Portable Restroom Operators Discuss Effective Work Tray Designs

Look for lighter weight, better strength and a simple design when hunting for the best tank-mounted equipment carrier.
Portable Restroom Operators Discuss Effective Work Tray Designs
90-degree bends A square channel created by a series of 90-degree bends is a simple solution to strengthening a tray.

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QUESTION: I’ve learned a lot about pumps from this column, but I never see much on the trays that are attached to the tank. I’ve seen the various ways they are made and I wonder which trays are best? Is there such a thing as the ‘best’ tray design?

Mitch Rankins
New Orleans, La.

ANSWER:  I’ve seen all sorts of designs and constructions of trays and some are better than others.  Let’s take a look at the various ways trays are made and attached to the vacuum tank.

Trays made from 3/16-inch steel plate are strong and durable. With the right bracing underneath, they last a long time. The drawback is obvious. Why add all that extra weight to your truck? Some of that weight can be used to haul waste.

The question then becomes: How can we lighten the trays, while at the same time giving them strength to last the life of the truck? One of the common answers has been to lighten the material of the tray and then add a pipe, as shown, to provide stiffness front to back.

It’s true that pipe can be an effective tray stiffener, however even the pipe can be bent and develop a few dips over time. And, depending on how the pipe is welded to the tray, that joint could become a potential location for premature rust, especially any spots where the pipe is not welded to the tray.

To me, it’s best to keep the tray design simple, clean and efficient. Consider having your builder bend the tray material in a series of 90-degree bends to square off the end. Each of these angle creases adds stiffness and strength to the full length of the tray.

These bends provide the best and longest-lasting tray designs currently in use. The trick is to have a press break that can accomplish those types of bends.

Each stiffening solution has its merits. When you buy your next truck, see what the manufacturer recommends for trays. Over the life of your tank and truck, you don’t want your trays looking like somebody’s mistake.

Where should I place the pump controls?

QUESTION:  I’m ready to buy my first vacuum truck. I’ve worked in the industry so hopefully I know what I’m doing. I would like your opinion on cab controls versus controls located near the pump. I’d rather control things from the outside rather than start the vacuum system from inside the cab.

Tim Pacheco
Albuquerque, N.M.

ANSWER: I tend to agree with your preference for the outside controls, but there is no wrong answer. Some drivers like to set the brake, pull the PTO switch to pump, and then get out and start pumping. The downside of that is that the driver must first get his hoses while the pump is running.

Having outside controls allows you to start and stop the system when you are ready. You can have your hoses ready when you are prepared to start the system or, more important, you can shut off the system when you’re done pumping. Most guys finish pumping, replace the hoses in their proper places and then climb in the cab to turn off the system and head to the next stop.

The real clincher for me is that outside controls give you immediate response to trouble. If you turn on the pump and there is unexpected noise, you can immediately switch off the pump, sparing it from any damage that may be occurring. If something is damaging the pump and the driver is still on the ground climbing into the cab, it might be too late.

In either case, the driver will have to determine the nature of the problem. But the saving grace might be minimal damage from the quicker powering down versus greater damage if the pump is allowed to run a few seconds longer.


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