This is a little off topic guys, but most of my time is spent down in this forum and you guys seem to give the best advice.

I own a landscaping company, and a new piece of equipment is coming in this week. This is my new chemical spray rig.

https://www.johndeerelandscapes.com/...0%20gallon.pdf

As you can see by the specs, its a pretty big size and 205 lbs empty. 50 gallons of water weighs in about 400lbs if I recall right, so about 600 full. This piece is getting mounted in the bed of my work truck. 2000 F250 short bed.

With that kind of weight, how would you guys recommend to mount this system? I want to try to get it mocked up by this weekend to drill any mounting holes before I get the bed shot with spray in bed liner.

Thanks in advance for the ideas.

 

Just an idea... but I'd see about mounting it to the truck frame itself, with an isolated mounting bolt assembly that passes through the bed, but is not secured by the bed.

And when mouting to the frame, I'd fab some angled brackets that mounted to the side web of the frame, not the top flange of the frame.

And then I'd bolt those brackets to the side of the frame in a manner so that the bolts are not in a direct vertical line on top of each other (like pre perforated page holes are... not good).

Here are some pics of my truck to help illustrate these ideas...



In this first pick, my angle bracket is mounted to the side web of the frame, not the top flange of the frame. In fact, my bracket is formed to provide it's own horizontal mounting flange for pass through bolting of any object above the frame.

Back to the frame, notice that the horizontal bolts are not one directly above the other, but are at diagonals to each other, to keep from having a vertical frame fracture at a concentrated loading point. The cut out divot on the bracket is to work around a rivet that isn't there on this side of the frame.



Taking a closer look at another feature of my mounting set up... isolation and flexibility. That is what the busing is for. It is a complex 4 piece bushing with dual durometers... more on that later. What is seen in this photo is, however, the proximate to the most twisted area of the frame, which also happens to be the area where most guys mount heavy Lincoln arc welders, and equipment like you are looking at.

A secure mounting is important, but in this area of the frame, so is a somewhat forgiving mounting. A system that absorbs frame twist at the cab to bed junction is ideal, because that area is furthest from and dead center between to fixed points... the ground under the front axle, and the ground under the rear axle. The ground can't be counted on to give as the axles articulate over it, so the part of the frame tasked with resolving any differences in the ground that the suspension couldn't work out is this center section of the frame.

This picture shows only part of a mount that forbids movement in lateral sheer, but permits frame twist. Here is a hidden part...



This is the end of a flat bar tie plate that I nested inbetween the bushings of my twist permitting, shear denying mount system. This flat bar spans the frame rails inside the lower channel of my bed. This makes the bed captured by and retained by the mounts, but the bed sheet metal channel not in any way relied upon to secure anything. The presence of the flat bar ties the vertical mounting bolts together in their middle shank portion, and the thickness of this flat bar (3/8"), combined with bolt holes drilled to close tolerances of the shank diameter of the bolts, discourages movement relative to each other, but allows an axial rocking between the head and the nut, within the allowances of the dual durometer bushings.

I didn't take these pics with your project in mind, I took them for other reasons, so this pic of the flat bar illustrates something else.... I ground the edges of the bar to avoid stress risers from the corners of the flat bar digging into the sheet metal of the under bed channel. The bar in the picture is held downside up. These bevel edges mount downward, on top of the inside of the 10g hat channel under the bed. You could just as easily make the same bevels on any heavy metal bridging material (including the frame to the equipment itself) to avoid the edge corners of the heavier metal "digging" into thinner metal when the truck is caught up in a full "twist ditch" maneuver.




Finally, here is a breakdown of the mounting hardware. I mentioned "dual durometer bushings" earlier. That is because each mount has four bushings... two skinnier interior bushings of a harder, more rigid durometer, and to exterior larger, tapered bushings of a more compliant, springier durometer.

Since the center of the bolts are restricted from changing distance from each other by both the angular brackets attached to the frame at the bottom of clamped assembly, and by the bridging flat bar that captures the object retained at the top of the clamped assembly, then the most movement within the range of flexibility will be at the upper and lower ends of the bolts. Movement will be greatest furthest way from the bolt center.

Hence, the larger diameter outer bushings is more forgiving and absorbtive of this movement than the smaller diameter inner bushings, which are installed as stabilizers to gradually limit the deviations allowed by the outer diameter bushings. The anticipated movement this mounting system might be forced to absorb is likely in precession opposing the twist induced, like the way a top spins when it begins to wobble.

The specific parts used for this mounting project are all randomely found objects. I collect and recycle old cast away parts, and repurpose them. The interior bushings are from an old package of Help! shock absorber bushings, the outer bushings are the ones that I replaced from the twin transverse track rods out of my old Quadravan, the flat bar was recycled from some farm equipment... in other words... entirely improvised.

The other rearward end of this four point mounting system is rigidly attached without the flexibility bushings, since it is nearer to the rear axle.

You asked for ideas. No one responded, so I pitched in a few crazy ones. In summary, I'd improvise ways to mount heavy, permanently mounted equipment securely by the frame, through the web, not the flanges, without necessarily relying on the strength of the sheet metal bed, while maintain some limited ductility to accommodate frame twist.

 

Short and simple. Bolt through the bed yo the frame. That's how I'd do it. Obviously if dimensions don't work that that can't be done.

 

This may be a little more time consuming than I think. I will take a look at it to see what is possible, but my just end up dropping it off with a Trailer & Truck shop and let them figure out the best way. I will just have to use my 08 for a day for work.

 

Just had a thought about this. There are what 4 bolts holding the bed down to the frame that you can see in the bed of the truck right? Trucks not here right now so I can't look. If this equipment comes in and the cage around the tank is long enough, I could use 2 of the bed bolts to bolt this down to the frame right? Basically get longer bolts to accommodate for the equipment.

And the next question. If I do drill the frame to add a couple bolts, should I drill the top or side?

 

"Top" of frame = Flange of frame = No drill zone

"Side" of frame = Web of frame = OK to drill

When drilling "side" of frame, drill no closer than 1" away from radius of flanges or other existing holes in frame. Keep holes less than .75" in dia.