. Now for your pump. If you don't plan on ever pulling a pup or having a hydraulic highlift tailgate, a pump with the control valve built in is the best. However, they come down fairly slowly. There are options to help this, a quick drop valve being one. That would require two control levers/cables/whatever. You could also use an electric over hydraulic valve like you use for side dump trailers. Best thing to do would be to get in touch with a shop that sets up dump trucks. They would be able to tell you more options on the hydraulics part. My.preference for PTO control is air-operated. They do make electric controls as well. Tailgate control is usually accomplished by a small, dual-acting air cylinder, the smaller the better (as long as it provides enough force). They do make make air open, spring close ones, but if you are ever going to spread, the spring close ones sometimes release on their own when you raise the box up. Once again, I prefer a dual acting cylinder with an 1½" bore. Nice and fast. Velvac makes a very nice air control for the cab. We had electric shakers on our dumps, they do make air ones. Air shakers are a little simpler to hook up, just some wires, a momentary switch, and an electric over air solenoid valve. An electric shaker would require a solenoid (just like the ones that use to be right by the battery to send power to the starter on older vehicles, or the glowplug solenoid on Ford diesels) to send battery voltage to the shaker. Would be operated by a momentary switch same as the air valve for an air shaker. I've never had to deal with tarps on dump trucks, so I'm not much help here. We do have electric tarps on our grain trailers, pretty expensive to have a remote control tarp though when you really wouldn't need it. I assume they make a two-way switch that can handle the amps the tarp motor requires that you would control with a three-way momentary switch in the cab. If you need more clarification on any of this, I'll be happy to explain in further detail.

 

[87silvert]

I would use a direct mount pto with air shift. Then I would use a Commercial C102 pump with built in valve. As for controls the vendor I know of that has everything is Buyers.

 

[Mobiltech]

I would strongly suggest you double the frame rails at least the back section up past the suspension mounts. The amount of weight on the frame at the hinge pins with the box in the air and a load that doesn't want to come out easily will bend a single channel frame.
A single acting cylinder with a pump and pto that 87silvert described is what most dump truck run around here.

 

[drillstix]

Thanks for your responses. The truck already has an air shift PTO that was used to run a Bowie pump. I'm not sure which hydraulic pump is on it however. We pulled the box off of a truck that had a fire under the hood and lost pretty much the whole cab, so we have the box with the hinges already in place. We also cut the piece of angle with the hinges that will go on our frame and will be cutting down our frame and planning to weld the hinges in. I guess the location of the hinges on the box is already set, but the location of the hinges on our frame will be a little further off the rear axle than I have seen on other trucks and won't be able to change because the box will be as close as possible to the cab. Assuming that the location of the hinges on the box is correct, is there any guideline for what is too far back for the hinges relative to the rear axle? Also, when we removed the box from the old truck, the only lines we cut other than hydraulic were air lines to the shaker and the tail gate. Shimmy, were you saying that even the air shakers still require some switches other than air? We were hoping that the tailgate and shaker would work with a couple of switches like the ones that most of our trucks use to dump the air bags and lock the diffs. Is this the kind of switch you were referring to?

Thanks.

 

[drillstix]

I must have been typing my reply while you posted Mobiltech. We figured that some reinforcement would be needed.

 

[Shimmy1]

For the shaker, probably fine. For the tailgate, may not allow enough volume for the cylinder to operate quickly, plus, you need a double acting valve unless you use that spring cylinder.

 

[Shimmy1]

As far as your question on the hinges, I would not want them more than 24" or so behind the centerline of the rearmost axle. If your not comfortable with the layout, you might want to consider moving the drivers back.