Snoopers

 In addition to trucks that haul cargo, there exists a wide variety of trucks that primarily perform services. One of the less common service trucks is the Snooper Truck.

Snooper trucks are used for bridge inspections. Snooper is a registered trademark of The Paxton Mitchell Comapny, but the name is often used generically.  These trucks work like a backwards bucket truck with the bucket moving down and back towards the truck rather than up and away.

The bridge inspectors are watching for tiny cracks that could be an indication of future problems, erosion and general condition of the bridge.

Bridges need to be inspected to ensure they are safe for the loads they carry. Sometimes a bridge will be posted with a lower weight limit as the result of the inspection. These bridges are called stucturally deficient. 

Bridges that are inadequate for the amount and type of traffic are called functionally obsolete. The bridge itself is fine, but replacement may be necessary to handle the current or future traffic demands.

I'd love to see your bridge inspection pictures or hear your related stories. Please comment below.

Photo by Aspen Aerials

Photo by N.E. Bridge Contractors

Photo by Oregon Department of Transportation.

Photo by Oregon Department of Transportation.

Drawing by Paxton-Mitchell Co.

Pneumatic Tankers

Image: Dave Swift

Pneumatic or "Dry bulk" tankers are used to haul powders and granular products. Many products that are transported in pneumatic tankers can also be transported in end dump, hopper or live floor trailers, but the pneumatic system has several advantages. These trailers are completely enclosed, keeping the load safe from contaminants, they don't have tip-over issues, and many facilities are dependent on this system to accept loads.

Common cargoes are foods like sugar and flour, cement ingredients, and potash.

The tank can be loaded two ways. Most often, they are gravity loaded through hatches at the top, but they can also be loaded through the bottom using the pneumatic system.

The pneumatic system works like a giant vacuum cleaner. It adds air to a tank to create an area of high pressure. When a valve is opened, the high pressure air naturally moves toward an area of low pressure (the destination tank), carrying the product with it. Aerators at the bottom of the hoppers also push air into the product, creating tiny spaces between the particles so that the product can flow efficiently. This same process can be used to load from a rail car or other tanks.

Some trucks are equipped with pumps while others rely on pumps at the unloading facility.

Pneumatic tankers come in several styles that operate in a similar manner. They all have some sort of hopper shape with a "product pipe" attached to the bottom of the hopper(s). The product pipe carries the product to its destination.

Watch a trucker explain the unloading process with only one PG word in a ten minute video below.

Image: Dave Swift

Image: Dave Swift

Ford Used to be a Player in the Big Truck Market

Now for a nostalgic break:

Ford used to build lots of Heavy Duty Class 8 and Class 9 trucks. Having started building big rigs in the late nineteen-forties. They generally followed industry design trends, building lots of cabovers in the 70's and culminating with the slippery AeroMax in the 90's. 

The Big Truck era ended when Ford sold the truck division to Freightliner in 1997. Freightliner would build the Ford designs for several years, badging them as Sterling trucks. 

Ford C-Series (1957 - 1990) Drawing credit: David Swift

Photo: Dick Coppello/Harry Patterson

A true relic by the time it retired, the C-Series was produced for more than four decades. Cosmetic changes were minimal. The most noticeable change in appearance might have been the appearance of the blue oval logo in place of the F O R D text and the old cog-and-lightning emblem.

Ford Aeromax (1988 - 1995)

The Aeromax was Ford's entry into the modern era. Following Kenworth's lead, Ford focused on aerodynamics to improve fuel efficiency. The Aeromax was based on the L-Series "Louisville" trucks (not covered here)

Ford W-Series (1966 - 1977)

Back in the day (before 1982) cabovers were necessary to comply with length limits. The STAA law did away with overall length limits, allowing conventional tractors to pull the long (53') trailers on most important highways. The W series was Fords entry for a decade before being replaced by the CL Series.

Detachable Gooseneck Trailers "Lowboys"

 

I was out on my mountain bike last Friday when I came across a lowboy carrying a, um, is that a well drilling rig? If you aren't familiar with these trailers, you might wonder how they could possibly get that thing on and off of the trailer.

You'll notice that the cargo is parked in a low spot between the rear axles of the truck and the trailer axles...hence the name lowboy. If you're asking why they don't just make the trailer higher so that the whole thing is flat, you might want to visit 11foot8.com for some clues. 

Trucks in most states are limited to 13.5' or 14' in height, so finding a way to take 18" off of the deck height allows you to haul more types of loads and fit under more bridges, signs and other overhead obstacles.

But that lower deck leads to a new problem. How to get equipment on and off? Enter the hero of our story, the detachable gooseneck trailer. These trailers are built with a hydraulic system behind the tractor's rear axles that allows the front of the trailer deck to be lowered to the ground. The portion of the trailer in front of the deck can be decoupled and the truck can be moved away leaving the trailer looking much like a ramp. Now equipment can be driven on or off relatively easily.

Reefers, Traffic, and Detective Work

Moving Trucks, Bedbuggers and Drop Frame Trailers

As a kid, one of my favorite trucks to see was a Mayflower moving van. I'm not sure why it attracted my attention. It may have been the forest green, yellow and red color scheme, the connection to Squanto or the romance of adventure at sea, but I think it was something more simple. These trucks look absolutely massive from the side because of their construction.

Drop frame moving van at warehouse loading dock. Image Credit David Swift

The name given to this class of trailers is "drop frame". The inside floor of the trailer drops behind the semi tires to increase the interior volume and decrease the height of the floor to make hand loading easier.

Moving vans make extensive use of E track, a system of metal channels with slots to secure the cargo, build partitions to separate customer's possessions and build decks to add a "second story" to the inside of the trailer. Protective blankets, decking beams and sheets of plywood can all be stored in belly boxes beneath the load floor. Most trailers have to be unloaded from back to front, but many moving vans have side doors to allow any part of the truck to be loaded or unloaded at any time.

Not everyone wants to be a moving van driver. It's more physically demanding than many other truck driving jobs because you actually need to help with the move. Other truckers call moving vans "bedbuggers". The upside is that many bedbuggers are equipped with an LCS. A Large Custom Sleeper is much larger than the sleepers on most semi trucks. It's like having a small motorhome attached to a 53 foot trailer. It is possible to use LCS's because moving vans tend to be loaded less heavily than other trucks.

Many moving vans have LCS's (Large Custom Sleepers)

Moving vans aren't the only type of trailer that uses drop frame construction. Look for future posts about exhibit trailers, enclosed auto carriers and electronics vans.

What's with the different types of wheels?

Our cars and trucks have all different kinds of wheels. The wheels on personal cars are often a fashion statement. If it's not the owner's style, it's the car designer's style.

Commercial truck wheels are all about function. Sure, you might see some polished aluminum wheels with spike shaped lugnuts, but most truck wheels are all about practicality.

The first thing you've probably noticed is that the front wheels look different from the rear wheels. That difference isn't so much the wheels themselves, but the way they are mounted. All of the wheels that are mounted next to the truck frame have the convex side mounted outward. This allows room for brake hardware on the inboard side. In the rear of the truck, a second tire is mounted on the same axle, this time, with the concave side facing out. This allows for shorter studs (bolts), a stronger arrangement.

A second visible difference has roots in technology, tradition, and thievery.

Most modern trucks have pilot style wheels. They look much like a basic car wheel with some holes around the edges and some bolts near the center. They are removed in one piece with the tire attached to the wheel.

Dayton or "spoke" style wheels are the older style. With this style, the tire and the outer rim are removed while the center star-shaped portion stays attached to the axle. The primary advantages of this style is that they are lighter weight and they require lower torque to install and remove. Roadside tire changes are much easier.

The other advantage to Dayton wheels is that they are incompatible with pilot wheels. That's why you see them on intermodal container chassis. A dishonest truck owner can't easily steal new tires from the trailer and install them on their truck.

Dayton wheels were more popular longer on East Coast than they were out west.

The third difference we sill learn about is more difficult to see.

There are two types of pilot wheels: Stud pilot or Budd (the earlier technology) and Hub pilot. Stud pilot wheels are lined up (piloted) on the wheel studs (you might think of them as bolts). The lug nuts have a cone shape where they contact the wheel. Hub pilot wheels, the new and more common style, have washers under the lugnuts. The washers make the lugnuts appear a little larger in diameter.


In another post, I will address steel vs. aluminum, super singles, and rotational weight. Did I miss anything? Please let me know in the comments below.

Chip Trucks

I grew up in a mill town. Cottage Grove, Oregon marks the southern end of the Willamette Valley (You may remember from history class that that's where the Oregon Trail ended). With a population of about seven thousand people, and surrounded by mountains and forests, There were at least six lumber mills in the immediate area.

I was fascinated by the trucks.

My dad was a third grade teacher in Drain, a tiny town nestled in the mountains a few miles south of our home. He would carpool to work with some of his coworkers, navigating the narrow, twisty and usually wet road that connected the two towns. One day, when I was about six, he saw a wreck.

He said that a chip truck had overturned on a corner and spilled its load. I was appalled, thinking of the bags of Doritos and Lays going to waste there in the ditch. My brothers and I asked if he'd managed to grab any.

As it turns out, a chip truck hauls wood chips. As wigwam burners were phased out and markets developed for wood by-products, there was a need to move sawdust, planer chips and hog fuel between locations.

Sometimes referred to as "possum-bellied", the shape of the trailer maximizes the amount of chips that will fit into the trailer and also helps to keep the center of gravity a bit lower.  These trucks are still prone to overturning.

Loading is done using overhead bins.

 Unloading is exciting, although the driver doesn't get to stay in the truck.

Log Trucks

It wasn't until my freshman year of college that I saw a flatbed trailer equipped with bunks transporting logs. I was travelling from LeTourneau College to a cross country meet at Stephen F. Austin University in Nacodoches, Texas.

The mills we passed looked strange. No towering stockpiles of logs equipped with sprinklers to maintain moisture content. Not everything is bigger in Texas after all. There were no huge log loaders splashing through Texas-sized puddles and it didn't smell like damp Douglas Fir bark. Worst of all, the log trucks were all wrong--for Oregon and Washington and other mountainous states.


Driving a log truck in one of these mountainous regions requires guts, skill and something other than a traditional fifth wheel setup. Steep gravel roads, switchbacks, narrow landslide prone double track goat trails, often on the edge of steep canyons that can be hundreds of feet deep.

It is very important that the wheels on the trailer follow the path taken by the truck. Enter the stinger steered pole trailer.